SyntaxFix

Programs & Examples On #Websocket

WebSocket is an API built on top of TCP sockets and a protocol for bi-directional, full-duplex communication between client and server without the overhead of HTTP.

Failed: Error in connection establishment: net::ERR_CONNECTION_REFUSED

CONNECTION_REFUSED is standard when the port is closed, but it could be rejected because SSL is failing authentication (one of a billion reasons). Did you configure SSL with Ratchet? (Apache is bypassed) Did you try without SSL in JavaScript?

I don't think Ratchet has built-in support for SSL. But even if it does you'll want to try the ws:// protocol first; it's a lot simpler, easier to debug, and closer to telnet. Chrome or the socket service may also be generating the REFUSED error if the service doesn't support SSL (because you explicitly requested SSL).

However the refused message is likely a server side problem, (usually port closed).

WebSockets and Apache proxy : how to configure mod_proxy_wstunnel?

As of Socket.IO 1.0 (May 2014), all connections begin with an HTTP polling request (more info here). That means that in addition to forwarding WebSocket traffic, you need to forward any transport=polling HTTP requests.

The solution below should redirect all socket traffic correctly, without redirecting any other traffic.

  1. Enable the following Apache2 mods:

    sudo a2enmod proxy rewrite proxy_http proxy_wstunnel

  2. Use these settings in your *.conf file (e.g. /etc/apache2/sites-available/mysite.com.conf). I've included comments to explain each piece:

    <VirtualHost *:80>
    ServerName www.mydomain.com

    # Enable the rewrite engine
    # Requires: sudo a2enmod proxy rewrite proxy_http proxy_wstunnel
    # In the rules/conds, [NC] means case-insensitve, [P] means proxy
    RewriteEngine On

    # socket.io 1.0+ starts all connections with an HTTP polling request
    RewriteCond %{QUERY_STRING} transport=polling       [NC]
    RewriteRule /(.*)           http://localhost:3001/$1 [P]

    # When socket.io wants to initiate a WebSocket connection, it sends an
    # "upgrade: websocket" request that should be transferred to ws://
    RewriteCond %{HTTP:Upgrade} websocket               [NC]
    RewriteRule /(.*)           ws://localhost:3001/$1  [P]

    # OPTIONAL: Route all HTTP traffic at /node to port 3001
    ProxyRequests Off
    ProxyPass           /node   http://localhost:3001
    ProxyPassReverse    /node   http://localhost:3001
</VirtualHost>

  3. I've included an extra section for routing /node traffic that I find handy, see here for more info.

Connecting client to server using Socket.io

Have you tried loading the socket.io script not from a relative URL?

You're using:

<script src="socket.io/socket.io.js"></script>

And:

socket.connect('http://127.0.0.1:8080');

You should try:

<script src="http://localhost:8080/socket.io/socket.io.js"></script>

And:

socket.connect('http://localhost:8080');

Switch localhost:8080 with whatever fits your current setup.

Also, depending on your setup, you may have some issues communicating to the server when loading the client page from a different domain (same-origin policy). This can be overcome in different ways (outside of the scope of this answer, google/SO it).

How to create websockets server in PHP

Need to convert the the key from hex to dec before base64_encoding and then send it for handshake.

$hashedKey = sha1($key. "258EAFA5-E914-47DA-95CA-C5AB0DC85B11",true);

$rawToken = "";
    for ($i = 0; $i < 20; $i++) {
      $rawToken .= chr(hexdec(substr($hashedKey,$i*2, 2)));
    }
$handshakeToken = base64_encode($rawToken) . "\r\n";

$handshakeResponse = "HTTP/1.1 101 Switching Protocols\r\nUpgrade: websocket\r\nConnection: Upgrade\r\nSec-WebSocket-Accept: $handshakeToken\r\n";

How to use Tomcat 8 in Eclipse?

The latest version of Springsource STS (3.6) supports Tomcat 8. It is based on eclipse Luna 4.4 and supports Java 8. Have at it!

Good beginners tutorial to socket.io?

To start with Socket.IO I suggest you read first the example on the main page:

http://socket.io/

On the server side, read the "How to use" on the GitHub source page:

https://github.com/Automattic/socket.io

And on the client side:

https://github.com/Automattic/socket.io-client

Finally you need to read this great tutorial:

http://howtonode.org/websockets-socketio

Hint: At the end of this blog post, you will have some links pointing on source code that could be some help.

What are Long-Polling, Websockets, Server-Sent Events (SSE) and Comet?

You can easily use Node.JS in your web app only for real-time communication. Node.JS is really powerful when it's about WebSockets. Therefore "PHP Notifications via Node.js" would be a great concept.

See this example: Creating a Real-Time Chat App with PHP and Node.js

javax.websocket client simple example

Use this library org.java_websocket

First thing you should import that library in build.gradle

repositories {
 mavenCentral()
 }

then add the implementation in dependency{}

implementation "org.java-websocket:Java-WebSocket:1.3.0"

Then you can use this code

In your activity declare object for Websocketclient like

private WebSocketClient mWebSocketClient;

then add this method for callback

 private void ConnectToWebSocket() {
URI uri;
try {
    uri = new URI("ws://your web socket url");
} catch (URISyntaxException e) {
    e.printStackTrace();
    return;
}

mWebSocketClient = new WebSocketClient(uri) {
    @Override
    public void onOpen(ServerHandshake serverHandshake) {
        Log.i("Websocket", "Opened");
        mWebSocketClient.send("Hello from " + Build.MANUFACTURER + " " + Build.MODEL);
    }

    @Override
    public void onMessage(String s) {
        final String message = s;
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                TextView textView = (TextView)findViewById(R.id.edittext_chatbox);
                textView.setText(textView.getText() + "\n" + message);
            }
        });
    }

    @Override
    public void onClose(int i, String s, boolean b) {
        Log.i("Websocket", "Closed " + s);
    }

    @Override
    public void onError(Exception e) {
        Log.i("Websocket", "Error " + e.getMessage());
    }
};
mWebSocketClient.connect();

}

What browsers support HTML5 WebSocket API?

Client side

  • Hixie-75:
    • Chrome 4.0 + 5.0
    • Safari 5.0.0
  • HyBi-00/Hixie-76:
  • HyBi-07+:
  • HyBi-10:
    • Chrome 14.0 + 15.0
    • Firefox 7.0 + 8.0 + 9.0 + 10.0 - prefixed: MozWebSocket
    • IE 10 (from Windows 8 developer preview)
  • HyBi-17/RFC 6455
    • Chrome 16
    • Firefox 11
    • Opera 12.10 / Opera Mobile 12.1

Any browser with Flash can support WebSocket using the web-socket-js shim/polyfill.

See caniuse for the current status of WebSockets support in desktop and mobile browsers.

See the test reports from the WS testsuite included in Autobahn WebSockets for feature/protocol conformance tests.

Server side

It depends on which language you use.

In Java/Java EE:

Some other Java implementations:

In C#:

In PHP:

In Python:

In C:

In Node.js:

  • Socket.io : Socket.io also has serverside ports for Python, Java, Google GO, Rack
  • sockjs : sockjs also has serverside ports for Python, Java, Erlang and Lua
  • WebSocket-Node - Pure JavaScript Client & Server implementation of HyBi-10.

Vert.x (also known as Node.x) : A node like polyglot implementation running on a Java 7 JVM and based on Netty with :

  • Support for Ruby(JRuby), Java, Groovy, Javascript(Rhino/Nashorn), Scala, ...
  • True threading. (unlike Node.js)
  • Understands multiple network protocols out of the box including: TCP, SSL, UDP, HTTP, HTTPS, Websockets, SockJS as fallback for WebSockets

Pusher.com is a Websocket cloud service accessible through a REST API.

DotCloud cloud platform supports Websockets, and Java (Jetty Servlet Container), NodeJS, Python, Ruby, PHP and Perl programming languages.

Openshift cloud platform supports websockets, and Java (Jboss, Spring, Tomcat & Vertx), PHP (ZendServer & CodeIgniter), Ruby (ROR), Node.js, Python (Django & Flask) plateforms.

For other language implementations, see the Wikipedia article for more information.

The RFC for Websockets : RFC6455

Difference between socket and websocket?

To answer your questions.

  1. Even though they achieve (in general) similar things, yes, they are really different. WebSockets typically run from browsers connecting to Application Server over a protocol similar to HTTP that runs over TCP/IP. So they are primarily for Web Applications that require a permanent connection to its server. On the other hand, plain sockets are more powerful and generic. They run over TCP/IP but they are not restricted to browsers or HTTP protocol. They could be used to implement any kind of communication.
  2. No. There is no reason.

How can I get the sha1 hash of a string in node.js?

See the crypto.createHash() function and the associated hash.update() and hash.digest() functions:

var crypto = require('crypto')
var shasum = crypto.createHash('sha1')
shasum.update('foo')
shasum.digest('hex') // => "0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33"

WebRTC vs Websockets: If WebRTC can do Video, Audio, and Data, why do I need Websockets?

Websockets use TCP protocol.

WebRTC is mainly UDP.

Thus main reason of using WebRTC instead of Websocket is latency. With websocket streaming you will have either high latency or choppy playback with low latency. With WebRTC you may achive low-latency and smooth playback which is crucial stuff for VoIP communications.

Just try to test these technology with a network loss, i.e. 2%. You will see high delays in the Websocket stream.

Maximum concurrent Socket.IO connections

I tried to use socket.io on AWS, I can at most keep around 600 connections stable.

And I found out it is because socket.io used long polling first and upgraded to websocket later.

after I set the config to use websocket only, I can keep around 9000 connections.

Set this config at client side:

const socket = require('socket.io-client')
const conn = socket(host, { upgrade: false, transports: ['websocket'] })

Differences between TCP sockets and web sockets, one more time

When you send bytes from a buffer with a normal TCP socket, the send function returns the number of bytes of the buffer that were sent. If it is a non-blocking socket or a non-blocking send then the number of bytes sent may be less than the size of the buffer. If it is a blocking socket or blocking send, then the number returned will match the size of the buffer but the call may block. With WebSockets, the data that is passed to the send method is always either sent as a whole "message" or not at all. Also, browser WebSocket implementations do not block on the send call.

But there are more important differences on the receiving side of things. When the receiver does a recv (or read) on a TCP socket, there is no guarantee that the number of bytes returned corresponds to a single send (or write) on the sender side. It might be the same, it may be less (or zero) and it might even be more (in which case bytes from multiple send/writes are received). With WebSockets, the recipient of a message is event-driven (you generally register a message handler routine), and the data in the event is always the entire message that the other side sent.

Note that you can do message based communication using TCP sockets, but you need some extra layer/encapsulation that is adding framing/message boundary data to the messages so that the original messages can be re-assembled from the pieces. In fact, WebSockets is built on normal TCP sockets and uses frame headers that contains the size of each frame and indicate which frames are part of a message. The WebSocket API re-assembles the TCP chunks of data into frames which are assembled into messages before invoking the message event handler once per message.

websocket closing connection automatically

You can actually set the timeout interval at the Jetty server side configuration using the WebSocketServletFactory instance. For example:

WebSocketHandler wsHandler = new WebSocketHandler() {
    @Override
    public void configure(WebSocketServletFactory factory) {
        factory.getPolicy().setIdleTimeout(1500);
        factory.register(MyWebSocketAdapter.class);
        ...
    }
}

Setting up a websocket on Apache?

I can't answer all questions, but I will do my best.

As you already know, WS is only a persistent full-duplex TCP connection with framed messages where the initial handshaking is HTTP-like. You need some server that's listening for incoming WS requests and that binds a handler to them.

Now it might be possible with Apache HTTP Server, and I've seen some examples, but there's no official support and it gets complicated. What would Apache do? Where would be your handler? There's a module that forwards incoming WS requests to an external shared library, but this is not necessary with the other great tools to work with WS.

WS server trends now include: Autobahn (Python) and Socket.IO (Node.js = JavaScript on the server). The latter also supports other hackish "persistent" connections like long polling and all the COMET stuff. There are other little known WS server frameworks like Ratchet (PHP, if you're only familiar with that).

In any case, you will need to listen on a port, and of course that port cannot be the same as the Apache HTTP Server already running on your machine (default = 80). You could use something like 8080, but even if this particular one is a popular choice, some firewalls might still block it since it's not supposed to be Web traffic. This is why many people choose 443, which is the HTTP Secure port that, for obvious reasons, firewalls do not block. If you're not using SSL, you can use 80 for HTTP and 443 for WS. The WS server doesn't need to be secure; we're just using the port.

Edit: According to Iharob Al Asimi, the previous paragraph is wrong. I have no time to investigate this, so please see his work for more details.

About the protocol, as Wikipedia shows, it looks like this:

Client sends:

GET /mychat HTTP/1.1
Host: server.example.com
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Key: x3JJHMbDL1EzLkh9GBhXDw==
Sec-WebSocket-Protocol: chat
Sec-WebSocket-Version: 13
Origin: http://example.com

Server replies:

HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: HSmrc0sMlYUkAGmm5OPpG2HaGWk=
Sec-WebSocket-Protocol: chat

and keeps the connection alive. If you can implement this handshaking and the basic message framing (encapsulating each message with a small header describing it), then you can use any client-side language you want. JavaScript is only used in Web browsers because it's built-in.

As you can see, the default "request method" is an initial HTTP GET, although this is not really HTTP and looses everything in common with HTTP after this handshaking. I guess servers that do not support

Upgrade: websocket
Connection: Upgrade

will reply with an error or with a page content.

WebSocket with SSL

To support the answer by @oberstet, if the cert is not trusted by the browser (for example you get a "this site is not secure, do you want to continue?") one solution is to open the browser options, navigate to the certificates settings and add the host and post that the websocket server is being served from to the certificate provider as an exception.

for example add 'example-wss-domain.org:6001' as an exception to 'Certificate Provider Ltd'.

In firefox, this can be done from 'about:preferences' and searching for 'Certificates'

Send message to specific client with socket.io and node.js

Also you can keep clients refferences. But this makes your memmory busy.

Create an empty object and set your clients into it.

const myClientList = {};

  server.on("connection", (socket) => {
    console.info(`Client connected [id=${socket.id}]`);
     myClientList[socket.id] = socket;   
  });
  socket.on("disconnect", (socket) => {
    delete myClientList[socket.id];
  });

then call your specific client by id from the object

myClientList[specificId].emit("blabla","somedata");

node.js, socket.io with SSL

For enterprise applications it should be noted that you should not be handling https in your code. It should be auto upgraded via IIS or nginx. The app shouldn't know about what protocols are used.

WebSockets vs. Server-Sent events/EventSource

Websockets and SSE (Server Sent Events) are both capable of pushing data to browsers, however they are not competing technologies.

Websockets connections can both send data to the browser and receive data from the browser. A good example of an application that could use websockets is a chat application.

SSE connections can only push data to the browser. Online stock quotes, or twitters updating timeline or feed are good examples of an application that could benefit from SSE.

In practice since everything that can be done with SSE can also be done with Websockets, Websockets is getting a lot more attention and love, and many more browsers support Websockets than SSE.

However, it can be overkill for some types of application, and the backend could be easier to implement with a protocol such as SSE.

Furthermore SSE can be polyfilled into older browsers that do not support it natively using just JavaScript. Some implementations of SSE polyfills can be found on the Modernizr github page.

Gotchas:

  • SSE suffers from a limitation to the maximum number of open connections, which can be specially painful when opening various tabs as the limit is per browser and set to a very low number (6). The issue has been marked as "Won't fix" in Chrome and Firefox. This limit is per browser + domain, so that means that you can open 6 SSE connections across all of the tabs to www.example1.com and another 6 SSE connections to www.example2.com (thanks Phate).
  • Only WS can transmit both binary data and UTF-8, SSE is limited to UTF-8. (Thanks to Chado Nihi).
  • Some enterprise firewalls with packet inspection have trouble dealing with WebSockets (Sophos XG Firewall, WatchGuard, McAfee Web Gateway).

HTML5Rocks has some good information on SSE. From that page:

Server-Sent Events vs. WebSockets

Why would you choose Server-Sent Events over WebSockets? Good question.

One reason SSEs have been kept in the shadow is because later APIs like WebSockets provide a richer protocol to perform bi-directional, full-duplex communication. Having a two-way channel is more attractive for things like games, messaging apps, and for cases where you need near real-time updates in both directions. However, in some scenarios data doesn't need to be sent from the client. You simply need updates from some server action. A few examples would be friends' status updates, stock tickers, news feeds, or other automated data push mechanisms (e.g. updating a client-side Web SQL Database or IndexedDB object store). If you'll need to send data to a server, XMLHttpRequest is always a friend.

SSEs are sent over traditional HTTP. That means they do not require a special protocol or server implementation to get working. WebSockets on the other hand, require full-duplex connections and new Web Socket servers to handle the protocol. In addition, Server-Sent Events have a variety of features that WebSockets lack by design such as automatic reconnection, event IDs, and the ability to send arbitrary events.

TLDR summary:

Advantages of SSE over Websockets:

  • Transported over simple HTTP instead of a custom protocol
  • Can be poly-filled with javascript to "backport" SSE to browsers that do not support it yet.
  • Built in support for re-connection and event-id
  • Simpler protocol
  • No trouble with corporate firewalls doing packet inspection

Advantages of Websockets over SSE:

  • Real time, two directional communication.
  • Native support in more browsers

Ideal use cases of SSE:

  • Stock ticker streaming
  • twitter feed updating
  • Notifications to browser

SSE gotchas:

  • No binary support
  • Maximum open connections limit

How to make cross domain request

If you're willing to transmit some data and that you don't need to be secured (any public infos) you can use a CORS proxy, it's very easy, you'll not have to change anything in your code or in server side (especially of it's not your server like the Yahoo API or OpenWeather). I've used it to fetch JSON files with an XMLHttpRequest and it worked fine.

getting the reason why websockets closed with close code 1006

In my and possibly @BIOHAZARD case it was nginx proxy timeout. In default it's 60 sec without activity in socket

I changed it to 24h in nginx and it resolved problem

proxy_read_timeout 86400s;
proxy_send_timeout 86400s;

Websocket onerror - how to read error description?

Alongside nmaier's answer, as he said you'll always receive code 1006. However, if you were to somehow theoretically receive other codes, here is code to display the results (via RFC6455).

you will almost never get these codes in practice so this code is pretty much pointless

var websocket;
if ("WebSocket" in window)
{
    websocket = new WebSocket("ws://yourDomainNameHere.org/");

    websocket.onopen = function (event) {
        $("#thingsThatHappened").html($("#thingsThatHappened").html() + "<br />" + "The connection was opened");
    };
    websocket.onclose = function (event) {
        var reason;
        alert(event.code);
        // See http://tools.ietf.org/html/rfc6455#section-7.4.1
        if (event.code == 1000)
            reason = "Normal closure, meaning that the purpose for which the connection was established has been fulfilled.";
        else if(event.code == 1001)
            reason = "An endpoint is \"going away\", such as a server going down or a browser having navigated away from a page.";
        else if(event.code == 1002)
            reason = "An endpoint is terminating the connection due to a protocol error";
        else if(event.code == 1003)
            reason = "An endpoint is terminating the connection because it has received a type of data it cannot accept (e.g., an endpoint that understands only text data MAY send this if it receives a binary message).";
        else if(event.code == 1004)
            reason = "Reserved. The specific meaning might be defined in the future.";
        else if(event.code == 1005)
            reason = "No status code was actually present.";
        else if(event.code == 1006)
           reason = "The connection was closed abnormally, e.g., without sending or receiving a Close control frame";
        else if(event.code == 1007)
            reason = "An endpoint is terminating the connection because it has received data within a message that was not consistent with the type of the message (e.g., non-UTF-8 [http://tools.ietf.org/html/rfc3629] data within a text message).";
        else if(event.code == 1008)
            reason = "An endpoint is terminating the connection because it has received a message that \"violates its policy\". This reason is given either if there is no other sutible reason, or if there is a need to hide specific details about the policy.";
        else if(event.code == 1009)
           reason = "An endpoint is terminating the connection because it has received a message that is too big for it to process.";
        else if(event.code == 1010) // Note that this status code is not used by the server, because it can fail the WebSocket handshake instead.
            reason = "An endpoint (client) is terminating the connection because it has expected the server to negotiate one or more extension, but the server didn't return them in the response message of the WebSocket handshake. <br /> Specifically, the extensions that are needed are: " + event.reason;
        else if(event.code == 1011)
            reason = "A server is terminating the connection because it encountered an unexpected condition that prevented it from fulfilling the request.";
        else if(event.code == 1015)
            reason = "The connection was closed due to a failure to perform a TLS handshake (e.g., the server certificate can't be verified).";
        else
            reason = "Unknown reason";

        $("#thingsThatHappened").html($("#thingsThatHappened").html() + "<br />" + "The connection was closed for reason: " + reason);
    };
    websocket.onmessage = function (event) {
        $("#thingsThatHappened").html($("#thingsThatHappened").html() + "<br />" + "New message arrived: " + event.data);
    };
    websocket.onerror = function (event) {
        $("#thingsThatHappened").html($("#thingsThatHappened").html() + "<br />" + "There was an error with your websocket.");
    };
}
else
{
    alert("Websocket is not supported by your browser");
    return;
}

websocket.send("Yo wazzup");

websocket.close();

See http://jsfiddle.net/gr0bhrqr/

websocket.send() parameter

As I understand it, you want the server be able to send messages through from client 1 to client 2. You cannot directly connect two clients because one of the two ends of a WebSocket connection needs to be a server.

This is some pseudocodish JavaScript:

Client:

var websocket = new WebSocket("server address");

websocket.onmessage = function(str) {
  console.log("Someone sent: ", str);
};

// Tell the server this is client 1 (swap for client 2 of course)
websocket.send(JSON.stringify({
  id: "client1"
}));

// Tell the server we want to send something to the other client
websocket.send(JSON.stringify({
  to: "client2",
  data: "foo"
}));

Server:

var clients = {};

server.on("data", function(client, str) {
  var obj = JSON.parse(str);

  if("id" in obj) {
    // New client, add it to the id/client object
    clients[obj.id] = client;
  } else {
    // Send data to the client requested
    clients[obj.to].send(obj.data);
  }
});

Sending websocket ping/pong frame from browser

There is no Javascript API to send ping frames or receive pong frames. This is either supported by your browser, or not. There is also no API to enable, configure or detect whether the browser supports and is using ping/pong frames. There was discussion about creating a Javascript ping/pong API for this. There is a possibility that pings may be configurable/detectable in the future, but it is unlikely that Javascript will be able to directly send and receive ping/pong frames.

However, if you control both the client and server code, then you can easily add ping/pong support at a higher level. You will need some sort of message type header/metadata in your message if you don't have that already, but that's pretty simple. Unless you are planning on sending pings hundreds of times per second or have thousands of simultaneous clients, the overhead is going to be pretty minimal to do it yourself.

Closing WebSocket correctly (HTML5, Javascript)

According to the protocol spec v76 (which is the version that browser with current support implement):

To close the connection cleanly, a frame consisting of just a 0xFF byte followed by a 0x00 byte is sent from one peer to ask that the other peer close the connection.

If you are writing a server, you should make sure to send a close frame when the server closes a client connection. The normal TCP socket close method can sometimes be slow and cause applications to think the connection is still open even when it's not.

The browser should really do this for you when you close or reload the page. However, you can make sure a close frame is sent by doing capturing the beforeunload event:

window.onbeforeunload = function() {
    websocket.onclose = function () {}; // disable onclose handler first
    websocket.close();
};

I'm not sure how you can be getting an onclose event after the page is refreshed. The websocket object (with the onclose handler) will no longer exist once the page reloads. If you are immediately trying to establish a WebSocket connection on your page as the page loads, then you may be running into an issue where the server is refusing a new connection so soon after the old one has disconnected (or the browser isn't ready to make connections at the point you are trying to connect) and you are getting an onclose event for the new websocket object.

HTTP headers in Websockets client API

More of an alternate solution, but all modern browsers send the domain cookies along with the connection, so using:

var authToken = 'R3YKZFKBVi';

document.cookie = 'X-Authorization=' + authToken + '; path=/';

var ws = new WebSocket(
    'wss://localhost:9000/wss/'
);

End up with the request connection headers:

Cookie: X-Authorization=R3YKZFKBVi

Creating a "Hello World" WebSocket example

I couldnt find a simple working example anywhere (as of Jan 19), so here is an updated version. I have chrome version 71.0.3578.98.

C# Websocket server : 

using System;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Security.Cryptography;

namespace WebSocketServer
{
    class Program
    {
    static Socket serverSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
    static private string guid = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";

    static void Main(string[] args)
    {
        serverSocket.Bind(new IPEndPoint(IPAddress.Any, 8080));
        serverSocket.Listen(1); //just one socket
        serverSocket.BeginAccept(null, 0, OnAccept, null);
        Console.Read();
    }

    private static void OnAccept(IAsyncResult result)
    {
        byte[] buffer = new byte[1024];
        try
        {
            Socket client = null;
            string headerResponse = "";
            if (serverSocket != null && serverSocket.IsBound)
            {
                client = serverSocket.EndAccept(result);
                var i = client.Receive(buffer);
                headerResponse = (System.Text.Encoding.UTF8.GetString(buffer)).Substring(0, i);
                // write received data to the console
                Console.WriteLine(headerResponse);
                Console.WriteLine("=====================");
            }
            if (client != null)
            {
                /* Handshaking and managing ClientSocket */
                var key = headerResponse.Replace("ey:", "`")
                          .Split('`')[1]                     // dGhlIHNhbXBsZSBub25jZQ== \r\n .......
                          .Replace("\r", "").Split('\n')[0]  // dGhlIHNhbXBsZSBub25jZQ==
                          .Trim();

                // key should now equal dGhlIHNhbXBsZSBub25jZQ==
                var test1 = AcceptKey(ref key);

                var newLine = "\r\n";

                var response = "HTTP/1.1 101 Switching Protocols" + newLine
                     + "Upgrade: websocket" + newLine
                     + "Connection: Upgrade" + newLine
                     + "Sec-WebSocket-Accept: " + test1 + newLine + newLine
                     //+ "Sec-WebSocket-Protocol: chat, superchat" + newLine
                     //+ "Sec-WebSocket-Version: 13" + newLine
                     ;

                client.Send(System.Text.Encoding.UTF8.GetBytes(response));
                var i = client.Receive(buffer); // wait for client to send a message
                string browserSent = GetDecodedData(buffer, i);
                Console.WriteLine("BrowserSent: " + browserSent);

                Console.WriteLine("=====================");
                //now send message to client
                client.Send(GetFrameFromString("This is message from server to client."));
                System.Threading.Thread.Sleep(10000);//wait for message to be sent
            }
        }
        catch (SocketException exception)
        {
            throw exception;
        }
        finally
        {
            if (serverSocket != null && serverSocket.IsBound)
            {
                serverSocket.BeginAccept(null, 0, OnAccept, null);
            }
        }
    }

    public static T[] SubArray<T>(T[] data, int index, int length)
    {
        T[] result = new T[length];
        Array.Copy(data, index, result, 0, length);
        return result;
    }

    private static string AcceptKey(ref string key)
    {
        string longKey = key + guid;
        byte[] hashBytes = ComputeHash(longKey);
        return Convert.ToBase64String(hashBytes);
    }

    static SHA1 sha1 = SHA1CryptoServiceProvider.Create();
    private static byte[] ComputeHash(string str)
    {
        return sha1.ComputeHash(System.Text.Encoding.ASCII.GetBytes(str));
    }

    //Needed to decode frame
    public static string GetDecodedData(byte[] buffer, int length)
    {
        byte b = buffer[1];
        int dataLength = 0;
        int totalLength = 0;
        int keyIndex = 0;

        if (b - 128 <= 125)
        {
            dataLength = b - 128;
            keyIndex = 2;
            totalLength = dataLength + 6;
        }

        if (b - 128 == 126)
        {
            dataLength = BitConverter.ToInt16(new byte[] { buffer[3], buffer[2] }, 0);
            keyIndex = 4;
            totalLength = dataLength + 8;
        }

        if (b - 128 == 127)
        {
            dataLength = (int)BitConverter.ToInt64(new byte[] { buffer[9], buffer[8], buffer[7], buffer[6], buffer[5], buffer[4], buffer[3], buffer[2] }, 0);
            keyIndex = 10;
            totalLength = dataLength + 14;
        }

        if (totalLength > length)
            throw new Exception("The buffer length is small than the data length");

        byte[] key = new byte[] { buffer[keyIndex], buffer[keyIndex + 1], buffer[keyIndex + 2], buffer[keyIndex + 3] };

        int dataIndex = keyIndex + 4;
        int count = 0;
        for (int i = dataIndex; i < totalLength; i++)
        {
            buffer[i] = (byte)(buffer[i] ^ key[count % 4]);
            count++;
        }

        return Encoding.ASCII.GetString(buffer, dataIndex, dataLength);
    }

    //function to create  frames to send to client 
    /// <summary>
    /// Enum for opcode types
    /// </summary>
    public enum EOpcodeType
    {
        /* Denotes a continuation code */
        Fragment = 0,

        /* Denotes a text code */
        Text = 1,

        /* Denotes a binary code */
        Binary = 2,

        /* Denotes a closed connection */
        ClosedConnection = 8,

        /* Denotes a ping*/
        Ping = 9,

        /* Denotes a pong */
        Pong = 10
    }

    /// <summary>Gets an encoded websocket frame to send to a client from a string</summary>
    /// <param name="Message">The message to encode into the frame</param>
    /// <param name="Opcode">The opcode of the frame</param>
    /// <returns>Byte array in form of a websocket frame</returns>
    public static byte[] GetFrameFromString(string Message, EOpcodeType Opcode = EOpcodeType.Text)
    {
        byte[] response;
        byte[] bytesRaw = Encoding.Default.GetBytes(Message);
        byte[] frame = new byte[10];

        int indexStartRawData = -1;
        int length = bytesRaw.Length;

        frame[0] = (byte)(128 + (int)Opcode);
        if (length <= 125)
        {
            frame[1] = (byte)length;
            indexStartRawData = 2;
        }
        else if (length >= 126 && length <= 65535)
        {
            frame[1] = (byte)126;
            frame[2] = (byte)((length >> 8) & 255);
            frame[3] = (byte)(length & 255);
            indexStartRawData = 4;
        }
        else
        {
            frame[1] = (byte)127;
            frame[2] = (byte)((length >> 56) & 255);
            frame[3] = (byte)((length >> 48) & 255);
            frame[4] = (byte)((length >> 40) & 255);
            frame[5] = (byte)((length >> 32) & 255);
            frame[6] = (byte)((length >> 24) & 255);
            frame[7] = (byte)((length >> 16) & 255);
            frame[8] = (byte)((length >> 8) & 255);
            frame[9] = (byte)(length & 255);

            indexStartRawData = 10;
        }

        response = new byte[indexStartRawData + length];

        int i, reponseIdx = 0;

        //Add the frame bytes to the reponse
        for (i = 0; i < indexStartRawData; i++)
        {
            response[reponseIdx] = frame[i];
            reponseIdx++;
        }

        //Add the data bytes to the response
        for (i = 0; i < length; i++)
        {
            response[reponseIdx] = bytesRaw[i];
            reponseIdx++;
        }

        return response;
    }
}
}

Client html and javascript:

_x000D_
_x000D_ 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"_x000D_
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">_x000D_
<html xmlns="http://www.w3.org/1999/xhtml">_x000D_
<head>_x000D_
    <script type="text/javascript">_x000D_
        var socket = new WebSocket('ws://localhost:8080/websession');_x000D_
        socket.onopen = function() {_x000D_
           // alert('handshake successfully established. May send data now...');_x000D_
     socket.send("Hi there from browser.");_x000D_
        };_x000D_
  socket.onmessage = function (evt) {_x000D_
                //alert("About to receive data");_x000D_
                var received_msg = evt.data;_x000D_
                alert("Message received = "+received_msg);_x000D_
            };_x000D_
        socket.onclose = function() {_x000D_
            alert('connection closed');_x000D_
        };_x000D_
    </script>_x000D_
</head>_x000D_
<body>_x000D_
</body>_x000D_
</html>
_x000D_
_x000D_
_x000D_

Which websocket library to use with Node.js?

Update: This answer is outdated as newer versions of libraries mentioned are released since then.

Socket.IO v0.9 is outdated and a bit buggy, and Engine.IO is the interim successor. Socket.IO v1.0 (which will be released soon) will use Engine.IO and be much better than v0.9. I'd recommend you to use Engine.IO until Socket.IO v1.0 is released.

"ws" does not support fallback, so if the client browser does not support websockets, it won't work, unlike Socket.IO and Engine.IO which uses long-polling etc if websockets are not available. However, "ws" seems like the fastest library at the moment.

See my article comparing Socket.IO, Engine.IO and Primus: https://medium.com/p/b63bfca0539

Differences between socket.io and websockets

Socket.IO uses WebSocket and when WebSocket is not available uses fallback algo to make real time connections.

Video streaming over websockets using JavaScript

Is WebSockets over TCP a fast enough protocol to stream a video of, say, 30fps?

Yes.. it is, take a look at this project. Websockets can easily handle HD videostreaming.. However, you should go for Adaptive Streaming. I explain here how you could implement it.

Currently we're working on a webbased instant messaging application with chat, filesharing and video/webcam support. With some bits and tricks we got streaming media through websockets (used HTML5 Media Capture to get the stream from our webcams).

You need to build a stream API and a Media Stream Transceiver to control the related media processing and transport.

Debugging WebSocket in Google Chrome

The other answers cover the most common scenario: watch the content of the frames (Developer Tools -> Network tab -> Right click on the websocket connection -> frames).

If you want to know some more informations, like which sockets are currently open/idle or be able to close them you'll find this url useful

chrome://net-internals/#sockets

WebSockets protocol vs HTTP

A regular REST API uses HTTP as the underlying protocol for communication, which follows the request and response paradigm, meaning the communication involves the client requesting some data or resource from a server, and the server responding back to that client. However, HTTP is a stateless protocol, so every request-response cycle will end up having to repeat the header and metadata information. This incurs additional latency in case of frequently repeated request-response cycles.

http

With WebSockets, although the communication still starts off as an initial HTTP handshake, it is further upgraded to follow the WebSockets protocol (i.e. if both the server and the client are compliant with the protocol as not all entities support the WebSockets protocol).

Now with WebSockets, it is possible to establish a full-duplex and persistent connection between the client and a server. This means that unlike a request and a response, the connection stays open for as long as the application is running (i.e. it’s persistent), and since it is full-duplex, two-way simultaneous communication is possible i.e now the server is capable of initiating communication and 'push' some data to the client when new data (that the client is interested in) becomes available.

websockets

The WebSockets protocol is stateful and allows you to implement the Publish-Subscribe (or Pub/Sub) messaging pattern which is the primary concept used in the real-time technologies where you are able to get new updates in the form of server push without the client having to request (refresh the page) repeatedly. Examples of such applications are Uber car's location tracking, Push Notifications, Stock market prices updating in real-time, chat, multiplayer games, live online collaboration tools, etc.

You can check out a deep dive article on Websockets which explains the history of this protocol, how it came into being, what it’s used for and how you can implement it yourself.

Here's a video from a presentation I did about WebSockets and how they are different from using the regular REST APIs: Standardisation and leveraging the exponential rise in data streaming

In what situations would AJAX long/short polling be preferred over HTML5 WebSockets?

For chat applications or any other application that is in constant conversation with the server, WebSockets are the best option. However, you can only use WebSockets with a server that supports them, so that may limit your ability to use them if you cannot install the required libraries. In which case, you would need to use Long Polling to obtain similar functionality.

Is there a WebSocket client implemented for Python?
  1. Take a look at the echo client under http://code.google.com/p/pywebsocket/ It's a Google project.
  2. A good search in github is: https://github.com/search?type=Everything&language=python&q=websocket&repo=&langOverride=&x=14&y=29&start_value=1 it returns clients and servers.
  3. Bret Taylor also implemented web sockets over Tornado (Python). His blog post at: Web Sockets in Tornado and a client implementation API is shown at tornado.websocket in the client side support section.

How to construct a WebSocket URI relative to the page URI?

easy:

location.href.replace(/^http/, 'ws') + '/to/ws'
// or if you hate regexp:
location.href.replace('http://', 'ws://').replace('https://', 'wss://') + '/to/ws'

How can I send and receive WebSocket messages on the server side?

C# Implementation

Browser -> Server

    private String DecodeMessage(Byte[] bytes)
    {
        String incomingData = String.Empty;
        Byte secondByte = bytes[1];
        Int32 dataLength = secondByte & 127;
        Int32 indexFirstMask = 2;
        if (dataLength == 126)
            indexFirstMask = 4;
        else if (dataLength == 127)
            indexFirstMask = 10;

        IEnumerable<Byte> keys = bytes.Skip(indexFirstMask).Take(4);
        Int32 indexFirstDataByte = indexFirstMask + 4;

        Byte[] decoded = new Byte[bytes.Length - indexFirstDataByte];
        for (Int32 i = indexFirstDataByte, j = 0; i < bytes.Length; i++, j++)
        {
            decoded[j] = (Byte)(bytes[i] ^ keys.ElementAt(j % 4));
        }

        return incomingData = Encoding.UTF8.GetString(decoded, 0, decoded.Length);
    }

Server -> Browser

    private static Byte[] EncodeMessageToSend(String message)
    {
        Byte[] response;
        Byte[] bytesRaw = Encoding.UTF8.GetBytes(message);
        Byte[] frame = new Byte[10];

        Int32 indexStartRawData = -1;
        Int32 length = bytesRaw.Length;

        frame[0] = (Byte)129;
        if (length <= 125)
        {
            frame[1] = (Byte)length;
            indexStartRawData = 2;
        }
        else if (length >= 126 && length <= 65535)
        {
            frame[1] = (Byte)126;
            frame[2] = (Byte)((length >> 8) & 255);
            frame[3] = (Byte)(length & 255);
            indexStartRawData = 4;
        }
        else
        {
            frame[1] = (Byte)127;
            frame[2] = (Byte)((length >> 56) & 255);
            frame[3] = (Byte)((length >> 48) & 255);
            frame[4] = (Byte)((length >> 40) & 255);
            frame[5] = (Byte)((length >> 32) & 255);
            frame[6] = (Byte)((length >> 24) & 255);
            frame[7] = (Byte)((length >> 16) & 255);
            frame[8] = (Byte)((length >> 8) & 255);
            frame[9] = (Byte)(length & 255);

            indexStartRawData = 10;
        }

        response = new Byte[indexStartRawData + length];

        Int32 i, reponseIdx = 0;

        //Add the frame bytes to the reponse
        for (i = 0; i < indexStartRawData; i++)
        {
            response[reponseIdx] = frame[i];
            reponseIdx++;
        }

        //Add the data bytes to the response
        for (i = 0; i < length; i++)
        {
            response[reponseIdx] = bytesRaw[i];
            reponseIdx++;
        }

        return response;
    }

What is the error "Every derived table must have its own alias" in MySQL?

Every derived table (AKA sub-query) must indeed have an alias. I.e. each query in brackets must be given an alias (AS whatever), which can the be used to refer to it in the rest of the outer query.

SELECT ID FROM (
    SELECT ID, msisdn FROM (
        SELECT * FROM TT2
    ) AS T
) AS T

In your case, of course, the entire query could be replaced with:

SELECT ID FROM TT2

How to concatenate two strings to build a complete path

 
#!/usr/bin/env bash

mvFiles() {
    local -a files=( file1 file2 ... ) \
             subDirs=( subDir1 subDir2 ) \
             subDirs=( "${subDirs[@]/#/$baseDir/}" )

    mkdir -p "${subDirs[@]}" || return 1

    local x
    for x in "${subDirs[@]}"; do
        cp "${files[@]}" "$x"
    done
}



main() {
    local baseDir
    [[ -t 1 ]] && echo 'Enter a path:'
    read -re baseDir
    mvFiles "$baseDir"
}

main "$@"

What is inf and nan?

Inf is infinity, it's a "bigger than all the other numbers" number. Try subtracting anything you want from it, it doesn't get any smaller. All numbers are < Inf. -Inf is similar, but smaller than everything.

NaN means not-a-number. If you try to do a computation that just doesn't make sense, you get NaN. Inf - Inf is one such computation. Usually NaN is used to just mean that some data is missing.

Difference between a script and a program?

For me, the main difference is that a script is interpreted, while a program is executed (i.e. the source is first compiled, and the result of that compilation is expected).


Wikipedia seems to agree with me on this :

Script :

"Scripts" are distinct from the core code of the application, which is usually written in a different language, and are often created or at least modified by the end-user.
Scripts are often interpreted from source code or bytecode, whereas the applications they control are traditionally compiled to native machine code.

Program :

The program has an executable form that the computer can use directly to execute the instructions.
The same program in its human-readable source code form, from which executable programs are derived (e.g., compiled)

How do I find out if the GPS of an Android device is enabled

Here is the snippet worked in my case

final LocationManager manager = (LocationManager) getSystemService(Context.LOCATION_SERVICE );
if ( !manager.isProviderEnabled( LocationManager.GPS_PROVIDER ) ) {
    buildAlertMessageNoGps();
}

`

What's the difference between event.stopPropagation and event.preventDefault?

Event.preventDefault- stops browser default behaviour. Now comes what is browser default behaviour. Assume you have a anchor tag and it has got a href attribute and this anchor tag is nested inside a div tag which has got a click event. Default behaviour of anchor tag is when clicked on the anchor tag it should navigate, but what event.preventDefault does is it stops the navigation in this case. But it never stops the bubbling of event or escalation of event i.e

<div class="container">
 <a href="#" class="element">Click Me!</a>
</div>

$('.container').on('click', function(e) {
 console.log('container was clicked');
});

$('.element').on('click', function(e) {
  e.preventDefault(); // Now link won't go anywhere
  console.log('element was clicked');
});

The result will be

"element was clicked"

"container was clicked"

Now event.StopPropation it stops bubbling of event or escalation of event. Now with above example 

$('.container').on('click', function(e) {
  console.log('container was clicked');
});

$('.element').on('click', function(e) {
  e.preventDefault(); // Now link won't go anywhere
  e.stopPropagation(); // Now the event won't bubble up
 console.log('element was clicked');
});

Result will be

"element was clicked"

For more info refer this link https://codeplanet.io/preventdefault-vs-stoppropagation-vs-stopimmediatepropagation/

Session only cookies with Javascript

Use the below code for a setup session cookie, it will work until browser close. (make sure not close tab)

function setCookie(cname, cvalue, exdays) {
    var d = new Date();
    d.setTime(d.getTime() + (exdays*24*60*60*1000));
    var expires = "expires="+ d.toUTCString();
    document.cookie = cname + "=" + cvalue + ";" + expires + ";path=/";
  }
  function getCookie(cname) {
    var name = cname + "=";
    var decodedCookie = decodeURIComponent(document.cookie);
    var ca = decodedCookie.split(';');
    for(var i = 0; i <ca.length; i++) {
      var c = ca[i];
      while (c.charAt(0) == ' ') {
        c = c.substring(1);
      }
      if (c.indexOf(name) == 0) {
        return c.substring(name.length, c.length);
      }
    }
    return false;
  }
  
  
  if(getCookie("KoiMilGaya")) {
    //alert('found'); 
    // Cookie found. Display any text like repeat user. // reload, other page visit, close tab and open again.. 
  } else {
    //alert('nothing');
    // Display popup or anthing here. it shows on first visit only.  
    // this will load again when user closer browser and open again. 
    setCookie('KoiMilGaya','1');
  }

How to create and use resources in .NET

The above method works good.

Another method (I am assuming web here) is to create your page. Add controls to the page. Then while in design mode go to: Tools > Generate Local Resource. A resource file will automatically appear in the solution with all the controls in the page mapped in the resource file.

To create resources for other languages, append the 4 character language to the end of the file name, before the extension (Account.aspx.en-US.resx, Account.aspx.es-ES.resx...etc).

To retrieve specific entries in the code-behind, simply call this method: GetLocalResourceObject([resource entry key/name]).

Understanding Spring @Autowired usage

TL;DR

The @Autowired annotation spares you the need to do the wiring by yourself in the XML file (or any other way) and just finds for you what needs to be injected where and does that for you.

Full explanation

The @Autowired annotation allows you to skip configurations elsewhere of what to inject and just does it for you. Assuming your package is com.mycompany.movies you have to put this tag in your XML (application context file):

<context:component-scan base-package="com.mycompany.movies" />

This tag will do an auto-scanning. Assuming each class that has to become a bean is annotated with a correct annotation like @Component (for simple bean) or @Controller (for a servlet control) or @Repository (for DAO classes) and these classes are somewhere under the package com.mycompany.movies, Spring will find all of these and create a bean for each one. This is done in 2 scans of the classes - the first time it just searches for classes that need to become a bean and maps the injections it needs to be doing, and on the second scan it injects the beans. Of course, you can define your beans in the more traditional XML file or with an @Configuration class (or any combination of the three).

The @Autowired annotation tells Spring where an injection needs to occur. If you put it on a method setMovieFinder it understands (by the prefix set + the @Autowired annotation) that a bean needs to be injected. In the second scan, Spring searches for a bean of type MovieFinder, and if it finds such bean, it injects it to this method. If it finds two such beans you will get an Exception. To avoid the Exception, you can use the @Qualifier annotation and tell it which of the two beans to inject in the following manner:

@Qualifier("redBean")
class Red implements Color {
   // Class code here
}

@Qualifier("blueBean")
class Blue implements Color {
   // Class code here
}

Or if you prefer to declare the beans in your XML, it would look something like this:

<bean id="redBean" class="com.mycompany.movies.Red"/>

<bean id="blueBean" class="com.mycompany.movies.Blue"/>

In the @Autowired declaration, you need to also add the @Qualifier to tell which of the two color beans to inject:

@Autowired
@Qualifier("redBean")
public void setColor(Color color) {
  this.color = color;
}

If you don't want to use two annotations (the @Autowired and @Qualifier) you can use @Resource to combine these two:

@Resource(name="redBean")
public void setColor(Color color) {
  this.color = color;
}

The @Resource (you can read some extra data about it in the first comment on this answer) spares you the use of two annotations and instead, you only use one.

I'll just add two more comments:

  1. Good practice would be to use @Inject instead of @Autowired because it is not Spring-specific and is part of the JSR-330 standard.
  2. Another good practice would be to put the @Inject / @Autowired on a constructor instead of a method. If you put it on a constructor, you can validate that the injected beans are not null and fail fast when you try to start the application and avoid a NullPointerException when you need to actually use the bean.

Update: To complete the picture, I created a new question about the @Configuration class.

How do you list volumes in docker containers?

We can do it without the -f Go template syntax:

docker inspect <CONTAINER_ID> | jq .[] | jq .Mounts[]

The first jq operation jq .[] strips the object {} wrapper.

The second jq operation will return all the Mount items.

input checkbox true or checked or yes

Only checked and checked="checked" are valid. Your other options depend on error recovery in browsers.

checked="yes" and checked="true" are particularly bad as they imply that checked="no" and checked="false" will set the default state to be unchecked … which they will not.

How to completely remove a dialog on close

 
$(dialogElement).empty();

$(dialogElement).remove();

this fixes it for real

Storing Objects in HTML5 localStorage

You cannot store key value without String Format.

LocalStorage only support String format for key/value.

That is why you should convert your data to string whatever it is Array or Object.

To Store data in localStorage first of all stringify it using JSON.stringify() method.

var myObj = [{name:"test", time:"Date 2017-02-03T08:38:04.449Z"}];
localStorage.setItem('item', JSON.stringify(myObj));

Then when you want to retrieve data , you need to parse the String to Object again.

var getObj = JSON.parse(localStorage.getItem('item'));

Hope it helps.

How to disable horizontal scrolling of UIScrollView?

Swift solution

Create two outlets, one for your view and one for your scroll view:

@IBOutlet weak var myView: UIView!
@IBOutlet weak var scrollView: UIScrollView!

Then in your viewDidLayoutSubviews you can add the following code:

let scrollSize = CGSize(width: myView.frame.size.width, 
                        height: myView.frame.size.height)
scrollView.contentSize = scrollSize

What we've done is collected the height and width of the view and set the scrollViews content size to match it. This will stop your scrollview from scrolling horizontally.

More Thoughts:

CGSizeMake takes a width & height using CGFloats. You may need to use your UIScrollViews existing height for the second parameter. Which would look like this:

let scrollSize = CGSize(width: myView.frame.size.width, 
                        height: scrollView.contentSize.height)

Opening XML page shows "This XML file does not appear to have any style information associated with it."

This XML file does not appear to have any style information associated with it. The document tree is shown below.

You will get this error in the client side when the client (the webbrowser) for some reason interprets the HTTP response content as text/xml instead of text/html and the parsed XML tree doesn't have any XML-stylesheet. In other words, the webbrowser incorrectly parsed the retrieved HTTP response content as XML instead of as HTML due to the wrong or missing HTTP response content type.

In case of JSF/Facelets files which have the default extension of .xhtml, that can in turn happen if the HTTP request hasn't invoked the FacesServlet and thus it wasn't able to parse the Facelets file and generate the desired HTML output based on the XHTML source code. Firefox is then merely guessing the HTTP response content type based on the .xhtml file extension which is in your Firefox configuration apparently by default interpreted as text/xml.

You need to make sure that the HTTP request URL, as you see in browser's address bar, matches the <url-pattern> of the FacesServlet as registered in webapp's web.xml, so that it will be invoked and be able to generate the desired HTML output based on the XHTML source code. If it's for example *.jsf, then you need to open the page by /some.jsf instead of /some.xhtml. Alternatively, you can also just change the <url-pattern> to *.xhtml. This way you never need to fiddle with virtual URLs.

See also:

Note thus that you don't actually need a XML stylesheet. This all was just misinterpretation by the webbrowser while trying to do its best to make something presentable out of the retrieved HTTP response content. It should actually have retrieved the properly generated HTML output, Firefox surely knows precisely how to deal with HTML content.

How to force ViewPager to re-instantiate its items

 
public class DayFlipper extends ViewPager {

private Flipperadapter adapter;
public class FlipperAdapter extends PagerAdapter {

    @Override
    public int getCount() {
        return DayFlipper.DAY_HISTORY;
    }

    @Override
    public void startUpdate(View container) {
    }

    @Override
    public Object instantiateItem(View container, int position) {
        Log.d(TAG, "instantiateItem(): " + position);

        Date d = DateHelper.getBot();
        for (int i = 0; i < position; i++) {
            d = DateHelper.getTomorrow(d);
        }

        d = DateHelper.normalize(d);

        CubbiesView cv = new CubbiesView(mContext);
        cv.setLifeDate(d);
        ((ViewPager) container).addView(cv, 0);
        // add map
        cv.setCubbieMap(mMap);
        cv.initEntries(d);
adpter = FlipperAdapter.this;
        return cv;
    }

    @Override
    public void destroyItem(View container, int position, Object object) {
        ((ViewPager) container).removeView((CubbiesView) object);
    }

    @Override
    public void finishUpdate(View container) {

    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view == ((CubbiesView) object);
    }

    @Override
    public Parcelable saveState() {
        return null;
    }

    @Override
    public void restoreState(Parcelable state, ClassLoader loader) {

    }

}

    ...

    public void refresh() {
    adapter().notifyDataSetChanged();
}
}

try this.

Cannot lower case button text in android studio

This is fixable in the application code by setting the button's TransformationMethod null, e.g.

mButton.setTransformationMethod(null);

OSX -bash: composer: command not found

If you have to run composer with sudo, you should change the directory of composer to 

/usr/bin

this was tested on Centos8.

Link and execute external JavaScript file hosted on GitHub

This is no longer possible. GitHub has explicitly disabled JavaScript hotlinking, and newer versions of browsers respect that setting.

Heads up: nosniff header support coming to Chrome and Firefox

How can I list ALL grants a user received?

Sorry guys, but selecting from all_tab_privs_recd where grantee = 'your user' will not give any output except public grants and current user grants if you run the select from a different (let us say, SYS) user. As documentation says,

ALL_TAB_PRIVS_RECD describes the following types of grants:

Object grants for which the current user is the grantee
Object grants for which an enabled role or PUBLIC is the grantee

So, if you're a DBA and want to list all object grants for a particular (not SYS itself) user, you can't use that system view.

In this case, you must perform a more complex query. Here is one taken (traced) from TOAD to select all object grants for a particular user:

select tpm.name privilege,
       decode(mod(oa.option$,2), 1, 'YES', 'NO') grantable,
       ue.name grantee,
       ur.name grantor,
       u.name owner,
       decode(o.TYPE#, 0, 'NEXT OBJECT', 1, 'INDEX', 2, 'TABLE', 3, 'CLUSTER',
                       4, 'VIEW', 5, 'SYNONYM', 6, 'SEQUENCE',
                       7, 'PROCEDURE', 8, 'FUNCTION', 9, 'PACKAGE',
                       11, 'PACKAGE BODY', 12, 'TRIGGER',
                       13, 'TYPE', 14, 'TYPE BODY',
                       19, 'TABLE PARTITION', 20, 'INDEX PARTITION', 21, 'LOB',
                       22, 'LIBRARY', 23, 'DIRECTORY', 24, 'QUEUE',
                       28, 'JAVA SOURCE', 29, 'JAVA CLASS', 30, 'JAVA RESOURCE',
                       32, 'INDEXTYPE', 33, 'OPERATOR',
                       34, 'TABLE SUBPARTITION', 35, 'INDEX SUBPARTITION',
                       40, 'LOB PARTITION', 41, 'LOB SUBPARTITION',
                       42, 'MATERIALIZED VIEW',
                       43, 'DIMENSION',
                       44, 'CONTEXT', 46, 'RULE SET', 47, 'RESOURCE PLAN',
                       66, 'JOB', 67, 'PROGRAM', 74, 'SCHEDULE',
                       48, 'CONSUMER GROUP',
                       51, 'SUBSCRIPTION', 52, 'LOCATION',
                       55, 'XML SCHEMA', 56, 'JAVA DATA',
                       57, 'EDITION', 59, 'RULE',
                       62, 'EVALUATION CONTEXT',
                       'UNDEFINED') object_type,
       o.name object_name,
       '' column_name
        from sys.objauth$ oa, sys.obj$ o, sys.user$ u, sys.user$ ur, sys.user$ ue,
             table_privilege_map tpm
        where oa.obj# = o.obj#
          and oa.grantor# = ur.user#
          and oa.grantee# = ue.user#
          and oa.col# is null
          and oa.privilege# = tpm.privilege
          and u.user# = o.owner#
          and o.TYPE# in (2, 4, 6, 9, 7, 8, 42, 23, 22, 13, 33, 32, 66, 67, 74, 57)
  and ue.name = 'your user'
  and bitand (o.flags, 128) = 0
union all -- column level grants
select tpm.name privilege,
       decode(mod(oa.option$,2), 1, 'YES', 'NO') grantable,
       ue.name grantee,
       ur.name grantor,
       u.name owner,
       decode(o.TYPE#, 2, 'TABLE', 4, 'VIEW', 42, 'MATERIALIZED VIEW') object_type,
       o.name object_name,
       c.name column_name
from sys.objauth$ oa, sys.obj$ o, sys.user$ u, sys.user$ ur, sys.user$ ue,
     sys.col$ c, table_privilege_map tpm
where oa.obj# = o.obj#
  and oa.grantor# = ur.user#
  and oa.grantee# = ue.user#
  and oa.obj# = c.obj#
  and oa.col# = c.col#
  and bitand(c.property, 32) = 0 /* not hidden column */
  and oa.col# is not null
  and oa.privilege# = tpm.privilege
  and u.user# = o.owner#
  and o.TYPE# in (2, 4, 42)
  and ue.name = 'your user'
  and bitand (o.flags, 128) = 0;

This will list all object grants (including column grants) for your (specified) user. If you don't want column level grants then delete all part of the select beginning with 'union' clause.

UPD: Studying the documentation I found another view that lists all grants in much simpler way:

select * from DBA_TAB_PRIVS where grantee = 'your user';

Bear in mind that there's no DBA_TAB_PRIVS_RECD view in Oracle.

Find ALL tweets from a user (not just the first 3,200)

You can use a tool I wrote that bypasses the limit.

It saves the Tweets in a JSON format.

https://github.com/pauldotknopf/twitter-dump

How to position the Button exactly in CSS

It seems some what center of the screen. So I would like to do like this

body { 
     background: url('http://oi44.tinypic.com/33tjudk.jpg') no-repeat center center fixed;    
     background-size:cover; 
     text-align: 0 auto; // Make the play button horizontal center
}

#play_button {
    position:absolute;  // absolutely positioned
    transition: .5s ease;
    top: 50%;  // Makes vertical center
}

HTML select drop-down with an input field

You can use input text with "list" attribute, which refers to the datalist of values.

_x000D_
_x000D_ 
<input type="text" name="city" list="cityname">_x000D_
    <datalist id="cityname">_x000D_
      <option value="Boston">_x000D_
      <option value="Cambridge">_x000D_
    </datalist>
_x000D_
_x000D_
_x000D_

This creates a free text input field that also has a drop-down to select predefined choices. Attribution for example and more information: https://www.w3.org/wiki/HTML/Elements/datalist

ORA-01882: timezone region not found

I had this problem when running automated tests from a continuous integration server. I tried adding the VM argument "-Duser.timezone=GMT" to the build parameters, but that didn't solve the problem. However, adding the environment variable "TZ=GMT" did fix it for me.

How to delete an app from iTunesConnect / App Store Connect

Here's the answer to my question I got back from Apple support.

Hi XXX,

I am following up with you about the deletion of your app, “XXX”. Recent changes have been made to the App Delete feature. In order to delete your app from iTunes Connect, you must now have one approved version before the delete button becomes available. For more information on the recent changes, please see the "Deleting an App" section of the iTunes Connect Guide (page 96-97):

You can only delete an app from the App Store if it was previously approved (meaning has one approved version).

From iTunes Connect Developer Guide - Transferring and Deleting Apps:

Apps that have not been approved yet can’t be deleted; instead, reject the app.

As of 2016, new changes have been made to iTunes Connect. Here are the screenshots of deleting an approved app from your account.

How to join (merge) data frames (inner, outer, left, right)

I would recommend checking out Gabor Grothendieck's sqldf package, which allows you to express these operations in SQL.

library(sqldf)

## inner join
df3 <- sqldf("SELECT CustomerId, Product, State 
              FROM df1
              JOIN df2 USING(CustomerID)")

## left join (substitute 'right' for right join)
df4 <- sqldf("SELECT CustomerId, Product, State 
              FROM df1
              LEFT JOIN df2 USING(CustomerID)")

I find the SQL syntax to be simpler and more natural than its R equivalent (but this may just reflect my RDBMS bias).

See Gabor's sqldf GitHub for more information on joins.

Convert blob to base64

There is a pure JavaSript way that is not depended on any stacks:

const blobToBase64 = blob => {
  const reader = new FileReader();
  reader.readAsDataURL(blob);
  return new Promise(resolve => {
    reader.onloadend = () => {
      resolve(reader.result);
    };
  });
};

For using this helper function you should set a callback, example:

blobToBase64(blobData).then(res => {
  // do what you wanna do
  console.log(res); // res is base64 now
});

I write this helper function for my problem on React Native project, I wanted to download an image and then store it as a cached image:

fetch(imageAddressAsStringValue)
  .then(res => res.blob())
  .then(blobToBase64)
  .then(finalResult => { 
    storeOnMyLocalDatabase(finalResult);
  });

Convert DataTable to CSV stream

I've used the following code, pillaged from someone's blog (pls forgive lack of citation). It takes care of quotations, newline and comma in a reasonably elegant way by quoting out each field value.

    /// <summary>
    /// Converts the passed in data table to a CSV-style string.      
    /// </summary>
    /// <param name="table">Table to convert</param>
    /// <returns>Resulting CSV-style string</returns>
    public static string ToCSV(this DataTable table)
    {
        return ToCSV(table, ",", true);
    }

    /// <summary>
    /// Converts the passed in data table to a CSV-style string.
    /// </summary>
    /// <param name="table">Table to convert</param>
    /// <param name="includeHeader">true - include headers<br/>
    /// false - do not include header column</param>
    /// <returns>Resulting CSV-style string</returns>
    public static string ToCSV(this DataTable table, bool includeHeader)
    {
        return ToCSV(table, ",", includeHeader);
    }

    /// <summary>
    /// Converts the passed in data table to a CSV-style string.
    /// </summary>
    /// <param name="table">Table to convert</param>
    /// <param name="includeHeader">true - include headers<br/>
    /// false - do not include header column</param>
    /// <returns>Resulting CSV-style string</returns>
     public static string ToCSV(this DataTable table, string delimiter, bool includeHeader)
    {
        var result = new StringBuilder();

        if (includeHeader)
        {
            foreach (DataColumn column in table.Columns)
            {
                result.Append(column.ColumnName);
                result.Append(delimiter);
            }

            result.Remove(--result.Length, 0);
            result.Append(Environment.NewLine);
        }

        foreach (DataRow row in table.Rows)
        {
            foreach (object item in row.ItemArray)
            {
                if (item is DBNull)
                    result.Append(delimiter);
                else
                {
                    string itemAsString = item.ToString();
                    // Double up all embedded double quotes
                    itemAsString = itemAsString.Replace("\"", "\"\"");

                    // To keep things simple, always delimit with double-quotes
                    // so we don't have to determine in which cases they're necessary
                    // and which cases they're not.
                    itemAsString = "\"" + itemAsString + "\"";

                    result.Append(itemAsString + delimiter);
                }
            }

            result.Remove(--result.Length, 0);
            result.Append(Environment.NewLine);
        }

        return result.ToString();
    }

Could not create the Java virtual machine

The problem got resolved when I edited the file /etc/bashrc with same contents as in /etc/profiles and in /etc/profiles.d/limits.sh and did a re-login.

Check if a string contains a number

You can use a combination of any and str.isdigit:

def num_there(s):
    return any(i.isdigit() for i in s)

The function will return True if a digit exists in the string, otherwise False.

Demo:

>>> king = 'I shall have 3 cakes'
>>> num_there(king)
True
>>> servant = 'I do not have any cakes'
>>> num_there(servant)
False

Git Ignores and Maven targets

It is possible to use patterns in a .gitignore file. See the gitignore man page. The pattern */target/* should ignore any directory named target and anything under it. Or you may try */target/** to ignore everything under target.

How to fetch JSON file in Angular 2

Here is a part of my code that parse JSON, it may be helpful for you:

import { Component, Input } from '@angular/core';
import { Injectable }     from '@angular/core';
import { Http, Response, Headers, RequestOptions } from '@angular/http';
import {Observable} from 'rxjs/Rx';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';

@Injectable()
export class AppServices{

    constructor(private http: Http) {
         var obj;
         this.getJSON().subscribe(data => obj=data, error => console.log(error));
    }

    public getJSON(): Observable<any> {
         return this.http.get("./file.json")
                         .map((res:any) => res.json())
                         .catch((error:any) => console.log(error));

     }
}

Linq to Sql: Multiple left outer joins

This may be cleaner (you dont need all the into statements):

var query = 
    from order in dc.Orders
    from vendor 
    in dc.Vendors
        .Where(v => v.Id == order.VendorId)
        .DefaultIfEmpty()
    from status 
    in dc.Status
        .Where(s => s.Id == order.StatusId)
        .DefaultIfEmpty()
    select new { Order = order, Vendor = vendor, Status = status } 
    //Vendor and Status properties will be null if the left join is null

Here is another left join example

var results = 
    from expense in expenseDataContext.ExpenseDtos
    where expense.Id == expenseId //some expense id that was passed in
    from category 
    // left join on categories table if exists
    in expenseDataContext.CategoryDtos
                         .Where(c => c.Id == expense.CategoryId)
                         .DefaultIfEmpty() 
    // left join on expense type table if exists
    from expenseType 
    in expenseDataContext.ExpenseTypeDtos
                         .Where(e => e.Id == expense.ExpenseTypeId)
                         .DefaultIfEmpty()
    // left join on currency table if exists
    from currency 
    in expenseDataContext.CurrencyDtos
                         .Where(c => c.CurrencyID == expense.FKCurrencyID)
                         .DefaultIfEmpty() 
    select new 
    { 
        Expense = expense,
        // category will be null if join doesn't exist
        Category = category,
        // expensetype will be null if join doesn't exist
        ExpenseType = expenseType,
        // currency will be null if join doesn't exist
        Currency = currency  
    }

How do I create a new Git branch from an old commit?

 
git checkout -b NEW_BRANCH_NAME COMMIT_ID

This will create a new branch called 'NEW_BRANCH_NAME' and check it out.

("check out" means "to switch to the branch")

git branch NEW_BRANCH_NAME COMMIT_ID

This just creates the new branch without checking it out.

in the comments many people seem to prefer doing this in two steps. here's how to do so in two steps:

git checkout COMMIT_ID
# you are now in the "detached head" state
git checkout -b NEW_BRANCH_NAME

Importing project into Netbeans

Try copying the src and web folder in different folder location and create New project with existing sources in Netbeans. This should work. Or remove the nbproject folder as well before importing.

How to import NumPy in the Python shell

On Debian/Ubuntu:

aptitude install python-numpy

On Windows, download the installer:

http://sourceforge.net/projects/numpy/files/NumPy/

On other systems, download the tar.gz and run the following:

$ tar xfz numpy-n.m.tar.gz
$ cd numpy-n.m
$ python setup.py install

Image resolution for new iPhone 6 and 6+, @3x support added?

UPDATE:

New link for the icons image size by apple.

https://developer.apple.com/ios/human-interface-guidelines/graphics/image-size-and-resolution/

enter image description here

Yes it's True here it is Apple provide Official documentation regarding icon's or image size

enter image description here

you have to set images for iPhone6 and iPhone6+

For iPhone 6:

750 x 1334 (@2x) for portrait

1334 x 750 (@2x) for landscape

For iPhone 6 Plus:

1242 x 2208 (@3x) for portrait

2208 x 1242 (@3x) for landscape

For more info regarding Images and it's resolution this is best ever helpful post

For setting images size for controls you can set 1x @2x and @3x like following:

enter image description here

Android findViewById() in Custom View

Try this in your constructor

MainActivity maniActivity = (MainActivity)context;
EditText firstName = (EditText) maniActivity.findViewById(R.id.display_name);

Retrieving parameters from a URL

Python 2:

import urlparse
url = 'http://foo.appspot.com/abc?def=ghi'
parsed = urlparse.urlparse(url)
print urlparse.parse_qs(parsed.query)['def']

Python 3:

import urllib.parse as urlparse
from urllib.parse import parse_qs
url = 'http://foo.appspot.com/abc?def=ghi'
parsed = urlparse.urlparse(url)
print(parse_qs(parsed.query)['def'])

parse_qs returns a list of values, so the above code will print ['ghi'].

Here's the Python 3 documentation.

CSS Transition doesn't work with top, bottom, left, right

Something that is not relevant for the OP, but maybe for someone else in the future:

For pixels (px), if the value is "0", the unit can be omitted: right: 0 and right: 0px both work.

However I noticed that in Firefox and Chrome this is not the case for the seconds unit (s). While transition: right 1s ease 0s works, transition: right 1s ease 0 (missing unit s for last value transition-delay) does not (it does work in Edge however).

In the following example, you'll see that right works for both 0px and 0, but transition only works for 0s and it doesn't work with 0.

_x000D_
_x000D_ 
#box {_x000D_
    border: 1px solid black;_x000D_
    height: 240px;_x000D_
    width: 260px;_x000D_
    margin: 50px;_x000D_
    position: relative;_x000D_
}_x000D_
.jump {_x000D_
    position: absolute;_x000D_
    width: 200px;_x000D_
    height: 50px;_x000D_
    color: white;_x000D_
    padding: 5px;_x000D_
}_x000D_
#jump1 {_x000D_
    background-color: maroon;_x000D_
    top: 0px;_x000D_
    right: 0px;_x000D_
    transition: right 1s ease 0s;_x000D_
}_x000D_
#jump2 {_x000D_
    background-color: green;_x000D_
    top: 60px;_x000D_
    right: 0;_x000D_
    transition: right 1s ease 0s;_x000D_
}_x000D_
#jump3 {_x000D_
    background-color: blue;_x000D_
    top: 120px;_x000D_
    right: 0px;_x000D_
    transition: right 1s ease 0;_x000D_
}_x000D_
#jump4 {_x000D_
    background-color: gray;_x000D_
    top: 180px;_x000D_
    right: 0;_x000D_
    transition: right 1s ease 0;_x000D_
}_x000D_
#box:hover .jump {_x000D_
    right: 50px;_x000D_
}
_x000D_ 
<div id="box">_x000D_
  <div class="jump" id="jump1">right: 0px<br>transition: right 1s ease 0s</div>_x000D_
  <div class="jump" id="jump2">right: 0<br>transition: right 1s ease 0s</div>_x000D_
  <div class="jump" id="jump3">right: 0px<br>transition: right 1s ease 0</div>_x000D_
  <div class="jump" id="jump4">right: 0<br>transition: right 1s ease 0</div>_x000D_
</div>
_x000D_
_x000D_
_x000D_

AJAX POST and Plus Sign ( + ) -- How to Encode?

If you have to do a curl in php, you should use urlencode() from PHP but individually!

strPOST = "Item1=" . $Value1 . "&Item2=" . urlencode("+")

If you do urlencode(strPOST), you will bring you another problem, you will have one Item1 and & will be change %xx value and be as one value, see down here the return!

Example 1

$strPOST = "Item1=" . $Value1 . "&Item2=" . urlencode("+") will give Item1=Value1&Item2=%2B

Example 2

$strPOST = urlencode("Item1=" . $Value1 . "&Item2=+") will give Item1%3DValue1%26Item2%3D%2B

Example 1 is the good way to prepare string for POST in curl

Example 2 show that the receptor will not see the equal and the ampersand to distinguish both value!

Easiest way to read from and write to files

 
FileStream fs = new FileStream(txtSourcePath.Text,FileMode.Open, FileAccess.Read);
using(StreamReader sr = new StreamReader(fs))
{
   using (StreamWriter sw = new StreamWriter(Destination))
   {
            sw.writeline("Your text");
    }
}

How do I change file permissions in Ubuntu

So that you don't mess up other permissions already on the file, use the flag +, such as via

sudo chmod -R o+rw /var/www

Displaying all table names in php from MySQL database

The square brackets in your code are used in the mysql documentation to indicate groups of optional parameters. They should not be in the actual query.

The only command you actually need is:

show tables;

If you want tables from a specific database, let's say the database "books", then it would be 

show tables from books;

You only need the LIKE part if you want to find tables whose names match a certain pattern. e.g., 

show tables from books like '%book%';

would show you the names of tables that have "book" somewhere in the name.

Furthermore, just running the "show tables" query will not produce any output that you can see. SQL answers the query and then passes it to PHP, but you need to tell PHP to echo it to the page.

Since it sounds like you're very new to SQL, I'd recommend running the mysql client from the command line (or using phpmyadmin, if it's installed on your system). That way you can see the results of various queries without having to go through PHP's functions for sending queries and receiving results.

If you have to use PHP, here's a very simple demonstration. Try this code after connecting to your database:

$result = mysql_query("show tables"); // run the query and assign the result to $result
while($table = mysql_fetch_array($result)) { // go through each row that was returned in $result
    echo($table[0] . "<BR>");    // print the table that was returned on that row.
}

Platform.runLater and Task in JavaFX

One reason to use an explicite Platform.runLater() could be that you bound a property in the ui to a service (result) property. So if you update the bound service property, you have to do this via runLater():

In UI thread also known as the JavaFX Application thread:

...    
listView.itemsProperty().bind(myListService.resultProperty());
...

in Service implementation (background worker):

...
Platform.runLater(() -> result.add("Element " + finalI));
...

In which case do you use the JPA @JoinTable annotation?

It's the only solution to map a ManyToMany association : you need a join table between the two entities tables to map the association.

It's also used for OneToMany (usually unidirectional) associations when you don't want to add a foreign key in the table of the many side and thus keep it independent of the one side.

Search for @JoinTable in the hibernate documentation for explanations and examples.

Windows 7 - 'make' is not recognized as an internal or external command, operable program or batch file

Search for make.exe using the search feature, when found, note down the absolute path to the file. You can do that by right-clicking on the filename in the search result and then properties, or open location folder (not sure of the exact wording, I'm not using an English locale).

When you open the command line console (cmd) instead of typing make, type the whole path and name, e.g. C:\Windows\System32\java (this is for java...).

Alternatively, if you don't want to provide the full path each time, then you have to possibilities:

  • make C:\Windows\System32\ the current working directory, using cd at cmd level.
  • add C:\Windows\System32\ to you PATH environment variable.

Refs:

How do I `jsonify` a list in Flask?

You can't but you can do it anyway like this. I needed this for jQuery-File-Upload

import json
# get this object
from flask import Response

#example data:

    js = [ { "name" : filename, "size" : st.st_size , 
        "url" : url_for('show', filename=filename)} ]
#then do this
    return Response(json.dumps(js),  mimetype='application/json')

How to fix "no valid 'aps-environment' entitlement string found for application" in Xcode 4.3?

Ran into this same issue myself. For me, the issue was that my product name ($TARGET_NAME) was not capitalized the same way presented in the certificate provided by apple. For example, i had com.companyid.APNDemo whereas the Apple cert was using com.companyid.apndemo.

I changed my target to be lowercase and it worked. Note: The clue for me was the codesigning setting in Build Settings was set to my default developer certificate; not the APNTest provisioning profile.

How do you stretch an image to fill a <div> while keeping the image's aspect-ratio?

That's impossible with just HTML and CSS, or at least wildly exotic and complicated. If you're willing to throw some javascript in, here's a solution using jQuery:

$(function() {
    $(window).resize(function() {
        var $i = $('img#image_to_resize');
        var $c = $img.parent();
        var i_ar = $i.width() / $i.height(), c_ar = $c.width() / $c.height();            
        $i.width(i_ar > c_ar ? $c.width() : $c.height() * (i_ar));
    });
    $(window).resize();
});

That will resize the image so that it will always fit inside the parent element, regardless of it's size. And as it's binded to the $(window).resize() event, when user resizes the window, the image will adjust.

This does not try to center the image in the container, that would be possible but I guess that's not what you're after.

Change Timezone in Lumen or Laravel 5

There is an easy way to set the default timezone in laravel or lumen.

This is helpful while working in multiple environments where you can use different timezone based on each environment.

  1. Open .env file present inside the your project directory
  2. Add APP_TIMEZONE=Asia/Kolkata in .env (Your can choose any timezone from the supported timezones)
  3. Open app.php present inside bootstrap folder of your project directory
  4. Add date_default_timezone_set(env('APP_TIMEZONE', 'UTC')); in app.php.

With this change your project will take your .env set timezone and if there is nothing set then take UTC by default.

After modifying the time zone setting run command php artisan config:clear so that your changes reflect in your application

How to get a unique computer identifier in Java (like disk ID or motherboard ID)?

The usage of MAC id is most easier way if the task is about logging the unique id a system.

the change of mac id is though possible, even the change of other ids of a system are also possible is that respective device is replaced.

so, unless what for a unique id is required is not known, we may not be able to find an appropriate solution.

However, the below link is helpful extracting mac addresses. http://www.stratos.me/2008/07/find-mac-address-using-java/

how to hide a vertical scroll bar when not needed

overflow: auto (or overflow-y: auto) is the correct way to go.

The problem is that your text area is taller than your div. The div ends up cutting off the textbox, so even though it looks like it should start scrolling when the text is taller than 159px it won't start scrolling until the text is taller than 400px which is the height of the textbox.

Try this: http://jsfiddle.net/G9rfq/1/

I set overflow:auto on the text box, and made the textbox the same size as the div.

Also I don't believe it's valid to have a div inside a label, the browser will render it, but it might cause some funky stuff to happen. Also your div isn't closed.

overlay opaque div over youtube iframe

Information from the Official Adobe site about this issue

The issue is when you embed a youtube link:

https://www.youtube.com/embed/kRvL6K8SEgY

in an iFrame, the default wmode is windowed which essentially gives it a z-index greater then everything else and it will overlay over anything.

Try appending this GET parameter to your URL:

wmode=opaque

like so:

https://www.youtube.com/embed/kRvL6K8SEgY?wmode=opaque

Make sure its the first parameter in the URL. Other parameters must go after

In the iframe tag:

Example:

<iframe class="youtube-player" type="text/html" width="520" height="330" src="http://www.youtube.com/embed/NWHfY_lvKIQ?wmode=opaque" frameborder="0"></iframe>

Powershell v3 Invoke-WebRequest HTTPS error

Lee's answer is great, but I also had issues with which protocols the web server supported.
After also adding the following lines, I could get the https request through. As pointed out in this answer https://stackoverflow.com/a/36266735

$AllProtocols = [System.Net.SecurityProtocolType]'Ssl3,Tls,Tls11,Tls12'
[System.Net.ServicePointManager]::SecurityProtocol = $AllProtocols

My full solution with Lee's code.

add-type @"
using System.Net;
using System.Security.Cryptography.X509Certificates;
public class TrustAllCertsPolicy : ICertificatePolicy {
    public bool CheckValidationResult(
        ServicePoint srvPoint, X509Certificate certificate,
        WebRequest request, int certificateProblem) {
        return true;
    }
}
"@
$AllProtocols = [System.Net.SecurityProtocolType]'Ssl3,Tls,Tls11,Tls12'
[System.Net.ServicePointManager]::SecurityProtocol = $AllProtocols
[System.Net.ServicePointManager]::CertificatePolicy = New-Object TrustAllCertsPolicy

How can I check if a string contains ANY letters from the alphabet?

Regex should be a fast approach:

re.search('[a-zA-Z]', the_string)

How can I convert a string to boolean in JavaScript?

@guinaps> Any string which isn't the empty string will evaluate to true by using them.

How about using the String.match() method

var str="true";
var boolStr=Boolean(str.match(/^true$/i));

this alone won't get the 1/0 or the yes/no, but it will catch the TRUE/true, as well, it will return false for any string that happens to have "true" as a substring.

EDIT

Below is a function to handle true/false, 1/0, yes/no (case-insensitive)

?function stringToBool(str) {
    var bool;
    if (str.match(/^(true|1|yes)$/i) !== null) {
        bool = true;
    } else if (str.match(/^(false|0|no)*$/i) !== null) {
        bool = false;
    } else {
        bool = null;
        if (console) console.log('"' + str + '" is not a boolean value');
    }
    return bool;
}

stringToBool('1'); // true
stringToBool('No'); // false
stringToBool('falsey'); // null ("falsey" is not a boolean value.)
stringToBool(''); // false

how to get current month and year

 
using System.Globalization;

LblMonth.Text = DateTime.Now.Month.ToString();

DateTimeFormatInfo dinfo = new DateTimeFormatInfo();
int month = Convert.ToInt16(LblMonth.Text);

LblMonth.Text = dinfo.GetMonthName(month);

Templated check for the existence of a class member function?

This is a C++11 solution for the general problem if "If I did X, would it compile?"

template<class> struct type_sink { typedef void type; }; // consumes a type, and makes it `void`
template<class T> using type_sink_t = typename type_sink<T>::type;
template<class T, class=void> struct has_to_string : std::false_type {}; \
template<class T> struct has_to_string<
  T,
  type_sink_t< decltype( std::declval<T>().toString() ) >
>: std::true_type {};

Trait has_to_string such that has_to_string<T>::value is true if and only if T has a method .toString that can be invoked with 0 arguments in this context.

Next, I'd use tag dispatching:

namespace details {
  template<class T>
  std::string optionalToString_helper(T* obj, std::true_type /*has_to_string*/) {
    return obj->toString();
  }
  template<class T>
  std::string optionalToString_helper(T* obj, std::false_type /*has_to_string*/) {
    return "toString not defined";
  }
}
template<class T>
std::string optionalToString(T* obj) {
  return details::optionalToString_helper( obj, has_to_string<T>{} );
}

which tends to be more maintainable than complex SFINAE expressions.

You can write these traits with a macro if you find yourself doing it alot, but they are relatively simple (a few lines each) so maybe not worth it:

#define MAKE_CODE_TRAIT( TRAIT_NAME, ... ) \
template<class T, class=void> struct TRAIT_NAME : std::false_type {}; \
template<class T> struct TRAIT_NAME< T, type_sink_t< decltype( __VA_ARGS__ ) > >: std::true_type {};

what the above does is create a macro MAKE_CODE_TRAIT. You pass it the name of the trait you want, and some code that can test the type T. Thus:

MAKE_CODE_TRAIT( has_to_string, std::declval<T>().toString() )

creates the above traits class.

As an aside, the above technique is part of what MS calls "expression SFINAE", and their 2013 compiler fails pretty hard.

Note that in C++1y the following syntax is possible:

template<class T>
std::string optionalToString(T* obj) {
  return compiled_if< has_to_string >(*obj, [&](auto&& obj) {
    return obj.toString();
  }) *compiled_else ([&]{ 
    return "toString not defined";
  });
}

which is an inline compilation conditional branch that abuses lots of C++ features. Doing so is probably not worth it, as the benefit (of code being inline) is not worth the cost (of next to nobody understanding how it works), but the existence of that above solution may be of interest.

How to download HTTP directory with all files and sub-directories as they appear on the online files/folders list?

No Software or Plugin required!

(only usable if you don't need recursive deptch)

Use bookmarklet. Drag this link in bookmarks, then edit and paste this code:

(function(){ var arr=[], l=document.links; var ext=prompt("select extension for download (all links containing that, will be downloaded.", ".mp3"); for(var i=0; i<l.length; i++) { if(l[i].href.indexOf(ext) !== false){ l[i].setAttribute("download",l[i].text); l[i].click(); } } })();

and go on page (from where you want to download files), and click that bookmarklet.

Cross-platform way of getting temp directory in Python

I use:

from pathlib import Path
import platform
import tempfile

tempdir = Path("/tmp" if platform.system() == "Darwin" else tempfile.gettempdir())

This is because on MacOS, i.e. Darwin, tempfile.gettempdir() and os.getenv('TMPDIR') return a value such as '/var/folders/nj/269977hs0_96bttwj2gs_jhhp48z54/T'; it is one that I do not always want.

Get all variables sent with POST?

Why not this, it's easy: 

extract($_POST);

Splitting a list into N parts of approximately equal length

 
def chunk_array(array : List, n: int) -> List[List]:
    chunk_size = len(array) // n 
    chunks = []
    i = 0
    while i < len(array):
        # if less than chunk_size left add the remainder to last element
        if len(array) - (i + chunk_size + 1) < 0:
            chunks[-1].append(*array[i:i + chunk_size])
            break
        else:
            chunks.append(array[i:i + chunk_size])
            i += chunk_size
    return chunks

here's my version (inspired from Max's)

Convert Xml to DataTable

 
DataSet ds = new DataSet();
ds.ReadXml(fileNamePath);

How can I get a list of locally installed Python modules?

For anyone wondering how to call pip list from a Python program you can use the following:

import pip
pip.main(['list])  # this will print all the packages

How to set header and options in axios?

You can initialize a default header axios.defaults.headers

 axios.defaults.headers = {
        'Content-Type': 'application/json',
        Authorization: 'myspecialpassword'
    }

   axios.post('https://myapi.com', { data: "hello world" })
        .then(response => {
            console.log('Response', response.data)
        })
        .catch(e => {
            console.log('Error: ', e.response.data)
        })

Is there an arraylist in Javascript?

Try this, maybe can help, it do what you want:

ListArray

_x000D_
_x000D_ 
var listArray = new ListArray();_x000D_
let element = {name: 'Edy', age: 27, country: "Brazil"};_x000D_
let element2 = {name: 'Marcus', age: 27, country: "Brazil"};_x000D_
listArray.push(element);_x000D_
listArray.push(element2);_x000D_
_x000D_
console.log(listArray.array)
_x000D_ 
<script src="https://marcusvi200.github.io/list-array/script/ListArray.js"></script>
_x000D_
_x000D_
_x000D_

How to use OpenFileDialog to select a folder?

Take a look at the Ookii Dialogs libraries which has an implementation of a folder browser dialog for Windows Forms and WPF respectively.

enter image description here

Ookii.Dialogs.WinForms

https://github.com/augustoproiete/ookii-dialogs-winforms

Ookii.Dialogs.Wpf

https://github.com/augustoproiete/ookii-dialogs-wpf

What is the difference between spark.sql.shuffle.partitions and spark.default.parallelism?

From the answer here, spark.sql.shuffle.partitions configures the number of partitions that are used when shuffling data for joins or aggregations.

spark.default.parallelism is the default number of partitions in RDDs returned by transformations like join, reduceByKey, and parallelize when not set explicitly by the user. Note that spark.default.parallelism seems to only be working for raw RDD and is ignored when working with dataframes.

If the task you are performing is not a join or aggregation and you are working with dataframes then setting these will not have any effect. You could, however, set the number of partitions yourself by calling df.repartition(numOfPartitions) (don't forget to assign it to a new val) in your code.

To change the settings in your code you can simply do:

sqlContext.setConf("spark.sql.shuffle.partitions", "300")
sqlContext.setConf("spark.default.parallelism", "300")

Alternatively, you can make the change when submitting the job to a cluster with spark-submit:

./bin/spark-submit --conf spark.sql.shuffle.partitions=300 --conf spark.default.parallelism=300

Print page numbers on pages when printing html

I know this is not a coding answer but it is what the OP wanted and what I have spent half the day trying to achieve - print from a web page with page numbers.

Yes, it is two steps instead of one but I haven't been able to find any CSS option despite several hours of searching. Real shame all the browsers removed the functionality that used to allow it.

Change PictureBox's image to image from my resources?

Ok...so first you need to import in your project the image

1)Select the picturebox in Form Design

2)Open PictureBox Tasks (it's the little arrow pinted to right on the edge on the picturebox)

3)Click on "Choose image..."

4)Select the second option "Project resource file:" (this option will create a folder called "Resources" which you can acces with Properties.Resources)

5)Click on import and select your image from your computer (now a copy of the image with the same name as the image will be sent in Resources folder created at step 4)

6)Click on ok

Now the image is in your project and you can use it with Properties command.Just type this code when you want to change the picture from picturebox:

pictureBox1.Image = Properties.Resources.myimage;

Note: myimage represent the name of the image...after typing the dot after Resources,in your options it will be your imported image file

tar: add all files and directories in current directory INCLUDING .svn and so on

in directory want to compress (current directory) try this :

tar -czf workspace.tar.gz . --exclude=./*.gz

Delimiter must not be alphanumeric or backslash and preg_match

Maybe not related to original code example, but I received the error "Delimiter must not be alphanumeric or backslash" and Googled here. Reason: I mixed order of parameters for preg_match. Pattern was the second parameter and string to match was first. Be careful :)

number several equations with only one number

First of all, you probably don't want the align environment if you have only one column of equations. In fact, your example is probably best with the cases environment. But to answer your question directly, used the aligned environment within equation - this way the outside environment gives the number:

\begin{equation}
  \begin{aligned}
  w^T x_i + b &\geq 1-\xi_i &\text{ if }& y_i=1,  \\
  w^T x_i + b &\leq -1+\xi_i & \text{ if } &y_i=-1,
  \end{aligned}
\end{equation}

The documentation of the amsmath package explains this and more.

How can I compare two time strings in the format HH:MM:SS?

Date object in js support comparison, set them same date for compare hh:mm:ss :

new Date ('1/1/1999 ' + '10:20:45') > new Date ('1/1/1999 ' + '5:10:10') 
> true

Display Python datetime without time

If you need the result to be timezone-aware, you can use the replace() method of datetime objects. This preserves timezone, so you can do

>>> from django.utils import timezone
>>> now = timezone.now()
>>> now
datetime.datetime(2018, 8, 30, 14, 15, 43, 726252, tzinfo=<UTC>)
>>> now.replace(hour=0, minute=0, second=0, microsecond=0)
datetime.datetime(2018, 8, 30, 0, 0, tzinfo=<UTC>)

Note that this returns a new datetime object -- now remains unchanged.

How does GPS in a mobile phone work exactly?

There's 3 satellites at least that you must be able to receive from of the 24-32 out there, and they each broadcast a time from a synchronized atomic clock. The differences in those times that you receive at any one time tell you how long the broadcast took to reach you, and thus where you are in relation to the satellites. So, it sort of reads from something, but it doesn't connect to that thing. Note that this doesn't tell you your orientation, many GPSes fake that (and speed) by interpolating data points.

If you don't count the cost of the receiver, it's a free service. Apparently there's higher resolution services out there that are restricted to military use. Those are likely a fixed cost for a license to decrypt the signals along with a confidentiality agreement.

Now your device may support GPS tracking, in which case it might communicate, say via GPRS, to a database which will store the location the device has found itself to be at, so that multiple devices may be tracked. That would require some kind of connection.

Maps are either stored on the device or received over a connection. Navigation is computed based on those maps' databases. These likely are a licensed item with a cost associated, though if you use a service like Google Maps they have the license with NAVTEQ and others.

Convert List<String> to List<Integer> directly

Guava Converters do the trick.

import com.google.common.base.Splitter;
import com.google.common.primitives.Longs;

final Iterable<Long> longIds = 
    Longs.stringConverter().convertAll(
        Splitter.on(',').trimResults().omitEmptyStrings()
            .splitToList("1,2,3"));

How to retrieve field names from temporary table (SQL Server 2008)

Anthony

try the below one. it will give ur expected output

select c.name as Fields from 
tempdb.sys.columns c
    inner join tempdb.sys.tables t
 ON c.object_id = t.object_id
where t.name like '#MyTempTable%'

PHP string "contains"

You can use stristr() or strpos(). Both return false if nothing is found.

How to view the current heap size that an application is using?

You can Use the tool : Eclipse Memory Analyzer Tool http://www.eclipse.org/mat/ .

It is very useful.

T-SQL: Selecting rows to delete via joins

Let's say you have 2 tables, one with a Master set (eg. Employees) and one with a child set (eg. Dependents) and you're wanting to get rid of all the rows of data in the Dependents table that cannot key up with any rows in the Master table.

delete from Dependents where EmpID in (
select d.EmpID from Employees e 
    right join Dependents d on e.EmpID = d.EmpID
    where e.EmpID is null)

The point to notice here is that you're just collecting an 'array' of EmpIDs from the join first, the using that set of EmpIDs to do a Deletion operation on the Dependents table.

Is there a way I can retrieve sa password in sql server 2005

There is no way to get the old password back. Log into the SQL server management console as a machine or domain admin using integrated authentication, you can then change any password (including sa).

Start the SQL service again and use the new created login (recovery in my example) Go via the security panel to the properties and change the password of the SA account.

enter image description here

Now write down the new SA password.

Jasmine.js comparing arrays

just for the record you can always compare using JSON.stringify

const arr = [1,2,3]; expect(JSON.stringify(arr)).toBe(JSON.stringify([1,2,3])); expect(JSON.stringify(arr)).toEqual(JSON.stringify([1,2,3]));

It's all meter of taste, this will also work for complex literal objects

Execute ssh with password authentication via windows command prompt

PuTTY's plink has a command-line argument for a password. Some other suggestions have been made in the answers to this question: using Expect (which is available for Windows), or writing a launcher in Python with Paramiko.

Where can I find my Facebook application id and secret key?

Just simply click on your app name and look on your right, you app id should be there

For your app secret, u have to click show.

enter image description here

Hope that helps !

Javascript change color of text and background to input value

Depending on which event you actually want to use (textbox change, or button click), you can try this:

HTML:

<input id="color" type="text" onchange="changeBackground(this);" />
<br />
<span id="coltext">This text should have the same color as you put in the text box</span>

JS:

function changeBackground(obj) {
    document.getElementById("coltext").style.color = obj.value;
}

DEMO: http://jsfiddle.net/6pLUh/

One minor problem with the button was that it was a submit button, in a form. When clicked, that submits the form (which ends up just reloading the page) and any changes from JavaScript are reset. Just using the onchange allows you to change the color based on the input.

Changing the "tick frequency" on x or y axis in matplotlib?

Since None of the above solutions worked for my usecase, here I provide a solution using None (pun!) which can be adapted to a wide variety of scenarios.

Here is a sample piece of code that produces cluttered ticks on both X and Y axes.

# Note the super cluttered ticks on both X and Y axis.

# inputs
x = np.arange(1, 101)
y = x * np.log(x) 

fig = plt.figure()     # create figure
ax = fig.add_subplot(111)
ax.plot(x, y)
ax.set_xticks(x)        # set xtick values
ax.set_yticks(y)        # set ytick values

plt.show()

Now, we clean up the clutter with a new plot that shows only a sparse set of values on both x and y axes as ticks.

# inputs
x = np.arange(1, 101)
y = x * np.log(x)

fig = plt.figure()       # create figure
ax = fig.add_subplot(111)
ax.plot(x, y)

ax.set_xticks(x)
ax.set_yticks(y)

# which values need to be shown?
# here, we show every third value from `x` and `y`
show_every = 3

sparse_xticks = [None] * x.shape[0]
sparse_xticks[::show_every] = x[::show_every]

sparse_yticks = [None] * y.shape[0]
sparse_yticks[::show_every] = y[::show_every]

ax.set_xticklabels(sparse_xticks, fontsize=6)   # set sparse xtick values
ax.set_yticklabels(sparse_yticks, fontsize=6)   # set sparse ytick values

plt.show()

Depending on the usecase, one can adapt the above code simply by changing show_every and using that for sampling tick values for X or Y or both the axes.

If this stepsize based solution doesn't fit, then one can also populate the values of sparse_xticks or sparse_yticks at irregular intervals, if that is what is desired.

ggplot legends - change labels, order and title

You need to do two things:

  1. Rename and re-order the factor levels before the plot
  2. Rename the title of each legend to the same title

The code:

dtt$model <- factor(dtt$model, levels=c("mb", "ma", "mc"), labels=c("MBB", "MAA", "MCC"))

library(ggplot2)
ggplot(dtt, aes(x=year, y=V, group = model, colour = model, ymin = lower, ymax = upper)) +
  geom_ribbon(alpha = 0.35, linetype=0)+ 
  geom_line(aes(linetype=model), size = 1) +       
  geom_point(aes(shape=model), size=4)  +      
  theme(legend.position=c(.6,0.8)) +
  theme(legend.background = element_rect(colour = 'black', fill = 'grey90', size = 1, linetype='solid')) +
  scale_linetype_discrete("Model 1") +
  scale_shape_discrete("Model 1") +
  scale_colour_discrete("Model 1")

enter image description here

However, I think this is really ugly as well as difficult to interpret. It's far better to use facets:

ggplot(dtt, aes(x=year, y=V, group = model, colour = model, ymin = lower, ymax = upper)) +
  geom_ribbon(alpha=0.2, colour=NA)+ 
  geom_line() +       
  geom_point()  +      
  facet_wrap(~model)

enter image description here

Calendar date to yyyy-MM-dd format in java

I found this code where date is compared in a format to compare with date field in database...may be this might be helpful to you...

When you convert the string to date using simpledateformat, it is hard to compare with the Date field in mysql databases.

So convert the java string date in the format using select STR_to_DATE('yourdate','%m/%d/%Y') --> in this format, then you will get the exact date format of mysql date field.

http://javainfinite.com/java/java-convert-string-to-date-and-compare/

jQuery plugin returning "Cannot read property of undefined"

I had same problem with 'parallax' plugin. I changed jQuery librery version to *jquery-1.6.4* from *jquery-1.10.2*. And error cleared.

Handling ExecuteScalar() when no results are returned

I have seen in VS2010 string getusername = command.ExecuteScalar(); gives compilation error, Cannot implicitly convert type object to string. So you need to write string getusername = command.ExecuteScalar().ToString(); when there is no record found in database it gives error Object reference not set to an instance of an object and when I comment '.ToString()', it is not give any error. So I can say ExecuteScalar not throw an exception. I think anserwer given by @Rune Grimstad is right.

SQL Server "cannot perform an aggregate function on an expression containing an aggregate or a subquery", but Sybase can

One option is to put the subquery in a LEFT JOIN:

select sum ( t.graduates ) - t1.summedGraduates 
from table as t
    left join 
     ( 
        select sum ( graduates ) summedGraduates, id
        from table  
        where group_code not in ('total', 'others' )
        group by id 
    ) t1 on t.id = t1.id
where t.group_code = 'total'
group by t1.summedGraduates

Perhaps a better option would be to use SUM with CASE:

select sum(case when group_code = 'total' then graduates end) -
    sum(case when group_code not in ('total','others') then graduates end)
from yourtable

SQL Fiddle Demo with both

Is it possible to implement a Python for range loop without an iterator variable?

We have had some fun with the following, interesting to share so: 

class RepeatFunction:
    def __init__(self,n=1): self.n = n
    def __call__(self,Func):
        for i in xrange(self.n):
            Func()
        return Func


#----usage
k = 0

@RepeatFunction(7)                       #decorator for repeating function
def Job():
    global k
    print k
    k += 1

print '---------'
Job()

Results: 

0
1
2
3
4
5
6
---------
7

JavaScript: Alert.Show(message) From ASP.NET Code-behind

Here is an easy way:

Response.Write("<script>alert('Hello');</script>");

How to convert string to boolean in typescript Angular 4

In your scenario, converting a string to a boolean can be done via something like someString === 'true' (as was already answered).

However, let me try to address your main issue: dealing with the local storage.

The local storage only supports strings as values; a good way of using it would thus be to always serialise your data as a string before storing it in the storage, and reversing the process when fetching it.

A possibly decent format for serialising your data in is JSON, since it is very easy to deal with in JavaScript.

The following functions could thus be used to interact with local storage, provided that your data can be serialised into JSON.

function setItemInStorage(key, item) {
  localStorage.setItem(key, JSON.stringify(item));
}

function getItemFromStorage(key) {
  return JSON.parse(localStorage.getItem(key));
}

Your example could then be rewritten as:

setItemInStorage('CheckOutPageReload', [this.btnLoginNumOne, this.btnLoginEdit]);

And:

if (getItemFromStorage('CheckOutPageReload')) {
  const pageLoadParams = getItemFromStorage('CheckOutPageReload');
  this.btnLoginNumOne = pageLoadParams[0];
  this.btnLoginEdit = pageLoadParams[1];
}

SQL Server Pivot Table with multiple column aggregates

I used your own pivot as a nested query and came to this result:

SELECT
  [sub].[chardate],
  SUM(ISNULL([Australia], 0)) AS [Transactions Australia],
  SUM(CASE WHEN [Australia] IS NOT NULL THEN [TotalAmount] ELSE 0 END) AS [Amount Australia],
  SUM(ISNULL([Austria], 0)) AS [Transactions Austria],
  SUM(CASE WHEN [Austria] IS NOT NULL THEN [TotalAmount] ELSE 0 END) AS [Amount Austria]
FROM
(
  select * 
  from  mytransactions
  pivot (sum (totalcount) for country in ([Australia], [Austria])) as pvt
) AS [sub]
GROUP BY
  [sub].[chardate],
  [sub].[numericmonth]
ORDER BY 
  [sub].[numericmonth] ASC

Here is the Fiddle.

How does DISTINCT work when using JPA and Hibernate

Depending on the underlying JPQL or Criteria API query type, DISTINCT has two meanings in JPA.

Scalar queries

For scalar queries, which return a scalar projection, like the following query:

List<Integer> publicationYears = entityManager
.createQuery(
    "select distinct year(p.createdOn) " +
    "from Post p " +
    "order by year(p.createdOn)", Integer.class)
.getResultList();

LOGGER.info("Publication years: {}", publicationYears);

The DISTINCT keyword should be passed to the underlying SQL statement because we want the DB engine to filter duplicates prior to returning the result set:

SELECT DISTINCT
    extract(YEAR FROM p.created_on) AS col_0_0_
FROM
    post p
ORDER BY
    extract(YEAR FROM p.created_on)

-- Publication years: [2016, 2018]

Entity queries

For entity queries, DISTINCT has a different meaning.

Without using DISTINCT, a query like the following one:

List<Post> posts = entityManager
.createQuery(
    "select p " +
    "from Post p " +
    "left join fetch p.comments " +
    "where p.title = :title", Post.class)
.setParameter(
    "title", 
    "High-Performance Java Persistence eBook has been released!"
)
.getResultList();

LOGGER.info(
    "Fetched the following Post entity identifiers: {}", 
    posts.stream().map(Post::getId).collect(Collectors.toList())
);

is going to JOIN the post and the post_comment tables like this:

SELECT p.id AS id1_0_0_,
       pc.id AS id1_1_1_,
       p.created_on AS created_2_0_0_,
       p.title AS title3_0_0_,
       pc.post_id AS post_id3_1_1_,
       pc.review AS review2_1_1_,
       pc.post_id AS post_id3_1_0__
FROM   post p
LEFT OUTER JOIN
       post_comment pc ON p.id=pc.post_id
WHERE
       p.title='High-Performance Java Persistence eBook has been released!'

-- Fetched the following Post entity identifiers: [1, 1]

But the parent post records are duplicated in the result set for each associated post_comment row. For this reason, the List of Post entities will contain duplicate Post entity references.

To eliminate the Post entity references, we need to use DISTINCT:

List<Post> posts = entityManager
.createQuery(
    "select distinct p " +
    "from Post p " +
    "left join fetch p.comments " +
    "where p.title = :title", Post.class)
.setParameter(
    "title", 
    "High-Performance Java Persistence eBook has been released!"
)
.getResultList();
 
LOGGER.info(
    "Fetched the following Post entity identifiers: {}", 
    posts.stream().map(Post::getId).collect(Collectors.toList())
);

But then DISTINCT is also passed to the SQL query, and that's not desirable at all:

SELECT DISTINCT
       p.id AS id1_0_0_,
       pc.id AS id1_1_1_,
       p.created_on AS created_2_0_0_,
       p.title AS title3_0_0_,
       pc.post_id AS post_id3_1_1_,
       pc.review AS review2_1_1_,
       pc.post_id AS post_id3_1_0__
FROM   post p
LEFT OUTER JOIN
       post_comment pc ON p.id=pc.post_id
WHERE
       p.title='High-Performance Java Persistence eBook has been released!'
 
-- Fetched the following Post entity identifiers: [1]

By passing DISTINCT to the SQL query, the EXECUTION PLAN is going to execute an extra Sort phase which adds overhead without bringing any value since the parent-child combinations always return unique records because of the child PK column:

Unique  (cost=23.71..23.72 rows=1 width=1068) (actual time=0.131..0.132 rows=2 loops=1)
  ->  Sort  (cost=23.71..23.71 rows=1 width=1068) (actual time=0.131..0.131 rows=2 loops=1)
        Sort Key: p.id, pc.id, p.created_on, pc.post_id, pc.review
        Sort Method: quicksort  Memory: 25kB
        ->  Hash Right Join  (cost=11.76..23.70 rows=1 width=1068) (actual time=0.054..0.058 rows=2 loops=1)
              Hash Cond: (pc.post_id = p.id)
              ->  Seq Scan on post_comment pc  (cost=0.00..11.40 rows=140 width=532) (actual time=0.010..0.010 rows=2 loops=1)
              ->  Hash  (cost=11.75..11.75 rows=1 width=528) (actual time=0.027..0.027 rows=1 loops=1)
                    Buckets: 1024  Batches: 1  Memory Usage: 9kB
                    ->  Seq Scan on post p  (cost=0.00..11.75 rows=1 width=528) (actual time=0.017..0.018 rows=1 loops=1)
                          Filter: ((title)::text = 'High-Performance Java Persistence eBook has been released!'::text)
                          Rows Removed by Filter: 3
Planning time: 0.227 ms
Execution time: 0.179 ms

Entity queries with HINT_PASS_DISTINCT_THROUGH

To eliminate the Sort phase from the execution plan, we need to use the HINT_PASS_DISTINCT_THROUGH JPA query hint:

List<Post> posts = entityManager
.createQuery(
    "select distinct p " +
    "from Post p " +
    "left join fetch p.comments " +
    "where p.title = :title", Post.class)
.setParameter(
    "title", 
    "High-Performance Java Persistence eBook has been released!"
)
.setHint(QueryHints.HINT_PASS_DISTINCT_THROUGH, false)
.getResultList();
 
LOGGER.info(
    "Fetched the following Post entity identifiers: {}", 
    posts.stream().map(Post::getId).collect(Collectors.toList())
);

And now, the SQL query will not contain DISTINCT but Post entity reference duplicates are going to be removed:

SELECT
       p.id AS id1_0_0_,
       pc.id AS id1_1_1_,
       p.created_on AS created_2_0_0_,
       p.title AS title3_0_0_,
       pc.post_id AS post_id3_1_1_,
       pc.review AS review2_1_1_,
       pc.post_id AS post_id3_1_0__
FROM   post p
LEFT OUTER JOIN
       post_comment pc ON p.id=pc.post_id
WHERE
       p.title='High-Performance Java Persistence eBook has been released!'
 
-- Fetched the following Post entity identifiers: [1]

And the Execution Plan is going to confirm that we no longer have an extra Sort phase this time:

Hash Right Join  (cost=11.76..23.70 rows=1 width=1068) (actual time=0.066..0.069 rows=2 loops=1)
  Hash Cond: (pc.post_id = p.id)
  ->  Seq Scan on post_comment pc  (cost=0.00..11.40 rows=140 width=532) (actual time=0.011..0.011 rows=2 loops=1)
  ->  Hash  (cost=11.75..11.75 rows=1 width=528) (actual time=0.041..0.041 rows=1 loops=1)
        Buckets: 1024  Batches: 1  Memory Usage: 9kB
        ->  Seq Scan on post p  (cost=0.00..11.75 rows=1 width=528) (actual time=0.036..0.037 rows=1 loops=1)
              Filter: ((title)::text = 'High-Performance Java Persistence eBook has been released!'::text)
              Rows Removed by Filter: 3
Planning time: 1.184 ms
Execution time: 0.160 ms

How can I count the rows with data in an Excel sheet?

You should use the sumif function in Excel:

=SUMIF(A5:C10;"Text_to_find";C5:C10)

This function takes a range like this square A5:C10 then you have some text to find this text can be in A or B then it will add the number from the C-row.

append new row to old csv file python

If the file exists and contains data, then it is possible to generate the fieldname parameter for csv.DictWriter automatically:

# read header automatically
with open(myFile, "r") as f:
    reader = csv.reader(f)
    for header in reader:
        break

# add row to CSV file
with open(myFile, "a", newline='') as f:
    writer = csv.DictWriter(f, fieldnames=header)
    writer.writerow(myDict)

Set textbox to readonly and background color to grey in jquery

Can add disable like below and can get data on submit. something like this .. DEMO

Html

<input type="hidden" name="email" value="email" />
<input type="text" id="dis" class="disable" value="email"   name="email" >

JS 

 $("#dis").attr('disabled','disabled');

CSS

    .disable { opacity : .35; background-color:lightgray; border:1px solid gray;}

Scroll RecyclerView to show selected item on top

what i did to restore the scroll position after refreshing the RecyclerView on button clicked:

if (linearLayoutManager != null) {

    index = linearLayoutManager.findFirstVisibleItemPosition();
    View v = linearLayoutManager.getChildAt(0);
    top = (v == null) ? 0 : (v.getTop() - linearLayoutManager.getPaddingTop());
    Log.d("TAG", "visible position " + " " + index);
}

else{
    index = 0;
}

linearLayoutManager = new LinearLayoutManager(getApplicationContext());
linearLayoutManager.scrollToPositionWithOffset(index, top);

getting the offset of the first visible item from the top before creating the linearLayoutManager object and after instantiating it the scrollToPositionWithOffset of the LinearLayoutManager object was called.

How to append data to div using JavaScript?

you can use jQuery. which make it very simple.

just download the jQuery file add jQuery into your HTML
or you can user online link:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>

and try this:

 $("#divID").append(data);

How to count the number of words in a sentence, ignoring numbers, punctuation and whitespace?

This is a simple word counter using regex. The script includes a loop which you can terminate it when you're done.

#word counter using regex
import re
while True:
    string =raw_input("Enter the string: ")
    count = len(re.findall("[a-zA-Z_]+", string))
    if line == "Done": #command to terminate the loop
        break
    print (count)
print ("Terminated")

How to cancel a pull request on github?

Super EASY way to close a Pull Request - LATEST!

  1. Navigate to the Original Repository where the pull request has been submitted to.
  2. Select the Pull requests tab
  3. Select your pull request that you wish to remove. This will open it up.
  4. Towards the bottom, just enter a valid comment for closure and press Close Pull Request button

enter image description here

Are querystring parameters secure in HTTPS (HTTP + SSL)?

Yes. The querystring is also encrypted with SSL. Nevertheless, as this article shows, it isn't a good idea to put sensitive information in the URL. For example:

URLs are stored in web server logs - typically the whole URL of each request is stored in a server log. This means that any sensitive data in the URL (e.g. a password) is being saved in clear text on the server

How to stop EditText from gaining focus at Activity startup in Android

EditText within a ListView does not work properly. It's better to use TableLayout with automatically generated rows when you are using EditText.

Best Practice: Software Versioning

I would use x.y.z kind of versioning

x - major release
y - minor release
z - build number

Changing minDate and maxDate on the fly using jQuery DatePicker

You have a couple of options...

1) You need to call the destroy() method not remove() so...

$('#date').datepicker('destroy');

Then call your method to recreate the datepicker object.

2) You can update the property of the existing object via

$('#date').datepicker('option', 'minDate', new Date(startDate));
$('#date').datepicker('option', 'maxDate', new Date(endDate));

or...

$('#date').datepicker('option', { minDate: new Date(startDate),
                                  maxDate: new Date(endDate) });

How do I enable saving of filled-in fields on a PDF form?

Open your PDF in Google Chrome. Edit the PDF as you want. Hit ctrl + p. Save as PDF to your desktop.

Accessing MVC's model property from Javascript

Contents of the Answer

1) How to access Model data in Javascript/Jquery code block in .cshtml file

2) How to access Model data in Javascript/Jquery code block in .js file

How to access Model data in Javascript/Jquery code block in .cshtml file

There are two types of c# variable (Model) assignments to JavaScript variable.

  1. Property assignment - Basic datatypes like int, string, DateTime (ex: Model.Name)
  2. Object assignment - Custom or inbuilt classes (ex: Model, Model.UserSettingsObj)

Lets look into the details of these two assignments.

For the rest of the answer lets consider the below AppUser Model as an example.

public class AppUser
{
    public string Name { get; set; }
    public bool IsAuthenticated { get; set; }
    public DateTime LoginDateTime { get; set; }
    public int Age { get; set; }
    public string UserIconHTML { get; set; }
}

And the values we assign this Model are

AppUser appUser = new AppUser
{
    Name = "Raj",
    IsAuthenticated = true,
    LoginDateTime = DateTime.Now,
    Age = 26,
    UserIconHTML = "<i class='fa fa-users'></i>"
};

Property assignment

Lets use different syntax for assignment and observe the results.

1) Without wrapping property assignment in quotes.

var Name = @Model.Name;  
var Age = @Model.Age;
var LoginTime = @Model.LoginDateTime; 
var IsAuthenticated = @Model.IsAuthenticated;   
var IconHtml = @Model.UserIconHTML;

enter image description here

As you can see there are couple of errors, Raj and True is considered to be javascript variables and since they dont exist its an variable undefined error. Where as for the dateTime varialble the error is unexpected number numbers cannot have special characters, The HTML tags are converted into its entity names so that the browser doesn't mix up your values and the HTML markup.

2) Wrapping property assignment in Quotes.

var Name = '@Model.Name';
var Age = '@Model.Age';
var LoginTime = '@Model.LoginDateTime';
var IsAuthenticated = '@Model.IsAuthenticated';
var IconHtml = '@Model.UserIconHTML';

enter image description here

The results are valid, So wrapping the property assignment in quotes gives us valid syntax. But note that the Number Age is now a string, So if you dont want that we can just remove the quotes and it will be rendered as a number type.

3) Using @Html.Raw but without wrapping it in quotes

 var Name = @Html.Raw(Model.Name);
 var Age = @Html.Raw(Model.Age);
 var LoginTime = @Html.Raw(Model.LoginDateTime);
 var IsAuthenticated = @Html.Raw(Model.IsAuthenticated);
 var IconHtml = @Html.Raw(Model.UserIconHTML);

enter image description here

The results are similar to our test case 1. However using @Html.Raw()on the HTML string did show us some change. The HTML is retained without changing to its entity names.

From the docs Html.Raw()

Wraps HTML markup in an HtmlString instance so that it is interpreted as HTML markup.

But still we have errors in other lines.

4) Using @Html.Raw and also wrapping it within quotes

var Name ='@Html.Raw(Model.Name)';
var Age = '@Html.Raw(Model.Age)';
var LoginTime = '@Html.Raw(Model.LoginDateTime)';
var IsAuthenticated = '@Html.Raw(Model.IsAuthenticated)';
var IconHtml = '@Html.Raw(Model.UserIconHTML)';

enter image description here

The results are good with all types. But our HTML data is now broken and this will break the scripts. The issue is because we are using single quotes ' to wrap the the data and even the data has single quotes.

We can overcome this issue with 2 approaches.

1) use double quotes " " to wrap the HTML part. As the inner data has only single quotes. (Be sure that after wrapping with double quotes there are no " within the data too)

  var IconHtml = "@Html.Raw(Model.UserIconHTML)";

2) Escape the character meaning in your server side code. Like

  UserIconHTML = "<i class=\"fa fa-users\"></i>"

Conclusion of property assignment

  • Use quotes for non numeric dataType.
  • Do Not use quotes for numeric dataType.
  • Use Html.Raw to interpret your HTML data as is.
  • Take care of your HTML data to either escape the quotes meaning in server side, Or use a different quote than in data during assignment to javascript variable.

Object assignment

Lets use different syntax for assignment and observe the results.

1) Without wrapping object assignment in quotes.

  var userObj = @Model;

enter image description here

When you assign a c# object to javascript variable the value of the .ToString() of that oject will be assigned. Hence the above result.

2 Wrapping object assignment in quotes

var userObj = '@Model';

enter image description here

3) Using Html.Raw without quotes.

   var userObj = @Html.Raw(Model);

enter image description here

4) Using Html.Raw along with quotes

   var userObj = '@Html.Raw(Model)';

enter image description here

The Html.Raw was of no much use for us while assigning a object to variable.

5) Using Json.Encode() without quotes

var userObj = @Json.Encode(Model); 

//result is like
var userObj = {&quot;Name&quot;:&quot;Raj&quot;,
               &quot;IsAuthenticated&quot;:true,
               &quot;LoginDateTime&quot;:&quot;\/Date(1482572875150)\/&quot;,
               &quot;Age&quot;:26,
               &quot;UserIconHTML&quot;:&quot;\u003ci class=\&quot;fa fa-users\&quot;\u003e\u003c/i\u003e&quot;
              };

We do see some change, We see our Model is being interpreted as a object. But we have those special characters changed into entity names. Also wrapping the above syntax in quotes is of no much use. We simply get the same result within quotes.

From the docs of Json.Encode()

Converts a data object to a string that is in the JavaScript Object Notation (JSON) format.

As you have already encountered this entity Name issue with property assignment and if you remember we overcame it with the use of Html.Raw. So lets try that out. Lets combine Html.Raw and Json.Encode

6) Using Html.Raw and Json.Encode without quotes.

var userObj = @Html.Raw(Json.Encode(Model));

Result is a valid Javascript Object

 var userObj = {"Name":"Raj",
     "IsAuthenticated":true,
     "LoginDateTime":"\/Date(1482573224421)\/",
     "Age":26,
     "UserIconHTML":"\u003ci class=\"fa fa-users\"\u003e\u003c/i\u003e"
 };

enter image description here

7) Using Html.Raw and Json.Encode within quotes.

var userObj = '@Html.Raw(Json.Encode(Model))';

enter image description here

As you see wrapping with quotes gives us a JSON data

Conslusion on Object assignment

  • Use Html.Raw and Json.Encode in combintaion to assign your object to javascript variable as JavaScript object.
  • Use Html.Raw and Json.Encode also wrap it within quotes to get a JSON

Note: If you have observed the DataTime data format is not right. This is because as said earlier Converts a data object to a string that is in the JavaScript Object Notation (JSON) format and JSON does not contain a date type. Other options to fix this is to add another line of code to handle this type alone using javascipt Date() object

var userObj.LoginDateTime = new Date('@Html.Raw(Model.LoginDateTime)'); 
//without Json.Encode

How to access Model data in Javascript/Jquery code block in .js file

Razor syntax has no meaning in .js file and hence we cannot directly use our Model insisde a .js file. However there is a workaround.

1) Solution is using javascript Global variables.

We have to assign the value to a global scoped javascipt variable and then use this variable within all code block of your .cshtml and .js files. So the syntax would be 

<script type="text/javascript">
  var userObj = @Html.Raw(Json.Encode(Model)); //For javascript object
  var userJsonObj = '@Html.Raw(Json.Encode(Model))'; //For json data
</script>

With this in place we can use the variables userObj and userJsonObj as and when needed.

Note: I personally dont suggest using global variables as it gets very hard for maintainance. However if you have no other option then you can use it with having a proper naming convention .. something like userAppDetails_global.

2) Using function() or closure Wrap all the code that is dependent on the model data in a function. And then execute this function from the .cshtml file .

external.js

 function userDataDependent(userObj){
  //.... related code
 }

.cshtml file

 <script type="text/javascript">
  userDataDependent(@Html.Raw(Json.Encode(Model))); //execute the function     
</script>

Note: Your external file must be referenced prior to the above script. Else the userDataDependent function is undefined.

Also note that the function must be in global scope too. So either solution we have to deal with global scoped players.

How to use range-based for() loop with std::map?

If you only want to see the keys/values from your map and like using boost, you can use the boost adaptors with the range based loops:

for (const auto& value : myMap | boost::adaptors::map_values)
{
    std::cout << value << std::endl;
}

there is an equivalent boost::adaptors::key_values

http://www.boost.org/doc/libs/1_51_0/libs/range/doc/html/range/reference/adaptors/reference/map_values.html

Enter key pressed event handler

In WPF, TextBox element will not get opportunity to use "Enter" button for creating KeyUp Event until you will not set property: AcceptsReturn="True".

But, it would`t solve the problem with handling KeyUp Event in TextBox element. After pressing "ENTER" you will get a new text line in TextBox.

I had solved problem of using KeyUp Event of TextBox element by using Bubble event strategy. It's short and easy. You have to attach a KeyUp Event handler in some (any) parent element:

XAML:

<Window x:Class="TextBox_EnterButtomEvent.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:TextBox_EnterButtomEvent"
    mc:Ignorable="d"
    Title="MainWindow" Height="350" Width="525">
<Grid KeyUp="Grid_KeyUp">
    <Grid.RowDefinitions>
        <RowDefinition/>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height ="0.3*"/>
        <RowDefinition Height="Auto"/>
        <RowDefinition Height="Auto"/>
        <RowDefinition/>
    </Grid.RowDefinitions>
    <Grid.ColumnDefinitions>
        <ColumnDefinition/>
        <ColumnDefinition/>
        <ColumnDefinition/>
    </Grid.ColumnDefinitions>
    <TextBlock Grid.Row="1" Grid.Column="1" Padding="0" TextWrapping="WrapWithOverflow">
        Input text end press ENTER:
    </TextBlock>
    <TextBox Grid.Row="2" Grid.Column="1" HorizontalAlignment="Stretch"/>
    <TextBlock Grid.Row="4" Grid.Column="1" Padding="0" TextWrapping="WrapWithOverflow">
        You have entered:
    </TextBlock>
    <TextBlock Name="txtBlock" Grid.Row="5" Grid.Column="1" HorizontalAlignment="Stretch"/>
</Grid></Window>

C# logical part (KeyUp Event handler is attached to a grid element):

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void Grid_KeyUp(object sender, KeyEventArgs e)
    {
        if(e.Key == Key.Enter)
        {
            TextBox txtBox = e.Source as TextBox;
            if(txtBox != null)
            {
                this.txtBlock.Text = txtBox.Text;
                this.txtBlock.Background = new SolidColorBrush(Colors.LightGray);
            }
        }
    }
}

Result:

Image with result

How to use Morgan logger?

Using morgan is pretty much straightforward. As the documentation suggests, there are different ways to get your desired output with morgan. It comes with preconfigured logging methods or you can define one yourself. Eg.

const morgan = require('morgan')

app.use(morgan('tiny')

This will give you the preconfiguration called tiny. You will notice in your terminal what it does. In case you are not satisfied with this and you want deeper e.g. lets say the request url, then this is where tokens come in.

morgan.token('url', function (req, res){ return '/api/myendpoint' })

then use it like so:

app.use(morgan(' :url ')

Check the documentation its all highlighted there.

How do I prevent mails sent through PHP mail() from going to spam?

There is no sure shot trick. You need to explore the reasons why your mails are classified as spam. SpamAssassin hase a page describing Some Tips for Legitimate Senders to Avoid False Positives. See also Coding Horror: So You'd Like to Send Some Email (Through Code)

Visual Studio Copy Project

If you want a copy, the fastest way of doing this would be to save the project. Then make a copy of the entire thing on the File System. Go back into Visual Studio and open the copy. From there, I would most likely recommend re-naming the project/solution so that you don't have two of the same name, but that is the fastest way to make a copy.

How to terminate the script in JavaScript?

There are many ways to exit a JS or Node script. Here are the most relevant:

// This will never exit!
setInterval((function() {  
    return;
}), 5000);

// This will exit after 5 seconds, with signal 1
setTimeout((function() {  
    return process.exit(1);
}), 5000);

// This will also exit after 5 seconds, and print its (killed) PID
setTimeout((function() {  
    return process.kill(process.pid);
}), 5000);

// This will also exit after 5 seconds and create a core dump.
setTimeout((function() {  
    return process.abort();
}), 5000);

If you're in the REPL (i.e. after running node on the command line), you can type .exit to exit.

Make xargs handle filenames that contain spaces

The xargs utility reads space, tab, newline and end-of-file delimited strings from the standard input and executes utility with the strings as arguments.

You want to avoid using space as a delimiter. This can be done by changing the delimiter for xargs. According to the manual:

 -0      Change xargs to expect NUL (``\0'') characters as separators,
         instead of spaces and newlines.  This is expected to be used in
         concert with the -print0 function in find(1).

Such as:

 find . -name "*.mp3" -print0 | xargs -0 mplayer

To answer the question about playing the seventh mp3; it is simpler to run

 mplayer "$(ls *.mp3 | sed -n 7p)"

What's the difference between SoftReference and WeakReference in Java?

This article can be super helpful to understand strong, soft, weak and phantom references.

To give you a summary,

If you only have weak references to an object (with no strong references), then the object will be reclaimed by GC in the very next GC cycle.

If you only have soft references to an object (with no strong references), then the object will be reclaimed by GC only when JVM runs out of memory.

So you can say that, strong references have ultimate power (can never be collected by GC)

Soft references are powerful than weak references (as they can escape GC cycle until JVM runs out of memory)

Weak references are even less powerful than soft references (as they cannot excape any GC cycle and will be reclaimed if object have no other strong reference).

Restaurant Analogy

  • Waiter - GC
  • You - Object in heap
  • Restaurant area/space - Heap space
  • New Customer - New object that wants table in restaurant

Now if you are a strong customer (analogous to strong reference), then even if a new customer comes in the restaurant or what so ever happnes, you will never leave your table (the memory area on heap). The waiter has no right to tell you (or even request you) to leave the restaurant.

If you are a soft customer (analogous to soft reference), then if a new customer comes in the restaurant, the waiter will not ask you to leave the table unless there is no other empty table left to accomodate the new customer. (In other words the waiter will ask you to leave the table only if a new customer steps in and there is no other table left for this new customer)

If you are a weak customer (analogous to weak reference), then waiter, at his will, can (at any point of time) ask you to leave the restaurant :P

How to view file history in Git?

Looks like you want git diff and/or git log. Also check out gitk

gitk path/to/file
git diff path/to/file
git log path/to/file

.setAttribute("disabled", false); changes editable attribute to false

Try doing this instead:

function enable(id)
{
    var eleman = document.getElementById(id);
    eleman.removeAttribute("disabled");        
}

To enable an element you have to remove the disabled attribute. Setting it to false still means it is disabled.

http://jsfiddle.net/SRK2c/

Why GDB jumps unpredictably between lines and prints variables as "<value optimized out>"?

Declare found as "volatile". This should tell the compiler to NOT optimize it out.

volatile int found = 0;

How to get cookie expiration date / creation date from javascript?

It's now possible with new chrome update for version 47 for 2016 , you can see it through developer tools on the resources tabenter image description here, select cookies and look for your cookie expiration date under "Expires/Max-age"

Create session factory in Hibernate 4

The method buildSessionFactory is deprecated from the Hibernate 4 release and it is replaced with the new API. If you are using the Hibernate 4.3.0 and above, your code has to be:

Configuration configuration = new Configuration().configure();

StandardServiceRegistryBuilder builder = new StandardServiceRegistryBuilder()
        .applySettings(configuration.getProperties());

SessionFactory factory = configuration.buildSessionFactory(builder.build());

HTML5 video (mp4 and ogv) problems in Safari and Firefox - but Chrome is all good

Just remove the inner quotes - they confuse Firefox. You can just use "video/ogg; codecs=theora,vorbis".

Also, that markup works in my Minefiled 3.7a5pre, so if your ogv file doesn't play, it may be a bogus file. How did you create it? You might want to register a bug with Firefox.

CLEAR SCREEN - Oracle SQL Developer shortcut?

In the Oracle SQL-plus:

shift+del

Java substring: 'string index out of range'

I"m guessing i'm getting this error because the string is trying to substring a Null value. But wouldn't the ".length() > 0" part eliminate that issue?

No, calling itemdescription.length() when itemdescription is null would not generate a StringIndexOutOfBoundsException, but rather a NullPointerException since you would essentially be trying to call a method on null.

As others have indicated, StringIndexOutOfBoundsException indicates that itemdescription is not at least 38 characters long. You probably want to handle both conditions (I assuming you want to truncate):

final String value;
if (itemdescription == null || itemdescription.length() <= 0) {
    value = "_";
} else if (itemdescription.length() <= 38) {
    value = itemdescription;
} else { 
    value = itemdescription.substring(0, 38);
}
pstmt2.setString(3, value);

Might be a good place for a utility function if you do that a lot...

How to convert string to XML using C#

 
string test = "<body><head>test header</head></body>";

XmlDocument xmltest = new XmlDocument();
xmltest.LoadXml(test);

XmlNodeList elemlist = xmltest.GetElementsByTagName("head");

string result = elemlist[0].InnerXml; 

//result -> "test header"

Add the loading screen in starting of the android application

use ProgressDialog.

ProgressDialog dialog=new ProgressDialog(context);
dialog.setMessage("message");
dialog.setCancelable(false);
dialog.setInverseBackgroundForced(false);
dialog.show();

hide it whenever your UI is ready with data. call : 

dialog.hide();

Pick any kind of file via an Intent in Android

This gives me the best result: 

    Intent intent;
    if (android.os.Build.MANUFACTURER.equalsIgnoreCase("samsung")) {
        intent = new Intent("com.sec.android.app.myfiles.PICK_DATA");
        intent.putExtra("CONTENT_TYPE", "*/*");
        intent.addCategory(Intent.CATEGORY_DEFAULT);
    } else {

        String[] mimeTypes =
                {"application/msword", "application/vnd.openxmlformats-officedocument.wordprocessingml.document", // .doc & .docx
                        "application/vnd.ms-powerpoint", "application/vnd.openxmlformats-officedocument.presentationml.presentation", // .ppt & .pptx
                        "application/vnd.ms-excel", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", // .xls & .xlsx
                        "text/plain",
                        "application/pdf",
                        "application/zip", "application/vnd.android.package-archive"};

        intent = new Intent(Intent.ACTION_GET_CONTENT); // or ACTION_OPEN_DOCUMENT
        intent.setType("*/*");
        intent.putExtra(Intent.EXTRA_MIME_TYPES, mimeTypes);
        intent.addCategory(Intent.CATEGORY_OPENABLE);
        intent.putExtra(Intent.EXTRA_LOCAL_ONLY, true);
    }

JavaScript - Get Browser Height

 
var winWidth = window.screen.width;
var winHeight = window.screen.height;

document.write(winWidth, winHeight);

Joining pandas dataframes by column names

you can use the left_on and right_on options as follows:

pd.merge(frame_1, frame_2, left_on='county_ID', right_on='countyid')

I was not sure from the question if you only wanted to merge if the key was in the left hand dataframe. If that is the case then the following will do that (the above will in effect do a many to many merge)

pd.merge(frame_1, frame_2, how='left', left_on='county_ID', right_on='countyid')

How can I analyze a heap dump in IntelliJ? (memory leak)

There also exists a 'JVM Debugger Memory View' found in the plugin repository, which could be useful.

Maven: How to change path to target directory from command line?

You should use profiles.

<profiles>
    <profile>
        <id>otherOutputDir</id>
        <build>
            <directory>yourDirectory</directory>
        </build>
    </profile>
</profiles>

And start maven with your profile

mvn compile -PotherOutputDir

If you really want to define your directory from the command line you could do something like this (NOT recommended at all) :

<properties>
    <buildDirectory>${project.basedir}/target</buildDirectory>
</properties>

<build>
    <directory>${buildDirectory}</directory>
</build>

And compile like this :

mvn compile -DbuildDirectory=test

That's because you can't change the target directory by using -Dproject.build.directory

How can I check if an ip is in a network in Python?

I don't know of anything in the standard library, but PySubnetTree is a Python library that will do subnet matching.

Best cross-browser method to capture CTRL+S with JQuery?

This was my solution, which is much easier to read than other suggestions here, can easily include other key combinations, and has been tested on IE, Chrome, and Firefox:

$(window).keydown(function(evt) {
    var key = String.fromCharCode(evt.keyCode);
    //ctrl+s
    if (key.toLowerCase() === "s" && evt.ctrlKey) {
        fnToRun();
        evt.preventDefault(true);
        return false;
    }
    return true;
});

jQuery see if any or no checkboxes are selected

You can use something like this

if ($("#formID input:checkbox:checked").length > 0)
{
    // any one is checked
}
else
{
   // none is checked
}

NameError: name 'datetime' is not defined

It can also be used as below:

from datetime import datetime
start_date = datetime(2016,3,1)
end_date = datetime(2016,3,10)

Read properties file outside JAR file

I did it by other way. 

Properties prop = new Properties();
    try {

        File jarPath=new File(MyClass.class.getProtectionDomain().getCodeSource().getLocation().getPath());
        String propertiesPath=jarPath.getParentFile().getAbsolutePath();
        System.out.println(" propertiesPath-"+propertiesPath);
        prop.load(new FileInputStream(propertiesPath+"/importer.properties"));
    } catch (IOException e1) {
        e1.printStackTrace();
    }
  1. Get Jar file path.
  2. Get Parent folder of that file.
  3. Use that path in InputStreamPath with your properties file name.

MySQL "Or" Condition

Wrap your AND logic in parenthesis, like this:

mysql_query("SELECT * FROM Drinks WHERE email='$Email' AND (date='$Date_Today' OR date='$Date_Yesterday' OR date='$Date_TwoDaysAgo' OR date='$Date_ThreeDaysAgo' OR date='$Date_FourDaysAgo' OR date='$Date_FiveDaysAgo' OR date='$Date_SixDaysAgo' OR date='$Date_SevenDaysAgo')");

Get random boolean in Java

You can use the following for an unbiased result:

Random random = new Random();
//For 50% chance of true
boolean chance50oftrue = (random.nextInt(2) == 0) ? true : false;

Note: random.nextInt(2) means that the number 2 is the bound. the counting starts at 0. So we have 2 possible numbers (0 and 1) and hence the probability is 50%!

If you want to give more probability to your result to be true (or false) you can adjust the above as following! 

Random random = new Random();

//For 50% chance of true
boolean chance50oftrue = (random.nextInt(2) == 0) ? true : false;

//For 25% chance of true
boolean chance25oftrue = (random.nextInt(4) == 0) ? true : false;

//For 40% chance of true
boolean chance40oftrue = (random.nextInt(5) < 2) ? true : false;

Center a position:fixed element

I used vw (viewport width) and vh (viewport height). viewport is your entire screen. 100vw is your screens total width and 100vh is total height. 

.class_name{
    width: 50vw;
    height: 50vh;
    border: 1px solid red;
    position: fixed;
    left: 25vw;top: 25vh;   
}

Which data structures and algorithms book should I buy?

If you want the algorithms to be implemented specifically in Java then there is Mitchell Waite's Series book "Data Structures & Algorithms in Java". It starts from basic data structures like linked lists, stacks and queues, and the basic algorithms for sorting and searching. Working your way through it you will eventually get to Tree data structures, Red-Black trees, 2-3 trees and Graphs.

All-in-all its not an extremely theoretical book, but if you just want an introduction in a language you are familiar with then its a good book. At the end of the day, if you want a deeper understanding of algorithms you're going to have to learn some of the more theoretical concepts, and read one of the classics, like Cormen/Leiserson/Rivest/Stein's Introduction to Algorithms.

Android "hello world" pushnotification example

you can follow this tutorial

http://www.androidbegin.com/tutorial/android-google-cloud-messaging-gcm-tutorial/

it helped me to do a push notification; or you can follow this other tutorial

http://www.tutorialeshtml5.com/2013/10/tutorial-simple-de-gcm-traves-de-php.html

but it's in spanish but you can download the code.

Random shuffling of an array

Here is a simple way using an ArrayList:

List<Integer> solution = new ArrayList<>();
for (int i = 1; i <= 6; i++) {
    solution.add(i);
}
Collections.shuffle(solution);

Issue with parsing the content from json file with Jackson & message- JsonMappingException -Cannot deserialize as out of START_ARRAY token

Your JSON string is malformed: the type of center is an array of invalid objects. Replace [ and ] with { and } in the JSON string around longitude and latitude so they will be objects:

[
    {
        "name" : "New York",
        "number" : "732921",
        "center" : {
                "latitude" : 38.895111, 
                "longitude" : -77.036667
            }
    },
    {
        "name" : "San Francisco",
        "number" : "298732",
        "center" : {
                "latitude" : 37.783333, 
                "longitude" : -122.416667
            }
    }
]

Populating a ListView using an ArrayList?

tutorial

Also look up ArrayAdapter interface:

ArrayAdapter(Context context, int textViewResourceId, List<T> objects)

Twitter Bootstrap 3.0 how do I "badge badge-important" now

Well, this is a terribly late answer but I think I'll still put my two cents in... I could have posted this as a comment because this answer doesn't essentially add any new solution but it does add value to the post as yet another alternative. But in a comment I wouldn't be able to give all the details because of character limit.

NOTE: This needs an edit to bootstrap CSS file - move style definitions for .badge above .label-default. Couldn't find any practical side effects due to the change in my limited testing.

While broc.seib's solution is probably the best way to achieve the requirement of OP with minimal addition to CSS, it is possible to achieve the same effect without any extra CSS at all just like Jens A. Koch's solution or by using .label-xxx contextual classes because they are easy to remember compared to progress-bar-xxx classes. I don't think that .alert-xxx classes give the same effect.

All you have to do is just use .badge and .label-xxx classes together (but in this order). Don't forget to make the changes mentioned in NOTE above.

<a href="#">Inbox <span class="badge label-warning">42</span></a> looks like this:

Badge with warning bg

IMPORTANT: This solution may break your styles if you decide to upgrade and forget to make the changes in your new local CSS file. My solution for this challenge was to copy all .label-xxx styles in my custom CSS file and load it after all other CSS files. This approach also helps when I use a CDN for loading BS3.

**P.S: ** Both the top rated answers have their pros and cons. It's just the way you prefer to do your CSS because there is no "only correct way" to do it.

Are there dictionaries in php?

Associative array in PHP actually considered as a dictionary.

An array in PHP is actually an ordered map. A map is a type that associates values to keys. it can be treated as an array, list (vector), hash table (an implementation of a map), dictionary, collection, stack, queue, and probably more.

<?php
$array = array(
    "foo" => "bar",
    "bar" => "foo",
);

// Using the short array syntax
$array = [
    "foo" => "bar",
    "bar" => "foo",
];
?>

An array is different than a dictionary in that arrays have both an index and a key. Dictionaries only have keys and no index.

SQLException: No suitable driver found for jdbc:derby://localhost:1527

Had the same, and it was solved by running with the classpath defining the derby.jar location.

java -cp <path-to-derby.jar> <Program>

To be more precise:

java -cp "lib/*:." Program

Where :. includes the current directory. And the lib/* does not include the jar extension (lib/*.jar).

Simple PHP Pagination script

 
 <?php
// Custom PHP MySQL Pagination Tutorial and Script
// You have to put your mysql connection data and alter the SQL queries(both queries)

mysql_connect("DATABASE_Host_Here","DATABASE_Username_Here","DATABASE_Password_Here") or die (mysql_error());
mysql_select_db("DATABASE_Name_Here") or die (mysql_error());
//////////////  QUERY THE MEMBER DATA INITIALLY LIKE YOU NORMALLY WOULD
$sql = mysql_query("SELECT id, firstname, country FROM myTable ORDER BY id ASC");
//////////////////////////////////// Pagination Logic ////////////////////////////////////////////////////////////////////////
$nr = mysql_num_rows($sql); // Get total of Num rows from the database query
if (isset($_GET['pn'])) { // Get pn from URL vars if it is present
    $pn = preg_replace('#[^0-9]#i', '', $_GET['pn']); // filter everything but numbers for security(new)
    //$pn = ereg_replace("[^0-9]", "", $_GET['pn']); // filter everything but numbers for security(deprecated)
} else { // If the pn URL variable is not present force it to be value of page number 1
    $pn = 1;
}
//This is where we set how many database items to show on each page
$itemsPerPage = 10;
// Get the value of the last page in the pagination result set
$lastPage = ceil($nr / $itemsPerPage);
// Be sure URL variable $pn(page number) is no lower than page 1 and no higher than $lastpage
if ($pn < 1) { // If it is less than 1
    $pn = 1; // force if to be 1
} else if ($pn > $lastPage) { // if it is greater than $lastpage
    $pn = $lastPage; // force it to be $lastpage's value
}
// This creates the numbers to click in between the next and back buttons
// This section is explained well in the video that accompanies this script
$centerPages = "";
$sub1 = $pn - 1;
$sub2 = $pn - 2;
$add1 = $pn + 1;
$add2 = $pn + 2;
if ($pn == 1) {
    $centerPages .= '&nbsp; <span class="pagNumActive">' . $pn . '</span> &nbsp;';
    $centerPages .= '&nbsp; <a href="' . $_SERVER['PHP_SELF'] . '?pn=' . $add1 . '">' . $add1 . '</a> &nbsp;';
} else if ($pn == $lastPage) {
    $centerPages .= '&nbsp; <a href="' . $_SERVER['PHP_SELF'] . '?pn=' . $sub1 . '">' . $sub1 . '</a> &nbsp;';
    $centerPages .= '&nbsp; <span class="pagNumActive">' . $pn . '</span> &nbsp;';
} else if ($pn > 2 && $pn < ($lastPage - 1)) {
    $centerPages .= '&nbsp; <a href="' . $_SERVER['PHP_SELF'] . '?pn=' . $sub2 . '">' . $sub2 . '</a> &nbsp;';
    $centerPages .= '&nbsp; <a href="' . $_SERVER['PHP_SELF'] . '?pn=' . $sub1 . '">' . $sub1 . '</a> &nbsp;';
    $centerPages .= '&nbsp; <span class="pagNumActive">' . $pn . '</span> &nbsp;';
    $centerPages .= '&nbsp; <a href="' . $_SERVER['PHP_SELF'] . '?pn=' . $add1 . '">' . $add1 . '</a> &nbsp;';
    $centerPages .= '&nbsp; <a href="' . $_SERVER['PHP_SELF'] . '?pn=' . $add2 . '">' . $add2 . '</a> &nbsp;';
} else if ($pn > 1 && $pn < $lastPage) {
    $centerPages .= '&nbsp; <a href="' . $_SERVER['PHP_SELF'] . '?pn=' . $sub1 . '">' . $sub1 . '</a> &nbsp;';
    $centerPages .= '&nbsp; <span class="pagNumActive">' . $pn . '</span> &nbsp;';
    $centerPages .= '&nbsp; <a href="' . $_SERVER['PHP_SELF'] . '?pn=' . $add1 . '">' . $add1 . '</a> &nbsp;';
}
// This line sets the "LIMIT" range... the 2 values we place to choose a range of rows from database in our query
$limit = 'LIMIT ' .($pn - 1) * $itemsPerPage .',' .$itemsPerPage;
// Now we are going to run the same query as above but this time add $limit onto the end of the SQL syntax
// $sql2 is what we will use to fuel our while loop statement below
$sql2 = mysql_query("SELECT id, firstname, country FROM myTable ORDER BY id ASC $limit");
//////////////////////////////// END Pagination Logic ////////////////////////////////////////////////////////////////////////////////
///////////////////////////////////// Pagination Display Setup /////////////////////////////////////////////////////////////////////
$paginationDisplay = ""; // Initialize the pagination output variable
// This code runs only if the last page variable is ot equal to 1, if it is only 1 page we require no paginated links to display
if ($lastPage != "1"){
    // This shows the user what page they are on, and the total number of pages
    $paginationDisplay .= 'Page <strong>' . $pn . '</strong> of ' . $lastPage. '&nbsp;  &nbsp;  &nbsp; ';
    // If we are not on page 1 we can place the Back button
    if ($pn != 1) {
        $previous = $pn - 1;
        $paginationDisplay .=  '&nbsp;  <a href="' . $_SERVER['PHP_SELF'] . '?pn=' . $previous . '"> Back</a> ';
    }
    // Lay in the clickable numbers display here between the Back and Next links
    $paginationDisplay .= '<span class="paginationNumbers">' . $centerPages . '</span>';
    // If we are not on the very last page we can place the Next button
    if ($pn != $lastPage) {
        $nextPage = $pn + 1;
        $paginationDisplay .=  '&nbsp;  <a href="' . $_SERVER['PHP_SELF'] . '?pn=' . $nextPage . '"> Next</a> ';
    }
}
///////////////////////////////////// END Pagination Display Setup ///////////////////////////////////////////////////////////////////////////
// Build the Output Section Here
$outputList = '';
while($row = mysql_fetch_array($sql2)){

    $id = $row["id"];
    $firstname = $row["firstname"];
    $country = $row["country"];

    $outputList .= '<h1>' . $firstname . '</h1><h2>' . $country . ' </h2><hr />';

} // close while loop
?>
<html>
<head>
<title>Simple Pagination</title>
</head>
<body>
   <div style="margin-left:64px; margin-right:64px;">
     <h2>Total Items: <?php echo $nr; ?></h2>
   </div>
      <div style="margin-left:58px; margin-right:58px; padding:6px; background-color:#FFF; border:#999 1px solid;"><?php echo $paginationDisplay; ?></div>
      <div style="margin-left:64px; margin-right:64px;"><?php print "$outputList"; ?></div>
      <div style="margin-left:58px; margin-right:58px; padding:6px; background-color:#FFF; border:#999 1px solid;"><?php echo $paginationDisplay; ?></div>
</body>
</html>

What is "android.R.layout.simple_list_item_1"?

as answered above by: kcoppock and Joril

go here : https://github.com/android/platform_frameworks_base/tree/master/core/res/res/layout

just right click the layout file you want, then select 'Save As', save somewhere, then copy it in 'layout' folder in your android project(eclipse)...

you can see how the layout looks like :)

way to go...

Set folder for classpath

If you are using Java 6 or higher you can use wildcards of this form:

java -classpath ".;c:\mylibs\*;c:\extlibs\*" MyApp

If you would like to add all subdirectories: lib\a\, lib\b\, lib\c\, there is no mechanism for this in except:

java -classpath ".;c:\lib\a\*;c:\lib\b\*;c:\lib\c\*" MyApp

There is nothing like lib\*\* or lib\** wildcard for the kind of job you want to be done.

Java Webservice Client (Best way)

You can find some resources related to developing web services client using Apache axis2 here.

http://today.java.net/pub/a/today/2006/12/13/invoking-web-services-using-apache-axis2.html

Below posts gives good explanations about developing web services using Apache axis2.

http://www.ibm.com/developerworks/opensource/library/ws-webaxis1/

http://wso2.org/library/136

Is SMTP based on TCP or UDP?

In theory SMTP can be handled by either TCP, UDP, or some 3rd party protocol.

As defined in RFC 821, RFC 2821, and RFC 5321:

SMTP is independent of the particular transmission subsystem and requires only a reliable ordered data stream channel.

In addition, the Internet Assigned Numbers Authority has allocated port 25 for both TCP and UDP for use by SMTP.

In practice however, most if not all organizations and applications only choose to implement the TCP protocol. For example, in Microsoft's port listing port 25 is only listed for TCP and not UDP.

The big difference between TCP and UDP that makes TCP ideal here is that TCP checks to make sure that every packet is received and re-sends them if they are not whereas UDP will simply send packets and not check for receipt. This makes UDP ideal for things like streaming video where every single packet isn't as important as keeping a continuous flow of packets from the server to the client.

Considering SMTP, it makes more sense to use TCP over UDP. SMTP is a mail transport protocol, and in mail every single packet is important. If you lose several packets in the middle of the message the recipient might not even receive the message and if they do they might be missing key information. This makes TCP more appropriate because it ensures that every packet is delivered.

Original purpose of <input type="hidden">?

I can only imagine of sending a value from the server to the client which is (unchanged) sent back to maintain a kind of a state.

Precisely. In fact, it's still being used for this purpose today because HTTP as we know it today is still, at least fundamentally, a stateless protocol.

This use case was actually first described in HTML 3.2 (I'm surprised HTML 2.0 didn't include such a description):

type=hidden
These fields should not be rendered and provide a means for servers to store state information with a form. This will be passed back to the server when the form is submitted, using the name/value pair defined by the corresponding attributes. This is a work around for the statelessness of HTTP. Another approach is to use HTTP "Cookies".

<input type=hidden name=customerid value="c2415-345-8563">

While it's worth mentioning that HTML 3.2 became a W3C Recommendation only after JavaScript's initial release, it's safe to assume that hidden fields have pretty much always served the same purpose.

How to use ng-repeat without an html element

If you use ng > 1.2, here is an example of using ng-repeat-start/end without generating unnecessary tags:

_x000D_
_x000D_ 
<html>_x000D_
  <head>_x000D_
    <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>_x000D_
    <script>_x000D_
      angular.module('mApp', []);_x000D_
    </script>_x000D_
  </head>_x000D_
  <body ng-app="mApp">_x000D_
    <table border="1" width="100%">_x000D_
      <tr ng-if="0" ng-repeat-start="elem in [{k: 'A', v: ['a1','a2']}, {k: 'B', v: ['b1']}, {k: 'C', v: ['c1','c2','c3']}]"></tr>_x000D_
_x000D_
      <tr>_x000D_
        <td rowspan="{{elem.v.length}}">{{elem.k}}</td>_x000D_
        <td>{{elem.v[0]}}</td>_x000D_
      </tr>_x000D_
      <tr ng-repeat="v in elem.v" ng-if="!$first">_x000D_
        <td>{{v}}</td>_x000D_
      </tr>_x000D_
_x000D_
      <tr ng-if="0" ng-repeat-end></tr>_x000D_
    </table>_x000D_
  </body>_x000D_
</html>
_x000D_
_x000D_
_x000D_

The important point: for tags used for ng-repeat-start and ng-repeat-end set ng-if="0", to let not be inserted in the page. In this way the inner content will be handled exactly as it is in knockoutjs (using commands in <!--...-->), and there will be no garbage.

How to generate and auto increment Id with Entity Framework

This is a guess :)

Is it because the ID is a string? What happens if you change it to int?

I mean:

 public int Id { get; set; }

What is the difference between a Relational and Non-Relational Database?

The difference between relational and non-relational is exactly that. The relational database architecture provides with constraints objects such as primary keys, foreign keys, etc that allows one to tie two or more tables in a relation. This is good so that we normalize our tables which is to say split information about what the database represents into many different tables, once can keep the integrity of the data.

For example, say you have a series of table that houses information about an employee. You could not delete a record from a table without deleting all the records that pertain to such record from the other tables. In this way you implement data integrity. The non-relational database doesn't provide this constraints constructs that will allow you to implement data integrity.

Unless you don't implement this constraint in the front end application that is utilized to populate the databases' tables, you are implementing a mess that can be compared with the wild west.

How do I download NLTK data?

you should add python to your PATH during installation of python...after installation.. open cmd prompt type command-pip install nltk then go to IDLE and open a new file..save it as file.py..then open file.py type the following: import nltk

nltk.download()

Bootstrap Carousel image doesn't align properly

Insert this on the css parent div class where your carousel is. 

<div class="parent_div">
     <div id="myCarousel" class="carousel slide">
            <div class="carousel-inner">
              <div class="item active">
                <img src="assets/img/slider_1.png" alt="">
                <div class="carousel-caption">
                </div>
              </div>
            </div>
     </div>      
</div>

CSS

.parent_div { 
margin: 0 auto;
min-width: [desired width];
max-width: [desired width];
}

How to set up fixed width for <td>?

For Bootstrap 4, you can simply use the class helper:

<table class="table">
  <thead>
    <tr>
      <td class="w-25">Col 1</td>
      <td class="w-25">Col 2</td>
      <td class="w-25">Col 3</td>
      <td class="w-25">Col 4</td>
    </tr>
  </thead>
  <tbody>
    <tr>
      ...

How to solve time out in phpmyadmin?

If any of you happen to use WAMP then at least in the current version (3.0.6 x64) there's a file located in <your-wamp-dir>\alias\phpmyadmin.conf which overrides some of your php.ini options.

Edit this part:

# To import big file you can increase values php_admin_value upload_max_filesize 512M php_admin_value post_max_size 512M php_admin_value max_execution_time 600 php_admin_value max_input_time 600

.bashrc: Permission denied

.bashrc is not meant to be executed but sourced. Try this instead:

. ~/.bashrc

Cheers!

How to Resize image in Swift?

Swift 4 Version

extension UIImage {
    func resizeImage(_ newSize: CGSize) -> UIImage? {
        func isSameSize(_ newSize: CGSize) -> Bool {
            return size == newSize
        }

        func scaleImage(_ newSize: CGSize) -> UIImage? {
            func getScaledRect(_ newSize: CGSize) -> CGRect {
                let ratio   = max(newSize.width / size.width, newSize.height / size.height)
                let width   = size.width * ratio
                let height  = size.height * ratio
                return CGRect(x: 0, y: 0, width: width, height: height)
            }

            func _scaleImage(_ scaledRect: CGRect) -> UIImage? {
                UIGraphicsBeginImageContextWithOptions(scaledRect.size, false, 0.0);
                draw(in: scaledRect)
                let image = UIGraphicsGetImageFromCurrentImageContext() ?? UIImage()
                UIGraphicsEndImageContext()
                return image
            }
            return _scaleImage(getScaledRect(newSize))
        }

        return isSameSize(newSize) ? self : scaleImage(newSize)!
    }
}

Apply CSS rules if browser is IE

I prefer using a separate file for ie rules, as described earlier.

<!--[if IE]><link rel="stylesheet" type="text/css" href="ie-style.css"/><![endif]-->

And inside it you can set up rules for different versions of ie using this:

.abc {...} /* ALL MSIE */
*html *.abc {...} /* MSIE 6 */
*:first-child+html .abc {...} /* MSIE 7 */

Centering image and text in R Markdown for a PDF report

There is now a much better solution, a lot more elegant, based on fenced div, which have been implemented in pandoc, as explained here:

::: {.center data-latex=""}
Some text here...
:::

All you need to do is to change your css file accordingly. The following chunk for instance does the job:

```{cat, engine.opts = list(file = "style.css")}
.center {
  text-align: center;
}
```

(Obviously, you can also directly type the content of the chunk into your .css file...).
The tex file includes the proper centering commands.
The crucial advantage of this method is that it allows writing markdown code inside the block.
In my previous answer, r ctrFmt("Centered **text** in html and pdf!") does not bold for the word "text", but it would if inside a fenced div.

For images, etc... the lua filter is available here

How to get only filenames within a directory using c#?

 
string[] fileEntries = Directory.GetFiles(directoryPath);

foreach (var file_name in fileEntries){
    string fileName = file_name.Substring(directoryPath.Length + 1);
    Console.WriteLine(fileName);
}

Project with path ':mypath' could not be found in root project 'myproject'

I got similar error after deleting a subproject, removed

"*compile project(path: ':MySubProject', configuration: 'android-endpoints')*"

in build.gradle (dependencies) under Gradle Scripts

Show popup after page load

Use this below code to display pop-up box on page load:

$(document).ready(function() { 
  var id = '#dialog';
  var maskHeight = $(document).height();
  var maskWidth = $(window).width();
  $('#mask').css({'width':maskWidth,'height':maskHeight}); 
  $('#mask').fadeIn(500); 
  $('#mask').fadeTo("slow",0.9); 
        var winH = $(window).height();
  var winW = $(window).width();
        $(id).css('top',  winH/2-$(id).height()/2);
  $(id).css('left', winW/2-$(id).width()/2);
     $(id).fadeIn(2000);  
     $('.window .close').click(function (e) {
  e.preventDefault();
  $('#mask').hide();
  $('.window').hide();
     });  
     $('#mask').click(function () {
  $(this).hide();
  $('.window').hide();
 });  

});

<div class="maintext">
<h2> Main text goes here...</h2>
</div>
<div id="boxes">
<div style="top: 50%; left: 50%; display: none;" id="dialog" class="window"> 
<div id="san">
<a href="#" class="close agree"><img src="close-icon.png" width="25" style="float:right; margin-right: -25px; margin-top: -20px;"></a>
<img src="san-web-corner.png" width="450">
</div>
</div>
<div style="width: 2478px; font-size: 32pt; color:white; height: 1202px; display: none; opacity: 0.4;" id="mask"></div>
</div>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.js"></script>

I refereed this code from here Demo

Call Javascript function from URL/address bar

You can use Data URIs. For example: data:text/html,<script>alert('hi');</script>

For more information visit: https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs

Setting size for icon in CSS

You could override the framework CSS (I guess you're using one) and set the size as you want, like this:

.pnx-msg-icon pnx-icon-msg-warning {
    width: 24px !important;
    height: 24px !important;
}

The "!important" property will make sure your code has priority to the framework's code. Make sure you are overriding the correct property, I don't know how the framework is working, this is just an example of !important usage.

How to destroy an object?

You're looking for unset().

But take into account that you can't explicitly destroy an object.

It will stay there, however if you unset the object and your script pushes PHP to the memory limits the objects not needed will be garbage collected. I would go with unset() (as opposed to setting it to null) as it seems to have better performance (not tested but documented on one of the comments from the PHP official manual).

That said, do keep in mind that PHP always destroys the objects as soon as the page is served. So this should only be needed on really long loops and/or heavy intensive pages.

Scala: what is the best way to append an element to an Array?

The easiest might be:

Array(1, 2, 3) :+ 4

Actually, Array can be implcitly transformed in a WrappedArray

How can I remove an element from a list, with lodash?

You can now use _.reject which allows you to filter based on what you need to get rid of, instead of what you need to keep.

unlike _.pull or _.remove that only work on arrays, ._reject is working on any Collection

obj.subTopics = _.reject(obj.subTopics, (o) => {
  return o.number >= 32;
});

Float vs Decimal in ActiveRecord

In Rails 4.1.0, I have faced problem with saving latitude and longitude to MySql database. It can't save large fraction number with float data type. And I change the data type to decimal and working for me. 

  def change
    change_column :cities, :latitude, :decimal, :precision => 15, :scale => 13
    change_column :cities, :longitude, :decimal, :precision => 15, :scale => 13
  end

How to get first character of a string in SQL?

It is simple to achieve by the following

DECLARE @SomeString NVARCHAR(20) = 'This is some string'
DECLARE @Result NVARCHAR(20)

Either

SET @Result = SUBSTRING(@SomeString, 2, 3)
SELECT @Result

@Result = his

or

SET @Result = LEFT(@SomeString, 6)
SELECT @Result

@Result = This i

Shrink to fit content in flexbox, or flex-basis: content workaround?

I want columns One and Two to shrink/grow to fit rather than being fixed.

Have you tried: flex-basis: auto

or this:

flex: 1 1 auto, which is short for:

  • flex-grow: 1 (grow proportionally)
  • flex-shrink: 1 (shrink proportionally)
  • flex-basis: auto (initial size based on content size)

or this:

main > section:first-child {
    flex: 1 1 auto;
    overflow-y: auto;
}

main > section:nth-child(2) {
    flex: 1 1 auto;
    overflow-y: auto;
}

main > section:last-child {
    flex: 20 1 auto;
    display: flex;
    flex-direction: column;  
}

revised demo

Related:

PostgreSQL "DESCRIBE TABLE"

Use the following SQL statement 

SELECT DATA_TYPE 
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE table_name = 'tbl_name' 
AND COLUMN_NAME = 'col_name'

If you replace tbl_name and col_name, it displays data type of the particular coloumn that you looking for.

How to edit an Android app?

Generally speaking, a software product isn't your "property already", as you said in the comment. Most of the times (I won't be irresponsible to say anything in open), it's licensed to you. A license to use some thing is not the same thing as owning (property rights) that very same thing.

That's because there are authorship, copyright, intellectual property rights applicable to it. I don't know how things work in United States (or in your country), but it's generally accepted that the work of a mind, a creative work, must not be changed in its nature as such to make the expression of art to be different than that expression that the author intended. That applies for example, in some cases, to architectural work (in most countries, you can't change the appearance of a building to "desfigure" the work of art of the architect, without his prior consent). Exceptions are made, obviously, when the author expressly authorizes such changes (e.g., Creative Commons licenses, open source licenses etc.).

Anyway, that's why you see in most EULAs the typical sentence: "this software is licensed, not sold". That's the purpose and reason why.

Now that you understand the reasons why you can't wander around changing other people's art, let me be technical.

There are possible ways to decompile Java programs. You can use dex2jar, it provides a somewhat good start for you to start looking for things and changes. And perhaps rebuild the code by mounting back the pieces together. Good luck, as most people obfuscate their codes to make that harder.

However, let me say that it's still forbidden to change programs, as I said above. And it's extremely unethical. It makes me sad that people do that with no scruples (not saying it's your case, just warning you). It shouldn't need people to be at the other side to understand that. Or maybe that's just me, who lives in a country where piracy is rampant.

The tools are always out there. But the conscience, unfortunately, not always.

edit: in case it isn't clear enough already, I do NOT approve the use of these programs. I use them myself to check how hard my own applications are to be reverse engineered. But I also think that explaning is always better than denial (better be here).

Checkbox Check Event Listener

Since I don't see the jQuery tag in the OP, here is a javascript only option :

document.addEventListener("DOMContentLoaded", function (event) {
    var _selector = document.querySelector('input[name=myCheckbox]');
    _selector.addEventListener('change', function (event) {
        if (_selector.checked) {
            // do something if checked
        } else {
            // do something else otherwise
        }
    });
});

See JSFIDDLE

How do I check CPU and Memory Usage in Java?

If you use the runtime/totalMemory solution that has been posted in many answers here (I've done that a lot), be sure to force two garbage collections first if you want fairly accurate/consistent results.

For effiency Java usually allows garbage to fill up all of memory before forcing a GC, and even then it's not usually a complete GC, so your results for runtime.freeMemory() always be somewhere between the "real" amount of free memory and 0.

The first GC doesn't get everything, it gets most of it.

The upswing is that if you just do the freeMemory() call you will get a number that is absolutely useless and varies widely, but if do 2 gc's first it is a very reliable gauge. It also makes the routine MUCH slower (seconds, possibly).

How can I shuffle an array?

You could use the Fisher-Yates Shuffle (code adapted from this site):

function shuffle(array) {
    let counter = array.length;

    // While there are elements in the array
    while (counter > 0) {
        // Pick a random index
        let index = Math.floor(Math.random() * counter);

        // Decrease counter by 1
        counter--;

        // And swap the last element with it
        let temp = array[counter];
        array[counter] = array[index];
        array[index] = temp;
    }

    return array;
}

How could I use requests in asyncio?

The answers above are still using the old Python 3.4 style coroutines. Here is what you would write if you got Python 3.5+.

aiohttp supports http proxy now

import aiohttp
import asyncio

async def fetch(session, url):
    async with session.get(url) as response:
        return await response.text()

async def main():
    urls = [
            'http://python.org',
            'https://google.com',
            'http://yifei.me'
        ]
    tasks = []
    async with aiohttp.ClientSession() as session:
        for url in urls:
            tasks.append(fetch(session, url))
        htmls = await asyncio.gather(*tasks)
        for html in htmls:
            print(html[:100])

if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    loop.run_until_complete(main())

What should a Multipart HTTP request with multiple files look like?

Well, note that the request contains binary data, so I'm not posting the request as such - instead, I've converted every non-printable-ascii character into a dot (".").

POST /cgi-bin/qtest HTTP/1.1
Host: aram
User-Agent: Mozilla/5.0 Gecko/2009042316 Firefox/3.0.10
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Referer: http://aram/~martind/banner.htm
Content-Type: multipart/form-data; boundary=2a8ae6ad-f4ad-4d9a-a92c-6d217011fe0f
Content-Length: 514

--2a8ae6ad-f4ad-4d9a-a92c-6d217011fe0f
Content-Disposition: form-data; name="datafile1"; filename="r.gif"
Content-Type: image/gif

GIF87a.............,...........D..;
--2a8ae6ad-f4ad-4d9a-a92c-6d217011fe0f
Content-Disposition: form-data; name="datafile2"; filename="g.gif"
Content-Type: image/gif

GIF87a.............,...........D..;
--2a8ae6ad-f4ad-4d9a-a92c-6d217011fe0f
Content-Disposition: form-data; name="datafile3"; filename="b.gif"
Content-Type: image/gif

GIF87a.............,...........D..;
--2a8ae6ad-f4ad-4d9a-a92c-6d217011fe0f--

Note that every line (including the last one) is terminated by a \r\n sequence.

Error in plot.new() : figure margins too large, Scatter plot

Just clear the plots and try executing the code again...It worked for me

Difference between try-catch and throw in java

All these keywords try, catch and throw are related to the exception handling concept in java. An exception is an event that occurs during the execution of programs. Exception disrupts the normal flow of an application. Exception handling is a mechanism used to handle the exception so that the normal flow of application can be maintained. Try-catch block is used to handle the exception. In a try block, we write the code which may throw an exception and in catch block we write code to handle that exception. Throw keyword is used to explicitly throw an exception. Generally, throw keyword is used to throw user defined exceptions.

For more detail visit Java tutorial for beginners.

ssh-copy-id no identities found error

In my case it was the missing .pub extension of a key. I pasted it from clipboard and saved as mykey. The following command returned described error:

ssh-copy-id -i mykey localhost

After renaming it with mv mykey mykey.pub, works correctly.

ssh-copy-id -i mykey.pub localhost

What is "export default" in JavaScript?

There are two different types of export, named and default. You can have multiple named exports per module but only one default export. Each type corresponds to one of the above. Source: MDN

Named Export

export class NamedExport1 { }

export class NamedExport2 { }

// Import class
import { NamedExport1 } from 'path-to-file'
import { NamedExport2 } from 'path-to-file'

// OR you can import all at once
import * as namedExports from 'path-to-file'

Default Export

export default class DefaultExport1 { }

// Import class
import DefaultExport1 from 'path-to-file' // No curly braces - {}

// You can use a different name for the default import

import Foo from 'path-to-file' // This will assign any default export to Foo.

Convert char* to string C++

 
std::string str(buffer, buffer + length);

Or, if the string already exists:

str.assign(buffer, buffer + length);

Edit: I'm still not completely sure I understand the question. But if it's something like what JoshG is suggesting, that you want up to length characters, or until a null terminator, whichever comes first, then you can use this:

std::string str(buffer, std::find(buffer, buffer + length, '\0'));

What is a Windows Handle?

A handle is a unique identifier for an object managed by Windows. It's like a pointer, but not a pointer in the sence that it's not an address that could be dereferenced by user code to gain access to some data. Instead a handle is to be passed to a set of functions that can perform actions on the object the handle identifies.

CSS 3 slide-in from left transition

Use CSS3 2D transform to avoid performance issues (mobile)

A common pitfall is to animate left/top/right/bottom properties instead of using to achieve the same effect. For a variety of reasons, the semantics of transforms make them easier to offload, but left/top/right/bottom are much more difficult.

Source: Mozilla Developer Network (MDN)

Demo:

_x000D_
_x000D_ 
var $slider = document.getElementById('slider');
var $toggle = document.getElementById('toggle');

$toggle.addEventListener('click', function() {
    var isOpen = $slider.classList.contains('slide-in');

    $slider.setAttribute('class', isOpen ? 'slide-out' : 'slide-in');
});
_x000D_ 
#slider {
    position: absolute;
    width: 100px;
    height: 100px;
    background: blue;
    transform: translateX(-100%);
    -webkit-transform: translateX(-100%);
}

.slide-in {
    animation: slide-in 0.5s forwards;
    -webkit-animation: slide-in 0.5s forwards;
}

.slide-out {
    animation: slide-out 0.5s forwards;
    -webkit-animation: slide-out 0.5s forwards;
}
    
@keyframes slide-in {
    100% { transform: translateX(0%); }
}

@-webkit-keyframes slide-in {
    100% { -webkit-transform: translateX(0%); }
}
    
@keyframes slide-out {
    0% { transform: translateX(0%); }
    100% { transform: translateX(-100%); }
}

@-webkit-keyframes slide-out {
    0% { -webkit-transform: translateX(0%); }
    100% { -webkit-transform: translateX(-100%); }
}
_x000D_ 
<div id="slider" class="slide-in">
    <ul>
        <li>Lorem</li>
        <li>Ipsum</li>
        <li>Dolor</li>
    </ul>
</div>

<button id="toggle" style="position:absolute; top: 120px;">Toggle</button>
_x000D_
_x000D_
_x000D_

How do you convert epoch time in C#?

In case you need to convert a timeval struct (seconds, microseconds) containing UNIX time to DateTime without losing precision, this is how:

DateTime _epochTime = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
private DateTime UnixTimeToDateTime(Timeval unixTime)
{
    return _epochTime.AddTicks(
        unixTime.Seconds * TimeSpan.TicksPerSecond +
        unixTime.Microseconds * TimeSpan.TicksPerMillisecond/1000);
}

How to write a PHP ternary operator

How to write a basic PHP Ternary Operator: 

($your_boolean) ? 'This is returned if true' : 'This is returned if false';

Example:

$myboolean = true;
echo ($myboolean) ? 'foobar' : "penguin";
foobar

echo (!$myboolean) ? 'foobar' : "penguin";
penguin

A PHP ternary operator with an 'elseif' crammed in there:

$chow = 3;
echo ($chow == 1) ? "one" : ($chow == 2) ? "two" : "three";
three

But please don't nest ternary operators except for parlor tricks. It's a bad code smell.

Optional Parameters in Web Api Attribute Routing

For an incoming request like /v1/location/1234, as you can imagine it would be difficult for Web API to automatically figure out if the value of the segment corresponding to '1234' is related to appid and not to deviceid.

I think you should change your route template to be like [Route("v1/location/{deviceOrAppid?}", Name = "AddNewLocation")] and then parse the deiveOrAppid to figure out the type of id.

Also you need to make the segments in the route template itself optional otherwise the segments are considered as required. Note the ? character in this case. For example: [Route("v1/location/{deviceOrAppid?}", Name = "AddNewLocation")]

How to delete all files and folders in a folder by cmd call

It takes 2 simple steps. [/q means quiet, /f means forced, /s means subdir]

  1. Empty out the directory to remove 

    del *.* /f/s/q

  2. Remove the directory 

    cd ..
rmdir dir_name /q/s

See picture

How to access static resources when mapping a global front controller servlet on /*

In section "12.2 Specification of Mappings" of the Servlet Specification, it says:

A string containing only the ’/’ character indicates the "default" servlet of the application.

So in theory, you could make your Servlet mapped to /* do:

getServletContext().getNamedDispatcher("/").forward(req,res);

... if you didn't want to handle it yourself.

However, in practice, it doesn't work.

In both Tomcat and Jetty, the call to getServletContext().getNamedDispatcher('/') returns null if there is a servlet mapped to '/*'

Generate list of all possible permutations of a string

Ruby answer that works:

class String
  def each_char_with_index
    0.upto(size - 1) do |index|
      yield(self[index..index], index)
    end
  end
  def remove_char_at(index)
    return self[1..-1] if index == 0
    self[0..(index-1)] + self[(index+1)..-1]
  end
end

def permute(str, prefix = '')
  if str.size == 0
    puts prefix
    return
  end
  str.each_char_with_index do |char, index|
    permute(str.remove_char_at(index), prefix + char)
  end
end

# example
# permute("abc")