Init function in javascript and how it works
I can't believe no-one has answered the ops question!
The last set of brackets are used for passing in the parameters to the anonymous function. So, the following example creates a function, then runs it with the x=5 and y=8
(function(x,y){
//code here
})(5,8)
This may seem not so useful, but it has its place. The most common one I have seen is
(function($){
//code here
})(jQuery)
which allows for jQuery to be in compatible mode, but you can refer to it as "$" within the anonymous function.
Make sure that the controller has a parameterless public constructor error
In my case, Unity turned out to be a red herring. My problem was a result of different projects targeting different versions of .NET. Unity was set up right and everything was registered with the container correctly. Everything compiled fine. But the type was in a class library, and the class library was set to target .NET Framework 4.0. The WebApi project using Unity was set to target .NET Framework 4.5. Changing the class library to also target 4.5 fixed the problem for me.
I discovered this by commenting out the DI constructor and adding default constructor. I commented out the controller methods and had them throw NotImplementedException. I confirmed that I could reach the controller, and seeing my NotImplementedException told me it was instantiating the controller fine. Next, in the default constructor, I manually instantiated the dependency chain instead of relying on Unity. It still compiled, but when I ran it the error message came back. This confirmed for me that I still got the error even when Unity was out of the picture. Finally, I started at the bottom of the chain and worked my way up, commenting out one line at a time and retesting until I no longer got the error message. This pointed me in the direction of the offending class, and from there I figured out that it was isolated to a single assembly.
Java: Reading integers from a file into an array
It looks like Java is trying to convert an empty string into a number. Do you have an empty line at the end of the series of numbers?
You could probably fix the code like this
String s = in.readLine();
int i = 0;
while (s != null) {
// Skip empty lines.
s = s.trim();
if (s.length() == 0) {
continue;
}
tall[i] = Integer.parseInt(s); // This is line 19.
System.out.println(tall[i]);
s = in.readLine();
i++;
}
in.close();
Webpack how to build production code and how to use it
You can add the plugins as suggested by @Vikramaditya.
Then to generate the production build. You have to run the the command
NODE_ENV=production webpack --config ./webpack.production.config.js
If using babel
, you will also need to prefix BABEL_ENV=node
to the above command.
Insecure content in iframe on secure page
Based on generality of this question, I think, that you'll need to setup your own HTTPS proxy on some server online. Do the following steps:
- Prepare your proxy server - install IIS, Apache
- Get valid SSL certificate to avoid security errors (free from startssl.com for example)
- Write a wrapper, which will download insecure content (how to below)
- From your site/app get https://yourproxy.com/?page=http://insecurepage.com
If you simply download remote site content via file_get_contents or similiar, you can still have insecure links to content. You'll have to find them with regex and also replace. Images are hard to solve, but Ï found workaround here: http://foundationphp.com/tutorials/image_proxy.php
Note: While this solution may have worked in some browsers when it was written in 2014, it no longer works. Navigating or redirecting to an HTTP URL in an iframe
embedded in an HTTPS page is not permitted by modern browsers, even if the frame started out with an HTTPS URL.
The best solution I created is to simply use google as the ssl proxy...
https://www.google.com/search?q=%http://yourhttpsite.com&btnI=Im+Feeling+Lucky
Tested and works in firefox.
Other Methods:
Use a Third party such as embed.ly (but it it really only good for well known http APIs).
Create your own redirect script on an https page you control (a simple javascript redirect on a relative linked page should do the trick. Something like: (you can use any langauge/method)
https://example.com
That has a iframe linking to...
https://example.com/utilities/redirect.html
Which has a simple js redirect script like...
document.location.href ="http://thenonsslsite.com";
Alternatively, you could add an RSS feed or write some reader/parser to read the http site and display it within your https site.
You could/should also recommend to the http site owner that they create an ssl connection. If for no other reason than it increases seo.
Unless you can get the http site owner to create an ssl certificate, the most secure and permanent solution would be to create an RSS feed grabing the content you need (presumably you are not actually 'doing' anything on the http site -that is to say not logging in to any system).
The real issue is that having http elements inside a https site represents a security issue. There are no completely kosher ways around this security risk so the above are just current work arounds.
Note, that you can disable this security measure in most browsers (yourself, not for others). Also note that these 'hacks' may become obsolete over time.
Counting in a FOR loop using Windows Batch script
Here is a batch file that generates all 10.x.x.x addresses
@echo off
SET /A X=0
SET /A Y=0
SET /A Z=0
:loop
SET /A X+=1
echo 10.%X%.%Y%.%Z%
IF "%X%" == "256" (
GOTO end
) ELSE (
GOTO loop2
GOTO loop
)
:loop2
SET /A Y+=1
echo 10.%X%.%Y%.%Z%
IF "%Y%" == "256" (
SET /A Y=0
GOTO loop
) ELSE (
GOTO loop3
GOTO loop2
)
:loop3
SET /A Z+=1
echo 10.%X%.%Y%.%Z%
IF "%Z%" == "255" (
SET /A Z=0
GOTO loop2
) ELSE (
GOTO loop3
)
:end
Reading binary file and looping over each byte
To sum up all the brilliant points of chrispy, Skurmedel, Ben Hoyt and Peter Hansen, this would be the optimal solution for processing a binary file one byte at a time:
with open("myfile", "rb") as f:
while True:
byte = f.read(1)
if not byte:
break
do_stuff_with(ord(byte))
For python versions 2.6 and above, because:
- python buffers internally - no need to read chunks
- DRY principle - do not repeat the read line
- with statement ensures a clean file close
- 'byte' evaluates to false when there are no more bytes (not when a byte is zero)
Or use J. F. Sebastians solution for improved speed
from functools import partial
with open(filename, 'rb') as file:
for byte in iter(partial(file.read, 1), b''):
# Do stuff with byte
Or if you want it as a generator function like demonstrated by codeape:
def bytes_from_file(filename):
with open(filename, "rb") as f:
while True:
byte = f.read(1)
if not byte:
break
yield(ord(byte))
# example:
for b in bytes_from_file('filename'):
do_stuff_with(b)
Failed to load resource: net::ERR_CONTENT_LENGTH_MISMATCH
Docker + NGINX
In my situation, the problem was nginx docker container disk space. I had 10GB of logs and when I reduce this amount it works.
Step by step (for rookies/newbies)
Enter in your container: docker exec -it <container_id> bash
Go to your logs, for example: cd /var/log/nginx
.
[optional] Show file size: ls -lh
for individual file size or du -h
for folder size.
Empty file(s) with > file_name
.
It works!.
For advanced developers/sysadmins
Empty your nginx log with > file_name
or similar.
Hope it helps
Getting String Value from Json Object Android
Please see my answer below, inspired by answers above but a bit more detailed...
// Get The Json Response (With Try Catch)
try {
String s = null;
if (response.body() != null) {
s = response.body().string();
// Convert Response Into Json Object (With Try Catch)
JSONObject json = null;
try {
json = new JSONObject(s);
// Extract The User Id From Json Object (With Try Catch)
String stringToExtract = null;
try {
stringToExtract = json.getString("NeededString");
} catch (JSONException e) {
e.printStackTrace();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
} catch (IOException e) {
e.printStackTrace();
}
How can I pad a String in Java?
Let's me leave an answer for some cases that you need to give left/right padding (or prefix/suffix string or spaces) before you concatenate to another string and you don't want to test length or any if condition.
The same to the selected answer, I would prefer the StringUtils
of Apache Commons but using this way:
StringUtils.defaultString(StringUtils.leftPad(myString, 1))
Explain:
myString
: the string I input, can be null
StringUtils.leftPad(myString, 1)
: if string is null, this statement would return null too
- then use
defaultString
to give empty string to prevent concatenate null
Abstract Class vs Interface in C++
Pure Virtual Functions are mostly used to define:
a) abstract classes
These are base classes where you have to derive from them and then implement the pure virtual functions.
b) interfaces
These are 'empty' classes where all functions are pure virtual and hence you have to derive and then implement all of the functions.
Pure virtual functions are actually functions which have no implementation in base class and have to be implemented in derived class.
Why do we use $rootScope.$broadcast in AngularJS?
What does $rootScope.$broadcast
do?
$rootScope.$broadcast
is sending an event through the application scope.
Any children scope of that app can catch it using a simple: $scope.$on()
.
It is especially useful to send events when you want to reach a scope that is not a direct parent (A branch of a parent for example)
!!! One thing to not do however is to use $rootScope.$on
from a controller. $rootScope
is the application, when your controller is destroyed that event listener will still exist, and when your controller will be created again, it will just pile up more event listeners. (So one broadcast will be caught multiple times). Use $scope.$on()
instead, and the listeners will also get destroyed.
What is the difference between $rootScope.$broadcast
& $rootScope.$broadcast.apply
?
Sometimes you have to use apply()
, especially when working with directives and other JS libraries. However since I don't know that code base, I wouldn't be able to tell if that's the case here.
PHP Create and Save a txt file to root directory
It's creating the file in the same directory as your script. Try this instead.
$content = "some text here";
$fp = fopen($_SERVER['DOCUMENT_ROOT'] . "/myText.txt","wb");
fwrite($fp,$content);
fclose($fp);
Java array reflection: isArray vs. instanceof
If you ever have a choice between a reflective solution and a non-reflective solution, never pick the reflective one (involving Class objects). It's not that it's "Wrong" or anything, but anything involving reflection is generally less obvious and less clear.
Import numpy on pycharm
I have encountered problem installing numpy package to pycharm and finally figured out. I hope it would be helpful for someone having the same problem in installing numpy and other packages on pycharm.
Pycharm Setting :
Go to File => Setting => Project => Project Interpreter. On this window select the appropriate project interpreter. After this, a list of packages under the selected project interpreter will be shown.
From the list select pip and check if the version column and the latest version column are the same. If different upgrade the version to the latest version by selecting the pip and using the upward triangle sign on the right side of the lists.
Once the upgrading completed successfully, you can now add new packages from the plus sign.
I hope this would be clear and useful for someone.
Ant is using wrong java version
Just had this issue, it happened because I'd first added the build file to the ant-view when the default JRE was 1.6.
There was no project-specific JRE and I changed the default to 1.5, even eclipse was running in 1.5, and JAVA_HOME was 1.5 too. Running the ant target from the command line used JRE 1.5, but within eclipse it still used 1.6.
I had to right-click the ant target, select Run As... and change the JRE under the JRE tab. This setting is remembered for subsequent runs.
How to get height of Keyboard?
The method by ZAFAR007 updated for Swift 5 in Xcode 10
override func viewDidLoad() {
super.viewDidLoad()
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
}
@objc func keyboardWillShow(notification: NSNotification) {
if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
let keyboardHeight : Int = Int(keyboardSize.height)
print("keyboardHeight",keyboardHeight)
}
}
Access a JavaScript variable from PHP
_GET accesses query string variables, test is not a querystring variable (PHP does not process the JS in any way). You need to rethink. You could make a php variable $test, and do something like:
<?php
$test = "tester";
?>
<script type="text/javascript" charset="utf-8">
var test = "<?php echo $test?>";
</script>
<?php
echo $test;
?>
Of course, I don't know why you want this, so I'm not sure the best solution.
EDIT: As others have noted, if the JavaScript variable is really generated on the client, you will need AJAX or a form to send it to the server.
Iterator over HashMap in Java
The cleanest way is to not (directly) use an iterator at all:
- type your map with generics
- use a foreach loop to iterate over the entries:
Like this:
Map<Integer, String> hm = new HashMap<Integer, String>();
hm.put(0, "zero");
hm.put(1, "one");
for (Map.Entry<Integer, String> entry : hm.entrySet()) {
// do something with the entry
System.out.println(entry.getKey() + " - " + entry.getValue());
// the getters are typed:
Integer key = entry.getKey();
String value = entry.getValue();
}
This is way more efficient than iterating over keys, because you avoid n calls to get(key)
.
How can I check if a directory exists?
You may also use access
in combination with opendir
to determine if the directory exists, and, if the name exists, but is not a directory. For example:
/* test that dir exists (1 success, -1 does not exist, -2 not dir) */
int
xis_dir (const char *d)
{
DIR *dirptr;
if (access ( d, F_OK ) != -1 ) {
// file exists
if ((dirptr = opendir (d)) != NULL) {
closedir (dirptr); /* d exists and is a directory */
} else {
return -2; /* d exists but is not a directory */
}
} else {
return -1; /* d does not exist */
}
return 1;
}
Converting characters to integers in Java
Character.getNumericValue(c)
The java.lang.Character.getNumericValue(char ch)
returns the int
value that the specified Unicode character represents. For example, the character '\u216C'
(the roman numeral fifty) will return an int with a value of 50.
The letters A-Z in their uppercase ('\u0041' through '\u005A')
, lowercase ('\u0061' through '\u007A')
, and full width variant ('\uFF21' through '\uFF3A' and '\uFF41' through '\uFF5A')
forms have numeric values from 10 through 35. This is independent of the Unicode specification, which does not assign numeric values to these char values.
This method returns the numeric value of the character, as a
nonnegative int value;
-2 if the character has a numeric value that is not a nonnegative integer;
-1 if the character has no numeric value.
And here is the link.
Differences between utf8 and latin1
UTF-8 is prepared for world domination, Latin1 isn't.
If you're trying to store non-Latin characters like Chinese, Japanese, Hebrew, Russian, etc using Latin1 encoding, then they will end up as mojibake. You may find the introductory text of this article useful (and even more if you know a bit Java).
Note that full 4-byte UTF-8 support was only introduced in MySQL 5.5. Before that version, it only goes up to 3 bytes per character, not 4 bytes per character. So, it supported only the BMP plane and not e.g. the Emoji plane. If you want full 4-byte UTF-8 support, upgrade MySQL to at least 5.5 or go for another RDBMS like PostgreSQL. In MySQL 5.5+ it's called utf8mb4
.
Bypass popup blocker on window.open when JQuery event.preventDefault() is set
Try using an a link element and click it with javascriipt
<a id="SimulateOpenLink" href="#" target="_blank" rel="noopener noreferrer"></a>
and the script
function openURL(url) {
document.getElementById("SimulateOpenLink").href = url
document.getElementById("SimulateOpenLink").click()
}
Use it like this
//do stuff
var id = 123123141;
openURL("/api/user/" + id + "/print") //this open webpage bypassing pop-up blocker
openURL("https://www.google.com") //Another link
Left function in c#
var value = fac.GetCachedValue("Auto Print Clinical Warnings")
// 0 = Start at the first character
// 1 = The length of the string to grab
if (value.ToLower().SubString(0, 1) == "y")
{
// Do your stuff.
}
Can jQuery check whether input content has changed?
Since the user can go into the OS menu and select paste using their mouse, there is no safe event that will trigger this for you. The only way I found that always works is to have a setInterval that checks if the input value has changed:
var inp = $('#input'),
val = saved = inp.val(),
tid = setInterval(function() {
val = inp.val();
if ( saved != val ) {
console.log('#input has changed');
saved = val;
},50);
You can also set this up using a jQuery special event.
Remove duplicated rows
Or you could nest the data in cols 4 and 5 into a single row with tidyr
:
library(tidyr)
df %>% nest(V4:V5)
# A tibble: 1 × 4
# V1 V2 V3 data
# <fctr> <int> <int> <list>
#1 platform_external_dbus 202 16 <tibble [5 × 2]>
The col 2 and 3 duplicates are now removed for statistical analysis, but you have kept the col 4 and 5 data in a tibble and can go back to the original data frame at any point with unnest()
.
How to add url parameters to Django template url tag?
1: HTML
<tbody>
{% for ticket in tickets %}
<tr>
<td class="ticket_id">{{ticket.id}}</td>
<td class="ticket_eam">{{ticket.eam}}</td>
<td class="ticket_subject">{{ticket.subject}}</td>
<td>{{ticket.zone}}</td>
<td>{{ticket.plaza}}</td>
<td>{{ticket.lane}}</td>
<td>{{ticket.uptime}}</td>
<td>{{ticket.downtime}}</td>
<td><a href="{% url 'ticket_details' ticket_id=ticket.id %}"><button data-toggle="modal" data-target="#modaldemo3" class="value-modal"><i class="icon ion-edit"></a></i></button> <button><i class="fa fa-eye-slash"></i></button>
</tr>
{% endfor %}
</tbody>
The {% url 'ticket_details' %} is the function name in your views
2: Views.py
def ticket_details(request, ticket_id):
print(ticket_id)
return render(request, ticket.html)
ticket_id is the parameter you will get from the ticket_id=ticket.id
3: URL.py
urlpatterns = [
path('ticket_details/?P<int:ticket_id>/', views.ticket_details, name="ticket_details") ]
/?P - where ticket_id is the name of the group and pattern is some pattern to match.
Checking network connection
Best way to do this is to make it check against an IP address that python always gives if it can't find the website. In this case this is my code:
import socket
print("website connection checker")
while True:
website = input("please input website: ")
print("")
print(socket.gethostbyname(website))
if socket.gethostbyname(website) == "92.242.140.2":
print("Website could be experiencing an issue/Doesn't exist")
else:
socket.gethostbyname(website)
print("Website is operational!")
print("")
How to deal with bad_alloc in C++?
You can catch it like any other exception:
try {
foo();
}
catch (const std::bad_alloc&) {
return -1;
}
Quite what you can usefully do from this point is up to you, but it's definitely feasible technically.
In general you cannot, and should not try, to respond to this error. bad_alloc
indicates that a resource cannot be allocated because not enough memory is available. In most scenarios your program cannot hope to cope with that, and terminating soon is the only meaningful behaviour.
Worse, modern operating systems often over-allocate: on such systems, malloc
and new
can return a valid pointer even if there is not enough free memory left – std::bad_alloc
will never be thrown, or is at least not a reliable sign of memory exhaustion. Instead, attempts to access the allocated memory will then result in a segmentation fault, which is not catchable (you can handle the segmentation fault signal, but you cannot resume the program afterwards).
The only thing you could do when catching std::bad_alloc
is to perhaps log the error, and try to ensure a safe program termination by freeing outstanding resources (but this is done automatically in the normal course of stack unwinding after the error gets thrown if the program uses RAII appropriately).
In certain cases, the program may attempt to free some memory and try again, or use secondary memory (= disk) instead of RAM but these opportunities only exist in very specific scenarios with strict conditions:
- The application must ensure that it runs on a system that does not overcommit memory, i.e. it signals failure upon allocation rather than later.
- The application must be able to free memory immediately, without any further accidental allocations in the meantime.
It’s exceedingly rare that applications have control over point 1 — userspace applications never do, it’s a system-wide setting that requires root permissions to change.1
OK, so let’s assume you’ve fixed point 1. What you can now do is for instance use a LRU cache for some of your data (probably some particularly large business objects that can be regenerated or reloaded on demand). Next, you need to put the actual logic that may fail into a function that supports retry — in other words, if it gets aborted, you can just relaunch it:
lru_cache<widget> widget_cache;
double perform_operation(int widget_id) {
std::optional<widget> maybe_widget = widget_cache.find_by_id(widget_id);
if (not maybe_widget) {
maybe_widget = widget_cache.store(widget_id, load_widget_from_disk(widget_id));
}
return maybe_widget->frobnicate();
}
…
for (int num_attempts = 0; num_attempts < MAX_NUM_ATTEMPTS; ++num_attempts) {
try {
return perform_operation(widget_id);
} catch (std::bad_alloc const&) {
if (widget_cache.empty()) throw;
widget_cache.remove_oldest();
}
}
But even here, using std::set_new_handler
instead of handling std::bad_alloc
provides the same benefit and would be much simpler.
1 If you’re creating an application that does control point 1, and you’re reading this answer, please shoot me an email, I’m genuinely curious about your circumstances.
What is the C++ Standard specified behavior of new
in c++?
The usual notion is that if new
operator cannot allocate dynamic memory of the requested size, then it should throw an exception of type std::bad_alloc
.
However, something more happens even before a bad_alloc
exception is thrown:
C++03 Section 3.7.4.1.3: says
An allocation function that fails to allocate storage can invoke the currently installed new_handler(18.4.2.2), if any. [Note: A program-supplied allocation function can obtain the address of the currently installed new_handler using the set_new_handler function (18.4.2.3).] If an allocation function declared with an empty exception-specification (15.4), throw(), fails to allocate storage, it shall return a null pointer. Any other allocation function that fails to allocate storage shall only indicate failure by throw-ing an exception of class std::bad_alloc (18.4.2.1) or a class derived from std::bad_alloc.
Consider the following code sample:
#include <iostream>
#include <cstdlib>
void outOfMemHandler()
{
std::cerr << "Unable to satisfy request for memory\n";
std::abort();
}
int main()
{
std::set_new_handler(outOfMemHandler);
int *pBigDataArray = new int[100000000L];
return 0;
}
In the above example, operator new
(most likely) will be unable to allocate space for 100,000,000 integers, and the function outOfMemHandler()
will be called, and the program will abort after issuing an error message.
As seen here the default behavior of new
operator when unable to fulfill a memory request, is to call the new-handler
function repeatedly until it can find enough memory or there is no more new handlers. In the above example, unless we call std::abort()
, outOfMemHandler()
would be called repeatedly. Therefore, the handler should either ensure that the next allocation succeeds, or register another handler, or register no handler, or not return (i.e. terminate the program). If there is no new handler and the allocation fails, the operator will throw an exception.
What is the new_handler
and set_new_handler
?
new_handler
is a typedef for a pointer to a function that takes and returns nothing, and set_new_handler
is a function that takes and returns a new_handler
.
Something like:
typedef void (*new_handler)();
new_handler set_new_handler(new_handler p) throw();
set_new_handler's parameter is a pointer to the function operator new
should call if it can't allocate the requested memory. Its return value is a pointer to the previously registered handler function, or null if there was no previous handler.
How to handle out of memory conditions in C++?
Given the behavior of new
a well designed user program should handle out of memory conditions by providing a proper new_handler
which does one of the following:
Make more memory available: This may allow the next memory allocation attempt inside operator new's loop to succeed. One way to implement this is to allocate a large block of memory at program start-up, then release it for use in the program the first time the new-handler is invoked.
Install a different new-handler: If the current new-handler can't make any more memory available, and of there is another new-handler that can, then the current new-handler can install the other new-handler in its place (by calling set_new_handler
). The next time operator new calls the new-handler function, it will get the one most recently installed.
(A variation on this theme is for a new-handler to modify its own behavior, so the next time it's invoked, it does something different. One way to achieve this is to have the new-handler modify static, namespace-specific, or global data that affects the new-handler's behavior.)
Uninstall the new-handler: This is done by passing a null pointer to set_new_handler
. With no new-handler installed, operator new
will throw an exception ((convertible to) std::bad_alloc
) when memory allocation is unsuccessful.
Throw an exception convertible to std::bad_alloc
. Such exceptions are not be caught by operator new
, but will propagate to the site originating the request for memory.
Not return: By calling abort
or exit
.
Class method decorator with self arguments?
Yes. Instead of passing in the instance attribute at class definition time, check it at runtime:
def check_authorization(f):
def wrapper(*args):
print args[0].url
return f(*args)
return wrapper
class Client(object):
def __init__(self, url):
self.url = url
@check_authorization
def get(self):
print 'get'
>>> Client('http://www.google.com').get()
http://www.google.com
get
The decorator intercepts the method arguments; the first argument is the instance, so it reads the attribute off of that. You can pass in the attribute name as a string to the decorator and use getattr
if you don't want to hardcode the attribute name:
def check_authorization(attribute):
def _check_authorization(f):
def wrapper(self, *args):
print getattr(self, attribute)
return f(self, *args)
return wrapper
return _check_authorization
A long bigger than Long.MAX_VALUE
You can't. If you have a method called isBiggerThanMaxLong(long)
it should always return false
.
If you were to increment the bits of Long.MAX_VALUE
, the next value should be Long.MIN_VALUE
. Read up on twos-complement and that should tell you why.
Querying a linked sql server
I use open query to perform this task like so:
select top 1 *
INTO [DATABASE_TO_INSERT_INTO].[dbo].[TABLE_TO_SELECT_INTO]
from openquery(
[LINKED_SERVER_NAME],
'select * from [DATABASE_ON_LINKED_SERVER].[dbo].[TABLE_TO_SELECT_FROM]'
)
The example above uses open query to select data from a database on a linked server into a database of your choosing.
Note: For completeness of reference, you may perform a simple select like so:
select top 1 * from openquery(
[LINKED_SERVER_NAME],
'select * from [DATABASE_ON_LINKED_SERVER].[dbo].[TABLE_TO_SELECT_FROM]'
)
How to stop app that node.js express 'npm start'
All the other solutions here are OS dependent. An independent solution for any OS uses socket.io as follows.
package.json
has two scripts:
"scripts": {
"start": "node server.js",
"stop": "node server.stop.js"
}
server.js - Your usual express stuff lives here
const express = require('express');
const app = express();
const server = http.createServer(app);
server.listen(80, () => {
console.log('HTTP server listening on port 80');
});
// Now for the socket.io stuff - NOTE THIS IS A RESTFUL HTTP SERVER
// We are only using socket.io here to respond to the npmStop signal
// To support IPC (Inter Process Communication) AKA RPC (Remote P.C.)
const io = require('socket.io')(server);
io.on('connection', (socketServer) => {
socketServer.on('npmStop', () => {
process.exit(0);
});
});
server.stop.js
const io = require('socket.io-client');
const socketClient = io.connect('http://localhost'); // Specify port if your express server is not using default port 80
socketClient.on('connect', () => {
socketClient.emit('npmStop');
setTimeout(() => {
process.exit(0);
}, 1000);
});
Test it out
npm start
(to start your server as usual)
npm stop
(this will now stop your running server)
The above code has not been tested (it is a cut down version of my code, my code does work) but hopefully it works as is. Either way, it provides the general direction to take if you want to use socket.io to stop your server.
How to tell if browser/tab is active
You would use the focus
and blur
events of the window:
var interval_id;
$(window).focus(function() {
if (!interval_id)
interval_id = setInterval(hard_work, 1000);
});
$(window).blur(function() {
clearInterval(interval_id);
interval_id = 0;
});
To Answer the Commented Issue of "Double Fire" and stay within jQuery ease of use:
$(window).on("blur focus", function(e) {
var prevType = $(this).data("prevType");
if (prevType != e.type) { // reduce double fire issues
switch (e.type) {
case "blur":
// do work
break;
case "focus":
// do work
break;
}
}
$(this).data("prevType", e.type);
})
Click to view Example Code Showing it working (JSFiddle)
How to iterate over associative arrays in Bash
You can access the keys with ${!array[@]}
:
bash-4.0$ echo "${!array[@]}"
foo bar
Then, iterating over the key/value pairs is easy:
for i in "${!array[@]}"
do
echo "key :" $i
echo "value:" ${array[$i]}
done
DLL References in Visual C++
You need to do a couple of things to use the library:
Make sure that you have both the *.lib and the *.dll from the library you want to use. If you don't have the *.lib, skip #2
Put a reference to the *.lib in the project. Right click the project name in the Solution Explorer and then select Configuration Properties->Linker->Input and put the name of the lib in the Additional Dependencies property.
You have to make sure that VS can find the lib you just added so you have to go to the Tools menu and select Options... Then under Projects and Solutions select VC++ Directories,edit Library Directory option. From within here you can set the directory that contains your new lib by selecting the 'Library Files' in the 'Show Directories For:' drop down box. Just add the path to your lib file in the list of directories. If you dont have a lib you can omit this, but while your here you will also need to set the directory which contains your header files as well under the 'Include Files'. Do it the same way you added the lib.
After doing this you should be good to go and can use your library. If you dont have a lib file you can still use the dll by importing it yourself. During your applications startup you can explicitly load the dll by calling LoadLibrary (see: http://msdn.microsoft.com/en-us/library/ms684175(VS.85).aspx for more info)
Cheers!
EDIT
Remember to use #include < Foo.h > as opposed to #include "foo.h". The former searches the include path. The latter uses the local project files.
how to print json data in console.log
This is an old post but I'm chiming in because (as Narem briefly mentioned) a few of the printf-like features are available with the console.log
formatters. In the case of the question, you can benefit from the string, number or json formatters for your data.
Examples:
console.log("Quantity %s, Price: %d", data.quantity-row_122, data.price-row_122);
console.log("Quantity and Price Data %j", data);
How to trigger SIGUSR1 and SIGUSR2?
They are signals that application developers use. The kernel shouldn't ever send these to a process. You can send them using kill(2)
or using the utility kill(1)
.
If you intend to use signals for synchronization you might want to check real-time signals (there's more of them, they are queued, their delivery order is guaranteed etc).
How to handle back button in activity
You can handle it like this:
for API level 5 and greater
@Override
public void onBackPressed() {
// your code.
}
older than API 5
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
// your code
return true;
}
return super.onKeyDown(keyCode, event);
}
DataTables: Uncaught TypeError: Cannot read property 'defaults' of undefined
I got the same error, I'm using laravel 5.4 with webpack, here package.json before:
{
...
...
"devDependencies": {
"jquery": "^1.12.4",
...
...
},
"dependencies": {
"datatables.net": "^2.1.1",
...
...
}
}
I had to move jquery
and datatables.net
npm packages under one of these "dependencies": {}
or "devDependencies": {}
in package.json
and the error disappeared, after:
{
...
...
"devDependencies": {
"jquery": "^1.12.4",
"datatables.net": "^2.1.1",
...
...
}
}
I hope that helps!
ISO C90 forbids mixed declarations and code in C
Up until the C99 standard, all declarations had to come before any statements in a block:
void foo()
{
int i, j;
double k;
char *c;
// code
if (c)
{
int m, n;
// more code
}
// etc.
}
C99 allowed for mixing declarations and statements (like C++). Many compilers still default to C89, and some compilers (such as Microsoft's) don't support C99 at all.
So, you will need to do the following:
Determine if your compiler supports C99 or later; if it does, configure it so that it's compiling C99 instead of C89;
If your compiler doesn't support C99 or later, you will either need to find a different compiler that does support it, or rewrite your code so that all declarations come before any statements within the block.
How to trap on UIViewAlertForUnsatisfiableConstraints?
You'll want to add a Symbolic Breakpoint
. Apple provides an excellent guide on how to do this.
- Open the Breakpoint Navigator
cmd+7
(cmd+8
in Xcode 9)
- Click the
Add
button in the lower left
- Select
Add Symbolic Breakpoint...
- Where it says
Symbol
just type in UIViewAlertForUnsatisfiableConstraints
You can also treat it like any other breakpoint, turning it on and off, adding actions, or log messages.
Rendering JSON in controller
What exactly do you want to know? ActiveRecord has methods that serialize records into JSON. For instance, open up your rails console and enter ModelName.all.to_json
and you will see JSON output. render :json
essentially calls to_json
and returns the result to the browser with the correct headers. This is useful for AJAX calls in JavaScript where you want to return JavaScript objects to use. Additionally, you can use the callback
option to specify the name of the callback you would like to call via JSONP.
For instance, lets say we have a User
model that looks like this: {name: 'Max', email:' [email protected]'}
We also have a controller that looks like this:
class UsersController < ApplicationController
def show
@user = User.find(params[:id])
render json: @user
end
end
Now, if we do an AJAX call using jQuery like this:
$.ajax({
type: "GET",
url: "/users/5",
dataType: "json",
success: function(data){
alert(data.name) // Will alert Max
}
});
As you can see, we managed to get the User with id 5 from our rails app and use it in our JavaScript code because it was returned as a JSON object. The callback option just calls a JavaScript function of the named passed with the JSON object as the first and only argument.
To give an example of the callback
option, take a look at the following:
class UsersController < ApplicationController
def show
@user = User.find(params[:id])
render json: @user, callback: "testFunction"
end
end
Now we can crate a JSONP request as follows:
function testFunction(data) {
alert(data.name); // Will alert Max
};
var script = document.createElement("script");
script.src = "/users/5";
document.getElementsByTagName("head")[0].appendChild(script);
The motivation for using such a callback is typically to circumvent the browser protections that limit cross origin resource sharing (CORS). JSONP isn't used that much anymore, however, because other techniques exist for circumventing CORS that are safer and easier.
Windows Explorer "Command Prompt Here"
Just type "cmd" to location bar, that's it. It will start a new command prompt in current path.
This solution was confirmed to work in Windows XP, Vista, 7, 8 and 10 (including Creators Update).
Keystrokes to move the focus to the location bar:
- AltD in English (pointed out by Tim Stewart in the comments)
- AltE in German
Python URLLib / URLLib2 POST
u = urllib2.urlopen('http://myserver/inout-tracker', data)
h.request('POST', '/inout-tracker/index.php', data, headers)
Using the path /inout-tracker
without a trailing /
doesn't fetch index.php
. Instead the server will issue a 302
redirect to the version with the trailing /
.
Doing a 302 will typically cause clients to convert a POST to a GET request.
Adding a dictionary to another
foreach(var newAnimal in NewAnimals)
Animals.Add(newAnimal.Key,newAnimal.Value)
Note: this throws an exception on a duplicate key.
Or if you really want to go the extension method route(I wouldn't), then you could define a general AddRange
extension method that works on any ICollection<T>
, and not just on Dictionary<TKey,TValue>
.
public static void AddRange<T>(this ICollection<T> target, IEnumerable<T> source)
{
if(target==null)
throw new ArgumentNullException(nameof(target));
if(source==null)
throw new ArgumentNullException(nameof(source));
foreach(var element in source)
target.Add(element);
}
(throws on duplicate keys for dictionaries)
Recommended SQL database design for tags or tagging
Normally I would agree with Yaakov Ellis but in this special case there is another viable solution:
Use two tables:
Table: Item
Columns: ItemID, Title, Content
Indexes: ItemID
Table: Tag
Columns: ItemID, Title
Indexes: ItemId, Title
This has some major advantages:
First it makes development much simpler: in the three-table solution for insert and update of item
you have to lookup the Tag
table to see if there are already entries. Then you have to join them with new ones. This is no trivial task.
Then it makes queries simpler (and perhaps faster). There are three major database queries which you will do: Output all Tags
for one Item
, draw a Tag-Cloud and select all items for one Tag Title.
All Tags for one Item:
3-Table:
SELECT Tag.Title
FROM Tag
JOIN ItemTag ON Tag.TagID = ItemTag.TagID
WHERE ItemTag.ItemID = :id
2-Table:
SELECT Tag.Title
FROM Tag
WHERE Tag.ItemID = :id
Tag-Cloud:
3-Table:
SELECT Tag.Title, count(*)
FROM Tag
JOIN ItemTag ON Tag.TagID = ItemTag.TagID
GROUP BY Tag.Title
2-Table:
SELECT Tag.Title, count(*)
FROM Tag
GROUP BY Tag.Title
Items for one Tag:
3-Table:
SELECT Item.*
FROM Item
JOIN ItemTag ON Item.ItemID = ItemTag.ItemID
JOIN Tag ON ItemTag.TagID = Tag.TagID
WHERE Tag.Title = :title
2-Table:
SELECT Item.*
FROM Item
JOIN Tag ON Item.ItemID = Tag.ItemID
WHERE Tag.Title = :title
But there are some drawbacks, too: It could take more space in the database (which could lead to more disk operations which is slower) and it's not normalized which could lead to inconsistencies.
The size argument is not that strong because the very nature of tags is that they are normally pretty small so the size increase is not a large one. One could argue that the query for the tag title is much faster in a small table which contains each tag only once and this certainly is true. But taking in regard the savings for not having to join and the fact that you can build a good index on them could easily compensate for this. This of course depends heavily on the size of the database you are using.
The inconsistency argument is a little moot too. Tags are free text fields and there is no expected operation like 'rename all tags "foo" to "bar"'.
So tldr: I would go for the two-table solution. (In fact I'm going to. I found this article to see if there are valid arguments against it.)
How do I make a text input non-editable?
Add readonly
:
<input type="text" value="3" class="field left" readonly>
If you want the value to be not submitted in a form, instead add the disabled
attribute.
<input type="text" value="3" class="field left" disabled>
There is no way to use CSS that always works to do this.
Why? CSS can't "disable" anything. You can still turn off display or visibility and use pointer-events: none
but pointer-events
doesn't work on versions of IE that came out earlier than IE 11.
Angular 4.3 - HttpClient set params
Using this you can avoid the loop.
// obj is the params object with key-value pair.
// This is how you convert that to HttpParams and pass this to GET API.
const params = Object.getOwnPropertyNames(obj)
.reduce((p, key) => p.set(key, obj[key]), new HttpParams());
Furthermore, I suggest making toHttpParams function in your commonly used service. So you can call the function to convert the object to the HttpParams.
/**
* Convert Object to HttpParams
* @param {Object} obj
* @returns {HttpParams}
*/
toHttpParams(obj: Object): HttpParams {
return Object.getOwnPropertyNames(obj)
.reduce((p, key) => p.set(key, obj[key]), new HttpParams());
}
Update:
Since 5.0.0-beta.6 (2017-09-03) they added new feature (accept
object map for HttpClient headers & params)
Going forward the object can be passed directly instead of HttpParams.
This is the other reason if you have used one common function like toHttpParams mentioned above, you can easily remove it or do changes if required.
Calling a parent window function from an iframe
parent.abc() will only work on same domain due to security purposes. i tried this workaround and mine worked perfectly.
<head>
<script>
function abc() {
alert("sss");
}
// window of the iframe
var innerWindow = document.getElementById('myFrame').contentWindow;
innerWindow.abc= abc;
</script>
</head>
<body>
<iframe id="myFrame">
<a onclick="abc();" href="#">Click Me</a>
</iframe>
</body>
Hope this helps. :)
How to get the employees with their managers
Perhaps your subquery (SELECT ename FROM EMP WHERE empno = mgr)
thinks, give me the employee records that are their own managers! (i.e., where the empno of a row is the same as the mgr of the same row.)
have you considered perhaps rewriting this to use an inner (self) join? (I'm asking, becuase i'm not even sure if the following will work or not.)
SELECT t1.ename, t1.empno, t2.ename as MANAGER, t1.mgr
from emp as t1
inner join emp t2 ON t1.mgr = t2.empno
order by t1.empno;
class << self idiom in Ruby
In fact if you write any C extensions for your Ruby projects there is really only one way to define a Module method.
rb_define_singleton_method
I know this self business just opens up all kinds of other questions so you could do better by searching each part.
Objects first.
foo = Object.new
Can I make a method for foo?
Sure
def foo.hello
'hello'
end
What do I do with it?
foo.hello
==>"hello"
Just another object.
foo.methods
You get all the Object methods plus your new one.
def foo.self
self
end
foo.self
Just the foo Object.
Try to see what happens if you make foo from other Objects like Class and Module. The examples from all the answers are nice to play with but you have to work with different ideas or concepts to really understand what is going on with the way the code is written. So now you have lots of terms to go look at.
Singleton,
Class,
Module,
self,
Object,
and Eigenclass was brought up but Ruby doesn't name Object Models that way. It's more like Metaclass.
Richard or __why shows you the idea here.
http://viewsourcecode.org/why/hacking/seeingMetaclassesClearly.html
And if the blows you away then try looking up Ruby Object Model in search.
Two videos that I know of on YouTube are Dave Thomas and Peter Cooper. They try to explain that concept too. It took Dave a long time to get it so don't worry.
I'm still working on it too. Why else would I be here?
Thanks for your question.
Also take a look at the standard library. It has a Singleton Module just as an FYI.
This is pretty good.
https://www.youtube.com/watch?v=i4uiyWA8eFk
How to list files inside a folder with SQL Server
You can use xp_dirtree
It takes three parameters:
Path of a Root Directory,
Depth up to which you want to get files and folders and
the last one is for showing folders only or both folders and files.
EXAMPLE: EXEC xp_dirtree 'C:\', 2, 1
How to cast or convert an unsigned int to int in C?
Some explain from C++Primer 5th Page 35
If we assign an out-of-range value to an object of unsigned type, the result is the remainder of the value modulo the number of values the target type can hold.
For example, an 8-bit unsigned char can hold values from 0 through 255, inclusive. If we assign a value outside the range, the compiler assigns the remainder of that value modulo 256.
unsigned char c = -1; // assuming 8-bit chars, c has value 255
If we assign an out-of-range value to an object of signed type, the result is undefined. The program might appear to work, it might crash, or it might produce garbage values.
Page 160:
If any operand is an unsigned type, the type to which the operands are converted depends on the relative sizes of the integral types on the machine.
...
When the signedness differs and the type of the unsigned operand is the same as or larger than that of the signed operand, the signed operand is converted to unsigned.
The remaining case is when the signed operand has a larger type than the unsigned operand. In this case, the result is machine dependent. If all values in the unsigned type fit in the large type, then the unsigned operand is converted to the signed type. If the values don't fit, then the signed operand is converted to the unsigned type.
For example, if the operands are long and unsigned int, and int and long have the same size, the length will be converted to unsigned int. If the long type has more bits, then the unsigned int will be converted to long.
I found reading this book is very helpful.
AngularJS $watch window resize inside directive
You can listen resize
event and fire where some dimension change
directive
(function() {
'use strict';
angular
.module('myApp.directives')
.directive('resize', ['$window', function ($window) {
return {
link: link,
restrict: 'A'
};
function link(scope, element, attrs){
scope.width = $window.innerWidth;
function onResize(){
// uncomment for only fire when $window.innerWidth change
// if (scope.width !== $window.innerWidth)
{
scope.width = $window.innerWidth;
scope.$digest();
}
};
function cleanUp() {
angular.element($window).off('resize', onResize);
}
angular.element($window).on('resize', onResize);
scope.$on('$destroy', cleanUp);
}
}]);
})();
In html
<div class="row" resize> ,
<div class="col-sm-2 col-xs-6" ng-repeat="v in tag.vod">
<h4 ng-bind="::v.known_as"></h4>
</div>
</div>
Controller :
$scope.$watch('width', function(old, newv){
console.log(old, newv);
})
How to clear APC cache entries?
This is not stated in the documentation, but to clear the opcode cache you must do:
apc_clear_cache('opcode');
EDIT: This seems to only apply to some older versions of APC..
No matter what version you are using you can't clear mod_php or fastcgi APC cache from a php cli script since the cli script will run from a different process as mod_php or fastcgi. You must call apc_clear_cache() from within the process (or child process) which you want to clear the cache for. Using curl to run a simple php script is one such approach.
Reference jars inside a jar
You can't. From the official tutorial:
By using the Class-Path header in the manifest, you can avoid having
to specify a long -classpath flag when invoking Java to run the your
application.
Note: The Class-Path header points to classes or JAR files on the
local network, not JAR files within the JAR file or classes accessible
over internet protocols. To load classes in JAR files within a JAR
file into the class path, you must write custom code to load those
classes. For example, if MyJar.jar contains another JAR file called
MyUtils.jar, you cannot use the Class-Path header in MyJar.jar's
manifest to load classes in MyUtils.jar into the class path.
Guid is all 0's (zeros)?
Use the static method Guid.NewGuid()
instead of calling the default constructor.
var responseObject = proxy.CallService(new RequestObject
{
Data = "misc. data",
Guid = Guid.NewGuid()
});
How to redirect to a 404 in Rails?
If you want to handle different 404s in different ways, consider catching them in your controllers. This will allow you to do things like tracking the number of 404s generated by different user groups, have support interact with users to find out what went wrong / what part of the user experience might need tweaking, do A/B testing, etc.
I have here placed the base logic in ApplicationController, but it can also be placed in more specific controllers, to have special logic only for one controller.
The reason I am using an if with ENV['RESCUE_404'], is so I can test the raising of AR::RecordNotFound in isolation. In tests, I can set this ENV var to false, and my rescue_from would not fire. This way I can test the raising separate from the conditional 404 logic.
class ApplicationController < ActionController::Base
rescue_from ActiveRecord::RecordNotFound, with: :conditional_404_redirect if ENV['RESCUE_404']
private
def conditional_404_redirect
track_404(@current_user)
if @current_user.present?
redirect_to_user_home
else
redirect_to_front
end
end
end
Why have header files and .cpp files?
Often you will want to have a definition of an interface without having to ship the entire code. For example, if you have a shared library, you would ship a header file with it which defines all the functions and symbols used in the shared library. Without header files, you would need to ship the source.
Within a single project, header files are used, IMHO, for at least two purposes:
- Clarity, that is, by keeping the interfaces separate from the implementation, it is easier to read the code
- Compile time. By using only the interface where possible, instead of the full implementation, the compile time can be reduced because the compiler can simply make a reference to the interface instead of having to parse the actual code (which, idealy, would only need to be done a single time).
Read from database and fill DataTable
Connection object is for illustration only. The DataAdapter is the key bit:
Dim strSql As String = "SELECT EmpCode,EmpID,EmpName FROM dbo.Employee"
Dim dtb As New DataTable
Using cnn As New SqlConnection(connectionString)
cnn.Open()
Using dad As New SqlDataAdapter(strSql, cnn)
dad.Fill(dtb)
End Using
cnn.Close()
End Using
Return list from async/await method
you can use the following
private async Task<List<string>> GetItems()
{
return await Task.FromResult(new List<string>
{
"item1", "item2", "item3"
});
}
Java/Groovy - simple date reformatting
With Groovy, you don't need the includes, and can just do:
String oldDate = '04-DEC-2012'
Date date = Date.parse( 'dd-MMM-yyyy', oldDate )
String newDate = date.format( 'M-d-yyyy' )
println newDate
To print:
12-4-2012
Not an enclosing class error Android Studio
you are calling the context of not existing activity...so just replace your code in onClick(View v) as
Intent intent=new Intent(this,Katra_home.class);
startActivity(intent);
it will definitely works....
Maintaining Session through Angular.js
Here is a kind of snippet for you:
app.factory('Session', function($http) {
var Session = {
data: {},
saveSession: function() { /* save session data to db */ },
updateSession: function() {
/* load data from db */
$http.get('session.json').then(function(r) { return Session.data = r.data;});
}
};
Session.updateSession();
return Session;
});
Here is Plunker example how you can use that:
http://plnkr.co/edit/Fg3uF4ukl5p88Z0AeQqU?p=preview
Is there a better way to do optional function parameters in JavaScript?
This is what I ended up with:
function WhoLikesCake(options) {
options = options || {};
var defaultOptions = {
a : options.a || "Huh?",
b : options.b || "I don't like cake."
}
console.log('a: ' + defaultOptions.b + ' - b: ' + defaultOptions.b);
// Do more stuff here ...
}
Called like this:
WhoLikesCake({ b : "I do" });
Node.js request CERT_HAS_EXPIRED
The best way to fix this:
Renew the certificate. This can be done for free using Greenlock which issues certificates via Let's Encrypt™ v2
A less insecure way to fix this:
'use strict';
var request = require('request');
var agentOptions;
var agent;
agentOptions = {
host: 'www.example.com'
, port: '443'
, path: '/'
, rejectUnauthorized: false
};
agent = new https.Agent(agentOptions);
request({
url: "https://www.example.com/api/endpoint"
, method: 'GET'
, agent: agent
}, function (err, resp, body) {
// ...
});
By using an agent
with rejectUnauthorized
you at least limit the security vulnerability to the requests that deal with that one site instead of making your entire node process completely, utterly insecure.
Other Options
If you were using a self-signed cert you would add this option:
agentOptions.ca = [ selfSignedRootCaPemCrtBuffer ];
For trusted-peer connections you would also add these 2 options:
agentOptions.key = clientPemKeyBuffer;
agentOptions.cert = clientPemCrtSignedBySelfSignedRootCaBuffer;
Bad Idea
It's unfortunate that process.env.NODE_TLS_REJECT_UNAUTHORIZED = '0';
is even documented. It should only be used for debugging and should never make it into in sort of code that runs in the wild. Almost every library that runs atop https
has a way of passing agent options through. Those that don't should be fixed.
How do I deal with "signed/unsigned mismatch" warnings (C4018)?
You can use:
- size_t type, to remove warning messages
- iterators + distance (like are first hint)
- only iterators
- function object
For example:
// simple class who output his value
class ConsoleOutput
{
public:
ConsoleOutput(int value):m_value(value) { }
int Value() const { return m_value; }
private:
int m_value;
};
// functional object
class Predicat
{
public:
void operator()(ConsoleOutput const& item)
{
std::cout << item.Value() << std::endl;
}
};
void main()
{
// fill list
std::vector<ConsoleOutput> list;
list.push_back(ConsoleOutput(1));
list.push_back(ConsoleOutput(8));
// 1) using size_t
for (size_t i = 0; i < list.size(); ++i)
{
std::cout << list.at(i).Value() << std::endl;
}
// 2) iterators + distance, for std::distance only non const iterators
std::vector<ConsoleOutput>::iterator itDistance = list.begin(), endDistance = list.end();
for ( ; itDistance != endDistance; ++itDistance)
{
// int or size_t
int const position = static_cast<int>(std::distance(list.begin(), itDistance));
std::cout << list.at(position).Value() << std::endl;
}
// 3) iterators
std::vector<ConsoleOutput>::const_iterator it = list.begin(), end = list.end();
for ( ; it != end; ++it)
{
std::cout << (*it).Value() << std::endl;
}
// 4) functional objects
std::for_each(list.begin(), list.end(), Predicat());
}
Url decode UTF-8 in Python
You can achieve an expected result with requests
library as well:
import requests
url = "http://www.mywebsite.org/Data%20Set.zip"
print(f"Before: {url}")
print(f"After: {requests.utils.unquote(url)}")
Output:
$ python3 test_url_unquote.py
Before: http://www.mywebsite.org/Data%20Set.zip
After: http://www.mywebsite.org/Data Set.zip
Might be handy if you are already using requests
, without using another library for this job.
Scala Doubles, and Precision
Here's another solution without BigDecimals
Truncate:
(math floor 1.23456789 * 100) / 100
Round:
(math rint 1.23456789 * 100) / 100
Or for any double n and precision p:
def truncateAt(n: Double, p: Int): Double = { val s = math pow (10, p); (math floor n * s) / s }
Similar can be done for the rounding function, this time using currying:
def roundAt(p: Int)(n: Double): Double = { val s = math pow (10, p); (math round n * s) / s }
which is more reusable, e.g. when rounding money amounts the following could be used:
def roundAt2(n: Double) = roundAt(2)(n)
typeof operator in C
It's a GNU extension. In a nutshell it's a convenient way to declare an object having the same type as another. For example:
int x; /* Plain old int variable. */
typeof(x) y; /* Same type as x. Plain old int variable. */
It works entirely at compile-time and it's primarily used in macros. One famous example of macro relying on typeof
is container_of
.
Select a Column in SQL not in Group By
You can use as below,
Select X.a, X.b, Y.c from (
Select X.a as a, sum (b) as sum_b from name_table X
group by X.a)X
left join from name_table Y on Y.a = X.a
Example;
CREATE TABLE #products (
product_name VARCHAR(MAX),
code varchar(3),
list_price [numeric](8, 2) NOT NULL
);
INSERT INTO #products VALUES ('paku', 'ACE', 2000)
INSERT INTO #products VALUES ('paku', 'ACE', 2000)
INSERT INTO #products VALUES ('Dinding', 'ADE', 2000)
INSERT INTO #products VALUES ('Kaca', 'AKB', 2000)
INSERT INTO #products VALUES ('paku', 'ACE', 2000)
--SELECT * FROM #products
SELECT distinct x.code, x.SUM_PRICE, product_name FROM (SELECT code, SUM(list_price) as SUM_PRICE From #products
group by code)x
left join #products y on y.code=x.code
DROP TABLE #products
How best to include other scripts?
I'd suggest that you create a setenv script whose sole purpose is to provide locations for various components across your system.
All other scripts would then source this script so that all locations are common across all scripts using the setenv script.
This is very useful when running cronjobs. You get a minimal environment when running cron, but if you make all cron scripts first include the setenv script then you are able to control and synchronise the environment that you want the cronjobs to execute in.
We used such a technique on our build monkey that was used for continuous integration across a project of about 2,000 kSLOC.
.toLowerCase not working, replacement function?
.toLowerCase function only exists on strings. You can call toString() on anything in javascript to get a string representation. Putting this all together:
var ans = 334;
var temp = ans.toString().toLowerCase();
alert(temp);
How do I change the formatting of numbers on an axis with ggplot?
I also found another way of doing this that gives proper 'x10(superscript)5' notation on the axes. I'm posting it here in the hope it might be useful to some. I got the code from here so I claim no credit for it, that rightly goes to Brian Diggs.
fancy_scientific <- function(l) {
# turn in to character string in scientific notation
l <- format(l, scientific = TRUE)
# quote the part before the exponent to keep all the digits
l <- gsub("^(.*)e", "'\\1'e", l)
# turn the 'e+' into plotmath format
l <- gsub("e", "%*%10^", l)
# return this as an expression
parse(text=l)
}
Which you can then use as
ggplot(data=df, aes(x=x, y=y)) +
geom_point() +
scale_y_continuous(labels=fancy_scientific)
Convert ascii value to char
To convert an int
ASCII value to character you can also use:
int asciiValue = 65;
char character = char(asciiValue);
cout << character; // output: A
cout << char(90); // output: Z
How can I clear the input text after clicking
Using jQuery ...
$('#submitButtonsId').click(
function(){
$(#myTextInput).val('');
});
Using pure Javascript ...
var btn = document.getElementById('submitButton');
btn.onclick = function(){ document.getElementById('myTextInput').value="" };
Get class name of object as string in Swift
Swift 3.0:
You can create an extension like this one.. It gives back the class name without the project name
extension NSObject {
var className: String {
return NSStringFromClass(self as! AnyClass).components(separatedBy: ".").last ?? ""
}
public class var className: String {
return NSStringFromClass(self).components(separatedBy: ".").last ?? ""
}
}
JQuery Calculate Day Difference in 2 date textboxes
1) Html
<input type="text" id="firstDate" name="firstDate"/>
<input type="text" id="secondDate" name="secondDate"/>
2) Jquery
$("#firstDate").datepicker({
});
$("#secondDate").datepicker({
onSelect: function () {
myfunc();
}
});
function myfunc(){
var start= $("#firstDate").datepicker("getDate");
var end= $("#secondDate").datepicker("getDate");
days = (end- start) / (1000 * 60 * 60 * 24);
alert(Math.round(days));
}
Jsfiddle working example here
How do I install PHP cURL on Linux Debian?
Type in console as root:
apt-get update && apt-get install php5-curl
or with sudo:
sudo apt-get update && sudo apt-get install php5-curl
Sorry I missread.
1st, check your DNS config and if you can ping any host at all,
ping google.com
ping zm.archive.ubuntu.com
If it does not work, check /etc/resolv.conf
or /etc/network/resolv.conf
, if not, change your apt-source to a different one.
/etc/apt/sources.list
Mirrors: http://www.debian.org/mirror/list
You should not use Ubuntu sources on Debian and vice versa.
null vs empty string in Oracle
In oracle an empty varchar2 and null are treated the same, and your observations show that.
when you write:
select * from table where a = '';
its the same as writing
select * from table where a = null;
and not a is null
which will never equate to true, so never return a row. same on the insert, a NOT NULL means you cant insert a null or an empty string (which is treated as a null)
How do I get an OAuth 2.0 authentication token in C#
You may use the following code to get the bearer token.
private string GetBearerToken()
{
var client = new RestClient("https://service.endpoint.com");
client.Authenticator = new HttpBasicAuthenticator("abc", "123");
var request = new RestRequest("api/oauth2/token", Method.POST);
request.AddHeader("content-type", "application/json");
request.AddParameter("application/json", "{ \"grant_type\":\"client_credentials\" }",
ParameterType.RequestBody);
var responseJson = _client.Execute(request).Content;
var token = JsonConvert.DeserializeObject<Dictionary<string, object>>(responseJson)["access_token"].ToString();
if(token.Length == 0)
{
throw new AuthenticationException("API authentication failed.");
}
return token;
}
React.js: How to append a component on click?
Don't use jQuery to manipulate the DOM when you're using React. React components should render a representation of what they should look like given a certain state; what DOM that translates to is taken care of by React itself.
What you want to do is store the "state which determines what gets rendered" higher up the chain, and pass it down. If you are rendering n
children, that state should be "owned" by whatever contains your component. eg:
class AppComponent extends React.Component {
state = {
numChildren: 0
}
render () {
const children = [];
for (var i = 0; i < this.state.numChildren; i += 1) {
children.push(<ChildComponent key={i} number={i} />);
};
return (
<ParentComponent addChild={this.onAddChild}>
{children}
</ParentComponent>
);
}
onAddChild = () => {
this.setState({
numChildren: this.state.numChildren + 1
});
}
}
const ParentComponent = props => (
<div className="card calculator">
<p><a href="#" onClick={props.addChild}>Add Another Child Component</a></p>
<div id="children-pane">
{props.children}
</div>
</div>
);
const ChildComponent = props => <div>{"I am child " + props.number}</div>;
How to create a new instance from a class object in Python
This is how you can dynamically create a class named Child
in your code, assuming Parent
already exists... even if you don't have an explicit Parent
class, you could use object
...
The code below defines __init__()
and then associates it with the class.
>>> child_name = "Child"
>>> child_parents = (Parent,)
>>> child body = """
def __init__(self, arg1):
# Initialization for the Child class
self.foo = do_something(arg1)
"""
>>> child_dict = {}
>>> exec(child_body, globals(), child_dict)
>>> childobj = type(child_name, child_parents, child_dict)
>>> childobj.__name__
'Child'
>>> childobj.__bases__
(<type 'object'>,)
>>> # Instantiating the new Child object...
>>> childinst = childobj()
>>> childinst
<__main__.Child object at 0x1c91710>
>>>
How would I get everything before a : in a string Python
I have benchmarked these various technics under Python 3.7.0 (IPython).
TLDR
- fastest (when the split symbol
c
is known): pre-compiled regex.
- fastest (otherwise):
s.partition(c)[0]
.
- safe (i.e., when
c
may not be in s
): partition, split.
- unsafe: index, regex.
Code
import string, random, re
SYMBOLS = string.ascii_uppercase + string.digits
SIZE = 100
def create_test_set(string_length):
for _ in range(SIZE):
random_string = ''.join(random.choices(SYMBOLS, k=string_length))
yield (random.choice(random_string), random_string)
for string_length in (2**4, 2**8, 2**16, 2**32):
print("\nString length:", string_length)
print(" regex (compiled):", end=" ")
test_set_for_regex = ((re.compile("(.*?)" + c).match, s) for (c, s) in test_set)
%timeit [re_match(s).group() for (re_match, s) in test_set_for_regex]
test_set = list(create_test_set(16))
print(" partition: ", end=" ")
%timeit [s.partition(c)[0] for (c, s) in test_set]
print(" index: ", end=" ")
%timeit [s[:s.index(c)] for (c, s) in test_set]
print(" split (limited): ", end=" ")
%timeit [s.split(c, 1)[0] for (c, s) in test_set]
print(" split: ", end=" ")
%timeit [s.split(c)[0] for (c, s) in test_set]
print(" regex: ", end=" ")
%timeit [re.match("(.*?)" + c, s).group() for (c, s) in test_set]
Results
String length: 16
regex (compiled): 156 ns ± 4.41 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)
partition: 19.3 µs ± 430 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)
index: 26.1 µs ± 341 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)
split (limited): 26.8 µs ± 1.26 µs per loop (mean ± std. dev. of 7 runs, 10000 loops each)
split: 26.3 µs ± 835 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)
regex: 128 µs ± 4.02 µs per loop (mean ± std. dev. of 7 runs, 10000 loops each)
String length: 256
regex (compiled): 167 ns ± 2.7 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)
partition: 20.9 µs ± 694 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)
index: 28.6 µs ± 2.73 µs per loop (mean ± std. dev. of 7 runs, 10000 loops each)
split (limited): 27.4 µs ± 979 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)
split: 31.5 µs ± 4.86 µs per loop (mean ± std. dev. of 7 runs, 10000 loops each)
regex: 148 µs ± 7.05 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)
String length: 65536
regex (compiled): 173 ns ± 3.95 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)
partition: 20.9 µs ± 613 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)
index: 27.7 µs ± 515 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)
split (limited): 27.2 µs ± 796 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)
split: 26.5 µs ± 377 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)
regex: 128 µs ± 1.5 µs per loop (mean ± std. dev. of 7 runs, 10000 loops each)
String length: 4294967296
regex (compiled): 165 ns ± 1.2 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)
partition: 19.9 µs ± 144 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)
index: 27.7 µs ± 571 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)
split (limited): 26.1 µs ± 472 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)
split: 28.1 µs ± 1.69 µs per loop (mean ± std. dev. of 7 runs, 10000 loops each)
regex: 137 µs ± 6.53 µs per loop (mean ± std. dev. of 7 runs, 10000 loops each)
How to parse a string into a nullable int
public static void Main(string[] args)
{
var myString = "abc";
int? myInt = ParseOnlyInt(myString);
// null
myString = "1234";
myInt = ParseOnlyInt(myString);
// 1234
}
private static int? ParseOnlyInt(string s)
{
return int.TryParse(s, out var i) ? i : (int?)null;
}
Display a RecyclerView in Fragment
Make sure that you have the correct layout, and that the RecyclerView id is inside the layout. Otherwise, you will be getting this error. I had the same problem, then I noticed the layout was wrong.
public class ColorsFragment extends Fragment {
public ColorsFragment() {}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
==> make sure you are getting the correct layout here. R.layout...
View rootView = inflater.inflate(R.layout.fragment_colors, container, false);
Android ImageView setImageResource in code
One easy way to map that country name that you have to an int
to be used in the setImageResource
method is:
int id = getResources().getIdentifier(lowerCountryCode, "drawable", getPackageName());
setImageResource(id);
But you should really try to use different folders resources for the countries that you want to support.
New warnings in iOS 9: "all bitcode will be dropped"
Your library was compiled without bitcode, but the bitcode option is enabled in your project settings. Say NO
to Enable Bitcode
in your target Build Settings and the Library Build Settings to remove the warnings.
For those wondering if enabling bitcode is required:
For iOS apps, bitcode is the default, but optional. For watchOS and tvOS apps, bitcode is required. If you provide bitcode, all apps and frameworks in the app bundle (all targets in the project) need to include bitcode.
https://help.apple.com/xcode/mac/current/#/devbbdc5ce4f
How to get current memory usage in android?
CAUTION: This answer measures memory usage/available of the DEVICE. This is NOT what is available to your app. To measure what your APP is doing, and is PERMITTED to do, Use android developer's answer.
Android docs - ActivityManager.MemoryInfo
parse /proc/meminfo command. You can find reference code here: Get Memory Usage in Android
use below code and get current RAM:
MemoryInfo mi = new MemoryInfo();
ActivityManager activityManager = (ActivityManager) getSystemService(ACTIVITY_SERVICE);
activityManager.getMemoryInfo(mi);
double availableMegs = mi.availMem / 0x100000L;
//Percentage can be calculated for API 16+
double percentAvail = mi.availMem / (double)mi.totalMem * 100.0;
Explanation of the number 0x100000L
1024 bytes == 1 Kibibyte
1024 Kibibyte == 1 Mebibyte
1024 * 1024 == 1048576
1048576 == 0x100000
It's quite obvious that the number is used to convert from bytes to mebibyte
P.S: we need to calculate total memory only once. so call point 1 only once in your code and then after, you can call code of point 2 repetitively.
Where is debug.keystore in Android Studio
I got this problem. The debug.keystore
file was missing.
So the only step that created a correct file for me was creating a new Android project in Android Studio.
It created me a new debug.keystore
under path C:\Users\username\.android\
.
This solution probably works only when you have not created any projects yet.
Working copy locked error in tortoise svn while committing
I had tried various things, including "Clean Up" on lower subdirectories. Finally, I tried updating the top level folder. Nothing. Then I read the "Clean up top level" tip. I tried that. The clean up part succeeded, but the lock remained. My solution was to go back to the top level, clean up, then clean up each red (!) folder I could drill down to. After all was "Cleaned up", the update worked perfectly. The "break lock" tip looks good, too, with the exception that someone on your team might have a legitimate lock on things.
Unable to copy file - access to the path is denied
So I just ran into the same issue, the cause of mine, I had my development folder shared so I could use a mac as a build host for an IOS application using Xamarin. The project was running on mac which took ownership of the dll therefore I could not make changes to that dll from anywhere else. Simply stopping the application on the mac returned ownership back to me which allowed full access again. I hope this make since.
@RequestParam vs @PathVariable
1) @RequestParam
is used to extract query parameters
http://localhost:3000/api/group/test?id=4
@GetMapping("/group/test")
public ResponseEntity<?> test(@RequestParam Long id) {
System.out.println("This is test");
return ResponseEntity.ok().body(id);
}
while @PathVariable
is used to extract data right from the URI:
http://localhost:3000/api/group/test/4
@GetMapping("/group/test/{id}")
public ResponseEntity<?> test(@PathVariable Long id) {
System.out.println("This is test");
return ResponseEntity.ok().body(id);
}
2) @RequestParam
is more useful on a traditional web application where data is mostly passed in the query parameters while @PathVariable
is more suitable for RESTful web services where URL contains values.
3) @RequestParam
annotation can specify default values if a query parameter is not present or empty by using a defaultValue
attribute, provided the required attribute is false
:
@RestController
@RequestMapping("/home")
public class IndexController {
@RequestMapping(value = "/name")
String getName(@RequestParam(value = "person", defaultValue = "John") String personName) {
return "Required element of request param";
}
}
Undefined index with $_POST
Your code assumes the existence of something:
$user = $_POST["username"];
PHP is letting you know that there is no "username" in the $_POST
array. In this instance, you would be safer checking to see if the value isset()
before attempting to access it:
if ( isset( $_POST["username"] ) ) {
/* ... proceed ... */
}
Alternatively, you could hi-jack the ||
operator to assign a default:
$user = $_POST["username"] || "visitor" ;
As long as the user's name isn't a falsy value, you can consider this method pretty reliable. A much safer route to default-assignment would be to use the ternary operator:
$user = isset( $_POST["username"] ) ? $_POST["username"] : "visitor" ;
Display QImage with QtGui
Drawing an image using a QLabel
seems like a bit of a kludge to me. With newer versions of Qt you can use a QGraphicsView
widget. In Qt Creator, drag a Graphics View
widget onto your UI and name it something (it is named mainImage
in the code below). In mainwindow.h
, add something like the following as private
variables to your MainWindow
class:
QGraphicsScene *scene;
QPixmap image;
Then just edit mainwindow.cpp
and make the constructor something like this:
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent), ui(new Ui::MainWindow)
{
ui->setupUi(this);
image.load("myimage.png");
scene = new QGraphicsScene(this);
scene->addPixmap(image);
scene->setSceneRect(image.rect());
ui->mainImage->setScene(scene);
}
jQuery: How to get the event object in an event handler function without passing it as an argument?
Write your event handler declaration like this:
<a href="#" onclick="myFunc(event,1,2,3)">click</a>
Then your "myFunc()" function can access the event.
The string value of the "onclick" attribute is converted to a function in a way that's almost exactly the same as the browser (internally) calling the Function constructor:
theAnchor.onclick = new Function("event", theOnclickString);
(except in IE). However, because "event" is a global in IE (it's a window attribute), you'll be able to pass it to the function that way in any browser.
Disabling of EditText in Android
if you use android:editable="false"
, eclipse will remind you this message "android:editable is deprecated: Use inputType instead".
So, I use android:focusable="false"
instead, it worked well for me.
How to get date in BAT file
This will give you DD MM YYYY YY HH Min Sec
variables and works on any Windows machine from XP Pro and later.
@echo off
for /f "tokens=2 delims==" %%a in ('wmic OS Get localdatetime /value') do set "dt=%%a"
set "YY=%dt:~2,2%" & set "YYYY=%dt:~0,4%" & set "MM=%dt:~4,2%" & set "DD=%dt:~6,2%"
set "HH=%dt:~8,2%" & set "Min=%dt:~10,2%" & set "Sec=%dt:~12,2%"
set "datestamp=%YYYY%%MM%%DD%" & set "timestamp=%HH%%Min%%Sec%"
set "fullstamp=%YYYY%-%MM%-%DD%_%HH%-%Min%-%Sec%"
echo datestamp: "%datestamp%"
echo timestamp: "%timestamp%"
echo fullstamp: "%fullstamp%"
pause
Git - How to fix "corrupted" interactive rebase?
It looks like Git tried to remove the .git/rebase-merge
directory but wasn't able to remove it completely. Have you tried copying that folder away? Also copy away the .git/rebase-apply
folder if that is present.
HTML Script tag: type or language (or omit both)?
The language
attribute has been deprecated for a long time, and should not be used.
When W3C was working on HTML5, they discovered all browsers have "text/javascript" as the default script type
, so they standardized it to be the default value. Hence, you don't need type
either.
For pages in XHTML 1.0 or HTML 4.01 omitting type
is considered invalid. Try validating the following:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<script src="http://example.com/test.js"></script>
</head>
<body/>
</html>
You will be informed of the following error:
Line 4, Column 41: required attribute "type" not specified
So if you're a fan of standards, use it. It should have no practical effect, but, when in doubt, may as well go by the spec.
How do I create a right click context menu in Java Swing?
You are probably manually calling setVisible(true)
on the menu. That can cause some nasty buggy behavior in the menu.
The show(Component, int x, int x)
method handles all of the things you need to happen, (Highlighting things on mouseover and closing the popup when necessary) where using setVisible(true)
just shows the menu without adding any additional behavior.
To make a right click popup menu simply create a JPopupMenu
.
class PopUpDemo extends JPopupMenu {
JMenuItem anItem;
public PopUpDemo() {
anItem = new JMenuItem("Click Me!");
add(anItem);
}
}
Then, all you need to do is add a custom MouseListener
to the components you would like the menu to popup for.
class PopClickListener extends MouseAdapter {
public void mousePressed(MouseEvent e) {
if (e.isPopupTrigger())
doPop(e);
}
public void mouseReleased(MouseEvent e) {
if (e.isPopupTrigger())
doPop(e);
}
private void doPop(MouseEvent e) {
PopUpDemo menu = new PopUpDemo();
menu.show(e.getComponent(), e.getX(), e.getY());
}
}
// Then on your component(s)
component.addMouseListener(new PopClickListener());
Of course, the tutorials have a slightly more in-depth explanation.
Note: If you notice that the popup menu is appearing way off from where the user clicked, try using the e.getXOnScreen()
and e.getYOnScreen()
methods for the x and y coordinates.
What should I do when 'svn cleanup' fails?
I had the exact same problem. I couldn't commit, and cleanup would fail.
Using a command-line client I was able to see an error message indicating that it was failing to move a file from .svn/props
to .svn/prop-base
.
I looked at the specific file and found that it was marked read-only. After removing the read-only attribute I was able to cleanup the folder and the commit my changes.
Displaying a 3D model in JavaScript/HTML5
I also needed what you've been searching for and did some research.
I found JSC3D (https://code.google.com/p/jsc3d/).
It's a project written entirely in Javascript and uses the HTML canvas. It has been tested for Opera, Chrome, Firefox, Safari, IE9 and more.
Then you have services as p3d.in and Sketchfab that give you a nice reader to view 3D models on a web page: they use HTML5 and WebGL. They both have a free version.
Android - Activity vs FragmentActivity?
ianhanniballake is right. You can get all the functionality of Activity
from FragmentActivity
. In fact, FragmentActivity
has more functionality.
Using FragmentActivity
you can easily build tab and swap
format. For each tab you can use different Fragment
(Fragments
are reusable). So for any FragmentActivity
you can reuse the same Fragment
.
Still you can use Activity
for single pages like list down something and edit element of the list in next page.
Also remember to use Activity
if you are using android.app.Fragment
; use FragmentActivity
if you are using android.support.v4.app.Fragment
. Never attach a android.support.v4.app.Fragment
to an android.app.Activity
, as this will cause an exception to be thrown.
Change background color for selected ListBox item
If selection is not important, it is better to use an ItemsControl wrapped in a ScrollViewer. This combination is more light-weight than the Listbox (which actually is derived from ItemsControl already) and using it would eliminate the need to use a cheap hack to override behavior that is already absent from the ItemsControl.
In cases where the selection behavior IS actually important, then this obviously will not work. However, if you want to change the color of the Selected Item Background in such a way that it is not visible to the user, then that would only serve to confuse them. In cases where your intention is to change some other characteristic to indicate that the item is selected, then some of the other answers to this question may still be more relevant.
Here is a skeleton of how the markup should look:
<ScrollViewer>
<ItemsControl>
<ItemsControl.ItemTemplate>
<DataTemplate>
...
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</ScrollViewer>
The SQL OVER() clause - when and why is it useful?
prkey whatsthat cash
890 "abb " 32 32
43 "abbz " 2 34
4 "bttu " 1 35
45 "gasstuff " 2 37
545 "gasz " 5 42
80009 "hoo " 9 51
2321 "ibm " 1 52
998 "krk " 2 54
42 "kx-5010 " 2 56
32 "lto " 4 60
543 "mp " 5 65
465 "multipower " 2 67
455 "O.N. " 1 68
7887 "prem " 7 75
434 "puma " 3 78
23 "retractble " 3 81
242 "Trujillo's stuff " 4 85
That's a result of query. Table used as source is the same exept that it has no last column. This column is a moving sum of third one.
Query:
SELECT prkey,whatsthat,cash,SUM(cash) over (order by whatsthat)
FROM public.iuk order by whatsthat,prkey
;
(table goes as public.iuk)
sql version: 2012
It's a little over dbase(1986) level, I don't know why 25+ years has been needed to finish it up.
WPF Binding to parent DataContext
I dont know about XamGrid
but that's what i'll do with a standard wpf DataGrid
:
<DataGrid>
<DataGrid.Columns>
<DataGridTemplateColumn>
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding DataContext.MyProperty, RelativeSource={RelativeSource AncestorType=MyUserControl}}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
<DataGridTemplateColumn.CellEditingTemplate>
<DataTemplate>
<TextBox Text="{Binding DataContext.MyProperty, RelativeSource={RelativeSource AncestorType=MyUserControl}}"/>
</DataTemplate>
</DataGridTemplateColumn.CellEditingTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
Since the TextBlock
and the TextBox
specified in the cell templates will be part of the visual tree, you can walk up and find whatever control you need.
Difference between Encapsulation and Abstraction
Encapsulation is wrapping up of data and methods in a single unit and making the data accessible only through methods(getter/setter) to ensure safety of data.
Abstraction is hiding internal implementation details of how work is done.
Take and example of following stack class:
Class Stack
{
private top;
void push();
int pop();
}
Now encapsulation helps to safeguard internal data as top cannot be accessed directly outside.
And abstraction helps to do push or pop on stack without worrying about what are steps to push or pop
javascript Unable to get property 'value' of undefined or null reference
You can't access element like you did (document.frm_new_user_request
). You have to use the function getElementById
:
document.getElementById("frm_new_user_request")
So getting a value from an input could look like this:
var value = document.getElementById("frm_new_user_request").value
Also you can use some JavaScript framework, e.g. jQuery, which simplifies operations with DOM (Document Object Model) and also hides differences between various browsers from you.
Getting a value from an input using jQuery would look like this:
- input with ID "element":
var value = $("#element).value
- input with class "element":
var value = $(".element).value
How to comment multiple lines in Visual Studio Code?
To change the setting on VS2019:
Tools->Options
Search for Keyboard
Under Show Commands Containing
search for ToggleLineComment
See what it is set to or change to whatever you like.
VERY IMPORTANT: sometimes it is required to select TextEditor
and not Global
. this killed me for hours.
Passing vector by reference
You don't need to use **arr, you can either use:
void do_something(int el, std::vector<int> *arr){
arr->push_back(el);
}
or:
void do_something(int el, std::vector<int> &arr){
arr.push_back(el);
}
**arr makes no sense but if you insist using it, do it this way:
void do_something(int el, std::vector<int> **arr){
(*arr)->push_back(el);
}
but again there is no reason to do so...
How to get a user's time zone?
func getCurrentTimeZone() -> String {
let localTimeZoneAbbreviation: Int = TimeZone.current.secondsFromGMT()
let gmtAbbreviation = (localTimeZoneAbbreviation / 60)
return "\(gmtAbbreviation)"
}
You can get current time zone abbreviation.
How can I match a string with a regex in Bash?
A Function To Do This
extract () {
if [ -f $1 ] ; then
case $1 in
*.tar.bz2) tar xvjf $1 ;;
*.tar.gz) tar xvzf $1 ;;
*.bz2) bunzip2 $1 ;;
*.rar) rar x $1 ;;
*.gz) gunzip $1 ;;
*.tar) tar xvf $1 ;;
*.tbz2) tar xvjf $1 ;;
*.tgz) tar xvzf $1 ;;
*.zip) unzip $1 ;;
*.Z) uncompress $1 ;;
*.7z) 7z x $1 ;;
*) echo "don't know '$1'..." ;;
esac
else
echo "'$1' is not a valid file!"
fi
}
Other Note
In response to Aquarius Power in the comment above, We need to store the regex on a var
The variable BASH_REMATCH is set after you match the expression, and ${BASH_REMATCH[n]} will match the nth group wrapped in parentheses ie in the following ${BASH_REMATCH[1]} = "compressed"
and ${BASH_REMATCH[2]} = ".gz"
if [[ "compressed.gz" =~ ^(.*)(\.[a-z]{1,5})$ ]];
then
echo ${BASH_REMATCH[2]} ;
else
echo "Not proper format";
fi
(The regex above isn't meant to be a valid one for file naming and extensions, but it works for the example)
How to manually set an authenticated user in Spring Security / SpringMVC
The new filtering feature in Servlet 2.4 basically alleviates the restriction that filters can only operate in the request flow before and after the actual request processing by the application server. Instead, Servlet 2.4 filters can now interact with the request dispatcher at every dispatch point. This means that when a Web resource forwards a request to another resource (for instance, a servlet forwarding the request to a JSP page in the same application), a filter can be operating before the request is handled by the targeted resource. It also means that should a Web resource include the output or function from other Web resources (for instance, a JSP page including the output from multiple other JSP pages), Servlet 2.4 filters can work before and after each of the included resources. .
To turn on that feature you need:
web.xml
<filter>
<filter-name>springSecurityFilterChain</filter-name>
<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>
<filter-mapping>
<filter-name>springSecurityFilterChain</filter-name>
<url-pattern>/<strike>*</strike></url-pattern>
<dispatcher>REQUEST</dispatcher>
<dispatcher>FORWARD</dispatcher>
</filter-mapping>
RegistrationController
return "forward:/login?j_username=" + registrationModel.getUserEmail()
+ "&j_password=" + registrationModel.getPassword();
C++ IDE for Linux?
If you like Eclipse for Java, I suggest Eclipse CDT.
Despite C/C++ support isn't so powerful as is for Java, it still offers most of the features. It has a nice feature named Managed Project that makes working with C/C++ projects easier if you don't have experience with Makefiles. But you can still use Makefiles.
I do C and Java coding and I'm really happy with CDT. I'm developing the firmware for a embedded device in C and a application in Java that talks to this device, and is really nice to use the same environment for both. I guess it probably makes me more productive.
How to insert 1000 rows at a time
Using a @Aaron Bertrand idea (FROM sys.all_columns
), this is something that will create 1000 records :
SELECT TOP (1000) LEFT(name,20) as names,
RIGHT(name,12) + '@' + LEFT(name,12) + '.com' as email,
sys.fn_sqlvarbasetostr(HASHBYTES('MD5', name)) as password
INTO db
FROM sys.all_columns
See SQLFIDDLE
Java 8 Lambda function that throws exception?
Create a custom return type that will propagate the checked exception. This is an alternative to creating a new interface that mirrors the existing functional interface with the slight modification of a "throws exception" on the functional interface's method.
Definition
CheckedValueSupplier
public static interface CheckedValueSupplier<V> {
public V get () throws Exception;
}
CheckedValue
public class CheckedValue<V> {
private final V v;
private final Optional<Exception> opt;
public Value (V v) {
this.v = v;
}
public Value (Exception e) {
this.opt = Optional.of(e);
}
public V get () throws Exception {
if (opt.isPresent()) {
throw opt.get();
}
return v;
}
public Optional<Exception> getException () {
return opt;
}
public static <T> CheckedValue<T> returns (T t) {
return new CheckedValue<T>(t);
}
public static <T> CheckedValue<T> rethrows (Exception e) {
return new CheckedValue<T>(e);
}
public static <V> CheckedValue<V> from (CheckedValueSupplier<V> sup) {
try {
return CheckedValue.returns(sup.get());
} catch (Exception e) {
return Result.rethrows(e);
}
}
public static <V> CheckedValue<V> escalates (CheckedValueSupplier<V> sup) {
try {
return CheckedValue.returns(sup.get());
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}
Usage
// Don't use this pattern with FileReader, it's meant to be an
// example. FileReader is a Closeable resource and as such should
// be managed in a try-with-resources block or in another safe
// manner that will make sure it is closed properly.
// This will not compile as the FileReader constructor throws
// an IOException.
Function<String, FileReader> sToFr =
(fn) -> new FileReader(Paths.get(fn).toFile());
// Alternative, this will compile.
Function<String, CheckedValue<FileReader>> sToFr = (fn) -> {
return CheckedValue.from (
() -> new FileReader(Paths.get("/home/" + f).toFile()));
};
// Single record usage
// The call to get() will propagate the checked exception if it exists.
FileReader readMe = pToFr.apply("/home/README").get();
// List of records usage
List<String> paths = ...; //a list of paths to files
Collection<CheckedValue<FileReader>> frs =
paths.stream().map(pToFr).collect(Collectors.toList());
// Find out if creation of a file reader failed.
boolean anyErrors = frs.stream()
.filter(f -> f.getException().isPresent())
.findAny().isPresent();
What's going on?
A single functional interface that throws a checked exception is created (CheckedValueSupplier
). This will be the only functional interface which allows checked exceptions. All other functional interfaces will leverage the CheckedValueSupplier
to wrap any code that throws a checked exception.
The CheckedValue
class will hold the result of executing any logic that throws a checked exception. This prevents propagation of a checked exception until the point at which code attempts to access the value that an instance of CheckedValue
contains.
The problems with this approach.
- We are now throwing "Exception" effectively hiding the specific type originally thrown.
- We are unaware that an exception occurred until
CheckedValue#get()
is called.
Consumer et al
Some functional interfaces (Consumer
for example) must be handled in a different manner as they don't provide a return value.
Function in lieu of Consumer
One approach is to use a function instead of a consumer, which applies when handling streams.
List<String> lst = Lists.newArrayList();
// won't compile
lst.stream().forEach(e -> throwyMethod(e));
// compiles
lst.stream()
.map(e -> CheckedValueSupplier.from(
() -> {throwyMethod(e); return e;}))
.filter(v -> v.getException().isPresent()); //this example may not actually run due to lazy stream behavior
Escalate
Alternatively, you can always escalate to a RuntimeException
. There are other answers that cover escalation of a checked exception from within a Consumer
.
Don't consume.
Just avoid functional interfaces all together and use a good-ole-fashioned for loop.
How to change the height of a div dynamically based on another div using css?
By specifying the positions we can achieve this,
.div1 {
width:300px;
height: auto;
background-color: grey;
border:1px solid;
position:relative;
overflow:auto;
}
.div2 {
width:150px;
height:auto;
background-color: #F4A460;
float:left;
}
.div3 {
width:150px;
height:100%;
position:absolute;
right:0px;
background-color: #FFFFE0;
float:right;
}
but it is not possible to achieve this using float.
How do I enter a multi-line comment in Perl?
POD is the official way to do multi line comments in Perl,
From faq.perl.org[perlfaq7]
The quick-and-dirty way to comment out more than one line of Perl is
to surround those lines with Pod directives. You have to put these
directives at the beginning of the line and somewhere where Perl
expects a new statement (so not in the middle of statements like the #
comments). You end the comment with =cut
, ending the Pod section:
=pod
my $object = NotGonnaHappen->new();
ignored_sub();
$wont_be_assigned = 37;
=cut
The quick-and-dirty method only works well when you don't plan to
leave the commented code in the source. If a Pod parser comes along,
your multiline comment is going to show up in the Pod translation. A
better way hides it from Pod parsers as well.
The =begin
directive can mark a section for a particular purpose. If
the Pod parser doesn't want to handle it, it just ignores it. Label
the comments with comment
. End the comment using =end
with the
same label. You still need the =cut
to go back to Perl code from the
Pod comment:
=begin comment
my $object = NotGonnaHappen->new();
ignored_sub();
$wont_be_assigned = 37;
=end comment
=cut
Nodejs cannot find installed module on Windows
I'll just quote from this node's blog post...
In general, the rule of thumb is:
- If you’re installing something that you want to use in your program, using require('whatever'), then install it locally, at the root of
your project.
- If you’re installing something that you want to use in your shell, on the command line or something, install it globally, so that its
binaries end up in your PATH environment variable.
...
Of course, there are some cases where you want to do both.
Coffee-script and Express both are good examples of apps that have a
command line interface, as well as a library. In those cases, you can
do one of the following:
- Install it in both places. Seriously, are you that short on disk space? It’s fine, really. They’re tiny JavaScript programs.
- Install it globally, and then npm link coffee-script or npm link express (if you’re on a platform that supports symbolic links.) Then
you only need to update the global copy to update all the symlinks as
well.
Making a DateTime field in a database automatic?
Just right click on that column and select properties and write getdate()
in Default value or binding
.like image:
If you want do it in CodeFirst
in EF
you should add this attributes befor of your column definition:
[Databasegenerated(Databaseoption.computed)]
this attributes can found in System.ComponentModel.Dataannotion.Schema
.
In my opinion first one is better:))
Should I use @EJB or @Inject
It may also be usefull to understand the difference in term of Session Bean Identity when using @EJB and @Inject.
According to the specifications the following code will always be true
:
@EJB Cart cart1;
@EJB Cart cart2;
… if (cart1.equals(cart2)) { // this test must return true ...}
Using @Inject instead of @EJB there is not the same.
see also stateless session beans identity for further info
C++ compile time error: expected identifier before numeric constant
You cannot do this:
vector<string> name(5); //error in these 2 lines
vector<int> val(5,0);
in a class outside of a method.
You can initialize the data members at the point of declaration, but not with ()
brackets:
class Foo {
vector<string> name = vector<string>(5);
vector<int> val{vector<int>(5,0)};
};
Before C++11, you need to declare them first, then initialize them e.g in a contructor
class Foo {
vector<string> name;
vector<int> val;
public:
Foo() : name(5), val(5,0) {}
};
Add content to a new open window
If you want to open a page or window with sending data POST or GET method you can use a code like this:
$.ajax({
type: "get", // or post method, your choice
url: yourFileForInclude.php, // any url in same origin
data: data, // data if you need send some data to page
success: function(msg){
console.log(msg); // for checking
window.open('about:blank').document.body.innerHTML = msg;
}
});
JavaScript: client-side vs. server-side validation
Well, I still find some room to answer.
In addition to answers from Rob and Nathan, I would add that having client-side validations matters. When you are applying validations on your webforms you must follow these guidelines:
Client-Side
- Must use client-side validations in order to filter genuine requests coming from genuine users at your website.
- The client-side validation should be used to reduce the errors that might occure during server side processing.
- Client-side validation should be used to minimize the server-side round-trips so that you save bandwidth and the requests per user.
Server-Side
- You SHOULD NOT assume the validation successfully done at client side is 100% perfect. No matter even if it serves less than 50 users. You never know which of your user/emplyee turn into an "evil" and do some harmful activity knowing you dont have proper validations in place.
- Even if its perfect in terms of validating email address, phone numbers or checking some valid inputs it might contain very harmful data. Which needs to be filtered at server-side no matter if its correct or incorrect.
- If client-side validation is bypassed, your server-side validations comes to rescue you from any potential damage to your server-side processing. In recent times, we have already heard lot of stories of SQL Injections and other sort of techniques that might be applied in order to gain some evil benefits.
Both types of validations play important roles in their respective scope but the most strongest is the server-side. If you receive 10k users at a single point of time then you would definitely end up filtering the number of requests coming to your webserver. If you find there was a single mistake like invalid email address then they post back the form again and ask your user to correct it which will definitely eat your server resources and bandwidth. So better you apply javascript validation. If javascript is disabled then your server side validation will come to rescue and i bet only a few users might have accidentlly disable it since 99.99% of websites use javascript and its already enabled by default in all modern browsers.
Import an existing git project into GitLab?
Gitlab is a little bit bugged on this feature.
You can lose a lot of time doing troubleshooting specially if your project is any big.
The best solution would be using the create/import tool, do not forget put your user name and password, otherwise it won't import anything at all.
Follow my screenshots
get current url in twig template?
{{ path(app.request.attributes.get('_route'),
app.request.attributes.get('_route_params')) }}
If you want to read it into a view variable:
{% set currentPath = path(app.request.attributes.get('_route'),
app.request.attributes.get('_route_params')) %}
The app
global view variable contains all sorts of useful shortcuts, such as app.session
and app.security.token.user
, that reference the services you might use in a controller.
Using SimpleXML to create an XML object from scratch
In PHP5, you should use the Document Object Model class instead.
Example:
$domDoc = new DOMDocument;
$rootElt = $domDoc->createElement('root');
$rootNode = $domDoc->appendChild($rootElt);
$subElt = $domDoc->createElement('foo');
$attr = $domDoc->createAttribute('ah');
$attrVal = $domDoc->createTextNode('OK');
$attr->appendChild($attrVal);
$subElt->appendChild($attr);
$subNode = $rootNode->appendChild($subElt);
$textNode = $domDoc->createTextNode('Wow, it works!');
$subNode->appendChild($textNode);
echo htmlentities($domDoc->saveXML());
Calling Web API from MVC controller
From my HomeController I want to call this Method and convert Json response to List
No you don't. You really don't want to add the overhead of an HTTP call and (de)serialization when the code is within reach. It's even in the same assembly!
Your ApiController goes against (my preferred) convention anyway. Let it return a concrete type:
public IEnumerable<QDocumentRecord> GetAllRecords()
{
listOfFiles = ...
return listOfFiles;
}
If you don't want that and you're absolutely sure you need to return HttpResponseMessage
, then still there's absolutely no need to bother with calling JsonConvert.SerializeObject()
yourself:
return Request.CreateResponse<List<QDocumentRecord>>(HttpStatusCode.OK, listOfFiles);
Then again, you don't want business logic in a controller, so you extract that into a class that does the work for you:
public class FileListGetter
{
public IEnumerable<QDocumentRecord> GetAllRecords()
{
listOfFiles = ...
return listOfFiles;
}
}
Either way, then you can call this class or the ApiController directly from your MVC controller:
public class HomeController : Controller
{
public ActionResult Index()
{
var listOfFiles = new DocumentsController().GetAllRecords();
// OR
var listOfFiles = new FileListGetter().GetAllRecords();
return View(listOfFiles);
}
}
But if you really, really must do an HTTP request, you can use HttpWebRequest
, WebClient
, HttpClient
or RestSharp
, for all of which plenty of tutorials exist.
Where will log4net create this log file?
Log4net is saving into your project folder. Something like: \SolutionFolder\ProjectFolder\bin\SolutionConfiguration\logs\log-file.txt
.
Where:
- SolutionFolder is where you save your solution
- ProjectFolder is the folder where your project lives into the solution and
- SolutionConfiguration is the folder that contais all the binaries of your project (the default is Debug or Release)
Hope this helps!
Convert javascript object or array to json for ajax data
I'm not entirely sure but I think you are probably surprised at how arrays are serialized in JSON. Let's isolate the problem. Consider following code:
var display = Array();
display[0] = "none";
display[1] = "block";
display[2] = "none";
console.log( JSON.stringify(display) );
This will print:
["none","block","none"]
This is how JSON actually serializes array. However what you want to see is something like:
{"0":"none","1":"block","2":"none"}
To get this format you want to serialize object, not array. So let's rewrite above code like this:
var display2 = {};
display2["0"] = "none";
display2["1"] = "block";
display2["2"] = "none";
console.log( JSON.stringify(display2) );
This will print in the format you want.
You can play around with this here: http://jsbin.com/oDuhINAG/1/edit?js,console
Can local storage ever be considered secure?
Well, the basic premise here is: no, it is not secure yet.
Basically, you can't run crypto in JavaScript: JavaScript Crypto Considered Harmful.
The problem is that you can't reliably get the crypto code into the browser, and even if you could, JS isn't designed to let you run it securely. So until browsers have a cryptographic container (which Encrypted Media Extensions provide, but are being rallied against for their DRM purposes), it will not be possible to do securely.
As far as a "Better way", there isn't one right now. Your only alternative is to store the data in plain text, and hope for the best. Or don't store the information at all. Either way.
Either that, or if you need that sort of security, and you need local storage, create a custom application...
Symfony - generate url with parameter in controller
make sure your controller extends Symfony\Bundle\FrameworkBundle\Controller\Controller;
you should also check app/console debug:router
in terminal to see what name symfony has named the route
in my case it used a minus instead of an underscore
i.e blog-show
$uri = $this->generateUrl('blog-show', ['slug' => 'my-blog-post']);
numpy division with RuntimeWarning: invalid value encountered in double_scalars
You can use np.logaddexp
(which implements the idea in @gg349's answer):
In [33]: d = np.array([[1089, 1093]])
In [34]: e = np.array([[1000, 4443]])
In [35]: log_res = np.logaddexp(-3*d[0,0], -3*d[0,1]) - np.logaddexp(-3*e[0,0], -3*e[0,1])
In [36]: log_res
Out[36]: -266.99999385580668
In [37]: res = exp(log_res)
In [38]: res
Out[38]: 1.1050349147204485e-116
Or you can use scipy.special.logsumexp
:
In [52]: from scipy.special import logsumexp
In [53]: res = np.exp(logsumexp(-3*d) - logsumexp(-3*e))
In [54]: res
Out[54]: 1.1050349147204485e-116
What does print(... sep='', '\t' ) mean?
The sep='\t' can be use in many forms, for example if you want to read tab separated value:
Example: I have a dataset tsv = tab separated value NOT comma separated value
df = pd.read_csv('gapminder.tsv').
when you try to read this, it will give you an error because you have tab separated value not csv. so you need to give read csv a different parameter called sep='\t'.
Now you can read:
df = pd.read_csv('gapminder.tsv, sep='\t'), with this you can read the it.
Array Size (Length) in C#
What has been missed so far is what I suddenly was irritated about:
How do I know the amount of items inside the array? Is .Length
equal .Count
of a List?
The answer is: the amount of items of type X which have been put into an array of type X created with new X[number]
you have to carry yourself!
Eg. using a counter: int countItemsInArray = 0
and countItemsInArray++
for every assignment to your array.
(The array just created with new X[number]
has all space for number
items (references) of type X already allocated, you can assign to any place inside as your first assignment, for example (if number
= 100 and the variable name = a
) a[50] = new X();
.
I don't know whether C# specifies the initial value of each place inside an array upon creation, if it doesn't or the initial value you cannot compare to (because it might be a value you yourself have put into the array), you would have to track which places inside the array you already assigned to too if you don't assign sequentially starting from 0
(in which case all places smaller than countItemsInArray
would be assigned to).)
In your question size of an array (length / number of items) depending on whether / is meant to stand for "alternative" or "divide by" the latter still has to be covered (the "number of items" I just gave as "amount of items" and others gave .Length
which corresponds to the value of number
in my code above):
C# has a sizeof
operator (https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/sizeof). It's safe to use for built-in types (such as int) (and only operates on types (not variables)). Thus the size of an array b
of type int
in bytes would be b.Length * sizeof(int)
.
(Due to all space of an array already being allocated on creation, like mentioned above, and sizeof
only working on types, no code like sizeof(variable)/sizeof(type)
would work or yield the amount of items without tracking.)
Python script to convert from UTF-8 to ASCII
import codecs
...
fichier = codecs.open(filePath, "r", encoding="utf-8")
...
fichierTemp = codecs.open("tempASCII", "w", encoding="ascii", errors="ignore")
fichierTemp.write(contentOfFile)
...
Use jQuery to change an HTML tag?
This the quick way to change HTML tags inside your DOM using jQuery. I find this replaceWith() function is very useful.
var text= $('p').text();
$('#change').on('click', function() {
target.replaceWith( "<h5>"+text+"</h5>" );
});
How to create circular ProgressBar in android?
It's easy to create this yourself
In your layout include the following ProgressBar
with a specific drawable (note you should get the width from dimensions instead). The max value is important here:
<ProgressBar
android:id="@+id/progressBar"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="150dp"
android:layout_height="150dp"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:max="500"
android:progress="0"
android:progressDrawable="@drawable/circular" />
Now create the drawable in your resources with the following shape. Play with the radius (you can use innerRadius
instead of innerRadiusRatio
) and thickness values.
circular (Pre Lollipop OR API Level < 21)
<shape
android:innerRadiusRatio="2.3"
android:shape="ring"
android:thickness="3.8sp" >
<solid android:color="@color/yourColor" />
</shape>
circular ( >= Lollipop OR API Level >= 21)
<shape
android:useLevel="true"
android:innerRadiusRatio="2.3"
android:shape="ring"
android:thickness="3.8sp" >
<solid android:color="@color/yourColor" />
</shape>
useLevel is "false" by default in API Level 21 (Lollipop) .
Start Animation
Next in your code use an ObjectAnimator
to animate the progress field of the ProgessBar
of your layout.
ProgressBar progressBar = (ProgressBar) view.findViewById(R.id.progressBar);
ObjectAnimator animation = ObjectAnimator.ofInt(progressBar, "progress", 0, 500); // see this max value coming back here, we animate towards that value
animation.setDuration(5000); // in milliseconds
animation.setInterpolator(new DecelerateInterpolator());
animation.start();
Stop Animation
progressBar.clearAnimation();
P.S. unlike examples above, it give smooth animation.
Is this the proper way to do boolean test in SQL?
With Postgres, you may use
select * from users where active
or
select * from users where active = 't'
If you want to use integer value, you have to consider it as a string.
You can't use integer value.
select * from users where active = 1 -- Does not work
select * from users where active = '1' -- Works
How to use [DllImport("")] in C#?
You can't declare an extern
local method inside of a method, or any other method with an attribute. Move your DLL import into the class:
using System.Runtime.InteropServices;
public class WindowHandling
{
[DllImport("User32.dll")]
public static extern int SetForegroundWindow(IntPtr point);
public void ActivateTargetApplication(string processName, List<string> barcodesList)
{
Process p = Process.Start("notepad++.exe");
p.WaitForInputIdle();
IntPtr h = p.MainWindowHandle;
SetForegroundWindow(h);
SendKeys.SendWait("k");
IntPtr processFoundWindow = p.MainWindowHandle;
}
}