Programs & Examples On #Webresource

Tomcat 8 throwing - org.apache.catalina.webresources.Cache.getResource Unable to add the resource

I had the same issue when upgrading from Tomcat 7 to 8: a continuous large flood of log warnings about cache.

1. Short Answer

Add this within the Context xml element of your $CATALINA_BASE/conf/context.xml:

<!-- The default value is 10240 kbytes, even when not added to context.xml.
So increase it high enough, until the problem disappears, for example set it to 
a value 5 times as high: 51200. -->
<Resources cacheMaxSize="51200" />

So the default is 10240 (10 mbyte), so set a size higher than this. Than tune for optimum settings where the warnings disappear. Note that the warnings may come back under higher traffic situations.

1.1 The cause (short explanation)

The problem is caused by Tomcat being unable to reach its target cache size due to cache entries that are less than the TTL of those entries. So Tomcat didn't have enough cache entries that it could expire, because they were too fresh, so it couldn't free enough cache and thus outputs warnings.

The problem didn't appear in Tomcat 7 because Tomcat 7 simply didn't output warnings in this situation. (Causing you and me to use poor cache settings without being notified.)

The problem appears when receiving a relative large amount of HTTP requests for resources (usually static) in a relative short time period compared to the size and TTL of the cache. If the cache is reaching its maximum (10mb by default) with more than 95% of its size with fresh cache entries (fresh means less than less than 5 seconds in cache), than you will get a warning message for each webResource that Tomcat tries to load in the cache.

1.2 Optional info

Use JMX if you need to tune cacheMaxSize on a running server without rebooting it.

The quickest fix would be to completely disable cache: <Resources cachingAllowed="false" />, but that's suboptimal, so increase cacheMaxSize as I just described.

2. Long Answer

2.1 Background information

A WebSource is a file or directory in a web application. For performance reasons, Tomcat can cache WebSources. The maximum of the static resource cache (all resources in total) is by default 10240 kbyte (10 mbyte). A webResource is loaded into the cache when the webResource is requested (for example when loading a static image), it's then called a cache entry. Every cache entry has a TTL (time to live), which is the time that the cache entry is allowed to stay in the cache. When the TTL expires, the cache entry is eligible to be removed from the cache. The default value of the cacheTTL is 5000 milliseconds (5 seconds).

There is more to tell about caching, but that is irrelevant for the problem.

2.2 The cause

The following code from the Cache class shows the caching policy in detail:

152  // Content will not be cached but we still need metadata size
153 long delta = cacheEntry.getSize();
154 size.addAndGet(delta);
156 if (size.get() > maxSize) {
157 // Process resources unordered for speed. Trades cache
158 // efficiency (younger entries may be evicted before older
159 // ones) for speed since this is on the critical path for
160 // request processing
161 long targetSize =
162 maxSize * (100 - TARGET_FREE_PERCENT_GET) / 100;
163 long newSize = evict(
164 targetSize, resourceCache.values().iterator());
165 if (newSize > maxSize) {
166 // Unable to create sufficient space for this resource
167 // Remove it from the cache
168 removeCacheEntry(path);
169 log.warn(sm.getString("cache.addFail", path));
170 }
171 }

When loading a webResource, the code calculates the new size of the cache. If the calculated size is larger than the default maximum size, than one or more cached entries have to be removed, otherwise the new size will exceed the maximum. So the code will calculate a "targetSize", which is the size the cache wants to stay under (as an optimum), which is by default 95% of the maximum. In order to reach this targetSize, entries have to be removed/evicted from the cache. This is done using the following code:

215  private long evict(long targetSize, Iterator<CachedResource> iter) {
217 long now = System.currentTimeMillis();
219 long newSize = size.get();
221 while (newSize > targetSize && iter.hasNext()) {
222 CachedResource resource = iter.next();
224 // Don't expire anything that has been checked within the TTL
225 if (resource.getNextCheck() > now) {
226 continue;
227 }
229 // Remove the entry from the cache
230 removeCacheEntry(resource.getWebappPath());
232 newSize = size.get();
233 }
235 return newSize;
236 }

So a cache entry is removed when its TTL is expired and the targetSize hasn't been reached yet.

After the attempt to free cache by evicting cache entries, the code will do:

165  if (newSize > maxSize) {
166 // Unable to create sufficient space for this resource
167 // Remove it from the cache
168 removeCacheEntry(path);
169 log.warn(sm.getString("cache.addFail", path));
170 }

So if after the attempt to free cache, the size still exceeds the maximum, it will show the warning message about being unable to free:

cache.addFail=Unable to add the resource at [{0}] to the cache for web application [{1}] because there was insufficient free space available after evicting expired cache entries - consider increasing the maximum size of the cache

2.3 The problem

So as the warning message says, the problem is

insufficient free space available after evicting expired cache entries - consider increasing the maximum size of the cache

If your web application loads a lot of uncached webResources (about maximum of cache, by default 10mb) within a short time (5 seconds), then you'll get the warning.

The confusing part is that Tomcat 7 didn't show the warning. This is simply caused by this Tomcat 7 code:

1606  // Add new entry to cache
1607 synchronized (cache) {
1608 // Check cache size, and remove elements if too big
1609 if ((cache.lookup(name) == null) && cache.allocate(entry.size)) {
1610 cache.load(entry);
1611 }
1612 }

combined with:

231  while (toFree > 0) {
232 if (attempts == maxAllocateIterations) {
233 // Give up, no changes are made to the current cache
234 return false;
235 }

So Tomcat 7 simply doesn't output any warning at all when it's unable to free cache, whereas Tomcat 8 will output a warning.

So if you are using Tomcat 8 with the same default caching configuration as Tomcat 7, and you got warnings in Tomcat 8, than your (and mine) caching settings of Tomcat 7 were performing poorly without warning.

2.4 Solutions

There are multiple solutions:

  1. Increase cache (recommended)
  2. Lower the TTL (not recommended)
  3. Suppress cache log warnings (not recommended)
  4. Disable cache

2.4.1. Increase cache (recommended)

As described here: http://tomcat.apache.org/tomcat-8.0-doc/config/resources.html

By adding <Resources cacheMaxSize="XXXXX" /> within the Context element in $CATALINA_BASE/conf/context.xml, where "XXXXX" stands for an increased cache size, specified in kbytes. The default is 10240 (10 mbyte), so set a size higher than this.

You'll have to tune for optimum settings. Note that the problem may come back when you suddenly have an increase in traffic/resource requests.

To avoid having to restart the server every time you want to try a new cache size, you can change it without restarting by using JMX.

To enable JMX, add this to $CATALINA_BASE/conf/server.xml within the Server element: <Listener className="org.apache.catalina.mbeans.JmxRemoteLifecycleListener" rmiRegistryPortPlatform="6767" rmiServerPortPlatform="6768" /> and download catalina-jmx-remote.jar from https://tomcat.apache.org/download-80.cgi and put it in $CATALINA_HOME/lib. Then use jConsole (shipped by default with the Java JDK) to connect over JMX to the server and look through the settings for settings to increase the cache size while the server is running. Changes in these settings should take affect immediately.

2.4.2. Lower the TTL (not recommended)

Lower the cacheTtl value by something lower than 5000 milliseconds and tune for optimal settings.

For example: <Resources cacheTtl="2000" />

This comes effectively down to having and filling a cache in ram without using it.

2.4.3. Suppress cache log warnings (not recommended)

Configure logging to disable the logger for org.apache.catalina.webresources.Cache.

For more info about logging in Tomcat: http://tomcat.apache.org/tomcat-8.0-doc/logging.html

2.4.4. Disable cache

You can disable the cache by setting cachingAllowed to false. <Resources cachingAllowed="false" />

Although I can remember that in a beta version of Tomcat 8, I was using JMX to disable the cache. (Not sure why exactly, but there may be a problem with disabling the cache via server.xml.)

java.lang.ClassNotFoundException: org.apache.jsp.index_jsp

In my case the problem is fixed by setting the right permissions for the tomcat home path:

cd /opt/apache-tomee-webprofile-7.1.0/
chown -R tomcat:tomcat *

How to add Headers on RESTful call using Jersey Client API

Try this!

Client client = ClientBuilder.newClient();

String jsonStr = client
            .target("http:....")
            .request(MediaType.APPLICATION_JSON)

            .header("WM_SVC.NAME", "RegistryService")
            .header("WM_QOS.CORRELATION_ID", "d1f0c0d2-2cf4-497b-b630-06d609d987b0")

            .get(String.class);

P.S You can add any number of headers like this!

Uri not Absolute exception getting while calling Restful Webservice

The problem is likely that you are calling URLEncoder.encode() on something that already is a URI.

How to send and receive JSON data from a restful webservice using Jersey API

The above problem can be solved by adding the following dependencies in your project, as i was facing the same problem.For more detail answer to this solution please refer link SEVERE:MessageBodyWriter not found for media type=application/xml type=class java.util.HashMap

    <dependency>
        <groupId>org.codehaus.jackson</groupId>
        <artifactId>jackson-mapper-asl</artifactId>
        <version>1.9.0</version>
    </dependency>


    <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.9.2</version>
    </dependency>   


    <dependency>
        <groupId>org.glassfish.jersey.media</groupId>
        <artifactId>jersey-media-json-jackson</artifactId>
        <version>2.25</version>
    </dependency>

Can not deserialize instance of java.util.ArrayList out of VALUE_STRING

Setting this attribute to ObjectMapper instance works,

objectMapper.enable(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY);

Jersey client: How to add a list as query parameter

i agree with you about alternative solutions which you mentioned above

1. Use POST instead of GET;
2. Transform the List into a JSON string and pass it to the service.

and its true that you can't add List to MultiValuedMap because of its impl class MultivaluedMapImpl have capability to accept String Key and String Value. which is shown in following figure

enter image description here

still you want to do that things than try following code.

Controller Class

package net.yogesh.test;

import java.util.List;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;

import com.google.gson.Gson;

@Path("test")
public class TestController {
       @Path("testMethod")
       @GET
       @Produces("application/text")
       public String save(
               @QueryParam("list") List<String> list) {

           return  new Gson().toJson(list) ;
       }
}

Client Class

package net.yogesh.test;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import javax.ws.rs.core.MultivaluedMap;

import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;
import com.sun.jersey.api.client.config.ClientConfig;
import com.sun.jersey.api.client.config.DefaultClientConfig;
import com.sun.jersey.core.util.MultivaluedMapImpl;

public class Client {
    public static void main(String[] args) {
        String op = doGet("http://localhost:8080/JerseyTest/rest/test/testMethod");
        System.out.println(op);
    }

    private static String doGet(String url){
        List<String> list = new ArrayList<String>();
        list = Arrays.asList(new String[]{"string1,string2,string3"});

        MultivaluedMap<String, String> params = new MultivaluedMapImpl();
        String lst = (list.toString()).substring(1, list.toString().length()-1);
        params.add("list", lst);

        ClientConfig config = new DefaultClientConfig();
        com.sun.jersey.api.client.Client client = com.sun.jersey.api.client.Client.create(config);
        WebResource resource = client.resource(url);

        ClientResponse response = resource.queryParams(params).type("application/x-www-form-urlencoded").get(ClientResponse.class);
        String en = response.getEntity(String.class);
        return en;
    }
}

hope this'll help you.

Jersey Exception : SEVERE: A message body reader for Java class

for Python and Swagger example:

import requests
base_url = 'https://petstore.swagger.io/v2'
def store_order(uid):
    api_url = f"{base_url}/store/order"
    api_data = {
        'id':uid,
        "petId": 0,
        "quantity": 0,
        "shipDate": "2020-04-08T07:56:05.832Z",
        "status": "placed",
        "complete": "true"
        }
    # is a kind of magic..
    r = requests.post(api_url, json=api_data)
    return r
print(store_order(0).content)    

Most important string with MIME type: r = requests.post(api_url, json=api_data)

How to access parameters in a RESTful POST method

Your @POST method should be accepting a JSON object instead of a string. Jersey uses JAXB to support marshaling and unmarshaling JSON objects (see the jersey docs for details). Create a class like:

@XmlRootElement
public class MyJaxBean {
    @XmlElement public String param1;
    @XmlElement public String param2;
}

Then your @POST method would look like the following:

@POST @Consumes("application/json")
@Path("/create")
public void create(final MyJaxBean input) {
    System.out.println("param1 = " + input.param1);
    System.out.println("param2 = " + input.param2);
}

This method expects to receive JSON object as the body of the HTTP POST. JAX-RS passes the content body of the HTTP message as an unannotated parameter -- input in this case. The actual message would look something like:

POST /create HTTP/1.1
Content-Type: application/json
Content-Length: 35
Host: www.example.com

{"param1":"hello","param2":"world"}

Using JSON in this way is quite common for obvious reasons. However, if you are generating or consuming it in something other than JavaScript, then you do have to be careful to properly escape the data. In JAX-RS, you would use a MessageBodyReader and MessageBodyWriter to implement this. I believe that Jersey already has implementations for the required types (e.g., Java primitives and JAXB wrapped classes) as well as for JSON. JAX-RS supports a number of other methods for passing data. These don't require the creation of a new class since the data is passed using simple argument passing.


HTML <FORM>

The parameters would be annotated using @FormParam:

@POST
@Path("/create")
public void create(@FormParam("param1") String param1,
                   @FormParam("param2") String param2) {
    ...
}

The browser will encode the form using "application/x-www-form-urlencoded". The JAX-RS runtime will take care of decoding the body and passing it to the method. Here's what you should see on the wire:

POST /create HTTP/1.1
Host: www.example.com
Content-Type: application/x-www-form-urlencoded;charset=UTF-8
Content-Length: 25

param1=hello&param2=world

The content is URL encoded in this case.

If you do not know the names of the FormParam's you can do the following:

@POST @Consumes("application/x-www-form-urlencoded")
@Path("/create")
public void create(final MultivaluedMap<String, String> formParams) {
    ...
}

HTTP Headers

You can using the @HeaderParam annotation if you want to pass parameters via HTTP headers:

@POST
@Path("/create")
public void create(@HeaderParam("param1") String param1,
                   @HeaderParam("param2") String param2) {
    ...
}

Here's what the HTTP message would look like. Note that this POST does not have a body.

POST /create HTTP/1.1
Content-Length: 0
Host: www.example.com
param1: hello
param2: world

I wouldn't use this method for generalized parameter passing. It is really handy if you need to access the value of a particular HTTP header though.


HTTP Query Parameters

This method is primarily used with HTTP GETs but it is equally applicable to POSTs. It uses the @QueryParam annotation.

@POST
@Path("/create")
public void create(@QueryParam("param1") String param1,
                   @QueryParam("param2") String param2) {
    ...
}

Like the previous technique, passing parameters via the query string does not require a message body. Here's the HTTP message:

POST /create?param1=hello&param2=world HTTP/1.1
Content-Length: 0
Host: www.example.com

You do have to be particularly careful to properly encode query parameters on the client side. Using query parameters can be problematic due to URL length restrictions enforced by some proxies as well as problems associated with encoding them.


HTTP Path Parameters

Path parameters are similar to query parameters except that they are embedded in the HTTP resource path. This method seems to be in favor today. There are impacts with respect to HTTP caching since the path is what really defines the HTTP resource. The code looks a little different than the others since the @Path annotation is modified and it uses @PathParam:

@POST
@Path("/create/{param1}/{param2}")
public void create(@PathParam("param1") String param1,
                   @PathParam("param2") String param2) {
    ...
}

The message is similar to the query parameter version except that the names of the parameters are not included anywhere in the message.

POST /create/hello/world HTTP/1.1
Content-Length: 0
Host: www.example.com

This method shares the same encoding woes that the query parameter version. Path segments are encoded differently so you do have to be careful there as well.


As you can see, there are pros and cons to each method. The choice is usually decided by your clients. If you are serving FORM-based HTML pages, then use @FormParam. If your clients are JavaScript+HTML5-based, then you will probably want to use JAXB-based serialization and JSON objects. The MessageBodyReader/Writer implementations should take care of the necessary escaping for you so that is one fewer thing that can go wrong. If your client is Java based but does not have a good XML processor (e.g., Android), then I would probably use FORM encoding since a content body is easier to generate and encode properly than URLs are. Hopefully this mini-wiki entry sheds some light on the various methods that JAX-RS supports.

Note: in the interest of full disclosure, I haven't actually used this feature of Jersey yet. We were tinkering with it since we have a number of JAXB+JAX-RS applications deployed and are moving into the mobile client space. JSON is a much better fit that XML on HTML5 or jQuery-based solutions.

A message body writer for Java type, class myPackage.B, and MIME media type, application/octet-stream, was not found

Make sure that all these libs are in your class path:

compile(group: 'com.sun.jersey', name: 'jersey-core',        version: '1.19.4') 
compile(group: 'com.sun.jersey', name: 'jersey-server',      version: '1.19.4') 
compile(group: 'com.sun.jersey', name: 'jersey-servlet',     version: '1.19.4')
compile(group: 'com.sun.jersey', name: 'jersey-json',        version: '1.19.4')
compile(group: 'com.sun.jersey', name: 'jersey-client',      version: '1.19.4')
compile(group: 'javax.ws.rs', name: 'jsr311-api', version: '1.1.1')
compile(group: 'org.codehaus.jackson', name: 'jackson-core-asl', version: '1.9.2')
compile(group: 'org.codehaus.jackson', name: 'jackson-mapper-asl', version: '1.9.2')
compile(group: 'org.codehaus.jackson', name: 'jackson-core-asl',   version: '1.9.2')
compile(group: 'org.codehaus.jackson', name: 'jackson-jaxrs',      version: '1.9.2')
compile(group: 'org.codehaus.jackson', name: 'jackson-xc',         version: '1.9.2')

Add "Pojo Mapping" and "Jackson Provider" to the jersey client config:

ClientConfig clientConfig = new DefaultClientConfig();
clientConfig.getFeatures().put(JSONConfiguration.FEATURE_POJO_MAPPING, Boolean.TRUE);
clientConfig.getClasses().add(JacksonJsonProvider.class);

This solve to me!

ClientResponse response = null;

response = webResource
        .type(MediaType.APPLICATION_JSON)
        .accept(MediaType.APPLICATION_JSON)
        .get(ClientResponse.class);


if (response.getStatus() == Response.Status.OK.getStatusCode()) {

    MyClass myclass = response.getEntity(MyClass.class);
    System.out.println(myclass);
}

Ignore self-signed ssl cert using Jersey Client

For Jersey 1.X

    TrustManager[] trustAllCerts = new TrustManager[]{new X509TrustManager() {

        public void checkClientTrusted(java.security.cert.X509Certificate[] chain, String authType) throws java.security.cert.CertificateException {}

        public void checkServerTrusted(java.security.cert.X509Certificate[] chain, String authType) throws java.security.cert.CertificateException {}

        public java.security.cert.X509Certificate[] getAcceptedIssuers() { 
            // or you can return null too
            return new java.security.cert.X509Certificate[0];
        }
    }};


    SSLContext sc = SSLContext.getInstance("TLS");
    sc.init(null, trustAllCerts, new SecureRandom());
    HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
    HttpsURLConnection.setDefaultHostnameVerifier(new HostnameVerifier() {
        public boolean verify(String string, SSLSession sslSession) {
            return true;
        }
    });

How do I get rid of an element's offset using CSS?

Just set the outline to none like this

[Identifier] { outline:none; }

Adding machineKey to web.config on web-farm sites

Make sure to learn from the padding oracle asp.net vulnerability that just happened (you applied the patch, right? ...) and use protected sections to encrypt the machine key and any other sensitive configuration.

An alternative option is to set it in the machine level web.config, so its not even in the web site folder.

To generate it do it just like the linked article in David's answer.

Using HTTPS with REST in Java

Check this out: http://code.google.com/p/resting/. I could use resting to consume HTTPS REST services.

What is the difference between server side cookie and client side cookie?

You probably mean the difference between Http Only cookies and their counter part?

Http Only cookies cannot be accessed (read from or written to) in client side JavaScript, only server side. If the Http Only flag is not set, or the cookie is created in (client side) JavaScript, the cookie can be read from and written to in (client side) JavaScript as well as server side.

Return a value of '1' a referenced cell is empty

Compare the cell with "" (empty line):

=IF(A1="",1,0)

How should I store GUID in MySQL tables?

if you have a char/varchar value formatted as the standard GUID, you can simply store it as BINARY(16) using the simple CAST(MyString AS BINARY16), without all those mind-boggling sequences of CONCAT + SUBSTR.

BINARY(16) fields are compared/sorted/indexed much faster than strings, and also take two times less space in the database

SELECT list is not in GROUP BY clause and contains nonaggregated column

As @Brian Riley already said you should either remove 1 column in your select

select countrylanguage.language ,sum(country.population*countrylanguage.percentage/100)
from countrylanguage
join country on countrylanguage.countrycode = country.code
group by countrylanguage.language
order by sum(country.population*countrylanguage.percentage) desc ;

or add it to your grouping

select countrylanguage.language, country.code, sum(country.population*countrylanguage.percentage/100)
from countrylanguage
join country on countrylanguage.countrycode = country.code
group by countrylanguage.language, country.code
order by sum(country.population*countrylanguage.percentage) desc ;

Sort array of objects by single key with date value

With this we can pass a key function to use for the sorting

Array.prototype.sortBy = function(key_func, reverse=false){
    return this.sort( (a, b) => {
        var keyA = key_func(a),
            keyB = key_func(b);
        if(keyA < keyB) return reverse? 1: -1;
        if(keyA > keyB) return reverse? -1: 1;
        return 0;
    }); 
}

Then for example if we have

var arr = [ {date: "01/12/00", balls: {red: "a8",  blue: 10}},
            {date: "12/13/05", balls: {red: "d6" , blue: 11}},
            {date: "03/02/04", balls: {red: "c4" , blue: 15}} ]

We can do

arr.sortBy(el => el.balls.red)
/* would result in
[ {date: "01/12/00", balls: {red: "a8", blue: 10}},
  {date: "03/02/04", balls: {red: "c4", blue: 15}},
  {date: "12/13/05", balls: {red: "d6", blue: 11}} ]
*/

or

arr.sortBy(el => new Date(el.date), true)   // second argument to reverse it
/* would result in
[ {date: "12/13/05", balls: {red: "d6", blue:11}},
  {date: "03/02/04", balls: {red: "c4", blue:15}},
  {date: "01/12/00", balls: {red: "a8", blue:10}} ]
*/

or

arr.sortBy(el => el.balls.blue + parseInt(el.balls.red[1]))
/* would result in
[ {date: "12/13/05", balls: {red: "d6", blue:11}},    // red + blue= 17
  {date: "01/12/00", balls: {red: "a8", blue:10}},    // red + blue= 18
  {date: "03/02/04", balls: {red: "c4", blue:15}} ]   // red + blue= 19
*/

Calling functions in a DLL from C++

When the DLL was created an import lib is usually automatically created and you should use that linked in to your program along with header files to call it but if not then you can manually call windows functions like LoadLibrary and GetProcAddress to get it working.

How to check if string input is a number?

Based on inspiration from answer. I defined a function as below. Looks like its working fine. Please let me know if you find any issue

def isanumber(inp):
    try:
        val = int(inp)
        return True
    except ValueError:
        try:
            val = float(inp)
            return True
        except ValueError:
            return False

How to specify maven's distributionManagement organisation wide?

Regarding the answer from Michael Wyraz, where you use alt*DeploymentRepository in your settings.xml or command on the line, be careful if you are using version 3.0.0-M1 of the maven-deploy-plugin (which is the latest version at the time of writing), there is a bug in this version that could cause a server authentication issue.

A workaround is as follows. In the value:

releases::default::https://YOUR_NEXUS_URL/releases

you need to remove the default section, making it:

releases::https://YOUR_NEXUS_URL/releases

The prior version 2.8.2 does not have this bug.

C#: How to access an Excel cell?

I think, that you have to declare the associated sheet!

Try something like this

objsheet(1).Cells[i,j].Value;

Capture characters from standard input without waiting for enter to be pressed

If you are on windows, you can use PeekConsoleInput to detect if there's any input,

HANDLE handle = GetStdHandle(STD_INPUT_HANDLE);
DWORD events;
INPUT_RECORD buffer;
PeekConsoleInput( handle, &buffer, 1, &events );

then use ReadConsoleInput to "consume" the input character ..

PeekConsoleInput(handle, &buffer, 1, &events);
if(events > 0)
{
    ReadConsoleInput(handle, &buffer, 1, &events);  
    return buffer.Event.KeyEvent.wVirtualKeyCode;
}
else return 0

to be honest this is from some old code I have, so you have to fiddle a bit with it.

The cool thing though is that it reads input without prompting for anything, so the characters are not displayed at all.

Zabbix server is not running: the information displayed may not be current

I was in the same trouble. For my case, that was a conflict between /etc/zabbix/zabbix_agentd.conf and zabbix_server.conf parameters. I adjusted

"DBHost=localhost", 
"DBName=zabbix",
"DBUser=zabbix",
"DBPassword=******", 
"DebugLevel=3"
"ListenPort".

If you run the default installation, you should keep ListenPort=10051 for the server and 10050 for the agent.

Cheers!

Remove a fixed prefix/suffix from a string in Bash

Using @Adrian Frühwirth answer:

function strip {
    local STRING=${1#$"$2"}
    echo ${STRING%$"$2"}
}

use it like this

HELLO=":hello:"
HELLO=$(strip "$HELLO" ":")
echo $HELLO # hello

Java - get the current class name?

The "$1" is not "useless non-sense". If your class is anonymous, a number is appended.

If you don't want the class itself, but its declaring class, then you can use getEnclosingClass(). For example:

Class<?> enclosingClass = getClass().getEnclosingClass();
if (enclosingClass != null) {
  System.out.println(enclosingClass.getName());
} else {
  System.out.println(getClass().getName());
}

You can move that in some static utility method.

But note that this is not the current class name. The anonymous class is different class than its enclosing class. The case is similar for inner classes.

blur vs focusout -- any real differences?

As stated in the JQuery documentation

The focusout event is sent to an element when it, or any element inside of it, loses focus. This is distinct from the blur event in that it supports detecting the loss of focus on descendant elements (in other words, it supports event bubbling).

await is only valid in async function

"await is only valid in async function"

But why? 'await' explicitly turns an async call into a synchronous call, and therefore the caller cannot be async (or asyncable) - at least, not because of the call being made at 'await'.

How to unset a JavaScript variable?

I am bit confused. If all you are wanting is for a variables value to not pass to another script then there is no need to delete the variable from the scope. Simply nullify the variable then explicit check if it is or is not null. Why go through the trouble of deleting the variable from scope? What purpose does this server that nullifying can not?

foo = null;
if(foo === null) or if(foo !== null)

Created Button Click Event c#

    public MainWindow()
    {
        // This button needs to exist on your form.
        myButton.Click += myButton_Click;
    }

    void myButton_Click(object sender, RoutedEventArgs e)
    {
        MessageBox.Show("Message here");
        this.Close();
    }

XPath using starts-with function

Try this

//ITEM/*[starts-with(text(),'2552')]/following-sibling::*

how to include js file in php?

Pekka has the correct answer (hence my making this answer a Community Wiki): Use src, not href, to specify the file.

Regarding:

When i try it this way:

<script type="text/javascript">
    document.write('<script type="text/javascript" src="datetimepicker_css.js"></script>');
</script>

the first tag in the document.write function closes
what is the correct way to do this?

You don't want or need document.write for this, but just in case you ever do need to put the characters </script> inside a script tag for some other reason: You do that by ensuring that the HTML parser (which doesn't understand JavaScript) doesn't see a literal </script>. There are a couple of ways of doing that. One way is to escape the / even though you don't need to:

<script type='text/javascript'>
alert("<\/script>"); // Works, HTML parser doesn't see this as a closing script tag
//      ^--- note the seemingly-unnecessary backslash
</script>

Or if you're feeling more paranoid:

<script type='text/javascript'>
alert("</scr" + "ipt>"); // Works, HTML parser doesn't see this as a closing script tag
</script>

...since in each case, JavaScript sees the string as </script> but the HTML parser doesn't.

Float sum with javascript

(parseFloat('2.3') + parseFloat('2.4')).toFixed(1);

its going to give you solution i suppose

What is the point of the diamond operator (<>) in Java 7?

This line causes the [unchecked] warning:

List<String> list = new LinkedList();

So, the question transforms: why [unchecked] warning is not suppressed automatically only for the case when new collection is created?

I think, it would be much more difficult task then adding <> feature.

UPD: I also think that there would be a mess if it were legally to use raw types 'just for a few things'.

Why does instanceof return false for some literals?

Primitives are a different kind of type than objects created from within Javascript. From the Mozilla API docs:

var color1 = new String("green");
color1 instanceof String; // returns true
var color2 = "coral";
color2 instanceof String; // returns false (color2 is not a String object)

I can't find any way to construct primitive types with code, perhaps it's not possible. This is probably why people use typeof "foo" === "string" instead of instanceof.

An easy way to remember things like this is asking yourself "I wonder what would be sane and easy to learn"? Whatever the answer is, Javascript does the other thing.

Pdf.js: rendering a pdf file using a base64 file source instead of url

According to the examples base64 encoding is directly supported, although I've not tested it myself. Take your base64 string (derived from a file or loaded with any other method, POST/GET, websockets etc), turn it to a binary with atob, and then parse this to getDocument on the PDFJS API likePDFJS.getDocument({data: base64PdfData}); Codetoffel answer does work just fine for me though.

datetime dtypes in pandas read_csv

You might try passing actual types instead of strings.

import pandas as pd
from datetime import datetime
headers = ['col1', 'col2', 'col3', 'col4'] 
dtypes = [datetime, datetime, str, float] 
pd.read_csv(file, sep='\t', header=None, names=headers, dtype=dtypes)

But it's going to be really hard to diagnose this without any of your data to tinker with.

And really, you probably want pandas to parse the the dates into TimeStamps, so that might be:

pd.read_csv(file, sep='\t', header=None, names=headers, parse_dates=True)

How to submit a form when the return key is pressed?

Here is how I do it with jQuery

j(".textBoxClass").keypress(function(e)
{
    // if the key pressed is the enter key
    if (e.which == 13)
    {
        // do work
    }
});

Other javascript wouldnt be too different. the catch is checking for keypress argument of "13", which is the enter key

Gradle Build Android Project "Could not resolve all dependencies" error

As Peter says, they won't be in Maven Central

from the Android SDK Manager download the 'Android Support Repository' and a Maven repo of the support libraries will be downloaded to your Android SDK directory (see 'extras' folder)

to deploy the libraries to your local .m2 repository you can use maven-android-sdk-deployer

2017 edit:

you can now reference the Google online M2 repo

repositories {
google()
jcenter()
}

iCheck check if checkbox is checked

I wrote some simple thing:

When you initialize icheck as:

$('input').iCheck({
    checkboxClass: 'icheckbox_square-blue',
    radioClass: 'iradio_square-blue',
    increaseArea: '20%' // optional
});

Add this code under it:

$('input').on('ifChecked', function (event){
    $(this).closest("input").attr('checked', true);          
});
$('input').on('ifUnchecked', function (event) {
    $(this).closest("input").attr('checked', false);
});

After this you can easily find your original checkbox's state. I wrote this code for using icheck in gridView and accessed its state from server side by C#.

Simply find your checkBox from its id.

how to add <script>alert('test');</script> inside a text box?

. I usually do it element.value="<script>alert('test');</script>".

If sounds like you are generating an inline <script> element, in which case the </script> will end the HTML element and cause the script to terminate in the middle of the string.

Escape the / so that it isn't treated as an end tag by the HTML parser:

element.value = "<script>alert('test');<\/script>"

How to convert int to date in SQL Server 2008

If your integer is timestamp in milliseconds use:

SELECT strftime("%Y-%d-%m", col_name, 'unixepoch') AS col_name

It will format milliseconds to yyyy-mm-dd string.

Fixed position but relative to container

Two HTML elements and pure CSS (modern browsers)

See this jsFiddle example. Resize and see how the fixed elements even move with the floated elements they are in. Use the inner-most scroll bar to see how the scroll would work on a site (fixed elements staying fixed).

As many here have stated, one key is not setting any positional settings on the fixed element (no top, right, bottom, or left values).

Rather, we put all the fixed elements (note how the last box has four of them) first in the box they are to be positioned off of, like so:

<div class="reference">
  <div class="fixed">Test</div>
  Some other content in.
</div>

Then we use margin-top and margin-left to "move" them in relation to their container, something like as this CSS does:

.fixed {
    position: fixed;
    margin-top: 200px; /* Push/pull it up/down */
    margin-left: 200px; /* Push/pull it right/left */
}

Note that because fixed elements ignore all other layout elements, the final container in our fiddle can have multiple fixed elements, and still have all those elements related to the top left corner. But this is only true if they are all placed first in the container, as this comparison fiddle shows that if dispersed within the container content, positioning becomes unreliable.

Whether the wrapper is static, relative, or absolute in positioning, it does not matter.

Selenium Webdriver: Entering text into text field

Agree with Subir Kumar Sao and Faiz.

element_enter.findElement(By.xpath("//html/body/div[1]/div[3]/div[1]/form/div/div/input")).sendKeys(barcode);

registerForRemoteNotificationTypes: is not supported in iOS 8.0 and later

I couldn't figure out what the "categories" NSSet variable should be set to, so if someone could fill me in I will gladly edit this post. The following does, however, bring up the push notification dialog.

[[UIApplication sharedApplication] registerForRemoteNotifications];
UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:(UIUserNotificationTypeBadge | UIUserNotificationTypeSound | UIUserNotificationTypeAlert) categories:nil];
[[UIApplication sharedApplication] registerUserNotificationSettings:settings];

Edit: I got a push notification to send to my phone with this code, so I'm not sure the categories parameter is necessary.

Nth max salary in Oracle

You can optimize the query using Dense_rank() function.

for Example :

select distinct salary from ( select salary ,dense_rank() over (order by salary desc) ranking from Employee ) where ranking = 6

Note: ranking 6 is the number of nth order.

How to restart tomcat 6 in ubuntu

if you are using extracted tomcat then,

startup.sh and shutdown.sh are two script located in TOMCAT/bin/ to start and shutdown tomcat, You could use that

if tomcat is installed then

/etc/init.d/tomcat5.5 start
/etc/init.d/tomcat5.5 stop
/etc/init.d/tomcat5.5 restart

Microsoft Visual C++ Compiler for Python 3.4

Visual Studio Community 2015 suffices to build extensions for Python 3.5. It's free but a 6 GB download (overkill). On my computer it installed vcvarsall at C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat

For Python 3.4 you'd need Visual Studio 2010. I don't think there's any free edition. See https://matthew-brett.github.io/pydagogue/python_msvc.html

How to use a different version of python during NPM install?

Ok, so you've found a solution already. Just wanted to share what has been useful to me so many times;

I have created setpy2 alias which helps me switch python.

alias setpy2="mkdir -p /tmp/bin; ln -s `which python2.7` /tmp/bin/python; export PATH=/tmp/bin:$PATH"

Execute setpy2 before you run npm install. The switch stays in effect until you quit the terminal, afterwards python is set back to system default.

You can make use of this technique for any other command/tool as well.

Two statements next to curly brace in an equation

That can be achieve in plain LaTeX without any specific package.

\documentclass{article}
\begin{document}
This is your only binary choices
\begin{math}
  \left\{
    \begin{array}{l}
      0\\
      1
    \end{array}
  \right.
\end{math}
\end{document}

This code produces something which looks what you seems to need.

curly braces in front of two lines

The same example as in the @Tombart can be obtained with similar code.

\documentclass{article}

\begin{document}

\begin{math}
  f(x)=\left\{
    \begin{array}{ll}
      1, & \mbox{if $x<0$}.\\
      0, & \mbox{otherwise}.
    \end{array}
  \right.
\end{math}

\end{document}

This code produces very similar results.

enter image description here

TypeScript: casting HTMLElement

TypeScript uses '<>' to surround casts, so the above becomes:

var script = <HTMLScriptElement>document.getElementsByName("script")[0];

However, unfortunately you cannot do:

var script = (<HTMLScriptElement[]>document.getElementsByName(id))[0];

You get the error

Cannot convert 'NodeList' to 'HTMLScriptElement[]'

But you can do :

(<HTMLScriptElement[]><any>document.getElementsByName(id))[0];

How can I get date in application run by node.js?

You would use the javascript date object:

MDN documentation for the Date object

var d = new Date();

Dictionary of dictionaries in Python?

Using collections.defaultdict is a big time-saver when you're building dicts and don't know beforehand which keys you're going to have.

Here it's used twice: for the resulting dict, and for each of the values in the dict.

import collections

def aggregate_names(errors):
    result = collections.defaultdict(lambda: collections.defaultdict(list))
    for real_name, false_name, location in errors:
        result[real_name][false_name].append(location)
    return result

Combining this with your code:

dictionary = aggregate_names(previousFunction(string))

Or to test:

EXAMPLES = [
    ('Fred', 'Frad', 123),
    ('Jim', 'Jam', 100),
    ('Fred', 'Frod', 200),
    ('Fred', 'Frad', 300)]
print aggregate_names(EXAMPLES)

JavaScriptSerializer - JSON serialization of enum as string

In .net core 3 this is now possible with the built-in classes in System.Text.Json (edit: System.Text.Json is also available as a NuGet package for .net core 2.0 and .net framework 4.7.2 and later versions according to the docs):

var person = new Person();
// Create and add a converter which will use the string representation instead of the numeric value.
var stringEnumConverter = new System.Text.Json.Serialization.JsonStringEnumConverter();
JsonSerializerOptions opts = new JsonSerializerOptions();
opts.Converters.Add(stringEnumConverter);
// Generate json string.
var json = JsonSerializer.Serialize<Person>(person, opts);

To configure JsonStringEnumConverter with attribute decoration for the specific property:

using System.Text.Json.Serialization;

[JsonConverter(typeof(JsonStringEnumConverter))]
public Gender Gender { get; set; }

If you want to always convert the enum as string, put the attribute at the enum itself.

[JsonConverter(typeof(JsonStringEnumConverter))] 
enum Gender { Male, Female }

Graphical DIFF programs for linux

If you use Vim, you can use the inbuilt diff functionality. vim -d file1 file2 takes you right into the diff screen, where you can do all sort of merge and deletes.

Scanner vs. StringTokenizer vs. String.Split

Let's start by eliminating StringTokenizer. It is getting old and doesn't even support regular expressions. Its documentation states:

StringTokenizer is a legacy class that is retained for compatibility reasons although its use is discouraged in new code. It is recommended that anyone seeking this functionality use the split method of String or the java.util.regex package instead.

So let's throw it out right away. That leaves split() and Scanner. What's the difference between them?

For one thing, split() simply returns an array, which makes it easy to use a foreach loop:

for (String token : input.split("\\s+") { ... }

Scanner is built more like a stream:

while (myScanner.hasNext()) {
    String token = myScanner.next();
    ...
}

or

while (myScanner.hasNextDouble()) {
    double token = myScanner.nextDouble();
    ...
}

(It has a rather large API, so don't think that it's always restricted to such simple things.)

This stream-style interface can be useful for parsing simple text files or console input, when you don't have (or can't get) all the input before starting to parse.

Personally, the only time I can remember using Scanner is for school projects, when I had to get user input from the command line. It makes that sort of operation easy. But if I have a String that I want to split up, it's almost a no-brainer to go with split().

How do I make HttpURLConnection use a proxy?

Since java 1.5 you can also pass a java.net.Proxy instance to the openConnection(proxy) method:

//Proxy instance, proxy ip = 10.0.0.1 with port 8080
Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("10.0.0.1", 8080));
conn = new URL(urlString).openConnection(proxy);

If your proxy requires authentication it will give you response 407.

In this case you'll need the following code:

    Authenticator authenticator = new Authenticator() {

        public PasswordAuthentication getPasswordAuthentication() {
            return (new PasswordAuthentication("user",
                    "password".toCharArray()));
        }
    };
    Authenticator.setDefault(authenticator);

Display the current time and date in an Android application

public class XYZ extends Activity {

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //setContentView(R.layout.main);

        Calendar c = Calendar.getInstance();
        System.out.println("Current time => "+c.getTime());

        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String formattedDate = df.format(c.getTime());
        // formattedDate have current date/time
        Toast.makeText(this, formattedDate, Toast.LENGTH_SHORT).show();


      // Now we display formattedDate value in TextView
        TextView txtView = new TextView(this);
        txtView.setText("Current Date and Time : "+formattedDate);
        txtView.setGravity(Gravity.CENTER);
        txtView.setTextSize(20);
        setContentView(txtView);
    }

}

enter image description here

CSS: Control space between bullet and <li>

You can use the padding-left attribute on the list items (not on the list itself!).

How to set selected value from Combobox?

try this

combobox.SelectedIndex = BindingSource.Item(9) where "9 = colum name 9 from table"

Find out free space on tablespace

I use this query

column "Tablespace" format a13
column "Used MB"    format 99,999,999
column "Free MB"    format 99,999,999
column "Total MB"   format 99,999,999
select
   fs.tablespace_name                          "Tablespace",
   (df.totalspace - fs.freespace)              "Used MB",
   fs.freespace                                "Free MB",
   df.totalspace                               "Total MB",
   round(100 * (fs.freespace / df.totalspace)) "Pct. Free"
from
   (select
      tablespace_name,
      round(sum(bytes) / 1048576) TotalSpace
   from
      dba_data_files
   group by
      tablespace_name
   ) df,
   (select
      tablespace_name,
      round(sum(bytes) / 1048576) FreeSpace
   from
      dba_free_space
   group by
      tablespace_name
   ) fs
where
   df.tablespace_name = fs.tablespace_name;

Most Pythonic way to provide global configuration variables in config.py?

How about using classes?

# config.py
class MYSQL:
    PORT = 3306
    DATABASE = 'mydb'
    DATABASE_TABLES = ['tb_users', 'tb_groups']

# main.py
from config import MYSQL

print(MYSQL.PORT) # 3306

How do I add a submodule to a sub-directory?

For those of you who share my weird fondness of manually editing config files, adding (or modifying) the following would also do the trick.

.git/config (personal config)

[submodule "cookbooks/apt"]
    url = https://github.com/opscode-cookbooks/apt

.gitmodules (committed shared config)

[submodule "cookbooks/apt"]
    path = cookbooks/apt
    url = https://github.com/opscode-cookbooks/apt

See this as well - difference between .gitmodules and specifying submodules in .git/config?

Laravel Password & Password_Confirmation Validation

I have used in this way.. Working fine!

 $inputs = request()->validate([
        'name' => 'required | min:6 | max: 20',
        'email' => 'required',
        'password' => 'required| min:4| max:7 |confirmed',
        'password_confirmation' => 'required| min:4'
  ]);

Parenthesis/Brackets Matching using Stack algorithm

Algorithm to use for checking well balanced parenthesis -

  1. Declare a map matchingParenMap and initialize it with closing and opening bracket of each type as the key-value pair respectively.
  2. Declare a set openingParenSet and initialize it with the values of matchingParenMap.
  3. Declare a stack parenStack which will store the opening brackets '{', '(', and '['.
  4. Now traverse the string expression input.

    1. If the current character is an opening bracket ( '{', '(', '[' ) then push it to the parenStack.

    2. If the current character is a closing bracket ( '}', ')', ']' ) then pop from parenStack and if the popped character is equal to the matching starting bracket in matchingParenMap then continue looping else return false.

  5. After complete traversal if no opening brackets are left in parenStack it means it is a well balanced expression.

I have explained the code snippet of the algorithm used on my blog. Check link - http://hetalrachh.home.blog/2019/12/25/stack-data-structure/

Selecting element by data attribute with jQuery

Native JS Examples

Get NodeList of elements

var elem = document.querySelectorAll('[data-id="container"]')

html: <div data-id="container"></div>

Get the first element

var firstElem = document.querySelector('[id="container"]')

html: <div id="container"></div>

Target a collection of nodes which returns a nodelist

document.getElementById('footer').querySelectorAll('[data-id]')

html:

<div class="footer">
    <div data-id="12"></div>
    <div data-id="22"></div>
</div>

Get elements based on multiple (OR) data values

document.querySelectorAll('[data-section="12"],[data-selection="20"]')

html:

<div data-selection="20"></div>
<div data-section="12"></div>

Get elements based on combined (AND) data values

document.querySelectorAll('[data-prop1="12"][data-prop2="20"]')

html:

<div data-prop1="12" data-prop2="20"></div>

Get items where the value starts with

document.querySelectorAll('[href^="https://"]')

How to force garbage collector to run?

You do not want to force the garbage collector to run.

However, if you ever did (as a purely academic exercise, of course):

GC.Collect()

getting exception "IllegalStateException: Can not perform this action after onSaveInstanceState"

this worked for me... found this out on my own... hope it helps you!

1) do NOT have a global "static" FragmentManager / FragmentTransaction.

2) onCreate, ALWAYS initialize the FragmentManager again!

sample below :-

public abstract class FragmentController extends AnotherActivity{
protected FragmentManager fragmentManager;
protected FragmentTransaction fragmentTransaction;
protected Bundle mSavedInstanceState;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mSavedInstanceState = savedInstanceState;
    setDefaultFragments();
}

protected void setDefaultFragments() {
    fragmentManager = getSupportFragmentManager();
    //check if on orientation change.. do not re-add fragments!
    if(mSavedInstanceState == null) {
        //instantiate the fragment manager

        fragmentTransaction = fragmentManager.beginTransaction();

        //the navigation fragments
        NavigationFragment navFrag = new NavigationFragment();
        ToolbarFragment toolFrag = new ToolbarFragment();

        fragmentTransaction.add(R.id.NavLayout, navFrag, "NavFrag");
        fragmentTransaction.add(R.id.ToolbarLayout, toolFrag, "ToolFrag");
        fragmentTransaction.commitAllowingStateLoss();

        //add own fragment to the nav (abstract method)
        setOwnFragment();
    }
}

AlertDialog styling - how to change style (color) of title, message, etc

Remove the panel background

 <item name="android:windowBackground">@color/transparent_color</item> 
 <color name="transparent_color">#00000000</color>

This is Mystyle:

 <style name="ThemeDialogCustom">
    <item name="android:windowFrame">@null</item>
    <item name="android:windowIsFloating">true</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowAnimationStyle">@android:style/Animation.Dialog</item>
    <item name="android:windowBackground">@color/transparent_color</item>
    <item name="android:windowSoftInputMode">stateUnspecified|adjustPan</item>
    <item name="android:colorBackgroundCacheHint">@null</item>
</style>

Which i have added to the constructor.

Add textColor :

<item name="android:textColor">#ff0000</item>

How to specify the download location with wget?

From the manual page:

-P prefix
--directory-prefix=prefix
           Set directory prefix to prefix.  The directory prefix is the
           directory where all other files and sub-directories will be
           saved to, i.e. the top of the retrieval tree.  The default
           is . (the current directory).

So you need to add -P /tmp/cron_test/ (short form) or --directory-prefix=/tmp/cron_test/ (long form) to your command. Also note that if the directory does not exist it will get created.

Fill background color left to right CSS

If you are like me and need to change color of text itself also while in the same time filling the background color check my solution.

Steps to create:

  1. Have two text, one is static colored in color on hover, and the other one in default state color which you will be moving on hover
  2. On hover move wrapper of the not static one text while in the same time move inner text of that wrapper to the opposite direction.
  3. Make sure to add overflow hidden where needed

Good thing about this solution:

  • Support IE9, uses only transform
  • Button (or element you are applying animation) is fluid in width, so no fixed values are being used here

Not so good thing about this solution:

  • A really messy markup, could be solved by using pseudo elements and att(data)?
  • There is some small glitch in animation when having more then one button next to each other, maybe it could be easily solved but I didn't take much time to investigate yet.

Check the pen ---> https://codepen.io/nikolamitic/pen/vpNoNq

<button class="btn btn--animation-from-right">
  <span class="btn__text-static">Cover left</span>
  <div class="btn__text-dynamic">
    <span class="btn__text-dynamic-inner">Cover left</span>
  </div>
</button>

.btn {
  padding: 10px 20px;
  position: relative;

  border: 2px solid #222;
  color: #fff;
  background-color: #222;
  position: relative;

  overflow: hidden;
  cursor: pointer;

  text-transform: uppercase;
  font-family: monospace;
  letter-spacing: -1px;

  [class^="btn__text"] {
    font-size: 24px;
  }

  .btn__text-dynamic,
  .btn__text-dynamic-inner {    
    display: flex;
    justify-content: center;
    align-items: center;

    position: absolute;
    top:0;
    left:0;
    right:0;
    bottom:0;
    z-index: 2;

    transition: all ease 0.5s;
  }

  .btn__text-dynamic {
    background-color: #fff;
    color: #222;

    overflow: hidden;
  }

  &:hover {
    .btn__text-dynamic {
      transform: translateX(-100%);
    }
    .btn__text-dynamic-inner {
      transform: translateX(100%);
    }
  }
}

.btn--animation-from-right {
    &:hover {
    .btn__text-dynamic {
      transform: translateX(100%);
    }
    .btn__text-dynamic-inner {
      transform: translateX(-100%);
    }
  }
}

You can remove .btn--animation-from-right modifier if you want to animate to the left.

Update query using Subquery in Sql Server

because you are just learning I suggest you practice converting a SELECT joins to UPDATE or DELETE joins. First I suggest you generate a SELECT statement joining these two tables:

SELECT *
FROM    tempDataView a
        INNER JOIN tempData b
            ON a.Name = b.Name

Then note that we have two table aliases a and b. Using these aliases you can easily generate UPDATE statement to update either table a or b. For table a you have an answer provided by JW. If you want to update b, the statement will be:

UPDATE  b
SET     b.marks = a.marks
FROM    tempDataView a
        INNER JOIN tempData b
            ON a.Name = b.Name

Now, to convert the statement to a DELETE statement use the same approach. The statement below will delete from a only (leaving b intact) for those records that match by name:

DELETE a
FROM    tempDataView a
        INNER JOIN tempData b
            ON a.Name = b.Name

You can use the SQL Fiddle created by JW as a playground

Permissions for /var/www/html

I have just been in a similar position with regards to setting the 777 permissions on the apache website hosting directory. After a little bit of tinkering it seems that changing the group ownership of the folder to the "apache" group allowed access to the folder based on the user group.

1) make sure that the group ownership of the folder is set to the group apache used / generates for use. (check /etc/groups, mine was www-data on Ubuntu)

2) set the folder permissions to 774 to stop "everyone" from having any change access, but allowing the owner and group permissions required.

3) add your user account to the group that has permission on the folder (mine was www-data).

Windows batch script to unhide files hidden by virus

this will unhide all files and folders on your computer

attrib -r -s -h /S /D

TCPDF Save file to folder?

You may try;

$this->Output(/path/to/file);

So for you, it will be like;

$this->Output(/kuitit/);  //or try ("/kuitit/")

Changing Shell Text Color (Windows)

This is extremely simple! Rather than importing odd modules for python or trying long commands you can take advantage of windows OS commands.

In windows, commands exist to change the command prompt text color. You can use this in python by starting with a: import os

Next you need to have a line changing the text color, place it were you want in your code. os.system('color 4')

You can figure out the other colors by starting cmd.exe and typing color help.

The good part? Thats all their is to it, to simple lines of code. -Day

Persist javascript variables across pages?

You can use http://rhaboo.org as a wrapper around localStorage. It stores complex objects but doesn't merely stringify and parse the whole thing like most such libraries do. That's really inefficient if you want to store a lot of data and add to it or change it in small chunks. Also, JSON discards a lot of important stuff like non-numerical properties of arrays.

In rhaboo you can write things like this:

var store = Rhaboo.persistent('Some name');

store.write('count', store.count ? store.count+1 : 1);

var laststamp = store.stamp ? store.stamp.toString() : "never";
store.write('stamp', new Date());

store.write('somethingfancy', {
  one: ['man', 'went'],
  2: 'mow',
  went: [  2, { mow: ['a', 'meadow' ] }, {}  ]
});

store.somethingfancy.went[1].mow.write(1, 'lawn');
console.log( store.somethingfancy.went[1].mow[1] ); //says lawn

BTW, I wrote rhaboo

Scroll to the top of the page using JavaScript?

Just Try, no need other plugin / frameworks

_x000D_
_x000D_
document.getElementById("jarscroolbtn").addEventListener("click", jarscrollfunction);_x000D_
_x000D_
function jarscrollfunction() {_x000D_
  var body = document.body; // For Safari_x000D_
  var html = document.documentElement; // Chrome, Firefox, IE and Opera _x000D_
  body.scrollTop = 0; _x000D_
  html.scrollTop = 0;_x000D_
}
_x000D_
<button id="jarscroolbtn">Scroll contents</button> 
_x000D_
_x000D_
_x000D_
_x000D_
_x000D_
html, body {_x000D_
  scroll-behavior: smooth;_x000D_
}
_x000D_
_x000D_
_x000D_

How to create a DateTime equal to 15 minutes ago?

If you are using time.time() and wants timestamp as output

Simply use

CONSTANT_SECONDS = 900 # time  in seconds (900 seconds = 15 min)

current_time = int(time.time())
time_before_15_min = current_time - CONSTANT_SECONDS

You can change 900 seconds as per your required time.

Get nodes where child node contains an attribute

Try

//book[title/@lang = 'it']

This reads:

  • get all book elements
    • that have at least one title
      • which has an attribute lang
        • with a value of "it"

You may find this helpful — it's an article entitled "XPath in Five Paragraphs" by Ronald Bourret.

But in all honesty, //book[title[@lang='it']] and the above should be equivalent, unless your XPath engine has "issues." So it could be something in the code or sample XML that you're not showing us -- for example, your sample is an XML fragment. Could it be that the root element has a namespace, and you aren't counting for that in your query? And you only told us that it didn't work, but you didn't tell us what results you did get.

install / uninstall APKs programmatically (PackageManager vs Intents)

Android P+ requires this permission in AndroidManifest.xml

<uses-permission android:name="android.permission.REQUEST_DELETE_PACKAGES" />

Then:

Intent intent = new Intent(Intent.ACTION_DELETE);
intent.setData(Uri.parse("package:com.example.mypackage"));
startActivity(intent);

to uninstall. Seems easier...

How to check if ping responded or not in a batch file

Simple version:

for /F "delims==, tokens=4" %a IN ('ping -n 2 127.0.0.1 ^| findstr /R "^Packets: Sent =.$"') DO (

if %a EQU 2 (
echo Success
) ELSE (
echo FAIL
)

)

But sometimes first ping just fail and second one work (or vice versa) right? So we want to get success when at least one ICMP reply has been returned successfully:

for /F "delims==, tokens=4" %a IN ('ping -n 2 192.168.1.1 ^| findstr /R "^Packets: Sent =.$"') DO (

if %a EQU 2 (
echo Success
) ELSE (
if %a EQU 1 (
echo Success
) ELSE (
echo FAIL
)
)

)

How to see indexes for a database or table in MySQL?

If you want to see all indexes across all databases all at once:

use information_schema;
SELECT * FROM statistics;

How to declare a type as nullable in TypeScript?

Union type is in my mind best option in this case:

interface Employee{
   id: number;
   name: string;
   salary: number | null;
}

// Both cases are valid
let employe1: Employee = { id: 1, name: 'John', salary: 100 };
let employe2: Employee = { id: 1, name: 'John', salary: null };

EDIT : For this to work as expected, you should enable the strictNullChecks in tsconfig.

How can I create a copy of an Oracle table without copying the data?

WHERE 1 = 0 or similar false conditions work, but I dislike how they look. Marginally cleaner code for Oracle 12c+ IMHO is

CREATE TABLE bar AS SELECT * FROM foo FETCH FIRST 0 ROWS ONLY;

Same limitations apply: only column definitions and their nullability are copied into a new table.

Please explain about insertable=false and updatable=false in reference to the JPA @Column annotation

You would do that when the responsibility of creating/updating the referenced column isn't in the current entity, but in another entity.

How to add a margin to a table row <tr>

I know this is kind of old, but I just got something along the same lines to work. Couldn't you do this?

tr.highlight {
    border-top: 10px solid;
    border-bottom: 10px solid;
    border-color: transparent;
}

Hope this helps.

Could not instantiate mail function. Why this error occurring

In Ubuntu (at least 12.04) it seems sendmail is not installed by default. You will have to install it using the command sudo apt-get install sendmail-bin

You may also need to configure the proper permissions for it as mentioned above.

Font from origin has been blocked from loading by Cross-Origin Resource Sharing policy

For those using Microsoft products with a web.config file:

Merge this with your web.config.

To allow on any domain replace value="domain" with value="*"

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.webserver>
    <httpprotocol>
      <customheaders>
        <add name="Access-Control-Allow-Origin" value="domain" />
      </customheaders>
    </httpprotocol>
  </system.webserver>
</configuration>

If you don't have permission to edit web.config, then add this line in your server-side code.

Response.AppendHeader("Access-Control-Allow-Origin", "domain");

$(document).on("click"... not working?

if this code does not work even under document ready, most probable you assigned a return false; somewhere in your js file to that button, if it is button try to change it to a ,span, anchor or div and test if it is working.

$(document).on("click","#test-element",function() {
        alert("click bound to document listening for #test-element");
});

unexpected T_VARIABLE, expecting T_FUNCTION

put public, protected or private before the $connection.

How to get date and time from server

No need to use date_default_timezone_set for the whole script, just specify the timezone you want with a DateTime object:

$now = new DateTime(null, new DateTimeZone('America/New_York'));
$now->setTimezone(new DateTimeZone('Europe/London'));    // Another way
echo $now->format("Y-m-d\TH:i:sO"); // something like "2015-02-11T06:16:47+0100" (ISO 8601)

I do not want to inherit the child opacity from the parent in CSS

There is no one size fits-all approach, but one thing that I found particularly helpful is setting opacity for a div's direct children, except for the one that you want to keep fully visible. In code:

<div class="parent">
    <div class="child1"></div>
    <div class="child2"></div>
    <div class="child3"></div>
    <div class="child4"></div>
</div>

and css:

div.parent > div:not(.child1){
    opacity: 0.5;
}

In case you have background colors/images on the parent you fix color opacity with rgba and background-image by applying alpha filters

Can't get Python to import from a different folder

My preferred way is to have __init__.py on every directory that contains modules that get used by other modules, and in the entry point, override sys.path as below:

def get_path(ss):
  return os.path.join(os.path.dirname(__file__), ss)
sys.path += [
  get_path('Server'), 
  get_path('Models')
]

This makes the files in specified directories visible for import, and I can import user from Server.py.

Nexus 7 (2013) and Win 7 64 - cannot install USB driver despite checking many forums and online resources

I also got this problem and found quite simple solution. I have Samsung adb driver installed on my system. I tried "Update driver" -> "Let me pick" -> "Already installed drivers" -> Samsung adb driver. That worked well.

Preserve Line Breaks From TextArea When Writing To MySQL

Here is what I use

$textToStore = nl2br(htmlentities($inputText, ENT_QUOTES, 'UTF-8'));

$inputText is the text provided by either the form or textarea. $textToStore is the returned text from nl2br and htmlentities, to be stored in your database. ENT_QUOTES will convert both double and single quotes, so you'll have no trouble with those.

How to get current user who's accessing an ASP.NET application?

If you're using membership you can do: Membership.GetUser()

Your code is returning the Windows account which is assigned with ASP.NET.

Additional Info Edit: You will want to include System.Web.Security

using System.Web.Security

Add borders to cells in POI generated Excel File

HSSFCellStyle style=workbook.createCellStyle();
style.setBorderBottom(HSSFCellStyle.BORDER_THIN);
style.setBorderTop(HSSFCellStyle.BORDER_THIN);
style.setBorderRight(HSSFCellStyle.BORDER_THIN);
style.setBorderLeft(HSSFCellStyle.BORDER_THIN);

Python Timezone conversion

Using pytz

from datetime import datetime
from pytz import timezone

fmt = "%Y-%m-%d %H:%M:%S %Z%z"
timezonelist = ['UTC','US/Pacific','Europe/Berlin']
for zone in timezonelist:

    now_time = datetime.now(timezone(zone))
    print now_time.strftime(fmt)

How to use 'hover' in CSS

You need to concatenate the selector and pseudo selector. You'll also need a style element to contain your styles. Most people use an external stylesheet, for lots of benefits (caching for one).

<a class="hover">click</a>

<style type="text/css">

    a.hover:hover {
        text-decoration: underline;

    }

</style>

Just a note: the hover class is not necessary, unless you are defining only certain links to have this behavior (which may be the case)

Detecting a long press with Android

Try this:

final GestureDetector gestureDetector = new GestureDetector(new GestureDetector.SimpleOnGestureListener() {
    public void onLongPress(MotionEvent e) {
        Log.e("", "Longpress detected");
    }
});

public boolean onTouchEvent(MotionEvent event) {
    return gestureDetector.onTouchEvent(event);
};

HTML - how to make an entire DIV a hyperlink?

You can put an <a> element inside the <div> and set it to display: block and height: 100%.

Determine a user's timezone

The most popular (==standard?) way of determining the time zone I've seen around is simply asking the users themselves. If your website requires subscription, this could be saved in the users' profile data. For anon users, the dates could be displayed as UTC or GMT or some such.

I'm not trying to be a smart aleck. It's just that sometimes some problems have finer solutions outside of any programming context.

Python: For each list element apply a function across the list

Doing it the mathy way...

nums = [1, 2, 3, 4, 5]
min_combo = (min(nums), max(nums))

Unless, of course, you have negatives in there. In that case, this won't work because you actually want the min and max absolute values - the numerator should be close to zero, and the denominator far from it, in either direction. And double negatives would break it.

get jquery `$(this)` id

Do you mean that for a select element with an id of "next" you need to perform some specific script?

$("#next").change(function(){
    //enter code here
});

How can I get just the first row in a result set AFTER ordering?

You can nest your queries:

select * from (
    select bla
    from bla
    where bla
    order by finaldate desc
)
where rownum < 2

excel formula to subtract number of days from a date

Here is what worked for me (Excel 14.0 - aka MS Office Pro Plus 2010):

=DATE(YEAR(A1), MONTH(A1), DAY(A1) - 16)

This takes the date (format mm/dd/yyyy) in cell A1 and subtracts 16 days with output in format of mm/dd/yyyy.

How do I fix maven error The JAVA_HOME environment variable is not defined correctly?

I had the same problem on Windows 7.

The JAVA_HOME environment variable is not defined correctly
This environment variable is needed to run this program
NB: JAVA_HOME should point to a JDK not a JRE

The solution turned out to be very simple - right click on command prompt shortcut and choose "Run as Administrator". After that, the problem disappeared)

How to exit in Node.js

adding

process.exit(1);

will do the trick for you

What is an MDF file?

Just to make this absolutely clear for all:

A .MDF file is “typically” a SQL Server data file however it is important to note that it does NOT have to be.

This is because .MDF is nothing more than a recommended/preferred notation but the extension itself does not actually dictate the file type.

To illustrate this, if someone wanted to create their primary data file with an extension of .gbn they could go ahead and do so without issue.

To qualify the preferred naming conventions:

  • .mdf - Primary database data file.
  • .ndf - Other database data files i.e. non Primary.
  • .ldf - Log data file.

Python Set Comprehension

primes = {x for x in range(2, 101) if all(x%y for y in range(2, min(x, 11)))}

I simplified the test a bit - if all(x%y instead of if not any(not x%y

I also limited y's range; there is no point in testing for divisors > sqrt(x). So max(x) == 100 implies max(y) == 10. For x <= 10, y must also be < x.

pairs = {(x, x+2) for x in primes if x+2 in primes}

Instead of generating pairs of primes and testing them, get one and see if the corresponding higher prime exists.

Convert Pandas Column to DateTime

If you have more than one column to be converted you can do the following:

df[["col1", "col2", "col3"]] = df[["col1", "col2", "col3"]].apply(pd.to_datetime)

How to transform numpy.matrix or array to scipy sparse matrix

In Python, the Scipy library can be used to convert the 2-D NumPy matrix into a Sparse matrix. SciPy 2-D sparse matrix package for numeric data is scipy.sparse

The scipy.sparse package provides different Classes to create the following types of Sparse matrices from the 2-dimensional matrix:

  1. Block Sparse Row matrix
  2. A sparse matrix in COOrdinate format.
  3. Compressed Sparse Column matrix
  4. Compressed Sparse Row matrix
  5. Sparse matrix with DIAgonal storage
  6. Dictionary Of Keys based sparse matrix.
  7. Row-based list of lists sparse matrix
  8. This class provides a base class for all sparse matrices.

CSR (Compressed Sparse Row) or CSC (Compressed Sparse Column) formats support efficient access and matrix operations.

Example code to Convert Numpy matrix into Compressed Sparse Column(CSC) matrix & Compressed Sparse Row (CSR) matrix using Scipy classes:

import sys                 # Return the size of an object in bytes
import numpy as np         # To create 2 dimentional matrix
from scipy.sparse import csr_matrix, csc_matrix 
# csr_matrix: used to create compressed sparse row matrix from Matrix
# csc_matrix: used to create compressed sparse column matrix from Matrix

create a 2-D Numpy matrix

A = np.array([[1, 0, 0, 0, 0, 0],\
              [0, 0, 2, 0, 0, 1],\
              [0, 0, 0, 2, 0, 0]])
print("Dense matrix representation: \n", A)
print("Memory utilised (bytes): ", sys.getsizeof(A))
print("Type of the object", type(A))

Print the matrix & other details:

Dense matrix representation: 
 [[1 0 0 0 0 0]
 [0 0 2 0 0 1]
 [0 0 0 2 0 0]]
Memory utilised (bytes):  184
Type of the object <class 'numpy.ndarray'>

Converting Matrix A to the Compressed sparse row matrix representation using csr_matrix Class:

S = csr_matrix(A)
print("Sparse 'row' matrix: \n",S)
print("Memory utilised (bytes): ", sys.getsizeof(S))
print("Type of the object", type(S))

The output of print statements:

Sparse 'row' matrix:
(0, 0) 1
(1, 2) 2
(1, 5) 1
(2, 3) 2
Memory utilised (bytes): 56
Type of the object: <class 'scipy.sparse.csr.csc_matrix'>

Converting Matrix A to Compressed Sparse Column matrix representation using csc_matrix Class:

S = csc_matrix(A)
print("Sparse 'column' matrix: \n",S)
print("Memory utilised (bytes): ", sys.getsizeof(S))
print("Type of the object", type(S))

The output of print statements:

Sparse 'column' matrix:
(0, 0) 1
(1, 2) 2
(2, 3) 2
(1, 5) 1
Memory utilised (bytes): 56
Type of the object: <class 'scipy.sparse.csc.csc_matrix'>

As it can be seen the size of the compressed matrices is 56 bytes and the original matrix size is 184 bytes.

For a more detailed explanation and code examples please refer to this article: https://limitlessdatascience.wordpress.com/2020/11/26/sparse-matrix-in-machine-learning/

Remove all padding and margin table HTML and CSS

Use a display block

style= "display: block";

How do you delete a column by name in data.table?

Very simple option in case you have many individual columns to delete in a data table and you want to avoid typing in all column names #careadviced

dt <- dt[, -c(1,4,6,17,83,104)]

This will remove columns based on column number instead.

It's obviously not as efficient because it bypasses data.table advantages but if you're working with less than say 500,000 rows it works fine

How to identify if a webpage is being loaded inside an iframe or directly into the browser window?

When in an iframe on the same origin as the parent, the window.frameElement method returns the element (e.g. iframe or object) in which the window is embedded. Otherwise, if browsing in a top-level context, or if the parent and the child frame have different origins, it will evaluate to null.

window.frameElement
  ? 'embedded in iframe or object'
  : 'not embedded or cross-origin'

This is an HTML Standard with basic support in all modern browsers.

Homebrew: Could not symlink, /usr/local/bin is not writable

While doing brew link node In addition I got the following issues as well:

Error: Could not symlink include/node /usr/local/include is not writable.

Linking /usr/local/Cellar/node/9.3.0... Error: Permission denied @ dir_s_mkdir - /usr/local/lib

To solve the above just go to /usr/local/ and check the availability of folders 'include' and 'lib', if those folders are not available just create them manually.

And run brew install node again

In HTML5, should the main navigation be inside or outside the <header> element?

It's completely up to you. You can either put them in the header or not, as long as the elements within them are internal navigation elements only (i.e. don't link to external sites such as a twitter or facebook account) then it's fine.

They tend to get placed in a header simply because that's where navigation often goes, but it's not set in stone.

You can read more about it at HTML5 Doctor.

Change the project theme in Android Studio?

In the AndroidManifest.xml, under the application tag, you can set the theme of your choice. To customize the theme, press Ctrl + Click on android:theme = "@style/AppTheme" in the Android manifest file. It will open styles.xml file where you can change the parent attribute of the style tag.

At parent= in styles.xml you can browse all available styles by using auto-complete inside the "". E.g. try parent="Theme." with your cursor right after the . and then pressing Ctrl + Space.

You can also preview themes in the preview window in Android Studio.

enter image description here

Assign a variable inside a Block to a variable outside a Block

To assign a variable inside block which outside of block always use __block specifier before that variable your code should be like this:-

__block Person *aPerson = nil;

"Press Any Key to Continue" function in C

You don't say what system you're using, but as you already have some answers that may or may not work for Windows, I'll answer for POSIX systems.

In POSIX, keyboard input comes through something called a terminal interface, which by default buffers lines of input until Return/Enter is hit, so as to deal properly with backspace. You can change that with the tcsetattr call:

#include <termios.h>

struct termios info;
tcgetattr(0, &info);          /* get current terminal attirbutes; 0 is the file descriptor for stdin */
info.c_lflag &= ~ICANON;      /* disable canonical mode */
info.c_cc[VMIN] = 1;          /* wait until at least one keystroke available */
info.c_cc[VTIME] = 0;         /* no timeout */
tcsetattr(0, TCSANOW, &info); /* set immediately */

Now when you read from stdin (with getchar(), or any other way), it will return characters immediately, without waiting for a Return/Enter. In addition, backspace will no longer 'work' -- instead of erasing the last character, you'll read an actual backspace character in the input.

Also, you'll want to make sure to restore canonical mode before your program exits, or the non-canonical handling may cause odd effects with your shell or whoever invoked your program.

Could not read JSON: Can not deserialize instance of hello.Country[] out of START_OBJECT token

For Spring-boot 1.3.3 the method exchange() for List is working as in the related answer

Spring Data Rest - _links

How do I prevent the error "Index signature of object type implicitly has an 'any' type" when compiling typescript with noImplicitAny flag enabled?

Another way to avoid the error is to use the cast like this:

let secondValue: string = (<any>someObject)[key]; (Note the parenthesis)

The only problem is that this isn't type-safe anymore, as you are casting to any. But you can always cast back to the correct type.

ps: I'm using typescript 1.7, not sure about previous versions.

PostgreSQL how to see which queries have run

While using Django with postgres 10.6, logging was enabled by default, and I was able to simply do:

tail -f /var/log/postgresql/*

Ubuntu 18.04, django 2+, python3+

how to configure apache server to talk to HTTPS backend server?

In my case, my server was configured to work only in https mode, and error occured when I try to access http mode. So changing http://my-service to https://my-service helped.

What is the best way to initialize a JavaScript Date to midnight?

Just wanted to clarify that the snippet from accepted answer gives the nearest midnight in the past:

var d = new Date();
d.setHours(0,0,0,0); // last midnight

If you want to get the nearest midnight in future, use the following code:

var d = new Date();
d.setHours(24,0,0,0); // next midnight

Converting HTML to PDF using PHP?

If you wish to create a pdf from php, pdflib will help you (as some others suggested).

Else, if you want to convert an HTML page to PDF via PHP, you'll find a little trouble outta here.. For 3 years I've been trying to do it as best as I can.

So, the options I know are:

DOMPDF : php class that wraps the html and builds the pdf. Works good, customizable (if you know php), based on pdflib, if I remember right it takes even some CSS. Bad news: slow when the html is big or complex.

HTML2PS: same as DOMPDF, but this one converts first to a .ps (ghostscript) file, then, to whatever format you need (pdf, jpg, png). For me is little better than dompdf, but has the same speed problem.. but, better compatibility with CSS.

Those two are php classes, but if you can install some software on the server, and access it throught passthru() or system(), give a look to these too:

wkhtmltopdf: based on webkit (safari's wrapper), is really fast and powerful.. seems like this is the best one (atm) for converting html pages to pdf on the fly; taking only 2 seconds for a 3 page xHTML document with CSS2. It is a recent project, anyway, the google.code page is often updated.

htmldoc : This one is a tank, it never really stops/crashes.. the project looks dead since 2007, but anyway if you don't need CSS compatibility this can be nice for you.

Javascript Get Values from Multiple Select Option Box

Take a look at HTMLSelectElement.selectedOptions.

HTML

<select name="north-america" multiple>
  <option valud="ca" selected>Canada</a>
  <option value="mx" selected>Mexico</a>
  <option value="us">USA</a>
</select>

JavaScript

var elem = document.querySelector("select");

console.log(elem.selectedOptions);
//=> HTMLCollection [<option value="ca">Canada</option>, <option value="mx">Mexico</option>]

This would also work on non-multiple <select> elements


Warning: Support for this selectedOptions seems pretty unknown at this point

console.log timestamps in Chrome?

I have this in most Node.JS apps. It also works in the browser.

function log() {
  const now = new Date();
  const currentDate = `[${now.toISOString()}]: `;
  const args = Array.from(arguments);
  args.unshift(currentDate);
  console.log.apply(console, args);
}

How to get ER model of database from server with Workbench

  1. Migrate your DB "simply make sure the tables and columns exist".
  2. Recommended to delete all your data (this freezes MySQL Workbench on my MAC everytime due to "software out of memory..")

  1. Open MySQL Workbench
  2. click + to make MySQL connection
  3. enter credentials and connect
  4. go to database tab
  5. click reverse engineer
  6. follow the wizard Next > Next ….
  7. DONE :)
  8. now you can click the arrange tab then choose auto-layout (keep clicking it until you are satisfied with the result)

Laravel Eloquent inner join with multiple conditions

You can see the following code to solved the problem

return $query->join('kg_shops', function($join)
{
    $join->on('kg_shops.id', '=', 'kg_feeds.shop_id');
    $join->where('kg_shops.active','=', 1);
});

Or another way to solved it

 return $query->join('kg_shops', function($join)
{
    $join->on('kg_shops.id', '=', 'kg_feeds.shop_id');
    $join->on('kg_shops.active','=', DB::raw('1'));
});

Why is vertical-align:text-top; not working in CSS

vertical-align is only supposed to work on elements that are rendered as inline. <span> is rendered as inline by default, but not all elements are. The paragraph block element, <p>, is rendered as a block by default. Table render types (e.g. table-cell) will allow you to use vertical-align as well.

Some browsers may allow you to use the vertical-align CSS property on items such as the paragraph block, but they are not supposed to. Text denoted as a paragraph should be filled with written-language content or the mark-up is incorrect and should be using one of a number of other options instead.

I hope this helps!

How can we stop a running java process through Windows cmd?

Open the windows cmd. First list all the java processes,

jps -m

now get the name and run below command,

for /f "tokens=1" %i in ('jps -m ^| find "Name_of_the_process"') do ( taskkill /F /PID %i )

or simply kill the process ID

taskkill /F /PID <ProcessID>

sample :)

C:\Users\tk>jps -m
15176 MessagingMain
18072 SoapUI-5.4.0.exe
15164 Jps -m
3420 org.eclipse.equinox.launcher_1.3.201.v20161025-1711.jar -os win32 -ws win32 -arch x86_64 -showsplash -launcher C:\Users\tk\eclipse\jee-neon\eclipse\eclipse.exe -name Eclipse --launcher.library C:\Users\tk\.p2\pool\plugins\org.eclipse.equinox.launcher.win32.win32.x86_64_1.1.401.v20161122-1740\eclipse_1617.dll -startup C:\Users\tk\eclipse\jee-neon\eclipse\\plugins/org.eclipse.equinox.launcher_1.3.201.v20161025-1711.jar --launcher.appendVmargs -exitdata 4b20_d0 -product org.eclipse.epp.package.jee.product -vm C:/Program Files/Java/jre1.8.0_131/bin/javaw.exe -vmargs -Dosgi.requiredJavaVersion=1.8 -XX:+UseG1GC -XX:+UseStringDeduplication -Dosgi.requiredJavaVersion=1.8 -Xms256m -Xmx1024m -Declipse.p2.max.threads=10 -Doomph.update.url=http://download.eclipse.org/oomph/updates/milestone/latest -Doomph.redirection.index.redirection=index:/->http://git.eclipse.org/c/oomph/org.eclipse.oomph.git/plain/setups/ -jar C:\Users\tk\

and

C:\Users\tk>for /f "tokens=1" %i in ('jps -m ^| find "MessagingMain"') do ( taskkill /F /PID %i )

C:\Users\tk>(taskkill /F /PID 15176  )
SUCCESS: The process with PID 15176 has been terminated.

or

C:\Users\tk>taskkill /F /PID 15176 
SUCCESS: The process with PID 15176 has been terminated.

How can I get a file's size in C++?

If you're on Linux, seriously consider just using the g_file_get_contents function from glib. It handles all the code for loading a file, allocating memory, and handling errors.

Convert String to Calendar Object in Java

Well, I think it would be a bad idea to replicate the code which is already present in classes like SimpleDateFormat.

On the other hand, personally I'd suggest avoiding Calendar and Date entirely if you can, and using Joda Time instead, as a far better designed date and time API. For example, you need to be aware that SimpleDateFormat is not thread-safe, so you either need thread-locals, synchronization, or a new instance each time you use it. Joda parsers and formatters are thread-safe.

Is JavaScript object-oriented?

JavaScript is Object-Based, not Object-Oriented. The difference is that Object-Based languages don't support proper inheritance, whereas Object-Oriented ones do.

There is a way to achieve 'normal' inheritance in JavaScript (Reference here), but the basic model is based on prototyping.

How do I perform query filtering in django templates

For anyone looking for an answer in 2020. This worked for me.

In Views:

 class InstancesView(generic.ListView):
        model = AlarmInstance
        context_object_name = 'settings_context'
        queryset = Group.objects.all()
        template_name = 'insta_list.html'

        @register.filter
        def filter_unknown(self, aVal):
            result = aVal.filter(is_known=False)
            return result

        @register.filter
        def filter_known(self, aVal):
            result = aVal.filter(is_known=True)
            return result

In template:

{% for instance in alarm.qar_alarm_instances|filter_unknown:alarm.qar_alarm_instances %}

In pseudocode:

For each in model.child_object|view_filter:filter_arg

Hope that helps.

Github: Can I see the number of downloads for a repo?

Formerly, there was two methods of download code in Github: clone or download as zip a .git repo, or upload a file (for example, a binary) for later download.

When download a repo (clone or download as zip), Github doesn't count the number of downloads for technical limitations. Clone a repository is a read-only operation. There is no authentication required. This operation can be done via many protocols, including HTTPS, the same protocol that the web page uses to show the repo in the browser. It's very difficult to count it.

See: http://git-scm.com/book/en/Git-on-the-Server-The-Protocols

Recently, Github deprecate the download functionality. This was because they understand that Github is focused in building software, and not in distribute binaries.

See: https://github.com/blog/1302-goodbye-uploads

Difference between string and text in rails?

If you are using oracle... STRING will be created as VARCHAR(255) column and TEXT, as a CLOB.

NATIVE_DATABASE_TYPES = {
    primary_key: "NUMBER(38) NOT NULL PRIMARY KEY",
    string: { name: "VARCHAR2", limit: 255 },
    text: { name: "CLOB" },
    ntext: { name: "NCLOB" },
    integer: { name: "NUMBER", limit: 38 },
    float: { name: "BINARY_FLOAT" },
    decimal: { name: "DECIMAL" },
    datetime: { name: "TIMESTAMP" },
    timestamp: { name: "TIMESTAMP" },
    timestamptz: { name: "TIMESTAMP WITH TIME ZONE" },
    timestampltz: { name: "TIMESTAMP WITH LOCAL TIME ZONE" },
    time: { name: "TIMESTAMP" },
    date: { name: "DATE" },
    binary: { name: "BLOB" },
    boolean: { name: "NUMBER", limit: 1 },
    raw: { name: "RAW", limit: 2000 },
    bigint: { name: "NUMBER", limit: 19 }
}

https://github.com/rsim/oracle-enhanced/blob/master/lib/active_record/connection_adapters/oracle_enhanced_adapter.rb

How do I remove leading whitespace in Python?

If you want to cut the whitespaces before and behind the word, but keep the middle ones.
You could use:

word = '  Hello World  '
stripped = word.strip()
print(stripped)

Create PostgreSQL ROLE (user) if it doesn't exist

Here is a generic solution using plpgsql:

CREATE OR REPLACE FUNCTION create_role_if_not_exists(rolename NAME) RETURNS TEXT AS
$$
BEGIN
    IF NOT EXISTS (SELECT * FROM pg_roles WHERE rolname = rolename) THEN
        EXECUTE format('CREATE ROLE %I', rolename);
        RETURN 'CREATE ROLE';
    ELSE
        RETURN format('ROLE ''%I'' ALREADY EXISTS', rolename);
    END IF;
END;
$$
LANGUAGE plpgsql;

Usage:

posgres=# SELECT create_role_if_not_exists('ri');
 create_role_if_not_exists 
---------------------------
 CREATE ROLE
(1 row)
posgres=# SELECT create_role_if_not_exists('ri');
 create_role_if_not_exists 
---------------------------
 ROLE 'ri' ALREADY EXISTS
(1 row)

How to get Toolbar from fragment?

In case fragments should have custom view of ToolBar you can implement ToolBar for each fragment separately.

add ToolBar into fragment_layout:

<android.support.v7.widget.Toolbar
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="?attr/colorPrimaryDark"/>

find it in fragment:

@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment, container, false);
        Toolbar toolbar = (Toolbar) view.findViewById(R.id.toolbar);

        //set toolbar appearance
        toolbar.setBackground(R.color.material_blue_grey_800);

        //for crate home button
        AppCompatActivity activity = (AppCompatActivity) getActivity();
        activity.setSupportActionBar(toolbar);
        activity.getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}

menu listener could be created two ways: override onOptionsItemSelected in your fragment:

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch(item.getItemId()){
        case android.R.id.home:
            getActivity().onBackPressed();
    }
    return super.onOptionsItemSelected(item);
}

or set listener for toolbar when create it in onCreateView():

toolbar.setOnMenuItemClickListener(new Toolbar.OnMenuItemClickListener() {
            @Override
            public boolean onMenuItemClick(MenuItem menuItem) {
                return false;
            }
        });

What is the default root pasword for MySQL 5.7

It seems things were designed to avoid developers to se the root user, a better solution would be:

sudo mysql -u root

Then create a normal user, set a password, then use that user to work.

create user 'user'@'localhost' identified by 'user1234';
grant all on your_database.* to 'user'@'localhost';
select host, user from mysql.user;

Then try to access:

mysql -u user -p

Boom!

What are carriage return, linefeed, and form feed?

On old paper-printer terminals, advancing to the next line involved two actions: moving the print head back to the beginning of the horizontal scan range (carriage return) and advancing the roll of paper being printed on (line feed).

Since we no longer use paper-printer terminals, those actions aren't really relevant anymore, but the characters used to signal them have stuck around in various incarnations.

What is "not assignable to parameter of type never" error in typescript?

I got the same error in ReactJS function component, using ReactJS useState hook. The solution was to declare the type of useState at initialisation:

const [items , setItems] = useState<IItem[]>([]); // replace IItem[] with your own typing: string, boolean...

Incrementing in C++ - When to use x++ or ++x?

Understanding the language syntax is important when considering clarity of code. Consider copying a character string, for example with post-increment:

char a[256] = "Hello world!";
char b[256];
int i = 0;
do {
  b[i] = a[i];
} while (a[i++]);

We want the loop to execute through encountering the zero character (which tests false) at the end of the string. That requires testing the value pre-increment and also incrementing the index. But not necessarily in that order - a way to code this with the pre-increment would be:

int i = -1;
do {
  ++i;
  b[i] = a[i];
} while (a[i]);

It is a matter of taste which is clearer and if the machine has a handfull of registers both should have identical execution time, even if a[i] is a function that is expensive or has side-effects. A significant difference might be the exit value of the index.

Using a .php file to generate a MySQL dump

Well, you can always use PHP's system function call.

http://php.net/manual/en/function.system.php

http://www.php.net/manual/en/function.exec.php

That runs any command-line program from PHP.

How do I loop through items in a list box and then remove those item?

Jefferson is right, you have to do it backwards.

Here's the c# equivalent:

for (var i == list.Items.Count - 1; i >= 0; i--)
{
    list.Items.RemoveAt(i);
}

How to remove all MySQL tables from the command-line without DROP database permissions?

Try this.

This works even for tables with constraints (foreign key relationships). Alternatively you can just drop the database and recreate, but you may not have the necessary permissions to do that.

mysqldump -u[USERNAME] -p[PASSWORD] \
  --add-drop-table --no-data [DATABASE] | \
  grep -e '^DROP \| FOREIGN_KEY_CHECKS' | \
  mysql -u[USERNAME] -p[PASSWORD] [DATABASE]

In order to overcome foreign key check effects, add show table at the end of the generated script and run many times until the show table command results in an empty set.

Delegation: EventEmitter or Observable in Angular

I found out another solution for this case without using Reactivex neither services. I actually love the rxjx API however I think it goes best when resolving an async and/or complex function. Using It in that way, Its pretty exceeded to me.

What I think you are looking for is for a broadcast. Just that. And I found out this solution:

<app>
  <app-nav (selectedTab)="onSelectedTab($event)"></app-nav>
       // This component bellow wants to know when a tab is selected
       // broadcast here is a property of app component
  <app-interested [broadcast]="broadcast"></app-interested>
</app>

 @Component class App {
   broadcast: EventEmitter<tab>;

   constructor() {
     this.broadcast = new EventEmitter<tab>();
   }

   onSelectedTab(tab) {
     this.broadcast.emit(tab)
   }    
 }

 @Component class AppInterestedComponent implements OnInit {
   broadcast: EventEmitter<Tab>();

   doSomethingWhenTab(tab){ 
      ...
    }     

   ngOnInit() {
     this.broadcast.subscribe((tab) => this.doSomethingWhenTab(tab))
   }
 }

This is a full working example: https://plnkr.co/edit/xGVuFBOpk2GP0pRBImsE

Memcached vs. Redis?

Memcached is multithreaded and fast.

Redis has lots of features and is very fast, but completely limited to one core as it is based on an event loop.

We use both. Memcached is used for caching objects, primarily reducing read load on the databases. Redis is used for things like sorted sets which are handy for rolling up time-series data.

DataTable: How to get item value with row name and column name? (VB)

'Create a class to hold the pair...

        Public Class ColumnValue
            Public ColumnName As String
            Public ColumnValue As New Object
        End Class

    'Build the pair...

        For Each row In [YourDataTable].Rows

              For Each item As DataColumn In row.Table.Columns
                Dim rowValue As New ColumnValue
                rowValue.ColumnName = item.Caption
                rowValue.ColumnValue = row.item(item.Ordinal)
                RowValues.Add(rowValue)
                rowValue = Nothing
              Next

        ' Now you can grab the value by the column name...

        Dim results = (From p In RowValues Where p.ColumnName = "MyColumn" Select  p.ColumnValue).FirstOrDefault    

        Next

Validation failed for one or more entities while saving changes to SQL Server Database using Entity Framework

This implementation wrap entity exception to exception with detail text. It handles DbEntityValidationException, DbUpdateException, datetime2 range errors (MS SQL), and include key of invalid entity in message (useful when savind many entities at one SaveChanges call).

First, override SaveChanges in DbContext class:

public class AppDbContext : DbContext
{
    public override int SaveChanges()
    {
        try
        {
            return base.SaveChanges();
        }
        catch (DbEntityValidationException dbEntityValidationException)
        {
            throw ExceptionHelper.CreateFromEntityValidation(dbEntityValidationException);
        }
        catch (DbUpdateException dbUpdateException)
        {
            throw ExceptionHelper.CreateFromDbUpdateException(dbUpdateException);
        }
    }   

    public override async Task<int> SaveChangesAsync(CancellationToken cancellationToken)
    {
        try
        {
            return await base.SaveChangesAsync(cancellationToken);
        }
        catch (DbEntityValidationException dbEntityValidationException)
        {
            throw ExceptionHelper.CreateFromEntityValidation(dbEntityValidationException);
        }
        catch (DbUpdateException dbUpdateException)
        {
            throw ExceptionHelper.CreateFromDbUpdateException(dbUpdateException);
        }
    }

ExceptionHelper class:

public class ExceptionHelper
{
    public static Exception CreateFromEntityValidation(DbEntityValidationException ex)
    {
        return new Exception(GetDbEntityValidationMessage(ex), ex);
    }

    public static string GetDbEntityValidationMessage(DbEntityValidationException ex)
    {
        // Retrieve the error messages as a list of strings.
        var errorMessages = ex.EntityValidationErrors
            .SelectMany(x => x.ValidationErrors)
            .Select(x => x.ErrorMessage);

        // Join the list to a single string.
        var fullErrorMessage = string.Join("; ", errorMessages);

        // Combine the original exception message with the new one.
        var exceptionMessage = string.Concat(ex.Message, " The validation errors are: ", fullErrorMessage);
        return exceptionMessage;
    }

    public static IEnumerable<Exception> GetInners(Exception ex)
    {
        for (Exception e = ex; e != null; e = e.InnerException)
            yield return e;
    }

    public static Exception CreateFromDbUpdateException(DbUpdateException dbUpdateException)
    {
        var inner = GetInners(dbUpdateException).Last();
        string message = "";
        int i = 1;
        foreach (var entry in dbUpdateException.Entries)
        {
            var entry1 = entry;
            var obj = entry1.CurrentValues.ToObject();
            var type = obj.GetType();
            var propertyNames = entry1.CurrentValues.PropertyNames.Where(x => inner.Message.Contains(x)).ToList();
            // check MS SQL datetime2 error
            if (inner.Message.Contains("datetime2"))
            {
                var propertyNames2 = from x in type.GetProperties()
                                        where x.PropertyType == typeof(DateTime) ||
                                            x.PropertyType == typeof(DateTime?)
                                        select x.Name;
                propertyNames.AddRange(propertyNames2);
            }

            message += "Entry " + i++ + " " + type.Name + ": " + string.Join("; ", propertyNames.Select(x =>
                string.Format("'{0}' = '{1}'", x, entry1.CurrentValues[x])));
        }
        return new Exception(message, dbUpdateException);
    }
}

Erase the current printed console line

Some worthwhile subtleties...

\33[2K erases the entire line your cursor is currently on

\033[A moves your cursor up one line, but in the same column i.e. not to the start of the line

\r brings your cursor to the beginning of the line (r is for carriage return N.B. carriage returns do not include a newline so cursor remains on the same line) but does not erase anything

In xterm specifically, I tried the replies mentioned above and the only way I found to erase the line and start again at the beginning is the sequence (from the comment above posted by @Stephan202 as well as @vlp and @mantal) \33[2K\r

On an implementation note, to get it to work properly for example in a countdown scenario since I wasn't using a new line character '\n' at the end of each fprintf(), so I had to fflush() the stream each time (to give you some context, I started xterm using a fork on a linux machine without redirecting stdout, I was just writing to the buffered FILE pointer fdfile with a non-blocking file descriptor I had sitting on the pseudo terminal address which in my case was /dev/pts/21):

fprintf(fdfile, "\33[2K\rT minus %d seconds...", i);
fflush(fdfile);

Note that I used both the \33[2K sequence to erase the line followed by the \r carriage return sequence to reposition the cursor at the beginning of the line. I had to fflush() after each fprintf() because I don't have a new line character at the end '\n'. The same result without needing fflush() would require the additional sequence to go up a line:

fprintf(fdfile, "\033[A\33[2K\rT minus %d seconds...\n", i);

Note that if you have something on the line immediately above the line you want to write on, it will get over-written with the first fprintf(). You would have to leave an extra line above to allow for the first movement up one line:

i = 3;
fprintf(fdfile, "\nText to keep\n");
fprintf(fdfile, "Text to erase****************************\n");
while(i > 0) { // 3 second countdown
    fprintf(fdfile, "\033[A\33[2KT\rT minus %d seconds...\n", i);
    i--;
    sleep(1);
}

How to run a task when variable is undefined in ansible?

Strictly stated you must check all of the following: defined, not empty AND not None.

For "normal" variables it makes a difference if defined and set or not set. See foo and bar in the example below. Both are defined but only foo is set.

On the other side registered variables are set to the result of the running command and vary from module to module. They are mostly json structures. You probably must check the subelement you're interested in. See xyz and xyz.msg in the example below:

cat > test.yml <<EOF
- hosts: 127.0.0.1

  vars:
    foo: ""          # foo is defined and foo == '' and foo != None
    bar:             # bar is defined and bar != '' and bar == None

  tasks:

  - debug:
      msg : ""
    register: xyz    # xyz is defined and xyz != '' and xyz != None
                     # xyz.msg is defined and xyz.msg == '' and xyz.msg != None

  - debug:
      msg: "foo is defined and foo == '' and foo != None"
    when: foo is defined and foo == '' and foo != None

  - debug:
      msg: "bar is defined and bar != '' and bar == None"
    when: bar is defined and bar != '' and bar == None

  - debug:
      msg: "xyz is defined and xyz != '' and xyz != None"
    when: xyz is defined and xyz != '' and xyz != None
  - debug:
      msg: "{{ xyz }}"

  - debug:
      msg: "xyz.msg is defined and xyz.msg == '' and xyz.msg != None"
    when: xyz.msg is defined and xyz.msg == '' and xyz.msg != None
  - debug:
      msg: "{{ xyz.msg }}"
EOF
ansible-playbook -v test.yml

Generating a UUID in Postgres for Insert statement?

PostgreSQL 13 supports natively gen_random_uuid ():

PostgreSQL includes one function to generate a UUID:

gen_random_uuid () ? uuid

This function returns a version 4 (random) UUID. This is the most commonly used type of UUID and is appropriate for most applications.

db<>fiddle demo

What is the difference between decodeURIComponent and decodeURI?

encodeURIComponent()

Converts the input into a URL-encoded string

encodeURI()

URL-encodes the input, but assumes a full URL is given, so returns a valid URL by not encoding the protocol (e.g. http://) and host name (e.g. www.stackoverflow.com).

decodeURIComponent() and decodeURI() are the opposite of the above

Prevent jQuery UI dialog from setting focus to first textbox

Simple workaround:

Just create a invisible element with tabindex=1 ... This will not focus the datepicker ...

eg.:

<a href="" tabindex="1"></a>
...
Here comes the input element

"React.Children.only expected to receive a single React element child" error when putting <Image> and <TouchableHighlight> in a <View>

The <TouchableHighlight> element is the source of the error. The <TouchableHighlight> element must have a child element.

Try running the code like this:

render() {
    const {height, width} = Dimensions.get('window');
    return (
        <View style={styles.container}>
            <Image 
                style={{
                    height:height,
                    width:width,
                }}
                source={require('image!foo')}
                resizeMode='cover' 
            />
            <TouchableHighlight style={styles.button}>
                <Text> This text is the target to be highlighted </Text>
            </TouchableHighlight>
        </View>
    );
}

How do I parse a string into a number with Dart?

In Dart 2 int.tryParse is available.

It returns null for invalid inputs instead of throwing. You can use it like this:

int val = int.tryParse(text) ?? defaultValue;

How to compare dates in datetime fields in Postgresql?

Use Date convert to compare with date: Try This:

select * from table 
where TO_DATE(to_char(timespanColumn,'YYYY-MM-DD'),'YYYY-MM-DD') = to_timestamp('2018-03-26', 'YYYY-MM-DD')

IntelliJ show JavaDocs tooltip on mouse over

I tried many ways mentioned here, especially the preference - editor - general - code completion - show documentation popup in.. isn't working in version 2019.2.2

Finally, i am just using F1 while caret is on the type/method and it displays the documentation nicely. This is not ideal but helpful.

$date + 1 year?

If you are using PHP 5.3, it is because you need to set the default time zone:

date_default_timezone_set()

ActionLink htmlAttributes

The problem is that your anonymous object property data-icon has an invalid name. C# properties cannot have dashes in their names. There are two ways you can get around that:

Use an underscore instead of dash (MVC will automatically replace the underscore with a dash in the emitted HTML):

@Html.ActionLink("Edit", "edit", "markets",
      new { id = 1 },
      new {@class="ui-btn-right", data_icon="gear"})

Use the overload that takes in a dictionary:

@Html.ActionLink("Edit", "edit", "markets",
      new { id = 1 },
      new Dictionary<string, object> { { "class", "ui-btn-right" }, { "data-icon", "gear" } });

How do I space out the child elements of a StackPanel?

Following up on Sergey's suggestion, you can define and reuse a whole Style (with various property setters, including Margin) instead of just a Thickness object:

<Style x:Key="MyStyle" TargetType="SomeItemType">
  <Setter Property="Margin" Value="0,5,0,5" />
  ...
</Style>

...

  <StackPanel>
    <StackPanel.Resources>
      <Style TargetType="SomeItemType" BasedOn="{StaticResource MyStyle}" />
    </StackPanel.Resources>
  ...
  </StackPanel>

Note that the trick here is the use of Style Inheritance for the implicit style, inheriting from the style in some outer (probably merged from external XAML file) resource dictionary.

Sidenote:

At first, I naively tried to use the implicit style to set the Style property of the control to that outer Style resource (say defined with the key "MyStyle"):

<StackPanel>
  <StackPanel.Resources>
    <Style TargetType="SomeItemType">
      <Setter Property="Style" Value={StaticResource MyStyle}" />
    </Style>
  </StackPanel.Resources>
</StackPanel>

which caused Visual Studio 2010 to shut down immediately with CATASTROPHIC FAILURE error (HRESULT: 0x8000FFFF (E_UNEXPECTED)), as described at https://connect.microsoft.com/VisualStudio/feedback/details/753211/xaml-editor-window-fails-with-catastrophic-failure-when-a-style-tries-to-set-style-property#

How to avoid java.util.ConcurrentModificationException when iterating through and removing elements from an ArrayList

"Should I clone the list first?"

That will be the easiest solution, remove from the clone, and copy the clone back after removal.

An example from my rummikub game:

SuppressWarnings("unchecked")
public void removeStones() {
  ArrayList<Stone> clone = (ArrayList<Stone>) stones.clone();
  // remove the stones moved to the table
  for (Stone stone : stones) {
      if (stone.isOnTable()) {
         clone.remove(stone);
      }
  }
  stones = (ArrayList<Stone>) clone.clone();
  sortStones();
}

How to read file with space separated values in pandas

If you can't get text parsing to work using the accepted answer (e.g if your text file contains non uniform rows) then it's worth trying with Python's csv library - here's an example using a user defined Dialect:

 import csv

 csv.register_dialect('skip_space', skipinitialspace=True)
 with open(my_file, 'r') as f:
      reader=csv.reader(f , delimiter=' ', dialect='skip_space')
      for item in reader:
          print(item)

How can I make Jenkins CI with Git trigger on pushes to master?

  1. Manage Jenkins/ configure system /GitHub Servers

  2. On jenkins job / git credentials and Branch Specifier (give the branch you want to look for pushes)

enter image description here

  1. Webhook on github

Using an array as needles in strpos

With the following code:

$flag = true;
foreach($find_letters as $letter)
    if(false===strpos($string, $letter)) {
        $flag = false; 
        break;
    }

Then check the value of $flag. If it is true, all letters have been found. If not, it's false.

How to get value by class name in JavaScript or jquery?

Try this:

$(document).ready(function(){
    var yourArray = [];
    $("span.HOEnZb").find("div").each(function(){
        if(($.trim($(this).text()).length>0)){
         yourArray.push($(this).text());
        }
    });
});

DEMO

List all environment variables from the command line

As mentioned in other answers, you can use set to list all the environment variables or use

set [environment_variable] to get a specific variable with its value.

set [environment_variable]= can be used to remove a variable from the workspace.

How Do I Get the Query Builder to Output Its Raw SQL Query as a String?

use debugbar package

composer require "barryvdh/laravel-debugbar": "2.3.*"

enter image description here

vba pass a group of cells as range to function

As written, your function accepts only two ranges as arguments.

To allow for a variable number of ranges to be used in the function, you need to declare a ParamArray variant array in your argument list. Then, you can process each of the ranges in the array in turn.

For example,

Function myAdd(Arg1 As Range, ParamArray Args2() As Variant) As Double
    Dim elem As Variant
    Dim i As Long
    For Each elem In Arg1
        myAdd = myAdd + elem.Value
    Next elem
    For i = LBound(Args2) To UBound(Args2)
        For Each elem In Args2(i)
            myAdd = myAdd + elem.Value
        Next elem
    Next i
End Function

This function could then be used in the worksheet to add multiple ranges.

myAdd usage

For your function, there is the question of which of the ranges (or cells) that can passed to the function are 'Sessions' and which are 'Customers'.

The easiest case to deal with would be if you decided that the first range is Sessions and any subsequent ranges are Customers.

Function calculateIt(Sessions As Range, ParamArray Customers() As Variant) As Double
    'This function accepts a single Sessions range and one or more Customers
    'ranges
    Dim i As Long
    Dim sessElem As Variant
    Dim custElem As Variant
    For Each sessElem In Sessions
        'do something with sessElem.Value, the value of each
        'cell in the single range Sessions
        Debug.Print "sessElem: " & sessElem.Value
    Next sessElem
    'loop through each of the one or more ranges in Customers()
    For i = LBound(Customers) To UBound(Customers)
        'loop through the cells in the range Customers(i)
        For Each custElem In Customers(i)
            'do something with custElem.Value, the value of
            'each cell in the range Customers(i)
            Debug.Print "custElem: " & custElem.Value
         Next custElem
    Next i
End Function

If you want to include any number of Sessions ranges and any number of Customers range, then you will have to include an argument that will tell the function so that it can separate the Sessions ranges from the Customers range.

This argument could be set up as the first, numeric, argument to the function that would identify how many of the following arguments are Sessions ranges, with the remaining arguments implicitly being Customers ranges. The function's signature would then be:

Function calculateIt(numOfSessionRanges, ParamAray Args() As Variant)

Or it could be a "guard" argument that separates the Sessions ranges from the Customers ranges. Then, your code would have to test each argument to see if it was the guard. The function would look like:

Function calculateIt(ParamArray Args() As Variant)

Perhaps with a call something like:

calculateIt(sessRange1,sessRange2,...,"|",custRange1,custRange2,...)

The program logic might then be along the lines of:

Function calculateIt(ParamArray Args() As Variant) As Double
   ...
   'loop through Args
   IsSessionArg = True
   For i = lbound(Args) to UBound(Args)
       'only need to check for the type of the argument
       If TypeName(Args(i)) = "String" Then
          IsSessionArg = False
       ElseIf IsSessionArg Then
          'process Args(i) as Session range
       Else
          'process Args(i) as Customer range
       End if
   Next i
   calculateIt = <somevalue>
End Function

What does \u003C mean?

Those are unicode escapes. The general unicode escapes looks like \uxxxx where xxxx are the hexadecimal digits of the ASCI characters. They are used mainly to insert special characters inside a javascript string.

C#: what is the easiest way to subtract time?

Check out all the DateTime methods here: http://msdn.microsoft.com/en-us/library/system.datetime.aspx

Add Returns a new DateTime that adds the value of the specified TimeSpan to the value of this instance.

AddDays Returns a new DateTime that adds the specified number of days to the value of this instance.

AddHours Returns a new DateTime that adds the specified number of hours to the value of this instance.

AddMilliseconds Returns a new DateTime that adds the specified number of milliseconds to the value of this instance.

AddMinutes Returns a new DateTime that adds the specified number of minutes to the value of this instance.

AddMonths Returns a new DateTime that adds the specified number of months to the value of this instance.

AddSeconds Returns a new DateTime that adds the specified number of seconds to the value of this instance.

AddTicks Returns a new DateTime that adds the specified number of ticks to the value of this instance.

AddYears Returns a new DateTime that adds the specified number of years to the value of this instance.

In practice, what are the main uses for the new "yield from" syntax in Python 3.3?

What are the situations where "yield from" is useful?

Every situation where you have a loop like this:

for x in subgenerator:
  yield x

As the PEP describes, this is a rather naive attempt at using the subgenerator, it's missing several aspects, especially the proper handling of the .throw()/.send()/.close() mechanisms introduced by PEP 342. To do this properly, rather complicated code is necessary.

What is the classic use case?

Consider that you want to extract information from a recursive data structure. Let's say we want to get all leaf nodes in a tree:

def traverse_tree(node):
  if not node.children:
    yield node
  for child in node.children:
    yield from traverse_tree(child)

Even more important is the fact that until the yield from, there was no simple method of refactoring the generator code. Suppose you have a (senseless) generator like this:

def get_list_values(lst):
  for item in lst:
    yield int(item)
  for item in lst:
    yield str(item)
  for item in lst:
    yield float(item)

Now you decide to factor out these loops into separate generators. Without yield from, this is ugly, up to the point where you will think twice whether you actually want to do it. With yield from, it's actually nice to look at:

def get_list_values(lst):
  for sub in [get_list_values_as_int, 
              get_list_values_as_str, 
              get_list_values_as_float]:
    yield from sub(lst)

Why is it compared to micro-threads?

I think what this section in the PEP is talking about is that every generator does have its own isolated execution context. Together with the fact that execution is switched between the generator-iterator and the caller using yield and __next__(), respectively, this is similar to threads, where the operating system switches the executing thread from time to time, along with the execution context (stack, registers, ...).

The effect of this is also comparable: Both the generator-iterator and the caller progress in their execution state at the same time, their executions are interleaved. For example, if the generator does some kind of computation and the caller prints out the results, you'll see the results as soon as they're available. This is a form of concurrency.

That analogy isn't anything specific to yield from, though - it's rather a general property of generators in Python.

Re-ordering factor levels in data frame

Assuming your dataframe is mydf:

mydf$task <- factor(mydf$task, levels = c("up", "down", "left", "right", "front", "back"))

How do I remove a comma off the end of a string?

have a look at the rtrim function

rtrim ($string , ",");

the above line will remove a char if the last char is a comma

How to dynamic filter options of <select > with jQuery?

This is a simple solution where you clone the lists options and keep them in an object for recovery later. The scripts cleans out the list and add only the options that contains the input text. This should also work cross browser. I got some help from this post: https://stackoverflow.com/a/5748709/542141

Html

<input id="search_input" placeholder="Type to filter">
<select id="theList" class="List" multiple="multiple">

or razor

@Html.ListBoxFor(g => g.SelectedItem, Model.items, new { @class = "List", @id = "theList" })

script

<script type="text/javascript">
  $(document).ready(function () {
    //copy options
    var options = $('#theList option').clone();
    //react on keyup in textbox
    $('#search_input').keyup(function () {
      var val = $(this).val();
      $('#theList').empty();
      //take only the options containing your filter text or all if empty
      options.filter(function (idx, el) {
        return val === '' || $(el).text().indexOf(val) >= 0;
      }).appendTo('#theList');//add it to list
     });
  });
</script>

Convert number of minutes into hours & minutes using PHP

You can achieve this with DateTime extension, which will also work for number of minutes that is larger than one day (>= 1440):

$minutes = 250;
$zero    = new DateTime('@0');
$offset  = new DateTime('@' . $minutes * 60);
$diff    = $zero->diff($offset);
echo $diff->format('%a Days, %h Hours, %i Minutes');

demo

What's the fastest way in Python to calculate cosine similarity given sparse matrix data?

Building off of Vaali's solution:

def sparse_cosine_similarity(sparse_matrix):
    out = (sparse_matrix.copy() if type(sparse_matrix) is csr_matrix else
           sparse_matrix.tocsr())
    squared = out.multiply(out)
    sqrt_sum_squared_rows = np.array(np.sqrt(squared.sum(axis=1)))[:, 0]
    row_indices, col_indices = out.nonzero()
    out.data /= sqrt_sum_squared_rows[row_indices]
    return out.dot(out.T)

This takes a sparse matrix (preferably a csr_matrix) and returns a csr_matrix. It should do the more intensive parts using sparse calculations with pretty minimal memory overhead. I haven't tested it extensively though, so caveat emptor (Update: I feel confident in this solution now that I've tested and benchmarked it)

Also, here is the sparse version of Waylon's solution in case it helps anyone, not sure which solution is actually better.

def sparse_cosine_similarity_b(sparse_matrix):
    input_csr_matrix = sparse_matrix.tocsr()
    similarity = input_csr_matrix * input_csr_matrix.T
    square_mag = similarity.diagonal()
    inv_square_mag = 1 / square_mag
    inv_square_mag[np.isinf(inv_square_mag)] = 0
    inv_mag = np.sqrt(inv_square_mag)
    return similarity.multiply(inv_mag).T.multiply(inv_mag)

Both solutions seem to have parity with sklearn.metrics.pairwise.cosine_similarity

:-D

Update:

Now I have tested both solutions against my existing Cython implementation: https://github.com/davidmashburn/sparse_dot/blob/master/test/benchmarks_v3_output_table.txt and it looks like the first algorithm performs the best of the three most of the time.

How can I check if an element exists in the visible DOM?

Use getElementById() if it's available.

Also, here's an easy way to do it with jQuery:

if ($('#elementId').length > 0) {
  // Exists.
}

And if you can't use third-party libraries, just stick to base JavaScript:

var element =  document.getElementById('elementId');
if (typeof(element) != 'undefined' && element != null)
{
  // Exists.
}

Difference between java.exe and javaw.exe

The difference is in the subsystem that each executable targets.

  • java.exe targets the CONSOLE subsystem.
  • javaw.exe targets the WINDOWS subsystem.

Transaction marked as rollback only: How do I find the cause

There is always a reason why the nested method roll back. If you don't see the reason, you need to change your logger level to debug, where you will see the more details where transaction failed. I changed my logback.xml by adding

<logger name="org.springframework.transaction" level="debug"/>
<logger name="org.springframework.orm.jpa" level="debug"/>

then I got this line in the log:

Participating transaction failed - marking existing transaction as rollback-only

So I just stepped through my code to see where this line is generated and found that there is a catch block which did not throw anything.

private Student add(Student s) {
        try {
            Student retval = studentRepository.save(s);
            return retval;
        } catch (Exception e) {
            
        }
        return null;
    }

How do I make a column unique and index it in a Ruby on Rails migration?

add_index :table_name, :column_name, unique: true

To index multiple columns together, you pass an array of column names instead of a single column name.

Difference between File.separator and slash in paths

Well, there are more OS's than Unix and Windows (Portable devices, etc), and Java is known for its portability. The best practice is to use it, so the JVM could determine which one is the best for that OS.

Good tool for testing socket connections?

netcat (nc.exe) is the right tool. I have a feeling that any tool that does what you want it to do will have exactly the same problem with your antivirus software. Just flag this program as "OK" in your antivirus software (how you do this will depend on what type of antivirus software you use).

Of course you will also need to configure your sysadmin to accept that you're not trying to do anything illegal...

get list of pandas dataframe columns based on data type

If you want a list of columns of a certain type, you can use groupby:

>>> df = pd.DataFrame([[1, 2.3456, 'c', 'd', 78]], columns=list("ABCDE"))
>>> df
   A       B  C  D   E
0  1  2.3456  c  d  78

[1 rows x 5 columns]
>>> df.dtypes
A      int64
B    float64
C     object
D     object
E      int64
dtype: object
>>> g = df.columns.to_series().groupby(df.dtypes).groups
>>> g
{dtype('int64'): ['A', 'E'], dtype('float64'): ['B'], dtype('O'): ['C', 'D']}
>>> {k.name: v for k, v in g.items()}
{'object': ['C', 'D'], 'int64': ['A', 'E'], 'float64': ['B']}

Convert Data URI to File then append to FormData

My preferred way is canvas.toBlob()

But anyhow here is yet another way to convert base64 to a blob using fetch ^^,

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_x000D_
var url = "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg=="_x000D_
_x000D_
fetch(url)_x000D_
.then(res => res.blob())_x000D_
.then(blob => {_x000D_
  var fd = new FormData()_x000D_
  fd.append('image', blob, 'filename')_x000D_
  _x000D_
  console.log(blob)_x000D_
_x000D_
  // Upload_x000D_
  // fetch('upload', {method: 'POST', body: fd})_x000D_
})
_x000D_
_x000D_
_x000D_

Format Date as "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"

Add another option, maybe not the most lightweight.

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dayjs.extend(dayjs_plugin_customParseFormat)
console.log(dayjs('2018-09-06 17:00:00').format( 'YYYY-MM-DDTHH:mm:ss.000ZZ'))
_x000D_
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dayjs.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/plugin/customParseFormat.js"></script>
_x000D_
_x000D_
_x000D_

WARNING: API 'variant.getJavaCompile()' is obsolete and has been replaced with 'variant.getJavaCompileProvider()'

keep you Project(not app) Build.gradle dependncies classpath version code is new

 dependencies {
    classpath 'com.android.tools.build:gradle:3.5.0-beta01'
    classpath 'com.novoda:bintray-release:0.8.1'
    // NOTE: Do not place your application dependencies here; they belong
    // in the individual module build.gradle files
}

What is the use of rt.jar file in java?

Your question is already answered here :

Basically, rt.jar contains all of the compiled class files for the base Java Runtime ("rt") Environment. Normally, javac should know the path to this file

Also, a good link on what happens if we try to include our class file in rt.jar.

How can I toggle word wrap in Visual Studio?

In Visual Studio 2005 Pro:

Ctrl + E, Ctrl + W

Or menu Edit ? Advanced ? Word Wrap.

How to restart Postgresql

Try this as root (maybe you can use sudo or su):

/etc/init.d/postgresql restart

Without any argument the script also gives you a hint on how to restart a specific version

[Uqbar@Feynman ~] /etc/init.d/postgresql
Usage: /etc/init.d/postgresql {start|stop|restart|reload|force-reload|status} [version ...]

Similarly, in case you have it, you can also use the service tool:

[Uqbar@Feynman ~] service postgresql
Usage: /etc/init.d/postgresql {start|stop|restart|reload|force reload|status} [version ...]

Please, pay attention to the optional [version ...] trailing argument. That's meant to allow you, the user, to act on a specific version, in case you were running multiple ones. So you can restart version X while keeping version Y and Z untouched and running.

Finally, in case you are running systemd, then you can use systemctl like this:

[support@Feynman ~] systemctl status postgresql
? postgresql.service - PostgreSQL database server
   Loaded: loaded (/usr/lib/systemd/system/postgresql.service; enabled; vendor preset: disabled)
   Active: active (running) since Wed 2017-11-14 12:33:35 CET; 7min ago
...

You can replace status with stop, start or restart as well as other actions. Please refer to the documentation for full details. In order to operate on multiple concurrent versions, the syntax is slightly different. For example to stop v12 and reload v13 you can run:

systemctl stop postgresql-12.service
systemctl reload postgresql-13.service

Thanks to @Jojo for pointing me to this very one. Finally Keep in mind that root permissions may be needed for non-informative tasks as in the other cases seen earlier.

How to check the multiple permission at single request in Android M?

I faced the same problem and below is the workaround I came up with:

public boolean checkForPermission(final String[] permissions, final int permRequestCode, int msgResourceId) {
        final List<String> permissionsNeeded = new ArrayList<>();
        for (int i = 0; i < permissions.length; i++) {
            final String perm = permissions[i];
            if (ContextCompat.checkSelfPermission(getActivity(), permissions[i]) != PackageManager.PERMISSION_GRANTED) {
                if (shouldShowRequestPermissionRationale(permissions[i])) {
                    final AlertDialog dialog = AlertDialog.newInstance( getResources().getString(R.string.permission_title), getResources().getString(msgResourceId) );
                    dialog.setPositiveButton("OK", new View.OnClickListener() {
                        @Override
                        public void onClick(View view) {
                            // add the request.
                            permissionsNeeded.add(perm);
                            dialog.dismiss();
                        }
                    });
                    dialog.show( getActivity().getSupportFragmentManager(), "HCFAlertDialog" );
                } else {
                    // add the request.
                    permissionsNeeded.add(perm);
                }
            }
        }

        if (permissionsNeeded.size() > 0) {
            // go ahead and request permissions
            requestPermissions(permissionsNeeded.toArray(new String[permissionsNeeded.size()]), permRequestCode);
            return false;
        } else {
            // no permission need to be asked so all good...we have them all.
            return true;
        }
    }

And you call the above method like this:

if ( checkForPermission( new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE, 
Manifest.permission.CAMERA}, REQUEST_PERMISSION_EXTERNAL_STORAGE_RESULT, R.string.permission_image) ) {
                        // DO YOUR STUFF

                    }

Make a DIV fill an entire table cell

div height=100% in table cell will work only when table has height attribute itself.

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_x000D_
<table border="1" style="height:300px; width: 100px;">
 <tr><td>cell1</td><td>cell2</td></tr>
 <tr>
   <td style="height: 100%">
     <div style="height: 100%; width: 100%; background-color:pink;"></div>
   </td>
   <td>long text long text long text long text long text long text</td>
 </tr>
</table>
_x000D_
_x000D_
_x000D_

UPD in FireFox you should also set height=100% value to the parent TD element

How to format numbers?

This is an article about your problem. Adding a thousands-seperator is not built in to JavaScript, so you'll have to write your own function like this (example taken from the linked page):

function addSeperator(nStr){
  nStr += '';
  x = nStr.split('.');
  x1 = x[0];
  x2 = x.length > 1 ? '.' + x[1] : '';
  var rgx = /(\d+)(\d{3})/;
  while (rgx.test(x1)) {
    x1 = x1.replace(rgx, '$1' + ',' + '$2');
  }
  return x1 + x2;
}

Reporting Services Remove Time from DateTime in Expression

Just use DateValue(Now) if you want the result to be of DateTime data type.

Test if element is present using Selenium WebDriver?

I would use something like (with Scala [the code in old "good" Java 8 may be similar to this]):

object SeleniumFacade {

  def getElement(bySelector: By, maybeParent: Option[WebElement] = None, withIndex: Int = 0)(implicit driver: RemoteWebDriver): Option[WebElement] = {
    val elements = maybeParent match {
      case Some(parent) => parent.findElements(bySelector).asScala
      case None => driver.findElements(bySelector).asScala
    }
    if (elements.nonEmpty) {
      Try { Some(elements(withIndex)) } getOrElse None
    } else None
  }
  ...
}

so then,

val maybeHeaderLink = SeleniumFacade getElement(By.xpath(".//a"), Some(someParentElement))

Accessing a resource via codebehind in WPF

You can use a resource key like this:

<UserControl.Resources>
    <SolidColorBrush x:Key="{x:Static local:Foo.MyKey}">Blue</SolidColorBrush>
</UserControl.Resources>
<Grid Background="{StaticResource {x:Static local:Foo.MyKey}}" />

public partial class Foo : UserControl
{
    public Foo()
    {
        InitializeComponent();
        var brush = (SolidColorBrush)FindResource(MyKey);
    }

    public static ResourceKey MyKey { get; } = CreateResourceKey();

    private static ComponentResourceKey CreateResourceKey([CallerMemberName] string caller = null)
    {
        return new ComponentResourceKey(typeof(Foo), caller); ;
    }
}

JFrame in full screen Java

First of all, that is the resolution you would want to use, 1650,1080.

Now add:

frame.setExtendedState(JFrame.MAXIMIZED_BOTH); 

If you have issues with the components on the JFrame, then after you have added all the components using the frame.add(component) method, add the following statement.

frame.pack();

Return HTML from ASP.NET Web API

Starting with AspNetCore 2.0, it's recommended to use ContentResult instead of the Produce attribute in this case. See: https://github.com/aspnet/Mvc/issues/6657#issuecomment-322586885

This doesn't rely on serialization nor on content negotiation.

[HttpGet]
public ContentResult Index() {
    return new ContentResult {
        ContentType = "text/html",
        StatusCode = (int)HttpStatusCode.OK,
        Content = "<html><body>Hello World</body></html>"
    };
}

GCD to perform task in main thread

For the asynchronous dispatch case you describe above, you shouldn't need to check if you're on the main thread. As Bavarious indicates, this will simply be queued up to be run on the main thread.

However, if you attempt to do the above using a dispatch_sync() and your callback is on the main thread, your application will deadlock at that point. I describe this in my answer here, because this behavior surprised me when moving some code from -performSelectorOnMainThread:. As I mention there, I created a helper function:

void runOnMainQueueWithoutDeadlocking(void (^block)(void))
{
    if ([NSThread isMainThread])
    {
        block();
    }
    else
    {
        dispatch_sync(dispatch_get_main_queue(), block);
    }
}

which will run a block synchronously on the main thread if the method you're in isn't currently on the main thread, and just executes the block inline if it is. You can employ syntax like the following to use this:

runOnMainQueueWithoutDeadlocking(^{
    //Do stuff
});

Autocomplete syntax for HTML or PHP in Notepad++. Not auto-close, autocompelete

Go to:

Settings -> Preferences You will see a dialog box. There click the Auto-completion tab where you can set the auto complete option.See image below: Follow it

If your code not detected automatically then you choose your coding language form Language menu

Jquery mouseenter() vs mouseover()

This example demonstrates the difference between the mousemove, mouseenter and mouseover events:

https://jsfiddle.net/z8g613yd/

HTML:

<div onmousemove="myMoveFunction()">
    <p>onmousemove: <br> <span id="demo">Mouse over me!</span></p>
</div>

<div onmouseenter="myEnterFunction()">
    <p>onmouseenter: <br> <span id="demo2">Mouse over me!</span></p>
</div>

<div onmouseover="myOverFunction()">
    <p>onmouseover: <br> <span id="demo3">Mouse over me!</span></p>
</div>

CSS:

div {
    width: 200px;
    height: 100px;
    border: 1px solid black;
    margin: 10px;
    float: left;
    padding: 30px;
    text-align: center;
    background-color: lightgray;
}

p {
    background-color: white;
    height: 50px;
}

p span {
    background-color: #86fcd4;
    padding: 0 20px;
}

JS:

var x = 0;
var y = 0;
var z = 0;

function myMoveFunction() {
    document.getElementById("demo").innerHTML = z += 1;
}

function myEnterFunction() {
    document.getElementById("demo2").innerHTML = x += 1;
}

function myOverFunction() {
    document.getElementById("demo3").innerHTML = y += 1;
}
  • onmousemove : occurs every time the mouse pointer is moved over the div element.
  • onmouseenter : only occurs when the mouse pointer enters the div element.
  • onmouseover : occurs when the mouse pointer enters the div element, and its child elements (p and span).

Flask Download a File

I was also developing a similar application. I was also getting not found error even though the file was there. This solve my problem. I mention my download folder in 'static_folder':

app = Flask(__name__,static_folder='pdf')

My code for the download is as follows:

@app.route('/pdf/<path:filename>', methods=['GET', 'POST'])
def download(filename):    
    return send_from_directory(directory='pdf', filename=filename)

This is how I am calling my file from html.

<a class="label label-primary" href=/pdf/{{  post.hashVal }}.pdf target="_blank"  style="margin-right: 5px;">Download pdf </a>
<a class="label label-primary" href=/pdf/{{  post.hashVal }}.png target="_blank"  style="margin-right: 5px;">Download png </a>

Thin Black Border for a Table

Style the td and th instead

td, th {
    border: 1px solid black;
}

And also to make it so there is no spacing between cells use:

table {
    border-collapse: collapse;
}

(also note, you have border-style: none; which should be border-style: solid;)

See an example here: http://jsfiddle.net/KbjNr/

maven-dependency-plugin (goals "copy-dependencies", "unpack") is not supported by m2e

I had the same problem when trying to load Hadoop project in eclipse. I tried the solutions above, and I believe it might have worked in Eclipse Kepler... not even sure anymore (tried too many things).

With all the problems I was having, I decided to move on to Eclipse Luna, and the solutions above did not work for me.

There was another post that recommended changing the ... tag to package. I started doing that, and it would "clear" the errors... However, I start to think that the changes would bite me later - I am not an expert on Maven.

Fortunately, I found out how to remove all the errors. Go to Window->Preferences->Maven-> Error/Warnings and change "Plugin execution not covered by lifecycle..." option to "Ignore". Hope it helps.