Programs & Examples On #Actioncontroller

ActionController is the main controller class in Ruby on Rails.

Basic example for sharing text or image with UIActivityViewController in Swift

I've used the implementation above and just now I came to know that it doesn't work on iPad running iOS 13. I had to add these lines before present() call in order to make it work

//avoiding to crash on iPad
if let popoverController = activityViewController.popoverPresentationController {
     popoverController.sourceRect = CGRect(x: UIScreen.main.bounds.width / 2, y: UIScreen.main.bounds.height / 2, width: 0, height: 0)
     popoverController.sourceView = self.view
     popoverController.permittedArrowDirections = UIPopoverArrowDirection(rawValue: 0)

That's how it works for me

func shareData(_ dataToShare: [Any]){

        let activityViewController = UIActivityViewController(activityItems: dataToShare, applicationActivities: nil)

        //exclude some activity types from the list (optional)
        //activityViewController.excludedActivityTypes = [

        //avoiding to crash on iPad
        if let popoverController = activityViewController.popoverPresentationController {
            popoverController.sourceRect = CGRect(x: UIScreen.main.bounds.width / 2, y: UIScreen.main.bounds.height / 2, width: 0, height: 0)
            popoverController.sourceView = self.view
            popoverController.permittedArrowDirections = UIPopoverArrowDirection(rawValue: 0)

        self.present(activityViewController, animated: true, completion: nil)


There is another scenario where this issue reproduces (as in my case). When THE CLIENT REQUEST doesn't contain the right extension on the url, the controller can't identify the desired result format.

For example: the controller is set to respond_to :json (as a single option, without a HTML response)- while the client call is set to /reservations instead of /reservations.json.

Bottom line, change the client call to /reservations.json.

Allow anything through CORS Policy

Try configuration at /config/application.rb:

config.middleware.insert_before 0, "Rack::Cors" do
  allow do
    origins '*'
    resource '*', :headers => :any, :methods => [:get, :post, :options, :delete, :put, :patch], credentials: true

Rails 4 Authenticity Token

All my tests were working fine. But for some reason I had set my environment variable to non-test:

export RAILS_ENV=something_non_test

I forgot to unset this variable because of which I started getting ActionController::InvalidAuthenticityToken exception.

After unsetting $RAILS_ENV, my tests started working again.

Why am I getting error for apple-touch-icon-precomposed.png

There’s a gem like quiet_assets that will silence these errors in your logs if, like me, you didn’t want to have to add these files to your Rails app:

Rails: How does the respond_to block work?

The meta-programming behind responder registration (see Parched Squid's answer) also allows you to do nifty stuff like this:

def index
  @posts = Post.all

  respond_to do |format|
    format.html  # index.html.erb
    format.json  { render :json => @posts }
    format.csv   { render :csv => @posts }

The csv line will cause to_csv to be called on each post when you visit /posts.csv. This makes it easy to export data as CSV (or any other format) from your rails site.

The js line will cause a javascript file /posts.js (or / to be rendered/executed. I've found that to be a light-weight way to create an Ajax enabled site using jQuery UI pop-ups.


Just adding the authenticity_token in form fixed it for me.

<%= hidden_field_tag :authenticity_token, form_authenticity_token %>

How to install Visual Studio 2015 on a different drive

I found these two links which might help you:



Basically, at least a portion needs to be installed on a system drive. I'm not sure if your D:\ corresponds to some external drive or an actual system drive but the symlink solution might help.

Good luck

SQL - Rounding off to 2 decimal places

CAST(QuantityLevel AS NUMERIC(18,2))

How to pass data from child component to its parent in ReactJS?

The idea is to send a callback to the child which will be called to give the data back

A complete and minimal example using functions:

App will create a Child which will compute a random number and send it back directly to the parent, which will console.log the result

const Child = ({ handleRandom }) => {

  return <span>child</span>
const App = () => <Child handleRandom={(num) => console.log(num)}/>

How do I convert 2018-04-10T04:00:00.000Z string to DateTime?

Update: Using DateTimeFormat, introduced in java 8:

The idea is to define two formats: one for the input format, and one for the output format. Parse with the input formatter, then format with the output formatter.

Your input format looks quite standard, except the trailing Z. Anyway, let's deal with this: "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'". The trailing 'Z' is the interesting part. Usually there's time zone data here, like -0700. So the pattern would be ...Z, i.e. without apostrophes.

The output format is way more simple: "dd-MM-yyyy". Mind the small y -s.

Here is the example code:

DateTimeFormatter inputFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'", Locale.ENGLISH);
DateTimeFormatter outputFormatter = DateTimeFormatter.ofPattern("dd-MM-yyy", Locale.ENGLISH);
LocalDate date = LocalDate.parse("2018-04-10T04:00:00.000Z", inputFormatter);
String formattedDate = outputFormatter.format(date);
System.out.println(formattedDate); // prints 10-04-2018

Original answer - with old API SimpleDateFormat

SimpleDateFormat inputFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
SimpleDateFormat outputFormat = new SimpleDateFormat("dd-MM-yyyy");
Date date = inputFormat.parse("2018-04-10T04:00:00.000Z");
String formattedDate = outputFormat.format(date);
System.out.println(formattedDate); // prints 10-04-2018

Border Height on CSS

No, you cannot set the border height.

Batch file to map a drive when the folder name contains spaces

I'm not sure this will help you to much by I once needed a batch file to open a game, the .exe was in a folder with blanks (duh!) and I tried : START "C:\Fold 1\fold 2\game.exe" and START C:\Fold 1\fold 2\game.exe - None worked, then I tried

   START C:\"Fold 1"\"fold 2"\game.exe and it worked 

Hope it helps :)

frequent issues arising in android view, Error parsing XML: unbound prefix

I'll throw in a little more for the newbies and for folks, like myself, that don't understand XML.

The answers above a pretty good, but the general answer is that you need a namespace for any namespace used in the config.xml file.

Translation: Any XML tag name that has is a tag with a namespace where blah is the namespace and fubar is the XML tag. The namespace lets you use many different tools to interpret the XML with their own tag names. For example, Intel XDK uses the namespace intelxdk and android uses android. Thus you need the following namespaces or the build throws up blood (i.e. Error parsing XML: unbound prefix) which is translated to: You used a namespace, but did not define it.


Android: ListView elements with multiple clickable buttons

Isn't the platform solution for this implementation to use a context menu that shows on a long press?

Is the question author aware of context menus? Stacking up buttons in a listview has performance implications, will clutter your UI and violate the recommended UI design for the platform.

On the flipside; context menus - by nature of not having a passive representation - are not obvious to the end user. Consider documenting the behaviour?

This guide should give you a good start.

PHP - warning - Undefined property: stdClass - fix?

If you want to use property_exists, you'll need to get the name of the class with get_class()

In this case it would be :

 if( property_exists( get_class($response), 'records' ) ){
       $role_arr = getRole($response->records);

Jquery get input array field

Put the input name between single quotes so that the brackets [] are treated as a string

var multi_members="";
$("input[name='bayi[]']:checked:enabled").each(function() {

How to forward declare a template class in namespace std?

The problem is not that you can't forward-declare a template class. Yes, you do need to know all of the template parameters and their defaults to be able to forward-declare it correctly:

namespace std {
  template<class T, class Allocator = std::allocator<T>>
  class list;

But to make even such a forward declaration in namespace std is explicitly prohibited by the standard: the only thing you're allowed to put in std is a template specialisation, commonly std::less on a user-defined type. Someone else can cite the relevant text if necessary.

Just #include <list> and don't worry about it.

Oh, incidentally, any name containing double-underscores is reserved for use by the implementation, so you should use something like TEST_H instead of __TEST__. It's not going to generate a warning or an error, but if your program has a clash with an implementation-defined identifier, then it's not guaranteed to compile or run correctly: it's ill-formed. Also prohibited are names beginning with an underscore followed by a capital letter, among others. In general, don't start things with underscores unless you know what magic you're dealing with.

Uploading Files in without using the FileUpload server control

As others has answer, the Request.Files is an HttpFileCollection that contains all the files that were posted, you only need to ask that object for the file like this:


But what happen when there are more than one input mark-up with the same attribute name:

Select file 1 <input type="file" name="myFiles" />
Select file 2 <input type="file" name="myFiles" />

On the server side the previous code Request.Files["myFile"] only return one HttpPostedFile object instead of the two files. I have seen on .net 4.5 an extension method called GetMultiple but for prevoious versions it doesn't exists, for that matter i propose the extension method as:

public static IEnumerable<HttpPostedFile> GetMultiple(this HttpFileCollection pCollection, string pName)
        for (int i = 0; i < pCollection.Count; i++)
            if (pCollection.GetKey(i).Equals(pName))
                yield return pCollection.Get(i);

This extension method will return all the HttpPostedFile objects that have the name "myFiles" in the HttpFileCollection if any exists.

How to hide only the Close (x) button?

We can hide close button on form by setting this.ControlBox=false;

Note that this hides all of those sizing buttons. Not just the X. In some cases that may be fine.

Force encode from US-ASCII to UTF-8 (iconv)

Short Answer

  • file only guesses at the file encoding and may be wrong (especially in cases where special characters only appear late in large files).
  • you can use hexdump to look at bytes of non-7-bit-ASCII text and compare against code tables for common encodings (ISO 8859-*, UTF-8) to decide for yourself what the encoding is.
  • iconv will use whatever input/output encoding you specify regardless of what the contents of the file are. If you specify the wrong input encoding, the output will be garbled.
  • even after running iconv, file may not report any change due to the limited way in which file attempts to guess at the encoding. For a specific example, see my long answer.
  • 7-bit ASCII (aka US ASCII) is identical at a byte level to UTF-8 and the 8-bit ASCII extensions (ISO 8859-*). So if your file only has 7-bit characters, then you can call it UTF-8, ISO 8859-* or US ASCII because at a byte level they are all identical. It only makes sense to talk about UTF-8 and other encodings (in this context) once your file has characters outside the 7-bit ASCII range.

Long Answer

I ran into this today and came across your question. Perhaps I can add a little more information to help other people who run into this issue.


First, the term ASCII is overloaded, and that leads to confusion.

7-bit ASCII only includes 128 characters (00-7F or 0-127 in decimal). 7-bit ASCII is also sometimes referred to as US-ASCII.



UTF-8 encoding uses the same encoding as 7-bit ASCII for its first 128 characters. So a text file that only contains characters from that range of the first 128 characters will be identical at a byte level whether encoded with UTF-8 or 7-bit ASCII.

Codepage layout

ISO 8859-* and other ASCII Extensions

The term extended ASCII (or high ASCII) refers to eight-bit or larger character encodings that include the standard seven-bit ASCII characters, plus additional characters.

Extended ASCII

ISO 8859-1 (aka "ISO Latin 1") is a specific 8-bit ASCII extension standard that covers most characters for Western Europe. There are other ISO standards for Eastern European languages and Cyrillic languages. ISO 8859-1 includes characters like Ö, é, ñ and ß for German and Spanish.

"Extension" means that ISO 8859-1 includes the 7-bit ASCII standard and adds characters to it by using the 8th bit. So for the first 128 characters, it is equivalent at a byte level to ASCII and UTF-8 encoded files. However, when you start dealing with characters beyond the first 128, your are no longer UTF-8 equivalent at the byte level, and you must do a conversion if you want your "extended ASCII" file to be UTF-8 encoded.

ISO 8859 and proprietary adaptations

Detecting encoding with file

One lesson I learned today is that we can't trust file to always give correct interpretation of a file's character encoding.

file (command)

The command tells only what the file looks like, not what it is (in the case where file looks at the content). It is easy to fool the program by putting a magic number into a file the content of which does not match it. Thus the command is not usable as a security tool other than in specific situations.

file looks for magic numbers in the file that hint at the type, but these can be wrong, no guarantee of correctness. file also tries to guess the character encoding by looking at the bytes in the file. Basically file has a series of tests that helps it guess at the file type and encoding.

My file is a large CSV file. file reports this file as US ASCII encoded, which is WRONG.

$ ls -lh
total 850832
-rw-r--r--  1 mattp  staff   415M Mar 14 16:38 source-file
$ file -b --mime-type source-file
$ file -b --mime-encoding source-file

My file has umlauts in it (ie Ö). The first non-7-bit-ascii doesn't show up until over 100k lines into the file. I suspect this is why file doesn't realize the file encoding isn't US-ASCII.

$ pcregrep -no '[^\x00-\x7F]' source-file | head -n1

I'm on a Mac, so using PCRE's grep. With GNU grep you could use the -P option. Alternatively on a Mac, one could install coreutils (via Homebrew or other) in order to get GNU grep.

I haven't dug into the source-code of file, and the man page doesn't discuss the text encoding detection in detail, but I am guessing file doesn't look at the whole file before guessing encoding.

Whatever my file's encoding is, these non-7-bit-ASCII characters break stuff. My German CSV file is ;-separated and extracting a single column doesn't work.

$ cut -d";" -f1 source-file > tmp
cut: stdin: Illegal byte sequence
$ wc -l *
 3081673 source-file
  102320 tmp
 3183993 total

Note the cut error and that my "tmp" file has only 102320 lines with the first special character on line 102321.

Let's take a look at how these non-ASCII characters are encoded. I dump the first non-7-bit-ascii into hexdump, do a little formatting, remove the newlines (0a) and take just the first few.

$ pcregrep -o '[^\x00-\x7F]' source-file | head -n1 | hexdump -v -e '1/1 "%02x\n"'

Another way. I know the first non-7-bit-ASCII char is at position 85 on line 102321. I grab that line and tell hexdump to take the two bytes starting at position 85. You can see the special (non-7-bit-ASCII) character represented by a ".", and the next byte is "M"... so this is a single-byte character encoding.

$ tail -n +102321 source-file | head -n1 | hexdump -C -s85 -n2
00000055  d6 4d                                             |.M|

In both cases, we see the special character is represented by d6. Since this character is an Ö which is a German letter, I am guessing that ISO 8859-1 should include this. Sure enough, you can see "d6" is a match (ISO/IEC 8859-1).

Important question... how do I know this character is an Ö without being sure of the file encoding? The answer is context. I opened the file, read the text and then determined what character it is supposed to be. If I open it in Vim it displays as an Ö because Vim does a better job of guessing the character encoding (in this case) than file does.

So, my file seems to be ISO 8859-1. In theory I should check the rest of the non-7-bit-ASCII characters to make sure ISO 8859-1 is a good fit... There is nothing that forces a program to only use a single encoding when writing a file to disk (other than good manners).

I'll skip the check and move on to conversion step.

$ iconv -f iso-8859-1 -t utf8 source-file > output-file
$ file -b --mime-encoding output-file

Hmm. file still tells me this file is US ASCII even after conversion. Let's check with hexdump again.

$ tail -n +102321 output-file | head -n1 | hexdump -C -s85 -n2
00000055  c3 96                                             |..|

Definitely a change. Note that we have two bytes of non-7-bit-ASCII (represented by the "." on the right) and the hex code for the two bytes is now c3 96. If we take a look, seems we have UTF-8 now (c3 96 is the encoding of Ö in UTF-8) UTF-8 encoding table and Unicode characters

But file still reports our file as us-ascii? Well, I think this goes back to the point about file not looking at the whole file and the fact that the first non-7-bit-ASCII characters don't occur until late in the file.

I'll use sed to stick a Ö at the beginning of the file and see what happens.

$ sed '1s/^/Ö\'$'\n/' source-file > test-file
$ head -n1 test-file
$ head -n1 test-file | hexdump -C
00000000  c3 96 0a                                          |...|

Cool, we have an umlaut. Note the encoding though is c3 96 (UTF-8). Hmm.

Checking our other umlauts in the same file again:

$ tail -n +102322 test-file | head -n1 | hexdump -C -s85 -n2
00000055  d6 4d                                             |.M|

ISO 8859-1. Oops! It just goes to show how easy it is to get the encodings screwed up. To be clear, I've managed to create a mix of UTF-8 and ISO 8859-1 encodings in the same file.

Let's try converting our new test file with the umlaut (Ö) at the front and see what happens.

$ iconv -f iso-8859-1 -t utf8 test-file > test-file-converted
$ head -n1 test-file-converted | hexdump -C
00000000  c3 83 c2 96 0a                                    |.....|
$ tail -n +102322 test-file-converted | head -n1 | hexdump -C -s85 -n2
00000055  c3 96                                             |..|

Oops. The first umlaut that was UTF-8 was interpreted as ISO 8859-1 since that is what we told iconv. The second umlaut is correctly converted from d6 (ISO 8859-1) to c3 96 (UTF-8).

I'll try again, but this time I will use Vim to do the Ö insertion instead of sed. Vim seemed to detect the encoding better (as "latin1" aka ISO 8859-1) so perhaps it will insert the new Ö with a consistent encoding.

$ vim source-file
$ head -n1 test-file-2
$ head -n1 test-file-2 | hexdump -C
00000000  d6 0d 0a                                          |...|
$ tail -n +102322 test-file-2 | head -n1 | hexdump -C -s85 -n2
00000055  d6 4d                                             |.M|

It looks good. It looks like ISO 8859-1 for new and old umlauts.

Now the test.

$ file -b --mime-encoding test-file-2
$ iconv -f iso-8859-1 -t utf8 test-file-2 > test-file-2-converted
$ file -b --mime-encoding test-file-2-converted

Boom! Moral of the story. Don't trust file to always guess your encoding right. It is easy to mix encodings within the same file. When in doubt, look at the hex.

A hack (also prone to failure) that would address this specific limitation of file when dealing with large files would be to shorten the file to make sure that special (non-ascii) characters appear early in the file so file is more likely to find them.

$ first_special=$(pcregrep -o1 -n '()[^\x00-\x7F]' source-file | head -n1 | cut -d":" -f1)
$ tail -n +$first_special source-file > /tmp/source-file-shorter
$ file -b --mime-encoding /tmp/source-file-shorter

You could then use (presumably correct) detected encoding to feed as input to iconv to ensure you are converting correctly.


Christos Zoulas updated file to make the amount of bytes looked at configurable. One day turn-around on the feature request, awesome! Allow altering how many bytes to read from analyzed files from the command line

The feature was released in file version 5.26.

Looking at more of a large file before making a guess about encoding takes time. However, it is nice to have the option for specific use-cases where a better guess may outweigh additional time and I/O.

Use the following option:

-P, --parameter name=value

    Set various parameter limits.

    Name    Default     Explanation
    bytes   1048576     max number of bytes to read from file

Something like...

bytes_to_scan=$(wc -c < $file_to_check)
file -b --mime-encoding -P bytes=$bytes_to_scan $file_to_check

... it should do the trick if you want to force file to look at the whole file before making a guess. Of course, this only works if you have file 5.26 or newer.

Forcing file to display UTF-8 instead of US-ASCII

Some of the other answers seem to focus on trying to make file display UTF-8 even if the file only contains plain 7-bit ascii. If you think this through you should probably never want to do this.

  1. If a file contains only 7-bit ascii but the file command is saying the file is UTF-8, that implies that the file contains some characters with UTF-8 specific encoding. If that isn't really true, it could cause confusion or problems down the line. If file displayed UTF-8 when the file only contained 7-bit ascii characters, this would be a bug in the file program.
  2. Any software that requires UTF-8 formatted input files should not have any problem consuming plain 7-bit ascii since this is the same on a byte level as UTF-8. If there is software that is using the file command output before accepting a file as input and it won't process the file unless it "sees" UTF-8...well that is pretty bad design. I would argue this is a bug in that program.

If you absolutely must take a plain 7-bit ascii file and convert it to UTF-8, simply insert a single non-7-bit-ascii character into the file with UTF-8 encoding for that character and you are done. But I can't imagine a use-case where you would need to do this. The easiest UTF-8 character to use for this is the Byte Order Mark (BOM) which is a special non-printing character that hints that the file is non-ascii. This is probably the best choice because it should not visually impact the file contents as it will generally be ignored.

Microsoft compilers and interpreters, and many pieces of software on Microsoft Windows such as Notepad treat the BOM as a required magic number rather than use heuristics. These tools add a BOM when saving text as UTF-8, and cannot interpret UTF-8 unless the BOM is present or the file contains only ASCII.

This is key:

or the file contains only ASCII

So some tools on windows have trouble reading UTF-8 files unless the BOM character is present. However this does not affect plain 7-bit ascii only files. I.e. this is not a reason for forcing plain 7-bit ascii files to be UTF-8 by adding a BOM character.

Here is more discussion about potential pitfalls of using the BOM when not needed (it IS needed for actual UTF-8 files that are consumed by some Microsoft apps).

Nevertheless if you still want to do it, I would be interested in hearing your use case. Here is how. In UTF-8 the BOM is represented by hex sequence 0xEF,0xBB,0xBF and so we can easily add this character to the front of our plain 7-bit ascii file. By adding a non-7-bit ascii character to the file, the file is no longer only 7-bit ascii. Note that we have not modified or converted the original 7-bit-ascii content at all. We have added a single non-7-bit-ascii character to the beginning of the file and so the file is no longer entirely composed of 7-bit-ascii characters.

$ printf '\xEF\xBB\xBF' > bom.txt # put a UTF-8 BOM char in new file
$ file bom.txt
bom.txt: UTF-8 Unicode text, with no line terminators
$ file plain-ascii.txt  # our pure 7-bit ascii file
plain-ascii.txt: ASCII text
$ cat bom.txt plain-ascii.txt > plain-ascii-with-utf8-bom.txt # put them together into one new file with the BOM first
$ file plain-ascii-with-utf8-bom.txt
plain-ascii-with-utf8-bom.txt: UTF-8 Unicode (with BOM) text

How to count days between two dates in PHP?

$datetime1 = new DateTime('2009-10-11');
$datetime2 = new DateTime('2009-10-13');
$interval = $datetime1->diff($datetime2);
echo $interval->format('%R%a days');


String to date in Oracle with milliseconds

I don't think you can use fractional seconds with to_date or the DATE type in Oracle. I think you need to_timestamp which returns a TIMESTAMP type.

pip installing in global site-packages instead of virtualenv

For me this was not a pip or virtualenv problem. It was a python problem. I had set my $PYTHONPATH manually in ~/.bash_profile (or ~/.bashrc) after following some tutorial online. This manually set $PYTHONPATH was available in the virtualenv as it probably should be allowed.

Additionally add2virtualenv was not adding my project path to my $PYTHONPATH for some reason within the virtualenv.

Just some forking paths for those who might still be stuck! Cheers!

How can I clear the input text after clicking

          $('#myinput').attr('value', '');_x000D_
<script src=""></script>_x000D_
  <button class="mybtn">CLEAR</button>_x000D_
  <input type="text" id="myinput" name="myinput" value="?????????">

Dump a list in a pickle file and retrieve it back later

Pickling will serialize your list (convert it, and it's entries to a unique byte string), so you can save it to disk. You can also use pickle to retrieve your original list, loading from the saved file.

So, first build a list, then use pickle.dump to send it to a file...

Python 3.4.1 (default, May 21 2014, 12:39:51) 
[GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.2.79)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> mylist = ['I wish to complain about this parrot what I purchased not half an hour ago from this very boutique.', "Oh yes, the, uh, the Norwegian Blue...What's,uh...What's wrong with it?", "I'll tell you what's wrong with it, my lad. 'E's dead, that's what's wrong with it!", "No, no, 'e's uh,...he's resting."]
>>> import pickle
>>> with open('parrot.pkl', 'wb') as f:
...   pickle.dump(mylist, f)

Then quit and come back later… and open with pickle.load...

Python 3.4.1 (default, May 21 2014, 12:39:51) 
[GCC 4.2.1 Compatible Apple LLVM 5.0 (clang-500.2.79)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import pickle
>>> with open('parrot.pkl', 'rb') as f:
...   mynewlist = pickle.load(f)
>>> mynewlist
['I wish to complain about this parrot what I purchased not half an hour ago from this very boutique.', "Oh yes, the, uh, the Norwegian Blue...What's,uh...What's wrong with it?", "I'll tell you what's wrong with it, my lad. 'E's dead, that's what's wrong with it!", "No, no, 'e's uh,...he's resting."]

Clear text from textarea with selenium

In my experience, this turned out to be the most efficient

driver.find_element_by_css_selector('foo').send_keys(u'\ue009' + u'\ue003')

We are sending Ctrl + Backspace to delete all characters from the input, you can also replace backspace with delete.

EDIT: removed Keys dependency

How to check for null in a single statement in scala?

If it instead returned Option[QueueObject] you could use a construct like getObject.foreach { QueueManager.add }. You can wrap it right inline with Option(getObject).foreach ... because Option[QueueObject](null) is None.

How to remove rows with any zero value

I prefer a simple adaptation of csgillespie's method, foregoing the need of a function definition:

d[apply(d!=0, 1, all),]

where d is your data frame.

How do you force Visual Studio to regenerate the .designer files for aspx/ascx files?

The solution the worked for me is:

I just copied the page and and pasted it in the same portion, then renamed the first page(what ever name) and renamed the copied page as the original page. Now the controls are accessible.

Display JSON Data in HTML Table

          <table id="myData">


           <script type="text/javascript">
              $('#search').click(function() {
                    alert("submit handler has fired");
                        type: 'POST',
                        url: 'cityResults.htm',
                        data: $('#cityDetails').serialize(),

                        success: function(data){ 
                            $.each(data, function( index, value ) {
                               var row = $("<tr><td>" + + "</td><td>" + value.cStatus + "</td></tr>");
                        error: function(jqXHR, textStatus, errorThrown){
                            alert('error: ' + textStatus + ': ' + errorThrown);
                    return false;//suppress natural form submission


loop through the data and append it to a table like the code above.

What does <![CDATA[]]> in XML mean?

As another example of its use:

If you have an RSS Feed (xml document) and want to include some basic HTML encoding in the display of the description, you can use CData to encode it:

  <title>Title of Feed Item</title>
      <a href="/mylink/article1"><img style="float: left; margin-right: 5px;" height="80" src="/mylink/image" alt=""/></a>
      Author Names
      <br/>Paragraph of text describing the article to be displayed</p>

The RSS Reader pulls in the description and renders the HTML within the CDATA.

Note - not all HTML tags work - I think it depends on the RSS reader you are using.

And as a explanation for why this example uses CData (and not the appropriate pubData and dc:creator tags): this is for website display using a RSS widget for which we have no real formatting control.

This enables us to specify the height and position of the included image, format the author names and date correctly, and so forth, without the need for a new widget. It also means I can script this and not have to add them by hand.

ActionBarActivity cannot resolve a symbol

Make sure that in the path to the project there is no foldername having whitespace. While creating a project the specified path folders must not contain any space in their naming.

Why I can't access remote Jupyter Notebook server?

Have you configured the file to allow external connections?

By default, Jupyter Notebook only accepts connections from localhost (eg, from the same computer that its running on). By modifying the NotebookApp.allow_origin option from the default ' ' to '*', you allow Jupyter to be accessed externally.

c.NotebookApp.allow_origin = '*' #allow all origins

You'll also need to change the IPs that the notebook will listen on:

c.NotebookApp.ip = '' # listen on all IPs

Also see the details in a subsequent answer in this thread.

Documentation on the Jupyter Notebook config file.

Add & delete view from Layout

I am removing view using start and count Method, i have added 3 view in linear Layout.

view.removeViews(0, 3);

How to make a div center align in HTML

<!DOCTYPE html>_x000D_
    <div style="text-align: center;">_x000D_
      <div style="width: 500px; margin: 0 auto; background: #000; color: #fff;">This DIV is centered</div>_x000D_

Tested and worked in IE, Firefox, Chrome, Safari and Opera. I did not test IE6. The outer text-align is needed for IE. Other browsers (and IE9?) will work when you give the DIV margin (left and right) value of auto. Margin "0 auto" is a shorthand for margin "0 auto 0 auto" (top right bottom left).

Note: the text is also centered inside the inner DIV, if you want it to remain on the left side just specify text-align: left; for the inner DIV.

Edit: IE 6, 7, 8 and 9 running on the Standards Mode will work with margins set to auto.

make iframe height dynamic based on content inside- JQUERY/Javascript

in my project there is one requirement that we have make dynamic screen like Alignment of Dashboard while loading, it should display on an entire page and should get adjust dynamically, if user is maximizing or resizing the browser’s window. For this I have created url and used iframe to open one of the dynamic report which is written in cognos BI.In jsp we have to embed BI report. I have used iframe to embed this report in jsp. following code is working in my case.

<iframe src= ${cognosUrl} onload=" +'px';" scrolling="no" style="width: 100%; min-height: 900px; border: none; overflow: hidden; height: 30px;"></iframe>

Getting a Request.Headers value

Header exists:

if (Request.Headers["XYZComponent"] != null)

or even better:

string xyzHeader = Request.Headers["XYZComponent"];
bool isXYZ;

if (bool.TryParse(xyzHeader, out isXYZ) && isXYZ)

which will check whether it is set to true. This should be fool-proof because it does not care on leading/trailing whitespace and is case-insensitive (bool.TryParse does work on null)

Addon: You could make this more simple with this extension method which returns a nullable boolean. It should work on both invalid input and null.

public static bool? ToBoolean(this string s)
    bool result;

    if (bool.TryParse(s, out result))
        return result;
        return null;

Usage (because this is an extension method and not instance method this will not throw an exception on null - it may be confusing, though):

if (Request.Headers["XYZComponent"].ToBoolean() == true)

Is there a way to add a gif to a Markdown file?

  1. have gif file.
  2. push gif file to your github repo
  3. click on that file on the github repo to get github address of the gif
  4. in your README file: ![alt-text](link)

example below: ![grab-landing-page](

Java JDBC connection status

Nothing. Just execute your query. If the connection has died, either your JDBC driver will reconnect (if it supports it, and you enabled it in your connection string--most don't support it) or else you'll get an exception.

If you check the connection is up, it might fall over before you actually execute your query, so you gain absolutely nothing by checking.

That said, a lot of connection pools validate a connection by doing something like SELECT 1 before handing connections out. But this is nothing more than just executing a query, so you might just as well execute your business query.

Bootstrap 4 File Input

With the help of jquery, it can be done like this. Code:

$("input.custom-file-input").on("change",function(){if(this.files.length){var filename=this.file[0].name;if(filename.length>23){filename=filename.substr(0,11)+"..."+filename.substr(-10);}$(this).siblings(".custom-file-label").text(filename);}});

Make browser window blink in task Bar

you could change the title of the web page with each new message to alert the user. I did this for a browser chat client and most users thought it worked well enough.

document.title = "[user] hello world";

Check if Cell value exists in Column, and then get the value of the NEXT Cell

How about this?


The "3" at the end means for column C.

Linq select object from list depending on objects attribute

if a.Correct is a bool flag for the correct answer then you need.

Answer answer = Answers.Single(a => a.Correct);

ASP.NET Core Web API Authentication

You can implement a middleware which handles Basic authentication.

public async Task Invoke(HttpContext context)
    var authHeader = context.Request.Headers.Get("Authorization");
    if (authHeader != null && authHeader.StartsWith("basic", StringComparison.OrdinalIgnoreCase))
        var token = authHeader.Substring("Basic ".Length).Trim();
        var credentialstring = Encoding.UTF8.GetString(Convert.FromBase64String(token));
        var credentials = credentialstring.Split(':');
        if(credentials[0] == "admin" && credentials[1] == "admin")
            var claims = new[] { new Claim("name", credentials[0]), new Claim(ClaimTypes.Role, "Admin") };
            var identity = new ClaimsIdentity(claims, "Basic");
            context.User = new ClaimsPrincipal(identity);
        context.Response.StatusCode = 401;
        context.Response.Headers.Set("WWW-Authenticate", "Basic realm=\"\"");
    await _next(context);

This code is written in a beta version of core. Hope it helps.

Count the number of occurrences of a character in a string in Javascript

let str = "aabgrhaab"
let charMap = {}

for(let char of text) {
   } else {
     charMap[char] = 1

console.log(charMap); //{a: 4, b: 2, g: 1, r: 1, h: 1}

Reverse a comparator in Java 8

You can also use Comparator.comparing(Function, Comparator)
It is convenient to chain comparators when necessary, e.g.:

Comparator<SomeEntity> ENTITY_COMPARATOR = comparing(SomeEntity::getProperty1, reverseOrder())
        .thenComparing(SomeEntity::getProperty3, reverseOrder());

Navigation bar with UIImage for title

Swift 5.1, Xcode 11

Sometimes if your image is in high resolution then, imageView shifts from centre, I would suggest using this method

  lazy var navigationTitleImageView = UIImageView()

  override func viewWillAppear(_ animated: Bool) {
    self.navigationTitleImageView.image = logo
    self.navigationTitleImageView.contentMode = .scaleAspectFit
    self.navigationTitleImageView.translatesAutoresizingMaskIntoConstraints = false
    if let navC = self.navigationController{
        self.navigationTitleImageView.centerXAnchor.constraint(equalTo: navC.navigationBar.centerXAnchor).isActive = true
        self.navigationTitleImageView.centerYAnchor.constraint(equalTo: navC.navigationBar.centerYAnchor, constant: 0).isActive = true
        self.navigationTitleImageView.widthAnchor.constraint(equalTo: navC.navigationBar.widthAnchor, multiplier: 0.2).isActive = true
        self.navigationTitleImageView.heightAnchor.constraint(equalTo: navC.navigationBar.widthAnchor, multiplier: 0.088).isActive = true

and viewWillDisappear()

  override func viewWillDisappear(_ animated: Bool) {

or else just reduce the image size

How to open Android Device Monitor in latest Android Studio 3.1

Now you can use device file explorer instead of device monitor. Go to

view > tool windows > device file explorer

screenshot: opening device file explorer in android studio 3.1.3

More details

  1. Click View > Tool Windows > Device File Explorer or click the Device File Explorer button in the tool window bar to open the Device File Explorer.
  2. Select a device from the drop down list.
  3. Interact with the device content in the file explorer window. Right-click on a file or directory to create a new file or directory, save the selected file or directory to your machine, upload, delete, or synchronize. Double-click a file to open it in Android Studio.

Android Studio saves files you open this way in a temporary directory outside of your project. If you make modifications to a file you opened using the Device File Explorer, and would like to save your changes back to the device, you must manually upload the modified version of the file to the device.

screenshot: The Device File Explorer tool window

When exploring a device's files, the following directories are particularly useful:


Contains data files for your app stored on internal storage


Contains user files stored on external user storage (pictures, etc.)

Note: Not all files on a hardware device are visible in the Device File Explorer. For example, in the data/data/ directory, entries corresponding to apps on the device that are not debuggable cannot be expanded in the Device File Explorer.

How an 'if (A && B)' statement is evaluated?

Yes, it is called Short-circuit Evaluation.

If the validity of the boolean statement can be assured after part of the statement, the rest is not evaluated.

This is very important when some of the statements have side-effects.

Should I use @EJB or @Inject

Update: This answer may be incorrect or out of date. Please see comments for details.

I switched from @Inject to @EJB because @EJB allows circular injection whereas @Inject pukes on it.

Details: I needed @PostConstruct to call an @Asynchronous method but it would do so synchronously. The only way to make the asynchronous call was to have the original call a method of another bean and have it call back the method of the original bean. To do this each bean needed a reference to the other -- thus circular. @Inject failed for this task whereas @EJB worked.

Address already in use: JVM_Bind java

I usually come across this when the port which the server (I use JBoss) is already in use

Usual suspects

  1. Apache Http Server => turn down the service if working in windows.
  2. IIS => stop the ISS using
  3. Skype =>yea I got skype attaching itself to port 80

To change the port to which JBoss 4.2.x binds itself go to:


here default is the instance of the server change the port here :

<Connector port="8080" address="${jboss.bind.address}" >

In the above example the port is bound to 8080

Replace whole line containing a string using Sed

I very often use regex to extract data from files I just used that to replace the literal quote \" with // nothing :-)

cat file.csv | egrep '^\"([0-9]{1,3}\.[0-9]{1,3}\.)' | sed  s/\"//g  | cut -d, -f1 > list.txt

How can I print literal curly-brace characters in a string and also use .format on it?

Try doing this:

x = " {{ Hello }} {0} "
print x.format(42)

PHP Array to JSON Array using json_encode();

I had a problem with accented characters when converting a PHP array to JSON. I put UTF-8 stuff all over the place but nothing solved my problem until I added this piece of code in my PHP while loop where I was pushing the array:

$es_words[] = array(utf8_encode("$word"),"$alpha","$audio");

It was only the '$word' variable that was giving a problem. Afterwards it did a jason_encode no problem.

Hope that helps

In Chrome 55, prevent showing Download button for HTML 5 video

As for current Chrome version (56) you can't remove it yet. Solution provided in other posts leads to overflowing some part of the video.

I've found another solution - you can make the preceding button to overlap the download button and simply cover it, by using this technique:

video::-webkit-media-controls-fullscreen-button {
   margin-right: -48px;
   z-index: 10;
   position: relative;
   background: #fafafa;
   background-image: url(;
   background-size: 35%;
   background-position: 50% 50%;
   background-repeat: no-repeat;


PS You might want to customise the icon, since it's for example only.

How to send a POST request using volley with string body?

You can refer to the following code (of course you can customize to get more details of the network response):

try {
    RequestQueue requestQueue = Volley.newRequestQueue(this);
    String URL = "http://...";
    JSONObject jsonBody = new JSONObject();
    jsonBody.put("Title", "Android Volley Demo");
    jsonBody.put("Author", "BNK");
    final String requestBody = jsonBody.toString();

    StringRequest stringRequest = new StringRequest(Request.Method.POST, URL, new Response.Listener<String>() {
        public void onResponse(String response) {
            Log.i("VOLLEY", response);
    }, new Response.ErrorListener() {
        public void onErrorResponse(VolleyError error) {
            Log.e("VOLLEY", error.toString());
    }) {
        public String getBodyContentType() {
            return "application/json; charset=utf-8";

        public byte[] getBody() throws AuthFailureError {
            try {
                return requestBody == null ? null : requestBody.getBytes("utf-8");
            } catch (UnsupportedEncodingException uee) {
      "Unsupported Encoding while trying to get the bytes of %s using %s", requestBody, "utf-8");
                return null;

        protected Response<String> parseNetworkResponse(NetworkResponse response) {
            String responseString = "";
            if (response != null) {
                responseString = String.valueOf(response.statusCode);
                // can get more details such as response.headers
            return Response.success(responseString, HttpHeaderParser.parseCacheHeaders(response));

} catch (JSONException e) {

Error in data frame undefined columns selected

Are you meaning?

data2 <- data1[good,]



you're selecting columns in a wrong way (using a logical vector of complete rows).

Consider that parameter pollutant is not used; is it a column name that you want to extract? if so it should be something like

data2 <- data1[good, pollutant]

Furthermore consider that you have to rbind the data.frames inside the for loop, otherwise you get only the last data.frame (its completed.cases)

And last but not least, i'd prefer generating filenames eg with

id <- 1:322
paste0( directory, "/", gsub(" ", "0", sprintf("%3d",id)), ".csv")

A little modified chunk of ?sprintf

The string fmt (in our case "%3d") contains normal characters, which are passed through to the output string, and also conversion specifications which operate on the arguments provided through .... The allowed conversion specifications start with a % and end with one of the letters in the set aAdifeEgGosxX%. These letters denote the following types:

  • d: integer

Eg a more general example

    sprintf("I am %10d years old", 25)
[1] "I am         25 years old"
          |        |
          1       10

PHP sessions that have already been started

None of the above was suitable, without calling session_start() in all php files that depend on $Session variables they will not be included. The Notice is so annoying and quickly fill up the Error_log. The only solution that I can find that works is this....

    error_reporting(E_ALL ^ E_NOTICE);

A Bad fix , but it works.

How to get calendar Quarter from a date in TSQL

To get the exact output you requested, you can use the below:


This will give you an outputs like: "2015 - Q1", "2013 - Q3", etc.

static constructors in C++? I need to initialize private static objects

Here's my variant of EFraim's solution; the difference is that, thanks to implicit template instantiation, the static constructor is only called if instances of the class are created, and that no definition in the .cpp file is needed (thanks to template instantiation magic).

In the .h file, you have:

template <typename Aux> class _MyClass
        static vector<char> a;
        _MyClass() {
            (void) _initializer; //Reference the static member to ensure that it is instantiated and its initializer is called.
        static struct _init
            _init() { for(char i='a'; i<='z'; i++) a.push_back(i); }
        } _initializer;

typedef _MyClass<void> MyClass;

template <typename Aux> vector<char> _MyClass<Aux>::a;
template <typename Aux> typename _MyClass<Aux>::_init _MyClass<Aux>::_initializer;

In the .cpp file, you can have:

void foobar() {
    MyClass foo; // [1]

    for (vector<char>::iterator it = MyClass::a.begin(); it < MyClass::a.end(); ++it) {
        cout << *it;
    cout << endl;

Note that MyClass::a is initialized only if line [1] is there, because that calls (and requires instantiation of) the constructor, which then requires instantiation of _initializer.

LINQ: Select where object does not contain items from list

I have not tried this, so I am not guarantueeing anything, however

foreach Bar f in filterBars
Foo search(Bar b)
    fooSelect = (from f in fooBunch
                 where !(from b in f.BarList select b.BarId).Contains(b.ID)
                 select f).ToList();

    return fooSelect;

How to copy Java Collections list

the simplest way to copy a List is to pass it to the constructor of the new list:

List<String> b = new ArrayList<>(a);

b will be a shallow copy of a

Looking at the source of Collections.copy(List,List) (I'd never seen it before) it seems to be for coping the elements index by index. using List.set(int,E) thus element 0 will over write element 0 in the target list etc etc. Not particularly clear from the javadocs I'd have to admit.

List<String> a = new ArrayList<>(a);

List<String> b = new ArrayList<>(a); // shallow copy 'a'

// the following will all hold
assert a.get(0) == b.get(0);
assert a.get(1) == b.get(1);
assert a.equals(b);
assert a != b; // 'a' is not the same object as 'b'


Upsert is what you want. UPSERT syntax was added to SQLite with version 3.24.0 (2018-06-04).

CREATE TABLE phonebook2(
  phonenumber TEXT,
  validDate DATE

INSERT INTO phonebook2(name,phonenumber,validDate)
  WHERE excluded.validDate>phonebook2.validDate;

Be warned that at this point the actual word "UPSERT" is not part of the upsert syntax.

The correct syntax is


and if you are doing INSERT INTO SELECT ... your select needs at least WHERE true to solve parser ambiguity about the token ON with the join syntax.

Be warned that INSERT OR REPLACE... will delete the record before inserting a new one if it has to replace, which could be bad if you have foreign key cascades or other delete triggers.

Convert integer to hex and hex to integer

Below are two functions: dbo.HexToInt and dbo.IntToHex, I use them for such conversion:

if OBJECT_ID('dbo.HexToInt') is not null
    drop function dbo.HexToInt
create function dbo.HexToInt (@chars varchar(max))
returns int
    declare @char varchar(1), @len int, @i int, @r int, @tmp int, @pow int
    set @chars = RTRIM(LTRIM(@chars))
    set @len = LEN(@chars)
    set @i = 1
    set @r = 0
    while @i <= @len
        set @pow = @len - @i
        set @char = SUBSTRING(@chars, @i, 1)
        if @char = '0'
            set @tmp = 0
        else if @char = '1'
            set @tmp = 1
        else if @char = '2'
            set @tmp = 2
        else if @char = '3'
            set @tmp = 3
        else if @char = '4'
            set @tmp = 4
        else if @char = '5'
            set @tmp = 5
        else if @char = '6'
            set @tmp = 6
        else if @char = '7'
            set @tmp = 7
        else if @char = '8'
            set @tmp = 8
        else if @char = '9'
            set @tmp = 9
        else if @char = 'A'
            set @tmp = 10
        else if @char = 'B'
            set @tmp = 11
        else if @char = 'C'
            set @tmp = 12
        else if @char = 'D'
            set @tmp = 13
        else if @char = 'E'
            set @tmp = 14
        else if @char = 'F'
            set @tmp = 15
        set @r = @r + @tmp * POWER(16,@pow)
        set @i = @i + 1     
    return @r

And the second one:

if OBJECT_ID('dbo.IntToHex') is not null
    drop function dbo.IntToHex
create function dbo.IntToHex (@val int)
returns varchar(max)
    declare @r varchar(max), @tmp int, @v1 int, @v2 int, @char varchar(1)
    set @tmp = @val
    set @r = ''
    while 1=1
        set @v1 = @tmp / 16
        set @v2 = @tmp % 16
        if @v2 = 0
            set @char = '0'
        else if @v2 = 1
            set @char = '1'
        else if @v2 = 2
            set @char = '2'
        else if @v2 = 3
            set @char = '3'
        else if @v2 = 4
            set @char = '4'
        else if @v2 = 5
            set @char = '5'
        else if @v2 = 6
            set @char = '6'
        else if @v2 = 7
            set @char = '7'
        else if @v2 = 8
            set @char = '8'
        else if @v2 = 9
            set @char = '9'
        else if @v2 = 10
            set @char = 'A'
        else if @v2 = 11
            set @char = 'B'
        else if @v2 = 12
            set @char = 'C'
        else if @v2 = 13
            set @char = 'D'
        else if @v2 = 14
            set @char = 'E'
        else if @v2 = 15
            set @char = 'F'
        set @tmp = @v1 
        set @r = @char + @r
        if @tmp = 0
    return @r

Compare two different files line by line in python

If you are specifically looking for getting the difference between two files, then this might help:

with open('first_file', 'r') as file1:
    with open('second_file', 'r') as file2:
        difference = set(file1).difference(file2)


with open('diff.txt', 'w') as file_out:
    for line in difference:

How to reload a div without reloading the entire page?

write a button tag and on click function

var x = document.getElementById('codeRefer').innerHTML;
  document.getElementById('codeRefer').innerHTML = x;

write this all in onclick function

Run bash command on jenkins pipeline

The Groovy script you provided is formatting the first line as a blank line in the resultant script. The shebang, telling the script to run with /bin/bash instead of /bin/sh, needs to be on the first line of the file or it will be ignored.

So instead, you should format your Groovy like this:

stage('Setting the variables values') {
    steps {
         sh '''#!/bin/bash
                 echo "hello world" 

And it will execute with /bin/bash.

What is the difference between #import and #include in Objective-C?

If you are familiar with C++ and macros, then

#import "Class.h" 

is similar to

#pragma once

#include "class.h"

which means that your Class will be loaded only once when your app runs.

Cannot open include file: 'stdio.h' - Visual Studio Community 2017 - C++ Error


  1. Windows 10 with Visual Studio 2017 (FRESH installation).

  2. 'C' project (ERROR like -> cannot open source file: 'stdio.h', 'windows.h', etc.).


  1. Run 'Visual Studio Installer'.

  2. Click button 'Modify'.

  3. Select 'Desktop development with C++'.

  4. From "Installation details"(usually on the right-sidebar) select:

    4.1. Windows 10 SDK(10.0.17134.0).

    • Version of SDK in 4.1. is just for example.
  5. Click button 'Modify', to apply changes.

  6. Right-click 'SomeProject' -> 'Properties'.
  7. 'Configuration:' -> 'All Configurations' and 'Platform:' -> 'All Platforms'.
  8. 'Configuration Properties' -> 'General' -> 'Windows SDK Version':
    • change(select from combobox) SDK version to currently installed;
  9. Click button 'Apply', to apply changes.

multiple conditions for filter in spark data frames

If we want partial match just like contains, we can chain the contain call like this :

def getSelectedTablesRows2(allTablesInfoDF: DataFrame, tableNames: Seq[String]): DataFrame = {

    val tableFilters = => lower(col("table_name")).contains(name))
    val finalFilter = tableFilters.fold(lit(false))((accu, newTableFilter) => accu or newTableFilter)


how to include js file in php?

Its more likely that the path to file.js from the page is what is wrong. as long as when you view the page, and view-source you see the tag, its working, now its time to debug whether or not your path is too relative, maybe you need a / in front of it.

Detect IE version (prior to v9) in JavaScript

function getIEVersion(){
     if (/MSIE |Trident\//.test( navigator.userAgent )=== false) return -1;
    /**[IE <=9]*/
    var isIE9L = typeof ( window.attachEvent ) === 'function' && !( window.opera ) == '[object Opera]' ) ? true : false;
    var re;
        re = new RegExp( "MSIE ([0-9]{1,}[\.0-9]{0,})" );
        if(re.exec( navigator.userAgent ) !== null)
            return parseFloat( RegExp.$1 );
        return -1;
    /**[/IE <=9]*/
    /** [IE >= 10]*/
    if(navigator.userAgent.indexOf( 'Trident/' ) > -1){
        re = new RegExp( "rv:([0-9]{1,}[\.0-9]{0,})" );
        if(re.exec( navigator.userAgent ) !== null)
            return parseFloat( RegExp.$1 );
        return -1;
    /**[/IE >= 10]*/
    return -1;

Check here ==>

var ieVersion = getIEVersion();

if(ieVersion < 0){
    //Not IE
//A version of IE

Learn more about browser navigator

Best practice to validate null and empty collection in Java

Personally, I prefer to use empty collections instead of null and have the algorithms work in a way that for the algorithm it does not matter if the collection is empty or not.

What is the difference between required and ng-required?

AngularJS form elements look for the required attribute to perform validation functions. ng-required allows you to set the required attribute depending on a boolean test (for instance, only require field B - say, a student number - if the field A has a certain value - if you selected "student" as a choice)

As an example, <input required> and <input ng-required="true"> are essentially the same thing

If you are wondering why this is this way, (and not just make <input required="true"> or <input required="false">), it is due to the limitations of HTML - the required attribute has no associated value - its mere presence means (as per HTML standards) that the element is required - so angular needs a way to set/unset required value (required="false" would be invalid HTML)

How to show current user name in a cell?

Example: to view the Windows User Name on Cell C5, you can use this script :

Range("C5").Value = ": " & Environ("USERNAME").

How to use a variable inside a regular expression?

From python 3.6 on you can also use Literal String Interpolation, "f-strings". In your particular case the solution would be:

if"\b(?=\w){TEXTO}\b(?!\w)", subject, re.IGNORECASE): something


Since there have been some questions in the comment on how to deal with special characters I'd like to extend my answer:

raw strings ('r'):

One of the main concepts you have to understand when dealing with special characters in regular expressions is to distinguish between string literals and the regular expression itself. It is very well explained here:

In short:

Let's say instead of finding a word boundary \b after TEXTO you want to match the string \boundary. The you have to write:

TEXTO = "Var"
subject = r"Var\boundary"

if"\b(?=\w){TEXTO}\\boundary(?!\w)", subject, re.IGNORECASE):

This only works because we are using a raw-string (the regex is preceded by 'r'), otherwise we must write "\\\\boundary" in the regex (four backslashes). Additionally, without '\r', \b' would not converted to a word boundary anymore but to a backspace!


Basically puts a backspace in front of any special character. Hence, if you expect a special character in TEXTO, you need to write:

if"\b(?=\w){re.escape(TEXTO)}\b(?!\w)", subject, re.IGNORECASE):

NOTE: For any version >= python 3.7: !, ", %, ', ,, /, :, ;, <, =, >, @, and ` are not escaped. Only special characters with meaning in a regex are still escaped. _ is not escaped since Python 3.3.(s. here)

Curly braces:

If you want to use quantifiers within the regular expression using f-strings, you have to use double curly braces. Let's say you want to match TEXTO followed by exactly 2 digits:

if"\b(?=\w){re.escape(TEXTO)}\d{{2}}\b(?!\w)", subject, re.IGNORECASE):

Which "href" value should I use for JavaScript links, "#" or "javascript:void(0)"?

Just to pick up the point some of the other have mentioned.

It's much better to bind the event 'onload'a or $('document').ready{}; then to put JavaScript directly into the click event.

In the case that JavaScript isn't available, I would use a href to the current URL, and perhaps an anchor to the position of the link. The page is still be usable for the people without JavaScript those who have won't notice any difference.

As I have it to hand, here is some jQuery which might help:

var [functionName] = function() {
   // do something

jQuery("[link id or other selector]").bind("click", [functionName]);

How do I find the PublicKeyToken for a particular dll?

Using sn.exe utility:

sn -T YourAssembly.dll

or loading the assembly in Reflector.

How can I pretty-print JSON in a shell script?

My JSON files were not parsed by any of these methods.

My problem was similar to the post Is Google data source JSON not valid?.

The answer to that post helped me find a solution.

It is considered to be invalid JSON without the string keys.


must be:

{"id": "name", "label": "Name", "type": "string"}

This link gives a nice comprehensive comparison of some of the different JSON parsers:

Which led me to I think this one parser is much more fault tolerant than many others.

How to use a variable for a key in a JavaScript object literal?

ES5 implementation to assign keys is below:

var obj = Object.create(null),
    objArgs = (
      (objArgs = {}),
      (objArgs.someKey = {
        value: 'someValue'
      }), objArgs);

Object.defineProperties(obj, objArgs);

I've attached a snippet I used to convert to bare object.

var obj = {_x000D_
  'key1': 'value1',_x000D_
  'key2': 'value2',_x000D_
  'key3': [_x000D_
  'key4': {_x000D_
    'key5': 'value5'_x000D_
var bareObj = function(obj) {_x000D_
  var objArgs,_x000D_
    bareObj = Object.create(null);_x000D_
  Object.entries(obj).forEach(function([key, value]) {_x000D_
    var objArgs = (_x000D_
      (objArgs = {}),_x000D_
      (objArgs[key] = {_x000D_
        value: value_x000D_
      }), objArgs);_x000D_
    Object.defineProperties(bareObj, objArgs);_x000D_
  return {_x000D_
    input: obj,_x000D_
    output: bareObj_x000D_
if (!Object.entries) {_x000D_
  Object.entries = function(obj){_x000D_
    var arr = [];_x000D_
      arr.push([key, obj[key]]);_x000D_
    return arr;_x000D_

install beautiful soup using pip

pip is a command line tool, not Python syntax.

In other words, run the command in your console, not in the Python interpreter:

pip install beautifulsoup4

You may have to use the full path:

C:\Python27\Scripts\pip install beautifulsoup4

or even

C:\Python27\Scripts\pip.exe install beautifulsoup4

Windows will then execute the pip program and that will use Python to install the package.

Another option is to use the Python -m command-line switch to run the pip module, which then operates exactly like the pip command:

python -m pip install beautifulsoup4


python.exe -m pip install beautifulsoup4

How to convert Windows end of line in Unix end of line (CR/LF to LF)

The tr command can also do this:

tr -d '\15\32' < winfile.txt > unixfile.txt

and should be available to you.

You'll need to run tr from within a script, since it cannot work with file names. For example, create a file


for f in `find -iname \*.java`; do
    echo "$f"
    tr -d '\15\32' < "$f" > "$"
    mv "$" "$f"
    recode CP1252...UTF-8 "$f"

Running would process all the java files in the current directory and its subdirectories.

VSCode Change Default Terminal

I just type following keywords in the opened terminal;

  1. powershell
  2. bash
  3. cmd
  4. node
  5. python (or python3)

See details in the below image. (VSCode version 1.19.1 - windows 10 OS) enter image description here

It works on VS Code Mac as well. I tried it with VSCode (Version 1.20.1)

How to store Configuration file and read it using React

With webpack you can put env-specific config into the externals field in webpack.config.js

externals: {
  'Config': JSON.stringify(process.env.NODE_ENV === 'production' ? {
    serverUrl: ""
  } : {
    serverUrl: "http://localhost:8090"

If you want to store the configs in a separate JSON file, that's possible too, you can require that file and assign to Config:

externals: {
  'Config': JSON.stringify(process.env.NODE_ENV === 'production' ? require('./') : require('./'))

Then in your modules, you can use the config:

var Config = require('Config')
fetchData(Config.serverUrl + '/Enterprises/...')

For React:

import Config from 'Config';
axios.get(this.app_url, {
        'headers': Config.headers

Not sure if it covers your use case but it's been working pretty well for us.

Add a linebreak in an HTML text area

In a text area, as in the form input, then just a normal line break will work:

This is a text area
line breaks are automatic

If you're talking about normal text on the page, the <br /> (or just <br> if using plain 'ole HTML4) is a line break.

However, I'd say that you often don't actually want a line break. Usually, your text is seperated into paragraphs:

  This is some text
  This is some more

Which is much better because it gives a clue as to how your text is structured to machines that read it. Machines that read it include screen readers for the partially sighted or blind, seperating text into paragraphs gives it a chance of being presented correctly to these users.

when exactly are we supposed to use "public static final String"?

You do not have to use final, but the final is making clear to everyone else - including the compiler - that this is a constant, and that's the good practice in it.

Why people doe that even if the constant will be used only in one place and only in the same class: Because in many cases it still makes sense. If you for example know it will be final during program run, but you intend to change the value later and recompile (easier to find), and also might use it more often later-on. It is also informing other programmers about the core values in the program flow at a prominent and combined place.

An aspect the other answers are missing out unfortunately, is that using the combination of public final needs to be done very carefully, especially if other classes or packages will use your class (which can be assumed because it is public).

Here's why:

  1. Because it is declared as final, the compiler will inline this field during compile time into any compilation unit reading this field. So far, so good.
  2. What people tend to forget is, because the field is also declared public, the compiler will also inline this value into any other compile unit. That means other classes using this field.

What are the consequences?

Imagine you have this:

class Foo {
  public static final String VERSION = "1.0";

class Bar {
  public static void main(String[] args) {
    System.out.println("I am using version " + Foo.VERSION);

After compiling and running Bar, you'll get:

I am using version 1.0

Now, you improve Foo and change the version to "1.1". After recompiling Foo, you run Bar and get this wrong output:

I am using version 1.0

This happens, because VERSION is declared final, so the actual value of it was already in-lined in Bar during the first compile run. As a consequence, to let the example of a public static final ... field propagate properly after actually changing what was declared final (you lied!;), you'd need to recompile every class using it.

I've seen this a couple of times and it is really hard to debug.

If by final you mean a constant that might change in later versions of your program, a better solution would be this:

class Foo {
  private static String version = "1.0";
  public static final String getVersion() {
    return version;

The performance penalty of this is negligible, since JIT code generator will inline it at run-time.

C# Convert List<string> to Dictionary<string, string>

Use this:

var dict = list.ToDictionary(x => x);

See MSDN for more info.

As Pranay points out in the comments, this will fail if an item exists in the list multiple times.
Depending on your specific requirements, you can either use var dict = list.Distinct().ToDictionary(x => x); to get a dictionary of distinct items or you can use ToLookup instead:

var dict = list.ToLookup(x => x);

This will return an ILookup<string, string> which is essentially the same as IDictionary<string, IEnumerable<string>>, so you will have a list of distinct keys with each string instance under it.

How to putAll on Java hashMap contents of one to another, but not replace existing keys and values?

You can make it in just 1 line if you change maps order in @erickson's solution:

mapWithNotSoImportantValues.putAll( mapWithImportantValues );

In this case you replace values in mapWithNotSoImportantValues with value from mapWithImportantValues with the same keys.

Formatting code in Notepad++

ANSWER AS OF June 2019

Install the XML Tools plugin from the Plugin Admin (in Notepad++ 7.7 at least)

Then click Plugins -> XML Tools -> Pretty Print (XML Only with Line breaks)

That did it for me.

How to remove decimal part from a number in C#

If you just need the integer part of the double then use explicit cast to int.

int number = (int) a;

You may use Convert.ToInt32 Method (Double), but this will round the number to the nearest integer.

value, rounded to the nearest 32-bit signed integer. If value is halfway between two whole numbers, the even number is returned; that is, 4.5 is converted to 4, and 5.5 is converted to 6.

jQuery UI Accordion Expand/Collapse All

A lot of these seem to be overcomplicated. I achieved what I wanted with just the following:



Writing a dict to txt file and reading it back?

I created my own functions which work really nicely:

def writeDict(dict, filename, sep):
    with open(filename, "a") as f:
        for i in dict.keys():            
            f.write(i + " " + sep.join([str(x) for x in dict[i]]) + "\n")

It will store the keyname first, followed by all values. Note that in this case my dict contains integers so that's why it converts to int. This is most likely the part you need to change for your situation.

def readDict(filename, sep):
    with open(filename, "r") as f:
        dict = {}
        for line in f:
            values = line.split(sep)
            dict[values[0]] = {int(x) for x in values[1:len(values)]}

How to print color in console using System.out.println?

If your terminal supports it, you can use ANSI escape codes to use color in your output. It generally works for Unix shell prompts; however, it doesn't work for Windows Command Prompt (Although, it does work for Cygwin). For example, you could define constants like these for the colors:

public static final String ANSI_RESET = "\u001B[0m";
public static final String ANSI_BLACK = "\u001B[30m";
public static final String ANSI_RED = "\u001B[31m";
public static final String ANSI_GREEN = "\u001B[32m";
public static final String ANSI_YELLOW = "\u001B[33m";
public static final String ANSI_BLUE = "\u001B[34m";
public static final String ANSI_PURPLE = "\u001B[35m";
public static final String ANSI_CYAN = "\u001B[36m";
public static final String ANSI_WHITE = "\u001B[37m";

Then, you could reference those as necessary.

For example, using the above constants, you could make the following red text output on supported terminals:

System.out.println(ANSI_RED + "This text is red!" + ANSI_RESET);

Update: You might want to check out the Jansi library. It provides an API and has support for Windows using JNI. I haven't tried it yet; however, it looks promising.

Update 2: Also, if you wish to change the background color of the text to a different color, you could try the following as well:

public static final String ANSI_BLACK_BACKGROUND = "\u001B[40m";
public static final String ANSI_RED_BACKGROUND = "\u001B[41m";
public static final String ANSI_GREEN_BACKGROUND = "\u001B[42m";
public static final String ANSI_YELLOW_BACKGROUND = "\u001B[43m";
public static final String ANSI_BLUE_BACKGROUND = "\u001B[44m";
public static final String ANSI_PURPLE_BACKGROUND = "\u001B[45m";
public static final String ANSI_CYAN_BACKGROUND = "\u001B[46m";
public static final String ANSI_WHITE_BACKGROUND = "\u001B[47m";

For instance:

System.out.println(ANSI_GREEN_BACKGROUND + "This text has a green background but default text!" + ANSI_RESET);
System.out.println(ANSI_RED + "This text has red text but a default background!" + ANSI_RESET);
System.out.println(ANSI_GREEN_BACKGROUND + ANSI_RED + "This text has a green background and red text!" + ANSI_RESET);

Correct way to write loops for promise.

Here's another method (ES6 w/std Promise). Uses lodash/underscore type exit criteria (return === false). Note that you could easily add an exitIf() method in options to run in doOne().

const whilePromise = (fnReturningPromise,options = {}) => { 
    // loop until fnReturningPromise() === false
    // options.delay - setTimeout ms (set to 0 for 1 tick to make non-blocking)
    return new Promise((resolve,reject) => {
        const doOne = () => {
            .then((...args) => {
                if (args.length && args[0] === false) {
                } else {
        const iterate = () => {
            if (options.delay !== undefined) {
            } else {

Get Line Number of certain phrase in file Python

listStr = open("file_name","mode")

if "search element" in listStr:
    print listStr.index("search element")  # This will gives you the line number

How to convert all tables from MyISAM into InnoDB?


  // connect your database here first

  mysql_connect('host', 'user', 'pass');

  $databases = mysql_query('SHOW databases');

  while($db = mysql_fetch_array($databases)) {
    echo "database => {$db[0]}\n";

    $tables = mysql_query('SHOW tables');

    while($tbl = mysql_fetch_array($tables)) {
      echo "table => {$tbl[0]}\n";
      mysql_query("ALTER TABLE {$tbl[0]} ENGINE=InnoDB");

Forking vs. Branching in GitHub

Forking creates an entirely new repository from existing repository (simply doing git clone on gitHub/bitbucket)

Forks are best used: when the intent of the ‘split’ is to create a logically independent project, which may never reunite with its parent.

Branch strategy creates a new branch over the existing/working repository

Branches are best used: when they are created as temporary places to work through a feature, with the intent to merge the branch with the origin.

More Specific :- In open source projects it is the owner of the repository who decides who can push to the repository. However, the idea of open source is that everybody can contribute to the project.

This problem is solved by forks: any time a developer wants to change something in an open source project, they don’t clone the official repository directly. Instead, they fork it to create a copy. When the work is finished, they make a pull request so that the owner of the repository can review the changes and decide whether to merge them to his project.

At its core forking is similar to feature branching, but instead of creating branches a fork of the repository is made, and instead of doing a merge request you create a pull request.

The below links provide the difference in a well-explained manner :

ImportError: No module named Crypto.Cipher

It could be a problem of loading python modules installed via pip. Refer to this answer Can't load Python modules installed via pip from site-packages directory and try something like

python -m pip install pycrypto

Making an asynchronous task in Flask

You can also try using multiprocessing.Process with daemon=True; the process.start() method does not block and you can return a response/status immediately to the caller while your expensive function executes in the background.

I experienced similar problem while working with falcon framework and using daemon process helped.

You'd need to do the following:

from multiprocessing import Process

@app.route('/render/<id>', methods=['POST'])
def render_script(id=None):
    heavy_process = Process(  # Create a daemonic process with heavy "my_func"
    return Response(

# Define some heavy function
def my_func():
    print("Process finished")

You should get a response immediately and, after 10s you should see a printed message in the console.

NOTE: Keep in mind that daemonic processes are not allowed to spawn any child processes.

Random float number generation

For C++, it can generate real float numbers within the range specified by dist variable

#include <random>  //If it doesnt work then use   #include <tr1/random>
#include <iostream>

using namespace std;

typedef std::tr1::ranlux64_base_01 Myeng; 
typedef std::tr1::normal_distribution<double> Mydist;

int main() { 
       Myeng eng; 
       eng.seed((unsigned int) time(NULL)); //initializing generator to January 1, 1970);
       Mydist dist(1,10); 

       dist.reset(); // discard any cached values 
       for (int i = 0; i < 10; i++)
           std::cout << "a random value == " << (int)dist(eng) << std::endl; 

       return (0);

Installing SciPy with pip

Besides all of these answers, If you install python of 32bit on your 64bit machine, you have to download scipy of 32-bit irrespective of your machine. In the above URL you can download the packages and command is: pip install

How to add new item to hash

It's as simple as:

irb(main):001:0> hash = {:item1 => 1}
=> {:item1=>1}
irb(main):002:0> hash[:item2] = 2
=> 2
irb(main):003:0> hash
=> {:item1=>1, :item2=>2}

How to get everything after last slash in a URL?

urlparse is fine to use if you want to (say, to get rid of any query string parameters).

import urllib.parse

urls = [

for i in urls:
    url_parts = urllib.parse.urlparse(i)
    path_parts = url_parts[2].rpartition('/')
    print('URL: {}\nreturns: {}\n'.format(i, path_parts[2]))


returns: TEST1

returns: TEST2

returns: 12345

returns: 12345

What is causing the error `string.split is not a function`?

Change this...

var string = document.location;

to this...

var string = document.location + '';

This is because document.location is a Location object. The default .toString() returns the location in string form, so the concatenation will trigger that.

You could also use document.URL to get a string.

How to set text color in submit button?

    font-size: 20px;

PHP not displaying errors even though display_errors = On

Check the error_reporting flag, must be E_ALL, but in some release of Plesk there are quotes ("E_ALL") instead of (E_ALL)

I solved this issue deleting the quotes (") in php.ini

from this:

error_reporting = "E_ALL"

to this:

error_reporting = E_ALL

How do I implement __getattribute__ without an infinite recursion error?

Python language reference:

In order to avoid infinite recursion in this method, its implementation should always call the base class method with the same name to access any attributes it needs, for example, object.__getattribute__(self, name).


def __getattribute__(self,name):
        return self.__dict__[name]

You're calling for an attribute called __dict__. Because it's an attribute, __getattribute__ gets called in search for __dict__ which calls __getattribute__ which calls ... yada yada yada

return  object.__getattribute__(self, name)

Using the base classes __getattribute__ helps finding the real attribute.

Apache is "Unable to initialize module" because of module's and PHP's API don't match after changing the PHP configuration

Before you phpize, make sure to update your path ($PS1) to point to the new PHP! phpize uses your environment, and if you still have vestiges of your old PHP in your path or other parts of the environment, things will get hairy!

Failed to open/create the internal network Vagrant on Windows10

I just ran into this problem with VirtualBox 5.1 on Windows 8. It turns out the problem was with the Kaspersky virus protection I have installed. It added the "Kaspersky Anti-Virus NDIS 6 Filter" on the host-only adapter on the windows side. When I disabled that filter the VM started properly:

host-only network adapter properties

How to iterate object keys using *ngFor

I think the most elegant way to do that is to use the javascript Object.keys like this (I had first implemented a pipe for that but for me, it just complicated my work unnecessary):

in the Component pass Object to template:

Object = Object;

then in the template:

<div *ngFor="let key of Object.keys(objs)">
   my key: {{key}}
   my object {{objs[key] | json}} <!-- hier I could use ngFor again with Object.keys(objs[key]) -->

If you have a lot of subobjects you should create a component that will print the object for you. By printing the values and keys as you want and on an subobject calling itselfe recursively.

Hier you can find an stackblitz demo for both methods.

How do you make Vim unhighlight what you searched for?

I have this in my .vimrc:

nnoremap ; :set invhlsearch<CR>

This way, ; will toggle search highlighting. Normally, the ; key repeats the latest t/T/f/F command, but I never really used that functionality. I find this setting much more useful, because I can change search highlighting on and off very quickly and can easily get a sense of where my search results are, at a glance.

Angular 4 img src is not found

Angular can only access static files like images and config files from assets folder. Nice way to download string path of remote stored image and load it to template.

  public concateInnerHTML(path: string): string {
        let front = "<img class='d-block' src='";
        let back = "' alt='slide'>";
        let result = front + path + back;
        return result;
     return null;

In a Component imlement DoCheck interface and past in it formula for database. Data base query is only a sample.

ngDoCheck(): void {
   this.concatedPathName = this.concateInnerHTML(database.query('src'));

And in html tamplate <div [innerHtml]="concatedPathName"></div>

AngularJS not detecting Access-Control-Allow-Origin header?

If you guys are having this problem in sails.js just set your cors.js to include Authorization as the allowed header

  *                                                                          *_x000D_
  * Which headers should be allowed for CORS requests? This is only used in  *_x000D_
  * response to preflight requests.                                          *_x000D_
  *                                                                          *_x000D_
  headers: 'Authorization' // this line here

Package opencv was not found in the pkg-config search path

it seems that the ubuntu community has completed the documentation on installing openCV,

so all you have to do now is to download the installation script from here and execute it.

don't forget to make it executable:

chmod +x



Processing $http response in service

Related to this I went through a similar problem, but not with get or post made by Angular but with an extension made by a 3rd party (in my case Chrome Extension).
The problem that I faced is that the Chrome Extension won't return then() so I was unable to do it the way in the solution above but the result is still Asynchronous.
So my solution is to create a service and to proceed to a callback

app.service('cookieInfoService', function() {
    this.getInfo = function(callback) {
        var model = {};
        chrome.cookies.get({url:serverUrl, name:'userId'}, function (response) {
            model.response= response;

Then in my controller

app.controller("MyCtrl", function ($scope, cookieInfoService) {
    cookieInfoService.getInfo(function (info) {

Hope this can help others getting the same issue.

How do you format the day of the month to say "11th", "21st" or "23rd" (ordinal indicator)?

String ordinal(int num)
    String[] suffix = {"th", "st", "nd", "rd", "th", "th", "th", "th", "th", "th"};
    int m = num % 100;
    return String.valueOf(num) + suffix[(m > 3 && m < 21) ? 0 : (m % 10)];

Mean Squared Error in Numpy?

You can use:

mse = ((A - B)**2).mean(axis=ax)


mse = (np.square(A - B)).mean(axis=ax)
  • with ax=0 the average is performed along the row, for each column, returning an array
  • with ax=1 the average is performed along the column, for each row, returning an array
  • with ax=None the average is performed element-wise along the array, returning a scalar value

Running SSH Agent when starting Git Bash on Windows

Put this in your ~/.bashrc (or a file that's source'd from it) which will stop it from being run multiple times unnecessarily per shell:

if [ -z "$SSH_AGENT_PID" ]; then
        eval `ssh-agent -s`

And then add "AddKeysToAgent yes" to ~/.ssh/config:

Host *
    AddKeysToAgent yes

ssh to your server (or git pull) normally and you'll only be asked for password/passphrase once per session.

How to upsert (update or insert) in SQL Server 2005

Try to check for existence:


    INSERT INTO dbo.Employee(Col1, ..., ColN)
    VALUES(Val1, .., ValN)


    UPDATE dbo.Employee
    SET Col1 = Val1, Col2 = Val2, ...., ColN = ValN
    WHERE ID = @SomeID

You could easily wrap this into a stored procedure and just call that stored procedure from the outside (e.g. from a programming language like C# or whatever you're using).

Update: either you can just write this entire statement in one long string (doable - but not really very useful) - or you can wrap it into a stored procedure:

CREATE PROCEDURE dbo.InsertOrUpdateEmployee
       @ID INT,
       @Name VARCHAR(50),
       @ItemName VARCHAR(50),  
       @ItemCatName VARCHAR(50),
       @ItemQty DECIMAL(15,2)
       INSERT INTO dbo.Table1(ID, Name, ItemName, ItemCatName, ItemQty)
       VALUES(@ID, @Name, @ItemName, @ItemCatName, @ItemQty)
       UPDATE dbo.Table1
       SET Name = @Name,
           ItemName = @ItemName,
           ItemCatName = @ItemCatName,
           ItemQty = @ItemQty
       WHERE ID = @ID

and then just call that stored procedure from your ADO.NET code

Node.js Web Application examples/tutorials

I would suggest you check out the various tutorials that are coming out lately. My current fav is:

Hope this helps.

Importing modules from parent folder

Relative imports (as in from .. import mymodule) only work in a package. To import 'mymodule' that is in the parent directory of your current module:

import os,sys,inspect
currentdir = os.path.dirname(os.path.abspath(inspect.getfile(inspect.currentframe())))
parentdir = os.path.dirname(currentdir)

import mymodule

edit: the __file__ attribute is not always given. Instead of using os.path.abspath(__file__) I now suggested using the inspect module to retrieve the filename (and path) of the current file

What is the best way to know if all the variables in a Class are null?

I think this is a solution that solves your problem easily: (return true if any of the parameters is not null)

  public boolean isUserEmpty(){ 
boolean isEmpty;
isEmpty =  isEmpty = Stream.of(id,
        .anyMatch(userParameter -> userParameter != null);

return isEmpty;}

Another solution to the same task is:(you can change it to if(isEmpty==0) checks if all the parameters are null.

public boolean isUserEmpty(){  
       long isEmpty;
            isEmpty = Stream.of(id,
                    .filter(userParameter -> userParameter != null).count();

            if (isEmpty > 0) {
                return true;
            } else {
                return false;

In Excel, how do I extract last four letters of a ten letter string?

No need to use a macro. Supposing your first string is in A1.

=RIGHT(A1, 4)

Drag this down and you will get your four last characters.

Edit: To be sure, if you ever have sequences like 'ABC DEF' and want the last four LETTERS and not CHARACTERS you might want to use trimspaces()


Edit: As per brettdj's suggestion, you may want to check that your string is actually 4-character long or more:


Python memory leaks

As far as best practices, keep an eye for recursive functions. In my case I ran into issues with recursion (where there didn't need to be). A simplified example of what I was doing:

def my_function():
    # lots of memory intensive operations
    # like operating on images or huge dictionaries and lists
    my_flag = True
    if my_flag:  # restart the function if a certain flag is true

def main():

operating in this recursive manner won't trigger the garbage collection and clear out the remains of the function, so every time through memory usage is growing and growing.

My solution was to pull the recursive call out of my_function() and have main() handle when to call it again. this way the function ends naturally and cleans up after itself.

def my_function():
    # lots of memory intensive operations
    # like operating on images or huge dictionaries and lists
    my_flag = True
    return my_flag

def main():
    result = my_function()
    if result:

Can I update a component's props in React.js?

A component cannot update its own props unless they are arrays or objects (having a component update its own props even if possible is an anti-pattern), but can update its state and the props of its children.

For instance, a Dashboard has a speed field in its state, and passes it to a Gauge child thats displays this speed. Its render method is just return <Gauge speed={this.state.speed} />. When the Dashboard calls this.setState({speed: this.state.speed + 1}), the Gauge is re-rendered with the new value for speed.

Just before this happens, Gauge's componentWillReceiveProps is called, so that the Gauge has a chance to compare the new value to the old one.

How can I delete using INNER JOIN with SQL Server?

Just add the name of the table between DELETE and FROM from where you want to delete records, because we have to specify the table to delete. Also remove the ORDER BY clause because there is nothing to order while deleting records.

So your final query should be like this:

    DELETE WorkRecord2 
      FROM WorkRecord2 
INNER JOIN Employee 
        ON EmployeeRun=EmployeeNo
     WHERE Company = '1' 
       AND Date = '2013-05-06';

How can I read a text file from the SD card in Android?

BufferedReader br = null;
try {
        String fpath = Environment.getExternalStorageDirectory() + <your file name>;
        try {
            br = new BufferedReader(new FileReader(fpath));
        } catch (FileNotFoundException e1) {
        String line = "";
        while ((line = br.readLine()) != null) {
         //Do something here 

How to set portrait and landscape media queries in css?

It can also be as simple as this.

@media (orientation: landscape) {


Documentation for using JavaScript code inside a PDF file

Here you can find "Adobe Acrobat Forms JavaScript Object Specification Version 4.0"

Revised: January 27, 1999

It’s very old, but it is still useful.

Outline radius?

Use this one: box-shadow: 0px 0px 0px 1px red;

How to write a stored procedure using phpmyadmin and how to use it through php?

I got it to work in phpAdmin , but only when I removed the "Number of records " phrase.

In my version of phpAdmin I could see the box for changing the delimiters.

Also to see the procedure in the database i went to the phpAdmin home, then information_schema database and then the routines table.

Where is the itoa function in Linux?

Following function allocates just enough memory to keep string representation of the given number and then writes the string representation into this area using standard sprintf method.

char *itoa(long n)
    int len = n==0 ? 1 : floor(log10l(labs(n)))+1;
    if (n<0) len++; // room for negative sign '-'

    char    *buf = calloc(sizeof(char), len+1); // +1 for null
    snprintf(buf, len+1, "%ld", n);
    return   buf;

Don't forget to free up allocated memory when out of need:

char *num_str = itoa(123456789L);
// ... 

N.B. As snprintf copies n-1 bytes, we have to call snprintf(buf, len+1, "%ld", n) (not just snprintf(buf, len, "%ld", n))

java.lang.IllegalAccessError: tried to access method

This happened to me when I had a class in one jar trying to access a private method in a class from another jar. I simply changed the private method to public, recompiled and deployed, and it worked ok afterwards.

Where is the visual studio HTML Designer?

The solution of creating a new HTML file with HTML (Web Forms) Designer worked for that file but not for other, individual HTML files that I wanted to edit.

I did find the Open With option in the Open File dialogue and was able to select the HTML (Web Forms) Editor there. Having clicked the "Set as Default" option in that window, VS then remembered to use that editor when I opened other HTML files.

Adding multiple columns AFTER a specific column in MySQL

If you want to add a single column after a specific field, then the following MySQL query should work:

    AFTER lastname

If you want to add multiple columns, then you need to use 'ADD' command each time for a column. Here is the MySQL query for this:

    AFTER lastname

Point to note

In the second method, the last ADD COLUMN column should actually be the first column you want to append to the table.

E.g: if you want to add count, log, status in the exact order after lastname, then the syntax would actually be:


How to store an output of shell script to a variable in Unix?

Two simple examples to capture output the pwd command:

$ b=$(pwd)
$ echo $b


$ a=`pwd`
$ echo $a

The first way is preferred. Note that there can't be any spaces after the = for this to work.

Example using a short script:


echo "hi there"


$ ./
hi there
$ a=$(
$ echo $a
hi there

In general a more flexible approach would be to return an exit value from the command and use it for further processing, though sometimes we just may want to capture the simple output from a command.

How to save local data in a Swift app?

Using NSCoding and NSKeyedArchiver is another great option for data that's too complex for NSUserDefaults, but for which CoreData would be overkill. It also gives you the opportunity to manage the file structure more explicitly, which is great if you want to use encryption.

How to set a default Value of a UIPickerView

In normal case, you can do something like this in viewDidLoad method;

[_picker selectRow:1 inComponent:0 animated:YES];

In my case, I'd like to fetch data from api server and display them onto UIPickerView then I want the picker to select the first item by default.

The UIPickerView will look like it selected the first item after it was created, but when you try to get the selected index by using selectedRowInComponent, you will get NSNull. That's because it detected nothing changed by the user (select 0 from 0 ).

Following is my solution (in viewWillAppear, after I fetched the data)

[_picker selectRow:1 inComponent:0 animated:NO];
[_picker selectRow:0 inComponent:0 animated:NO];

Its a bit dirty, but dont worry, the UI rendering in iOS is very fast ;)

Turning a string into a Uri in Android


See doc:

String: an RFC 2396-compliant, encoded URI

Url must be canonicalized before using, like this:


Can I use Twitter Bootstrap and jQuery UI at the same time?

If you're running into javascript namespace collisions, you can use Bootstrap's noConflict() function make it cede functionality to jQuery UI.

Using only CSS, show div on hover over <a>

Don't forget. if you are trying to hover around an image, you have to put it around a container. css:

.brand:hover + .brand-sales {
    display: block;

.brand-sales {
    display: none;

If you hover on this:

<span className="brand">
   <img src="" 
     alt"some image class="product-card-place-logo"/>

This will show:

<div class="product-card-sales-container brand-sales">
    <div class="product-card-">Message from the business goes here. They can talk alot or not</div>

Get folder name from full file path

This can also be done like so;

var directoryName = System.IO.Path.GetFileName(@"c:\projects\roott\wsdlproj\devlop\beta2\text");

Python and SQLite: insert into table

This will work for a multiple row df having the dataframe as df with the same name of the columns in the df as the db.

tuples = list(df.itertuples(index=False, name=None))

columns_list = df.columns.tolist()
marks = ['?' for _ in columns_list]
columns_list = f'({(",".join(columns_list))})'
marks = f'({(",".join(marks))})'

table_name = 'whateveryouwant'

c.executemany(f'INSERT OR REPLACE INTO {table_name}{columns_list} VALUES {marks}', tuples)

Difference between except: and except Exception as e: in Python


accepts all exceptions, whereas

except Exception as e:

only accepts exceptions that you're meant to catch.

Here's an example of one that you're not meant to catch:

>>> try:
...     input()
... except:
...     pass
>>> try:
...     input()
... except Exception as e:
...     pass
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>

The first one silenced the KeyboardInterrupt!

Here's a quick list:

issubclass(BaseException, BaseException)
#>>> True
issubclass(BaseException, Exception)
#>>> False

issubclass(KeyboardInterrupt, BaseException)
#>>> True
issubclass(KeyboardInterrupt, Exception)
#>>> False

issubclass(SystemExit, BaseException)
#>>> True
issubclass(SystemExit, Exception)
#>>> False

If you want to catch any of those, it's best to do

except BaseException:

to point out that you know what you're doing.

All exceptions stem from BaseException, and those you're meant to catch day-to-day (those that'll be thrown for the programmer) inherit too from Exception.

Jquery Chosen plugin - dynamically populate list by Ajax

var object = $("#lstValue_chosen").find('.chosen-choices').find('input[type="text"]')[0];
var _KeyCode = event.which || event.keyCode;
if (_KeyCode != 37 && _KeyCode != 38 && _KeyCode != 39 && _KeyCode != 40) { 

    if (object.value != "") {
        var SelectedObjvalue = object.value;
        if (SelectedObjvalue.length > 0) {
            var obj = { value: SelectedObjvalue };
            var SelectedListValue = $('#lstValue').val();
            var Uniqueid = $('#uniqueid').val();

                url: '/Admin/GetUserListBox?SelectedValue=' + SelectedListValue + '&Uniqueid=' + Uniqueid,
                data: { value: SelectedObjvalue },
                type: 'GET',
                async: false,
                success: function (response) {
                    if (response.length > 0) {
                        var options = '';                            
                        $.each(response, function (i, obj) {
                            options += '<option value="' + obj.Value + '">' + obj.Text + '</option>';
                        object.value = SelectedObjvalue;
                error: function (xhr, ajaxOptions, thrownError) {
                    //jAlert("Error. Please, check the data.", " Deactivate User");

Which characters are valid/invalid in a JSON key name?

It is worth mentioning that while starting the keys with numbers is valid, it could cause some unintended issues.


var testObject = {
    "1tile": "test value"
console.log(testObject.1tile); // fails, invalid syntax
console.log(testObject["1tile"]; // workaround

Live-stream video from one android phone to another over WiFi

You can use IP Webcam, or perhaps use DLNA. For example Samsung devices come with an app called AllShare which can share and access DLNA enabled devices on the network. I think IP Webcam is your best bet, though. You should be able to open the stream it creates using MX Video player or something like that.

How to delete a column from a table in MySQL

To delete column use this,

ALTER TABLE `tbl_Country` DROP `your_col`

Convert string to Boolean in javascript

Actually you don't get the meaning of Boolean method.It always return true if the variable is not null or empty.

var variable = some value; Boolean(variable);

If my variable have some value then it will return true else return false You can't use Boolean as you think.

Unrecognized SSL message, plaintext connection? Exception

I face the same issue from Java application built in Jdevelopr IDE. I solved the issue by unchecking the use of proxy form Project properties.

You can find it in the following: Project Properties -> (from left panle )Run/Debug/Profile ->Click (edit) form the right panel -> Tool Setting from the left panel -> uncheck (Use Proxy) option.

What are the various "Build action" settings in Visual Studio project properties and what do they do?

How about this page from Microsoft Connect (explaining the DesignData and DesignDataWithDesignTimeCreatableTypes) types. Quoting:

The following describes the two Build Actions for Sample Data files.

Sample data .xaml files must be assigned one of the below Build Actions:

DesignData: Sample data types will be created as faux types. Use this Build Action when the sample data types are not creatable or have read-only properties that you want to defined sample data values for.

DesignDataWithDesignTimeCreatableTypes: Sample data types will be created using the types defined in the sample data file. Use this Build Action when the sample data types are creatable using their default empty constructor.

Not so incredibly exhaustive, but it at least gives a hint. This MSDN walkthrough also gives some ideas. I don't know whether these Build Actions are applicable for non-Silverlight projects also.

"Unable to find remote helper for 'https'" during git clone

I got the same problem today: git http broken after years of happy service. It seems caused by some Perl lib updates. Tried some sane suggestions on web, none worked. Had enough, I just removed all git stuff, got a new tarball from, compiled and installed, and all things are back to normal. Give it try, or you can go dig deep into your logs...

How to build a Horizontal ListView with RecyclerView?

Trying to build a horizontal ListView is taking too much time. I have resolved it in two ways.

1.By using a ViewPager whose adapter extends from PagerAdapter.

2.By using RecyclerView just as above. Need to apply LayoutManager as in the following code:

LinearLayoutManager layoutManager
    = new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false);

RecyclerView myList = (RecyclerView) findViewById(;

Python: split a list based on a condition?

def partition(pred, seq):
  return reduce( lambda (yes, no), x: (yes+[x], no) if pred(x) else (yes, no+[x]), seq, ([], []) )

Regular expression to limit number of characters to 10

You can use curly braces to control the number of occurrences. For example, this means 0 to 10:


The options are:

  • {3} Exactly 3 occurrences;
  • {6,} At least 6 occurrences;
  • {2,5} 2 to 5 occurrences.

See the regular expression reference.

Your expression had a + after the closing curly brace, hence the error.

Neither user 10102 nor current process has android.permission.READ_PHONE_STATE

On Android >=6.0, We have to request permission runtime.

Step1: add in AndroidManifest.xml file

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

Step2: Request permission.

int permissionCheck = ContextCompat.checkSelfPermission(this, Manifest.permission.READ_PHONE_STATE);

if (permissionCheck != PackageManager.PERMISSION_GRANTED) {
    ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_PHONE_STATE}, REQUEST_READ_PHONE_STATE);
} else {

Step3: Handle callback when you request permission.

public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
    switch (requestCode) {
            if ((grantResults.length > 0) && (grantResults[0] == PackageManager.PERMISSION_GRANTED)) {


Edit: Read official guide here Requesting Permissions at Run Time

How to discard uncommitted changes in SourceTree?

On the unstaged file, click on the three dots on the right side. Once you click it, a popover menu will appear where you can then Discard file.

How do I wait until Task is finished in C#?

async Task<int> AccessTheWebAsync()  
    // You need to add a reference to System.Net.Http to declare client.  
    HttpClient client = new HttpClient();  

    // GetStringAsync returns a Task<string>. That means that when you await the  
    // task you'll get a string (urlContents).  
    Task<string> getStringTask = 


    // You can do work here that doesn't rely on the string from GetStringAsync.  

    // The await operator suspends AccessTheWebAsync.  
    //  - AccessTheWebAsync can't continue until getStringTask is complete.  
    //  - Meanwhile, control returns to the caller of AccessTheWebAsync.  
    //  - Control resumes here when getStringTask is complete.   
    //  - The await operator then retrieves the string result from 
    string urlContents = await getStringTask;  

    // The return statement specifies an integer result.  
    // Any methods that are awaiting AccessTheWebenter code hereAsync retrieve the length 
    return urlContents.Length;  

How to exclude property from Json Serialization

If you are using System.Text.Json then you can use [JsonIgnore].
FQ: System.Text.Json.Serialization.JsonIgnoreAttribute

Official Microsoft Docs: JsonIgnoreAttribute

As stated here:

The library is built-in as part of the .NET Core 3.0 shared framework.
For other target frameworks, install the System.Text.Json NuGet package. The package supports:

  • .NET Standard 2.0 and later versions
  • .NET Framework 4.6.1 and later versions
  • .NET Core 2.0, 2.1, and 2.2

Get text from DataGridView selected cells

the Best of both worlds.....

Private Sub tsbSendNewsLetter_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tsbSendNewsLetter.Click
        Dim tmpstr As String = ""
        Dim cnt As Integer = 0
        Dim virgin As Boolean = True
        For cnt = 0 To (dgvDetails.Rows.Count - 1)
            If Not dgvContacts.Rows(cnt).Cells(9).Value.ToString() Is Nothing Then
                If Not dgvContacts.Rows(cnt).Cells(9).Value.ToString().Length = 0 Then
                    If Not virgin Then
                        tmpstr += ", "
                    End If
                    tmpstr += dgvContacts.Rows(cnt).Cells(9).Value.ToString()
                    virgin = False
                End If
            End If
        Dim email As New qkuantusMailer()
        email.txtMailTo.Text = tmpstr
    End Sub

Change button text from Xcode?

Yes. There is a method on UIButton -setTitle:forState: use that.

Android Color Picker

I ended up here looking for a HSV color picker that offered transparency and copy/paste of the hex value. None of the existing answers met those needs, so here's the library I ended up writing:

HSV-Alpha Color Picker for Android (GitHub).

HSV-Alpha Color Picker Demo (Google Play).

I hope it's useful for somebody else.

Color Picker Dialog

HTML5 : Iframe No scrolling?

In HTML5 there is no scrolling attribute because "its function is better handled by CSS" see for other changes. Well and the CSS solution:

CSS solution:

HTML4's scrolling="no" is kind of an alias of the CSS's overflow: hidden, to do so it is important to set size attributes width/height:

  width: 250px; /*or any other size*/
  height: 300px; /*or any other size*/
  overflow: hidden;

Add this class to your iframe and you're done:

<iframe src="" class="noScrolling"></iframe>

! IMPORTANT NOTE ! : overflow: hidden for <iframe> is not fully supported by all modern browsers yet(even chrome doesn't support it yet) so for now (2013) it's still better to use Transitional version and use scrolling="no" and overflow:hidden at the same time :)

UPDATE 2020: the above is still true, oveflow for iframes is still not supported by all majors

400 vs 422 response to POST of data

Firstly this is a very good question.

400 Bad Request - When a critical piece of information is missing from the request

e.g. The authorization header or content type header. Which is absolutely required by the server to understand the request. This can differ from server to server.

422 Unprocessable Entity - When the request body can't be parsed.

This is less severe than 400. The request has reached the server. The server has acknowledged the request has got the basic structure right. But the information in the request body can't be parsed or understood.

e.g. Content-Type: application/xml when request body is JSON.

Here's an article listing status codes and its use in REST APIs.

Adding Access-Control-Allow-Origin header response in Laravel 5.3 Passport

You could also use the great laravel-cors package by barryvdh.

After you have the package installed, the easiest way to get CORS support for all your routes is to add the middleware like this in Http/Kernel.php:

protected $middleware = [

If you dont want to have CORS support on all your routes you should make a new OPTIONS route for /oauth/token and add the cors middleware to that route only.

Edit for Laravel 8

Laravel 8 already has CORS Support built in - HandleCors middleware is defined in your global middleware stack by default and can be configured in your application's config/cors.php config file.

If you update your Laravel application be sure to change out barryvdh's package with the supplied middleware: \Fruitcake\Cors\HandleCors::class

How to drop a table if it exists?

Do like this, it is the easiest way.

qry will be your own query, whatever you want in the select list.

set @qry = ' select * into TempData from (' + @qry + ')Tmp  '

exec (@qry)

select * from TempData 

drop table TempData

How to printf long long

First of all, %d is for a int

So %1.16lld makes no sense, because %d is an integer

That typedef you do, is also unnecessary, use the type straight ahead, makes a much more readable code.

What you want to use is the type double, for calculating pi and then using %f or %1.16f.

__FILE__, __LINE__, and __FUNCTION__ usage in C++

__FUNCTION__ is non standard, __func__ exists in C99 / C++11. The others (__LINE__ and __FILE__) are just fine.

It will always report the right file and line (and function if you choose to use __FUNCTION__/__func__). Optimization is a non-factor since it is a compile time macro expansion; it will never affect performance in any way.

Check if a temporary table exists and delete if it exists before creating a temporary table

My code uses a Source table that changes, and a Destination table that must match those changes.

-- Sample SQL to update only rows in a "Destination" Table
--  based on only rows that have changed in a "Source" table

-- Drop and Create a Temp Table to use as the "Source" Table
IF OBJECT_ID('tempdb..#tSource') IS NOT NULL drop table #tSource
create table #tSource (Col1 int, Col2 int, Col3 int, Col4 int)

-- Insert some values into the source
Insert #tSource (Col1, Col2, Col3, Col4) Values(1,1,1,1)
Insert #tSource (Col1, Col2, Col3, Col4) Values(2,1,1,2)
Insert #tSource (Col1, Col2, Col3, Col4) Values(3,1,1,3)
Insert #tSource (Col1, Col2, Col3, Col4) Values(4,1,1,4)
Insert #tSource (Col1, Col2, Col3, Col4) Values(5,1,1,5)
Insert #tSource (Col1, Col2, Col3, Col4) Values(6,1,1,6)

-- Drop and Create a Temp Table to use as the "Destination" Table
IF OBJECT_ID('tempdb..#tDest') IS NOT NULL drop Table #tDest
create table #tDest (Col1 int, Col2 int, Col3 int, Col4 int)

-- Add all Rows from the Source to the Destination
Insert #tDest
Select Col1, Col2, Col3, Col4 from #tSource

-- Look at both tables to see that they are the same
select *
from #tSource
Select *
from #tDest

-- Make some changes to the Source
update #tSource
    Set Col3=19
    Where Col1=1
update #tSource
    Set Col3=29
    Where Col1=2
update #tSource
    Set Col2=38
    Where Col1=3
update #tSource
    Set Col2=48
    Where Col1=4

-- Look at the Differences
-- Note: Only 4 rows are different. 2 Rows have remained the same.
Select Col1, Col2, Col3, Col4
from #tSource
Select Col1, Col2, Col3, Col4
from #tDest

-- Update only the rows that have changed
-- Note: I am using Col1 like an ID column
Update #tDest
    Set Col2=S.Col2,
From    (   Select Col1, Col2, Col3, Col4
            from #tSource
            Select Col1, Col2, Col3, Col4
            from #tDest
        ) S
Where #tDest.Col1=S.Col1 

-- Look at the tables again to see that
--  the destination table has changed to match
--  the source table.

select *
from #tSource
Select *
from #tDest

-- Clean Up
drop table #tSource
drop table #tDest

How to escape special characters of a string with single backslashes

Utilize the output of built-in repr to deal with \r\n\t and process the output of re.escape is what you want:

re.escape(repr(a)[1:-1]).replace('\\\\', '\\')

.substring error: "is not a function"

You can use substr

for example:

new Date().getFullYear().toString().substr(-2)

Android XML Percent Symbol

To allow the app using formatted strings from resources you should correct your xml. So, for example

<string name="app_name">Your App name, ver.%d</string>

should be replaced with

<string name="app_name">Your App name, ver.%1$d</string>

You can see this for details.

JPA EntityManager: Why use persist() over merge()?

I was getting lazyLoading exceptions on my entity because I was trying to access a lazy loaded collection that was in session.

What I would do was in a separate request, retrieve the entity from session and then try to access a collection in my jsp page which was problematic.

To alleviate this, I updated the same entity in my controller and passed it to my jsp, although I imagine when I re-saved in session that it will also be accessible though SessionScope and not throw a LazyLoadingException, a modification of example 2:

The following has worked for me:

// scenario 2 MY WAY
// tran starts
e = new MyEntity();
e = em.merge(e); // re-assign to the same entity "e"

//access e from jsp and it will work dandy!!

Eclipse: The declared package does not match the expected package

Suppose your project has a package like package name1.name2.name3.name4 (declared package)

Your package explorer shows
package top level named name1.name2
sub packages named name3.name4

You will have errors because Eclipse extracts the package name from the file directory structure on disk starting at the point you import from.

My case was a bit more involved, perhaps because I was using a symbolic link to a folder outside my workspace.

I first tried Build Path.Java Build Path.Source Tab.Link Source Button.Browse to the folder before name1 in your package.Folder-name as you like (i think). But had issues.

Then I removed the folder from the build path and tried File > Import... > General > File System > click Next > From Directory > Browse... to folder above name1 > click Advanced button > check Create links in workspace > click Finish button.

How to add trendline in python matplotlib dot (scatter) graphs?

as explained here

With help from numpy one can calculate for example a linear fitting.

# plot the data itself

# calc the trendline
z = numpy.polyfit(x, y, 1)
p = numpy.poly1d(z)
# the line equation:
print "y=%.6fx+(%.6f)"%(z[0],z[1])

How can I change the remote/target repository URL on Windows?

One more way to do this is:

git config remote.origin.url

To see the existing URL just do:

git config remote.origin.url

how to deal with google map inside of a hidden div (Updated picture)

I guess the original question is with a map that is initalized in a hidden div of the page. I solved a similar problem by resizing the map in the hidden div upon document ready, after it is initialized, regardless of its display status. In my case, I have 2 maps, one is shown and one is hidden when they are initialized and I don't want to initial a map every time it is shown. It is an old post, but I hope it helps anyone who are looking.


This is trivial when you use SUMPRODUCT. Por ejemplo:


You could put the above formula in cell B3, where A3 is the name you want to find in worksheet2.

How to declare a global variable in React?

Why don't you try using Context?

You can declare a global context variable in any of the parent components and this variable will be accessible across the component tree by this.context.varname. You only have to specify childContextTypes and getChildContext in the parent component and thereafter you can use/modify this from any component by just specifying contextTypes in the child component.

However, please take a note of this as mentioned in docs:

Just as global variables are best avoided when writing clear code, you should avoid using context in most cases. In particular, think twice before using it to "save typing" and using it instead of passing explicit props.

C++ callback using class member

MyClass and YourClass could both be derived from SomeonesClass which has an abstract (virtual) Callback method. Your addHandler would accept objects of type SomeonesClass and MyClass and YourClass can override Callback to provide their specific implementation of callback behavior.

Is there a replacement for unistd.h for Windows (Visual C)?

Create your own unistd.h header and include the needed headers for function prototypes.

Where does Oracle SQL Developer store connections?

If you have previously installed SQL Developer then it will store the connection details in the 'connection.xml' which will be located in below mentioned path.

C:\Users\Username\AppData\Roaming\SQL Developer\system3.1.07.42\o.jdeveloper.db.connection.

Once you get that 'connection.xml' try to import it into SQLDeveloper by right clicking to CONNECTIONS.

How do you parse and process HTML/XML in PHP?

The best method for parse xml:

$rss = simplexml_load_string($xml);
$i = 0;
foreach ($rss->channel->item as $feedItem) {
  echo $title=$feedItem->title;
  echo '<br>';
  echo $link=$feedItem->link;
  echo '<br>';
  if($feedItem->description !='') {
  } else {
  echo $des;
  echo '<br>';
  if($i>5) break;

Shorthand for if-else statement

Most answers here will work fine if you have just two conditions in your if-else. For more which is I guess what you want, you'll be using arrays. Every names corresponding element in names array you'll have an element in the hasNames array with the exact same index. Then it's a matter of these four lines.

names = "true";
var names = ["true","false","1","2"];
var hasNames = ["Y","N","true","false"];
var intIndex = names.indexOf(name);
hasName = hasNames[intIndex ];

This method could also be implemented using Objects and properties as illustrated by Benjamin.

Adding a collaborator to my free GitHub account?

Clear Instructions On How to Add A Collaborator - 2020 Update

Pictures are worth a thousand words. Let's put that to the test:

Picture Instructions (Click to Zoom in):

Picture Instructions

.......and videos/gifs are worth another thousand more:

Gif Instructions (Click to Zoom in):

Hopefully the pictures/gif make it easier for you to configure this!

enter image description here

How to display image with JavaScript?

You could make use of the Javascript DOM API. In particular, look at the createElement() method.

You could create a re-usable function that will create an image like so...

function show_image(src, width, height, alt) {
    var img = document.createElement("img");
    img.src = src;
    img.width = width;
    img.height = height;
    img.alt = alt;

    // This next line will just add it to the <body> tag

Then you could use it like this...

<button onclick=
                 'Google Logo');">Add Google Logo</button> 

See a working example on jsFiddle:

How to set dialog to show in full screen?

The easiest way I found

Dialog dialog=new Dialog(this,;

iCheck check if checkbox is checked

To know if the iCheck box is checked

var isChecked = $("#myicheckboxid").prop("checked"); Repeater get current index, pointer, or counter

Add a label control to your Repeater's ItemTemplate. Handle OnItemCreated event.


<asp:Repeater ID="rptr" runat="server" OnItemCreated="RepeaterItemCreated">
        <div id="width:50%;height:30px;background:#0f0a0f;">
            <asp:Label ID="lblSr" runat="server" 
               style="width:30%;float:left;text-align:right;text-indent:-2px;" />
               style="width:65%;float:right;text-align:left;text-indent:-2px;" >
            <%# Eval("Item") %>

Code Behind:

    protected void RepeaterItemCreated(object sender, RepeaterItemEventArgs e)
        Label l = e.Item.FindControl("lblSr") as Label;
        if (l != null)
            l.Text = e.Item.ItemIndex + 1+"";

How to add one column into existing SQL Table

The syntax you need is

ALTER TABLE Products ADD LastUpdate  varchar(200) NULL

This is a metadata only operation

Is Android using NTP to sync time?

Not an exact answer to your question, but a bit of information: if your device does use NTP for time (eg. if it is a tablet with no 3G or GPS capabilities), the server can be configured in /system/etc/gps.conf - obviously this file can only be edited with root access, but is viewable on non-rooted devices.

Is there a way to perform "if" in python's lambda

what you need exactly is

def fun():
    raise Exception()
f = lambda x:print x if x==2 else fun()

now call the function the way you need


Value cannot be null. Parameter name: source

I know this is a long way from the year 2013 of the question, but this symptom can show up if you don't have lazy loading enabled when migrating an ASP.NET 5 app to ASP.NET Core, and then trying to upgrade to Entity Framework Core 2.x (from EF 6). Entity Framework Core has moved lazy loading proxy support to a separate package, so you have to install it.

This is particularly true if all you have loaded is an Entity Framework Core Sql Server package (which turns on Entity Framework just fine).

After installing the proxies package, then, as the docs say, invoke .UseLazyLoadingProxies() on the DbContext options builder (in your Startup DI setup section, or wherever you configure your DbContext), and the navigational property that was throwing the above exception will stop throwing it, and will work as Entity Framework 6 used to.

How do I get the value of a registry key and ONLY the value using powershell

NONE of these answers work for situations where the value name contains spaces, dots, or other characters that are reserved in PowerShell. In that case you have to wrap the name in double quotes as per - for example:

PS> Get-ItemProperty Registry::HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\VisualStudio\SxS\VS7

14.0         : C:\Program Files (x86)\Microsoft Visual Studio 14.0\
12.0         : C:\Program Files (x86)\Microsoft Visual Studio 12.0\
11.0         : C:\Program Files (x86)\Microsoft Visual Studio 11.0\
15.0         : C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\
PSPath       : Microsoft.PowerShell.Core\Registry::HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\VisualStudio\SxS\V
PSParentPath : Microsoft.PowerShell.Core\Registry::HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\VisualStudio\SxS
PSChildName  : VS7
PSProvider   : Microsoft.PowerShell.Core\Registry

If you want to access any of the 14.0, 12.0, 11.0, 15.0 values, the solution from the accepted answer will not work - you will get no output:

PS> (Get-ItemProperty Registry::HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\VisualStudio\SxS\VS7 -Name 15.0).15.0

What does work is quoting the value name, which you should probably be doing anyway for safety:

PS> (Get-ItemProperty "Registry::HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\VisualStudio\SxS\VS7" -Name "15.0")."15.0"
C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\

Thus, the accepted answer should be modified as such:

PS> $key = "Registry::HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\VisualStudio\SxS\VS7"
PS> $value = "15.0"
PS> (Get-ItemProperty -Path $key -Name $value).$value
C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\

This works in PowerShell 2.0 through 5.0 (although you should probably be using Get-ItemPropertyValue in v5).

How to add a boolean datatype column to an existing table in sql?

Below query worked for me with default value false;

ALTER TABLE cti_contract_account ADD ready_to_audit BIT DEFAULT 0 NOT NULL;

gnuplot plotting multiple line graphs

In addition to the answers above the command below will also work. I post it because it makes more sense to me. In each case it is 'using x-value-column: y-value-column'

plot 'ls.dat' using 1:2, 'ls.dat' using 1:3, 'ls.dat' using 1:4 

note that the command above assumes that you have a file named ls.dat with tab separated columns of data where column 1 is x, column 2 is y1, column 3 is y2 and column 4 is y3.

Grunt watch error - Waiting...Fatal error: watch ENOSPC

In my case it was related to vs-code running on my Linux machine. I ignored a warning which popped up about file watcher bla bla. The solution is on the vs-code docs page for linux

The solution is almost same (if not same) as the accepted answers, just has more explanation for anyone who gets here after running into the issues from vs-code.

Disable html5 video autoplay

remove the autoplay in video tag. use code like this

<video class="embed-responsive-item"  controls>_x000D_
   <source src="">_x000D_
   Your browser does not support the video tag._x000D_

it is 100% working

How can I combine flexbox and vertical scroll in a full-height app?

Thanks to that gave me the answer.

The solution is setting a height to the vertical scrollable element. For example:

#container article {
    flex: 1 1 auto;
    overflow-y: auto;
    height: 0px;

The element will have height because flexbox recalculates it unless you want a min-height so you can use height: 100px; that it is exactly the same as: min-height: 100px;

#container article {
    flex: 1 1 auto;
    overflow-y: auto;
    height: 100px; /* == min-height: 100px*/

So the best solution if you want a min-height in the vertical scroll:

#container article {
    flex: 1 1 auto;
    overflow-y: auto;
    min-height: 100px;

If you just want full vertical scroll in case there is no enough space to see the article:

#container article {
    flex: 1 1 auto;
    overflow-y: auto;
    min-height: 0px;

The final code:

Can you have multiple $(document).ready(function(){ ... }); sections?

Yes it is possible to have multiple $(document).ready() calls. However, I don't think you can know in which way they will be executed. (source)

How to refer to relative paths of resources when working with a code repository

import os
cwd = os.getcwd()
path = os.path.join(cwd, "my_file")
f = open(path)

You also try to normalize your cwd using os.path.abspath(os.getcwd()). More info here.

Converting milliseconds to minutes and seconds with Javascript

Event though ,oment.js does not provide such functionality, if you come here and you are already using moment.js, try this:

function formatDuration(ms) {
  var duration = moment.duration(ms);
  return Math.floor(duration.asHours()) + moment.utc(duration.asMilliseconds()).format(":mm:ss");

You will get something like x:xx:xx.

In the case you may want to skip the hour, when the duration is only < 60minutes.

function formatDuration(ms) {
  var duration = moment.duration(ms);
  if (duration.asHours() > 1) {
    return Math.floor(duration.asHours()) + moment.utc(duration.asMilliseconds()).format(":mm:ss");
  } else {
    return moment.utc(duration.asMilliseconds()).format("mm:ss");

This workaround in moment was introduced in this Issue.

How to make inline plots in Jupyter Notebook larger?

The question is about matplotlib, but for the sake of any R users that end up here given the language-agnostic title:

If you're using an R kernel, just use:

options(repr.plot.width=4, repr.plot.height=3)