How to detect Esc Key Press in React and how to handle it

You'll want to listen for escape's keyCode (27) from the React SyntheticKeyBoardEvent onKeyDown:

const EscapeListen = React.createClass({
  handleKeyDown: function(e) {
    if (e.keyCode === 27) {
      console.log('You pressed the escape key!')
    }
  },

  render: function() {
    return (
      <input type='text'
             onKeyDown={this.handleKeyDown} />
    )
  }
})

Brad Colthurst's CodePen posted in the question's comments is helpful for finding key codes for other keys.

C# HttpWebRequest The underlying connection was closed: An unexpected error occurred on a send

Your project supports .Net Framework 4.0 and .Net Framework 4.5. If you have upgrade issues

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

instead of can use;

ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072;

Display unescaped HTML in Vue.js

You can use the directive v-html to show it. like this:

<td v-html="desc"></td>

Python iterating through object attributes

Iterate over an objects attributes in python:

class C:
    a = 5
    b = [1,2,3]
    def foobar():
        b = "hi"    

for attr, value in C.__dict__.iteritems():
    print "Attribute: " + str(attr or "")
    print "Value: " + str(value or "")

Prints:

python test.py
Attribute: a
Value: 5
Attribute: foobar
Value: <function foobar at 0x7fe74f8bfc08>
Attribute: __module__
Value: __main__
Attribute: b
Value: [1, 2, 3]
Attribute: __doc__
Value:

How to delete an app from iTunesConnect / App Store Connect

Edit December 2018: Apple seem to have finally added a button for removing the app in certain situations, including apps that never went on sale (thanks to @iwill for pointing that out), basically making the below answer irrelevant.

Edit: turns out the deleted apps still appear in Xcode -> Organizer -> Archives and there is no way to delete them from there even if there are no archives! So more looks like a fake delete of sorts.

Currently (Edit: as of July 2016) there is no way of deleting your app if it never went on sale.

However, all information except for SKU can be edited and thus reused for a new app, including the app name, Bundle ID, icon, etc etc. Because SKU can be anything (some people say they use numbers 1, 2, 3 for example) then it shouldn't be a big deal to use something unrelated for your new app.

(Honestly though I'm hoping Apple will fix this soon. I almost hear some Apple devs finding excuses for not implementing it (you know, it will break the database and will kill innocent pandas) and some managers telling the devs to just frigging do it regardless.)

Position Absolute + Scrolling

So gaiour is right, but if you're looking for a full height item that doesn't scroll with the content, but is actually the height of the container, here's the fix. Have a parent with a height that causes overflow, a content container that has a 100% height and overflow: scroll, and a sibling then can be positioned according to the parent size, not the scroll element size. Here is the fiddle: http://jsfiddle.net/M5cTN/196/

and the relevant code:

html:

<div class="container">
  <div class="inner">
    Lorem ipsum ...
  </div>
  <div class="full-height"></div>
</div>

css:

.container{
  height: 256px;
  position: relative;
}
.inner{
  height: 100%;
  overflow: scroll;
}
.full-height{
  position: absolute;
  left: 0;
  width: 20%;
  top: 0;
  height: 100%;
}

Javascript to export html table to Excel

For UTF 8 Conversion and Currency Symbol Export Use this:

var tableToExcel = (function() {
  var uri = 'data:application/vnd.ms-excel;base64,'
    , template = '<html xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns="http://www.w3.org/TR/REC-html40"><head><!--[if gte mso 9]><?xml version="1.0" encoding="UTF-8" standalone="yes"?><x:ExcelWorkbook><x:ExcelWorksheets><x:ExcelWorksheet><x:Name>{worksheet}</x:Name><x:WorksheetOptions><x:DisplayGridlines/></x:WorksheetOptions></x:ExcelWorksheet></x:ExcelWorksheets></x:ExcelWorkbook></xml><![endif]--></head><body><table>{table}</table></body></html>'
    , base64 = function(s) { return window.btoa(unescape(encodeURIComponent(s))) }
    , format = function(s, c) { return s.replace(/{(\w+)}/g, function(m, p) { return c[p]; }) }
  return function(table, name) {
      if (!table.nodeType) table = document.getElementById(table)
      var ctx = { worksheet: name || 'Worksheet', table: table.innerHTML }
    window.location.href = uri + base64(format(template, ctx))
  }
})()

RabbitMQ / AMQP: single queue, multiple consumers for same message?

RabbitMQ / AMQP: single queue, multiple consumers for same message and page refresh.

rabbit.on('ready', function () {    });
    sockjs_chat.on('connection', function (conn) {

        conn.on('data', function (message) {
            try {
                var obj = JSON.parse(message.replace(/\r/g, '').replace(/\n/g, ''));

                if (obj.header == "register") {

                    // Connect to RabbitMQ
                    try {
                        conn.exchange = rabbit.exchange(exchange, { type: 'topic',
                            autoDelete: false,
                            durable: false,
                            exclusive: false,
                            confirm: true
                        });

                        conn.q = rabbit.queue('my-queue-'+obj.agentID, {
                            durable: false,
                            autoDelete: false,
                            exclusive: false
                        }, function () {
                            conn.channel = 'my-queue-'+obj.agentID;
                            conn.q.bind(conn.exchange, conn.channel);

                            conn.q.subscribe(function (message) {
                                console.log("[MSG] ---> " + JSON.stringify(message));
                                conn.write(JSON.stringify(message) + "\n");
                            }).addCallback(function(ok) {
                                ctag[conn.channel] = ok.consumerTag; });
                        });
                    } catch (err) {
                        console.log("Could not create connection to RabbitMQ. \nStack trace -->" + err.stack);
                    }

                } else if (obj.header == "typing") {

                    var reply = {
                        type: 'chatMsg',
                        msg: utils.escp(obj.msga),
                        visitorNick: obj.channel,
                        customField1: '',
                        time: utils.getDateTime(),
                        channel: obj.channel
                    };

                    conn.exchange.publish('my-queue-'+obj.agentID, reply);
                }

            } catch (err) {
                console.log("ERROR ----> " + err.stack);
            }
        });

        // When the visitor closes or reloads a page we need to unbind from RabbitMQ?
        conn.on('close', function () {
            try {

                // Close the socket
                conn.close();

                // Close RabbitMQ           
               conn.q.unsubscribe(ctag[conn.channel]);

            } catch (er) {
                console.log(":::::::: EXCEPTION SOCKJS (ON-CLOSE) ::::::::>>>>>>> " + er.stack);
            }
        });
    });

Python string to unicode

Decode it with the unicode-escape codec:

>>> a="Hello\u2026"
>>> a.decode('unicode-escape')
u'Hello\u2026'
>>> print _
Hello…

This is because for a non-unicode string the \u2026 is not recognised but is instead treated as a literal series of characters (to put it more clearly, 'Hello\\u2026'). You need to decode the escapes, and the unicode-escape codec can do that for you.

Note that you can get unicode to recognise it in the same way by specifying the codec argument:

>>> unicode(a, 'unicode-escape')
u'Hello\u2026'

But the a.decode() way is nicer.

iTunes Connect: How to choose a good SKU?

You are able to choose one that you like, but it has to be unique.

Every time I have to enter the SKU I use the App identifier (e.g. de.mycompany.myappname) because this is already unique.

Escaping backslash in string - javascript

I think this is closer to the answer you're looking for:

<input type="file">

$file = $(file);
var filename = fileElement[0].files[0].name;

How do I decode a string with escaped unicode?

Edit (2017-10-12):

@MechaLynx and @Kevin-Weber note that unescape() is deprecated from non-browser environments and does not exist in TypeScript. decodeURIComponent is a drop-in replacement. For broader compatibility, use the below instead:

decodeURIComponent(JSON.parse('"http\\u00253A\\u00252F\\u00252Fexample.com"'));
> 'http://example.com'

Original answer:

unescape(JSON.parse('"http\\u00253A\\u00252F\\u00252Fexample.com"'));
> 'http://example.com'

You can offload all the work to JSON.parse

fileReader.readAsBinaryString to upload files

The best way in browsers that support it, is to send the file as a Blob, or using FormData if you want a multipart form. You do not need a FileReader for that. This is both simpler and more efficient than trying to read the data.

If you specifically want to send it as multipart/form-data, you can use a FormData object:

var xmlHttpRequest = new XMLHttpRequest();
xmlHttpRequest.open("POST", '/pushfile', true);
var formData = new FormData();
// This should automatically set the file name and type.
formData.append("file", file);
// Sending FormData automatically sets the Content-Type header to multipart/form-data
xmlHttpRequest.send(formData);

You can also send the data directly, instead of using multipart/form-data. See the documentation. Of course, this will need a server-side change as well.

// file is an instance of File, e.g. from a file input.
var xmlHttpRequest = new XMLHttpRequest();
xmlHttpRequest.open("POST", '/pushfile', true);

xmlHttpRequest.setRequestHeader("Content-Type", file.type);

// Send the binary data.
// Since a File is a Blob, we can send it directly.
xmlHttpRequest.send(file);

For browser support, see: http://caniuse.com/#feat=xhr2 (most browsers, including IE 10+).

Can I change the scroll speed using css or jQuery?

No. Scroll speed is determined by the browser (and usually directly by the settings on the computer/device). CSS and Javascript don't (or shouldn't) have any way to affect system settings.

That being said, there are likely a number of ways you could try to fake a different scroll speed by moving your own content around in such a way as to counteract scrolling. However, I think doing so is a HORRIBLE idea in terms of usability, accessibility, and respect for your users, but I would start by finding events that your target browsers fire that indicate scrolling.

Once you can capture the scroll event (assuming you can), then you would be able to adjust your content dynamically so that the portion you want is visible.

Another approach would be to deal with this in Flash, which does give you at least some level of control over scrolling events.

PHP decoding and encoding json with unicode characters

$json = array('tag' => 'Odómetro'); // Original array
$json = json_encode($json); // {"Tag":"Od\u00f3metro"}
$json = json_decode($json); // Od\u00f3metro becomes  OdÃ³metro
echo $json->{'tag'}; // OdÃ³metro
echo utf8_decode($json->{'tag'}); // Odómetro

You were close, just use utf8_decode.

How to update and delete a cookie?

http://www.quirksmode.org/js/cookies.html

update would just be resetting it using createCookie

function createCookie(name,value,days) {
    if (days) {
        var date = new Date();
        date.setTime(date.getTime() + (days * 24 * 60 * 60 *1000));
        var expires = "; expires=" + date.toGMTString();
    } else {
        var expires = "";
    }
    document.cookie = name + "=" + value + expires + "; path=/";
}

function readCookie(name) {
    var nameEQ = name + "=";
    var ca = document.cookie.split(';');
    for(var i=0;i < ca.length;i++) {
        var c = ca[i];
        while (c.charAt(0)==' ') {
            c = c.substring(1,c.length);
        }
        if (c.indexOf(nameEQ) == 0) {
            return c.substring(nameEQ.length,c.length);
        }
    }
    return null;
}

function eraseCookie(name) {
    createCookie(name,"",-1);
}

String length in bytes in JavaScript

In NodeJS, Buffer.byteLength is a method specifically for this purpose:

let strLengthInBytes = Buffer.byteLength(str); // str is UTF-8

Note that by default the method assumes the string is in UTF-8 encoding. If a different encoding is required, pass it as the second argument.

Ruby on Rails: how to render a string as HTML?

Or you can try CGI.unescapeHTML method.

CGI.unescapeHTML "&lt;p&gt;This is a Paragraph.&lt;/p&gt;"
=> "<p>This is a Paragraph.</p>"

Writing/outputting HTML strings unescaped

Supposing your content is inside a string named mystring...

You can use:

@Html.Raw(mystring)

Alternatively you can convert your string to HtmlString or any other type that implements IHtmlString in model or directly inline and use regular @:

@{ var myHtmlString = new HtmlString(mystring);}
@myHtmlString

raw vs. html_safe vs. h to unescape html

The best safe way is: <%= sanitize @x %>

It will avoid XSS!

How to unescape a Java string literal in Java?

The Problem

The org.apache.commons.lang.StringEscapeUtils.unescapeJava() given here as another answer is really very little help at all.

It forgets about \0 for null.
It doesn’t handle octal at all.
It can’t handle the sorts of escapes admitted by the java.util.regex.Pattern.compile() and everything that uses it, including \a, \e, and especially \cX.
It has no support for logical Unicode code points by number, only for UTF-16.
This looks like UCS-2 code, not UTF-16 code: they use the depreciated charAt interface instead of the codePoint interface, thus promulgating the delusion that a Java char is guaranteed to hold a Unicode character. It’s not. They only get away with this because no UTF-16 surrogate will wind up looking for anything they’re looking for.

The Solution

I wrote a string unescaper which solves the OP’s question without all the irritations of the Apache code.

/*
 *
 * unescape_perl_string()
 *
 *      Tom Christiansen <[email protected]>
 *      Sun Nov 28 12:55:24 MST 2010
 *
 * It's completely ridiculous that there's no standard
 * unescape_java_string function.  Since I have to do the
 * damn thing myself, I might as well make it halfway useful
 * by supporting things Java was too stupid to consider in
 * strings:
 * 
 *   => "?" items  are additions to Java string escapes
 *                 but normal in Java regexes
 *
 *   => "!" items  are also additions to Java regex escapes
 *   
 * Standard singletons: ?\a ?\e \f \n \r \t
 * 
 *      NB: \b is unsupported as backspace so it can pass-through
 *          to the regex translator untouched; I refuse to make anyone
 *          doublebackslash it as doublebackslashing is a Java idiocy
 *          I desperately wish would die out.  There are plenty of
 *          other ways to write it:
 *
 *              \cH, \12, \012, \x08 \x{8}, \u0008, \U00000008
 *
 * Octal escapes: \0 \0N \0NN \N \NN \NNN
 *    Can range up to !\777 not \377
 *    
 *      TODO: add !\o{NNNNN}
 *          last Unicode is 4177777
 *          maxint is 37777777777
 *
 * Control chars: ?\cX
 *      Means: ord(X) ^ ord('@')
 *
 * Old hex escapes: \xXX
 *      unbraced must be 2 xdigits
 *
 * Perl hex escapes: !\x{XXX} braced may be 1-8 xdigits
 *       NB: proper Unicode never needs more than 6, as highest
 *           valid codepoint is 0x10FFFF, not maxint 0xFFFFFFFF
 *
 * Lame Java escape: \[IDIOT JAVA PREPROCESSOR]uXXXX must be
 *                   exactly 4 xdigits;
 *
 *       I can't write XXXX in this comment where it belongs
 *       because the damned Java Preprocessor can't mind its
 *       own business.  Idiots!
 *
 * Lame Python escape: !\UXXXXXXXX must be exactly 8 xdigits
 * 
 * TODO: Perl translation escapes: \Q \U \L \E \[IDIOT JAVA PREPROCESSOR]u \l
 *       These are not so important to cover if you're passing the
 *       result to Pattern.compile(), since it handles them for you
 *       further downstream.  Hm, what about \[IDIOT JAVA PREPROCESSOR]u?
 *
 */

public final static
String unescape_perl_string(String oldstr) {

    /*
     * In contrast to fixing Java's broken regex charclasses,
     * this one need be no bigger, as unescaping shrinks the string
     * here, where in the other one, it grows it.
     */

    StringBuffer newstr = new StringBuffer(oldstr.length());

    boolean saw_backslash = false;

    for (int i = 0; i < oldstr.length(); i++) {
        int cp = oldstr.codePointAt(i);
        if (oldstr.codePointAt(i) > Character.MAX_VALUE) {
            i++; /****WE HATES UTF-16! WE HATES IT FOREVERSES!!!****/
        }

        if (!saw_backslash) {
            if (cp == '\\') {
                saw_backslash = true;
            } else {
                newstr.append(Character.toChars(cp));
            }
            continue; /* switch */
        }

        if (cp == '\\') {
            saw_backslash = false;
            newstr.append('\\');
            newstr.append('\\');
            continue; /* switch */
        }

        switch (cp) {

            case 'r':  newstr.append('\r');
                       break; /* switch */

            case 'n':  newstr.append('\n');
                       break; /* switch */

            case 'f':  newstr.append('\f');
                       break; /* switch */

            /* PASS a \b THROUGH!! */
            case 'b':  newstr.append("\\b");
                       break; /* switch */

            case 't':  newstr.append('\t');
                       break; /* switch */

            case 'a':  newstr.append('\007');
                       break; /* switch */

            case 'e':  newstr.append('\033');
                       break; /* switch */

            /*
             * A "control" character is what you get when you xor its
             * codepoint with '@'==64.  This only makes sense for ASCII,
             * and may not yield a "control" character after all.
             *
             * Strange but true: "\c{" is ";", "\c}" is "=", etc.
             */
            case 'c':   {
                if (++i == oldstr.length()) { die("trailing \\c"); }
                cp = oldstr.codePointAt(i);
                /*
                 * don't need to grok surrogates, as next line blows them up
                 */
                if (cp > 0x7f) { die("expected ASCII after \\c"); }
                newstr.append(Character.toChars(cp ^ 64));
                break; /* switch */
            }

            case '8':
            case '9': die("illegal octal digit");
                      /* NOTREACHED */

    /*
     * may be 0 to 2 octal digits following this one
     * so back up one for fallthrough to next case;
     * unread this digit and fall through to next case.
     */
            case '1':
            case '2':
            case '3':
            case '4':
            case '5':
            case '6':
            case '7': --i;
                      /* FALLTHROUGH */

            /*
             * Can have 0, 1, or 2 octal digits following a 0
             * this permits larger values than octal 377, up to
             * octal 777.
             */
            case '0': {
                if (i+1 == oldstr.length()) {
                    /* found \0 at end of string */
                    newstr.append(Character.toChars(0));
                    break; /* switch */
                }
                i++;
                int digits = 0;
                int j;
                for (j = 0; j <= 2; j++) {
                    if (i+j == oldstr.length()) {
                        break; /* for */
                    }
                    /* safe because will unread surrogate */
                    int ch = oldstr.charAt(i+j);
                    if (ch < '0' || ch > '7') {
                        break; /* for */
                    }
                    digits++;
                }
                if (digits == 0) {
                    --i;
                    newstr.append('\0');
                    break; /* switch */
                }
                int value = 0;
                try {
                    value = Integer.parseInt(
                                oldstr.substring(i, i+digits), 8);
                } catch (NumberFormatException nfe) {
                    die("invalid octal value for \\0 escape");
                }
                newstr.append(Character.toChars(value));
                i += digits-1;
                break; /* switch */
            } /* end case '0' */

            case 'x':  {
                if (i+2 > oldstr.length()) {
                    die("string too short for \\x escape");
                }
                i++;
                boolean saw_brace = false;
                if (oldstr.charAt(i) == '{') {
                        /* ^^^^^^ ok to ignore surrogates here */
                    i++;
                    saw_brace = true;
                }
                int j;
                for (j = 0; j < 8; j++) {

                    if (!saw_brace && j == 2) {
                        break;  /* for */
                    }

                    /*
                     * ASCII test also catches surrogates
                     */
                    int ch = oldstr.charAt(i+j);
                    if (ch > 127) {
                        die("illegal non-ASCII hex digit in \\x escape");
                    }

                    if (saw_brace && ch == '}') { break; /* for */ }

                    if (! ( (ch >= '0' && ch <= '9')
                                ||
                            (ch >= 'a' && ch <= 'f')
                                ||
                            (ch >= 'A' && ch <= 'F')
                          )
                       )
                    {
                        die(String.format(
                            "illegal hex digit #%d '%c' in \\x", ch, ch));
                    }

                }
                if (j == 0) { die("empty braces in \\x{} escape"); }
                int value = 0;
                try {
                    value = Integer.parseInt(oldstr.substring(i, i+j), 16);
                } catch (NumberFormatException nfe) {
                    die("invalid hex value for \\x escape");
                }
                newstr.append(Character.toChars(value));
                if (saw_brace) { j++; }
                i += j-1;
                break; /* switch */
            }

            case 'u': {
                if (i+4 > oldstr.length()) {
                    die("string too short for \\u escape");
                }
                i++;
                int j;
                for (j = 0; j < 4; j++) {
                    /* this also handles the surrogate issue */
                    if (oldstr.charAt(i+j) > 127) {
                        die("illegal non-ASCII hex digit in \\u escape");
                    }
                }
                int value = 0;
                try {
                    value = Integer.parseInt( oldstr.substring(i, i+j), 16);
                } catch (NumberFormatException nfe) {
                    die("invalid hex value for \\u escape");
                }
                newstr.append(Character.toChars(value));
                i += j-1;
                break; /* switch */
            }

            case 'U': {
                if (i+8 > oldstr.length()) {
                    die("string too short for \\U escape");
                }
                i++;
                int j;
                for (j = 0; j < 8; j++) {
                    /* this also handles the surrogate issue */
                    if (oldstr.charAt(i+j) > 127) {
                        die("illegal non-ASCII hex digit in \\U escape");
                    }
                }
                int value = 0;
                try {
                    value = Integer.parseInt(oldstr.substring(i, i+j), 16);
                } catch (NumberFormatException nfe) {
                    die("invalid hex value for \\U escape");
                }
                newstr.append(Character.toChars(value));
                i += j-1;
                break; /* switch */
            }

            default:   newstr.append('\\');
                       newstr.append(Character.toChars(cp));
           /*
            * say(String.format(
            *       "DEFAULT unrecognized escape %c passed through",
            *       cp));
            */
                       break; /* switch */

        }
        saw_backslash = false;
    }

    /* weird to leave one at the end */
    if (saw_backslash) {
        newstr.append('\\');
    }

    return newstr.toString();
}

/*
 * Return a string "U+XX.XXX.XXXX" etc, where each XX set is the
 * xdigits of the logical Unicode code point. No bloody brain-damaged
 * UTF-16 surrogate crap, just true logical characters.
 */
 public final static
 String uniplus(String s) {
     if (s.length() == 0) {
         return "";
     }
     /* This is just the minimum; sb will grow as needed. */
     StringBuffer sb = new StringBuffer(2 + 3 * s.length());
     sb.append("U+");
     for (int i = 0; i < s.length(); i++) {
         sb.append(String.format("%X", s.codePointAt(i)));
         if (s.codePointAt(i) > Character.MAX_VALUE) {
             i++; /****WE HATES UTF-16! WE HATES IT FOREVERSES!!!****/
         }
         if (i+1 < s.length()) {
             sb.append(".");
         }
     }
     return sb.toString();
 }

private static final
void die(String foa) {
    throw new IllegalArgumentException(foa);
}

private static final
void say(String what) {
    System.out.println(what);
}

If it helps others, you’re welcome to it — no strings attached. If you improve it, I’d love for you to mail me your enhancements, but you certainly don’t have to.

Get the last item in an array

This question has been around a long time, so I'm surprised that no one mentioned just putting the last element back on after a pop().

arr.pop() is exactly as efficient as arr[arr.length-1], and both are the same speed as arr.push().

Therefore, you can get away with:

---EDITED [check that thePop isn't undefined before pushing]---

let thePop = arr.pop()
thePop && arr.push(thePop)

---END EDIT---

Which can be reduced to this (same speed [EDIT: but unsafe!]):

arr.push(thePop = arr.pop())    //Unsafe if arr empty

This is twice as slow as arr[arr.length-1], but you don't have to stuff around with an index. That's worth gold on any day.

Of the solutions I've tried, and in multiples of the Execution Time Unit (ETU) of arr[arr.length-1]:

[Method]..............[ETUs 5 elems]...[ETU 1 million elems]

arr[arr.length - 1]      ------> 1              -----> 1

let myPop = arr.pop()
arr.push(myPop)          ------> 2              -----> 2

arr.slice(-1).pop()      ------> 36             -----> 924  

arr.slice(-1)[0]         ------> 36             -----> 924  

[...arr].pop()           ------> 120            -----> ~21,000,000 :)

The last three options, ESPECIALLY [...arr].pop(), get VERY much worse as the size of the array increases. On a machine without the memory limitations of my machine, [...arr].pop() probably maintains something like it's 120:1 ratio. Still, no one likes a resource hog.

Xcode "Build and Archive" from command line

For Xcode 7, you have a much simpler solution. The only extra work is that you have to create a configuration plist file for exporting archive.

(Compared to Xcode 6, in the results of xcrun xcodebuild -help, -exportFormat and -exportProvisioningProfile options are not mentioned any more; the former is deleted, and the latter is superseded by -exportOptionsPlist.)

Step 1, change directory to the folder including .xcodeproject or .xcworkspace file.

cd MyProjectFolder

Step 2, use Xcode or /usr/libexec/PlistBuddy exportOptions.plist to create export options plist file. By the way, xcrun xcodebuild -help will tell you what keys you have to insert to the plist file.

Step 3, create .xcarchive file (folder, in fact) as follows(build/ directory will be automatically created by Xcode right now),

xcrun xcodebuild -scheme MyApp -configuration Release archive -archivePath build/MyApp.xcarchive

Step 4, export as .ipa file like this, which differs from Xcode6

xcrun xcodebuild -exportArchive -exportPath build/ -archivePath build/MyApp.xcarchive/ -exportOptionsPlist exportOptions.plist

Now, you get an ipa file in build/ directory. Just send it to apple App Store.

By the way, the ipa file created by Xcode 7 is much larger than by Xcode 6.

Get list of all input objects using JavaScript, without accessing a form object

var inputs = document.getElementsByTagName('input');
for (var i = 0; i < inputs.length; ++i) {
  // ...
}

Unescape HTML entities in Javascript?

In case you're looking for it, like me - meanwhile there's a nice and safe JQuery method.

https://api.jquery.com/jquery.parsehtml/

You can f.ex. type this in your console:

var x = "test &amp;";
> undefined
$.parseHTML(x)[0].textContent
> "test &"

So $.parseHTML(x) returns an array, and if you have HTML markup within your text, the array.length will be greater than 1.

Get webpage contents with Python?

Also you can use faster_than_requests package. That's very fast and simple:

import faster_than_requests as r
content = r.get2str("http://test.com/")

Look at this comparison:

Parse JSON in C#

Thank you all for your help. This is my final version, and it works thanks to your combined help ! I am only showing the changes i made, all the rest is taken from Joe Chung's work

public class GoogleSearchResults
    {
        [DataMember]
        public ResponseData responseData { get; set; }

        [DataMember]
        public string responseDetails { get; set; }

        [DataMember]
        public int responseStatus { get; set; }
    }

and

 [DataContract]
    public class ResponseData
    {
        [DataMember]
        public List<Results> results { get; set; }
    }

How to unescape HTML character entities in Java?

I tried Apache Commons StringEscapeUtils.unescapeHtml3() in my project, but wasn't satisfied with its performance. Turns out, it does a lot of unnecessary operations. For one, it allocates a StringWriter for every call, even if there's nothing to unescape in the string. I've rewritten that code differently, now it works much faster. Whoever finds this in google is welcome to use it.

Following code unescapes all HTML 3 symbols and numeric escapes (equivalent to Apache unescapeHtml3). You can just add more entries to the map if you need HTML 4.

package com.example;

import java.io.StringWriter;
import java.util.HashMap;

public class StringUtils {

    public static final String unescapeHtml3(final String input) {
        StringWriter writer = null;
        int len = input.length();
        int i = 1;
        int st = 0;
        while (true) {
            // look for '&'
            while (i < len && input.charAt(i-1) != '&')
                i++;
            if (i >= len)
                break;

            // found '&', look for ';'
            int j = i;
            while (j < len && j < i + MAX_ESCAPE + 1 && input.charAt(j) != ';')
                j++;
            if (j == len || j < i + MIN_ESCAPE || j == i + MAX_ESCAPE + 1) {
                i++;
                continue;
            }

            // found escape 
            if (input.charAt(i) == '#') {
                // numeric escape
                int k = i + 1;
                int radix = 10;

                final char firstChar = input.charAt(k);
                if (firstChar == 'x' || firstChar == 'X') {
                    k++;
                    radix = 16;
                }

                try {
                    int entityValue = Integer.parseInt(input.substring(k, j), radix);

                    if (writer == null) 
                        writer = new StringWriter(input.length());
                    writer.append(input.substring(st, i - 1));

                    if (entityValue > 0xFFFF) {
                        final char[] chrs = Character.toChars(entityValue);
                        writer.write(chrs[0]);
                        writer.write(chrs[1]);
                    } else {
                        writer.write(entityValue);
                    }

                } catch (NumberFormatException ex) { 
                    i++;
                    continue;
                }
            }
            else {
                // named escape
                CharSequence value = lookupMap.get(input.substring(i, j));
                if (value == null) {
                    i++;
                    continue;
                }

                if (writer == null) 
                    writer = new StringWriter(input.length());
                writer.append(input.substring(st, i - 1));

                writer.append(value);
            }

            // skip escape
            st = j + 1;
            i = st;
        }

        if (writer != null) {
            writer.append(input.substring(st, len));
            return writer.toString();
        }
        return input;
    }

    private static final String[][] ESCAPES = {
        {"\"",     "quot"}, // " - double-quote
        {"&",      "amp"}, // & - ampersand
        {"<",      "lt"}, // < - less-than
        {">",      "gt"}, // > - greater-than

        // Mapping to escape ISO-8859-1 characters to their named HTML 3.x equivalents.
        {"\u00A0", "nbsp"}, // non-breaking space
        {"\u00A1", "iexcl"}, // inverted exclamation mark
        {"\u00A2", "cent"}, // cent sign
        {"\u00A3", "pound"}, // pound sign
        {"\u00A4", "curren"}, // currency sign
        {"\u00A5", "yen"}, // yen sign = yuan sign
        {"\u00A6", "brvbar"}, // broken bar = broken vertical bar
        {"\u00A7", "sect"}, // section sign
        {"\u00A8", "uml"}, // diaeresis = spacing diaeresis
        {"\u00A9", "copy"}, // © - copyright sign
        {"\u00AA", "ordf"}, // feminine ordinal indicator
        {"\u00AB", "laquo"}, // left-pointing double angle quotation mark = left pointing guillemet
        {"\u00AC", "not"}, // not sign
        {"\u00AD", "shy"}, // soft hyphen = discretionary hyphen
        {"\u00AE", "reg"}, // ® - registered trademark sign
        {"\u00AF", "macr"}, // macron = spacing macron = overline = APL overbar
        {"\u00B0", "deg"}, // degree sign
        {"\u00B1", "plusmn"}, // plus-minus sign = plus-or-minus sign
        {"\u00B2", "sup2"}, // superscript two = superscript digit two = squared
        {"\u00B3", "sup3"}, // superscript three = superscript digit three = cubed
        {"\u00B4", "acute"}, // acute accent = spacing acute
        {"\u00B5", "micro"}, // micro sign
        {"\u00B6", "para"}, // pilcrow sign = paragraph sign
        {"\u00B7", "middot"}, // middle dot = Georgian comma = Greek middle dot
        {"\u00B8", "cedil"}, // cedilla = spacing cedilla
        {"\u00B9", "sup1"}, // superscript one = superscript digit one
        {"\u00BA", "ordm"}, // masculine ordinal indicator
        {"\u00BB", "raquo"}, // right-pointing double angle quotation mark = right pointing guillemet
        {"\u00BC", "frac14"}, // vulgar fraction one quarter = fraction one quarter
        {"\u00BD", "frac12"}, // vulgar fraction one half = fraction one half
        {"\u00BE", "frac34"}, // vulgar fraction three quarters = fraction three quarters
        {"\u00BF", "iquest"}, // inverted question mark = turned question mark
        {"\u00C0", "Agrave"}, // ? - uppercase A, grave accent
        {"\u00C1", "Aacute"}, // ? - uppercase A, acute accent
        {"\u00C2", "Acirc"}, // ? - uppercase A, circumflex accent
        {"\u00C3", "Atilde"}, // ? - uppercase A, tilde
        {"\u00C4", "Auml"}, // ? - uppercase A, umlaut
        {"\u00C5", "Aring"}, // ? - uppercase A, ring
        {"\u00C6", "AElig"}, // ? - uppercase AE
        {"\u00C7", "Ccedil"}, // ? - uppercase C, cedilla
        {"\u00C8", "Egrave"}, // ? - uppercase E, grave accent
        {"\u00C9", "Eacute"}, // ? - uppercase E, acute accent
        {"\u00CA", "Ecirc"}, // ? - uppercase E, circumflex accent
        {"\u00CB", "Euml"}, // ? - uppercase E, umlaut
        {"\u00CC", "Igrave"}, // ? - uppercase I, grave accent
        {"\u00CD", "Iacute"}, // ? - uppercase I, acute accent
        {"\u00CE", "Icirc"}, // ? - uppercase I, circumflex accent
        {"\u00CF", "Iuml"}, // ? - uppercase I, umlaut
        {"\u00D0", "ETH"}, // ? - uppercase Eth, Icelandic
        {"\u00D1", "Ntilde"}, // ? - uppercase N, tilde
        {"\u00D2", "Ograve"}, // ? - uppercase O, grave accent
        {"\u00D3", "Oacute"}, // ? - uppercase O, acute accent
        {"\u00D4", "Ocirc"}, // ? - uppercase O, circumflex accent
        {"\u00D5", "Otilde"}, // ? - uppercase O, tilde
        {"\u00D6", "Ouml"}, // ? - uppercase O, umlaut
        {"\u00D7", "times"}, // multiplication sign
        {"\u00D8", "Oslash"}, // ? - uppercase O, slash
        {"\u00D9", "Ugrave"}, // ? - uppercase U, grave accent
        {"\u00DA", "Uacute"}, // ? - uppercase U, acute accent
        {"\u00DB", "Ucirc"}, // ? - uppercase U, circumflex accent
        {"\u00DC", "Uuml"}, // ? - uppercase U, umlaut
        {"\u00DD", "Yacute"}, // ? - uppercase Y, acute accent
        {"\u00DE", "THORN"}, // ? - uppercase THORN, Icelandic
        {"\u00DF", "szlig"}, // ? - lowercase sharps, German
        {"\u00E0", "agrave"}, // ? - lowercase a, grave accent
        {"\u00E1", "aacute"}, // ? - lowercase a, acute accent
        {"\u00E2", "acirc"}, // ? - lowercase a, circumflex accent
        {"\u00E3", "atilde"}, // ? - lowercase a, tilde
        {"\u00E4", "auml"}, // ? - lowercase a, umlaut
        {"\u00E5", "aring"}, // ? - lowercase a, ring
        {"\u00E6", "aelig"}, // ? - lowercase ae
        {"\u00E7", "ccedil"}, // ? - lowercase c, cedilla
        {"\u00E8", "egrave"}, // ? - lowercase e, grave accent
        {"\u00E9", "eacute"}, // ? - lowercase e, acute accent
        {"\u00EA", "ecirc"}, // ? - lowercase e, circumflex accent
        {"\u00EB", "euml"}, // ? - lowercase e, umlaut
        {"\u00EC", "igrave"}, // ? - lowercase i, grave accent
        {"\u00ED", "iacute"}, // ? - lowercase i, acute accent
        {"\u00EE", "icirc"}, // ? - lowercase i, circumflex accent
        {"\u00EF", "iuml"}, // ? - lowercase i, umlaut
        {"\u00F0", "eth"}, // ? - lowercase eth, Icelandic
        {"\u00F1", "ntilde"}, // ? - lowercase n, tilde
        {"\u00F2", "ograve"}, // ? - lowercase o, grave accent
        {"\u00F3", "oacute"}, // ? - lowercase o, acute accent
        {"\u00F4", "ocirc"}, // ? - lowercase o, circumflex accent
        {"\u00F5", "otilde"}, // ? - lowercase o, tilde
        {"\u00F6", "ouml"}, // ? - lowercase o, umlaut
        {"\u00F7", "divide"}, // division sign
        {"\u00F8", "oslash"}, // ? - lowercase o, slash
        {"\u00F9", "ugrave"}, // ? - lowercase u, grave accent
        {"\u00FA", "uacute"}, // ? - lowercase u, acute accent
        {"\u00FB", "ucirc"}, // ? - lowercase u, circumflex accent
        {"\u00FC", "uuml"}, // ? - lowercase u, umlaut
        {"\u00FD", "yacute"}, // ? - lowercase y, acute accent
        {"\u00FE", "thorn"}, // ? - lowercase thorn, Icelandic
        {"\u00FF", "yuml"}, // ? - lowercase y, umlaut
    };

    private static final int MIN_ESCAPE = 2;
    private static final int MAX_ESCAPE = 6;

    private static final HashMap<String, CharSequence> lookupMap;
    static {
        lookupMap = new HashMap<String, CharSequence>();
        for (final CharSequence[] seq : ESCAPES) 
            lookupMap.put(seq[1].toString(), seq[0]);
    }

}

How to jump to a particular line in a huge text file?

If you know in advance the position in the file (rather the line number), you can use file.seek() to go to that position.

Edit: you can use the linecache.getline(filename, lineno) function, which will return the contents of the line lineno, but only after reading the entire file into memory. Good if you're randomly accessing lines from within the file (as python itself might want to do to print a traceback) but not good for a 15MB file.

Remove last character of a StringBuilder?

stringBuilder.Remove(stringBuilder.Length - 1, 1);

How to print to the console in Android Studio?

If your app is launched from device, not IDE, you can do later in menu: Run - Attach Debugger to Android Process.

This can be useful when debugging notifications on closed application.

Assigning multiple styles on an HTML element

In HTML the style tag has the following syntax:

style="property1:value1;property2:value2"

so in your case:

<h2 style="text-align:center;font-family:tahoma">TITLE</h2>

Hope this helps.

Default fetch type for one-to-one, many-to-one and one-to-many in Hibernate

It depends on whether you are using JPA or Hibernate.

From the JPA 2.0 spec, the defaults are:

OneToMany: LAZY
ManyToOne: EAGER
ManyToMany: LAZY
OneToOne: EAGER

And in hibernate, all is Lazy

UPDATE:

The latest version of Hibernate aligns with the above JPA defaults.

How do I clear this setInterval inside a function?

the_int=window.clearInterval(the_int);

Creating a Plot Window of a Particular Size

A convenient function for saving plots is ggsave(), which can automatically guess the device type based on the file extension, and smooths over differences between devices. You save with a certain size and units like this:

ggsave("mtcars.png", width = 20, height = 20, units = "cm")

In R markdown, figure size can be specified by chunk:

```{r, fig.width=6, fig.height=4}  
plot(1:5)
```

Change Toolbar color in Appcompat 21

again this is all in the link you supplied

to change the text to white all you have to do is change the theme.

use this theme

<android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/activity_my_toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
    app:popupTheme="@style/ThemeOverlay.AppCompat.Light"/>

Windows batch file file download from a URL

' Create an HTTP object
myURL = "http://www.google.com"
Set objHTTP = CreateObject( "WinHttp.WinHttpRequest.5.1" )

' Download the specified URL
objHTTP.Open "GET", myURL, False
objHTTP.Send
intStatus = objHTTP.Status

If intStatus = 200 Then
  WScript.Echo " " & intStatus & " A OK " +myURL
Else
  WScript.Echo "OOPS" +myURL
End If

then

C:\>cscript geturl.vbs
Microsoft (R) Windows Script Host Version 5.7
Copyright (C) Microsoft Corporation. All rights reserved.

200 A OK http://www.google.com

or just double click it to test in windows

How to style components using makeStyles and still have lifecycle methods in Material UI?

I used withStyles instead of makeStyle

EX :

import { withStyles } from '@material-ui/core/styles';
import React, {Component} from "react";

const useStyles = theme => ({
        root: {
           flexGrow: 1,
         },
  });

class App extends Component {
       render() {
                const { classes } = this.props;
                return(
                    <div className={classes.root}>
                       Test
                </div>
                )
          }
} 

export default withStyles(useStyles)(App)

HTML embed autoplay="false", but still plays automatically

the below codes helped me with the same problem. Let me know if it helped.

<!DOCTYPE html>
<html>
<body>


<audio controls>

<source src="YOUR AUDIO FILE" type="audio/mpeg">
Your browser does not support the audio element.
</audio>



</body>
</html>

Difference between setTimeout with and without quotes and parentheses

What happens in reality in case you pass string as a first parameter of function

setTimeout('string',number)

is value of first param got evaluated when it is time to run (after numberof miliseconds passed). Basically it is equal to

setTimeout(eval('string'), number)

This is

an alternative syntax that allows you to include a string instead of a function, which is compiled and executed when the timer expires. This syntax is not recommended for the same reasons that make using eval() a security risk.

So samples which you refer are not good samples, and may be given in different context or just simple typo.

If you invoke like this setTimeout(something, number), first parameter is not string, but pointer to a something called something. And again if something is string - then it will be evaluated. But if it is function, then function will be executed. jsbin sample

Adding a month to a date in T SQL

DATEADD is the way to go with this

See the W3Schools tutorial: http://www.w3schools.com/sql/func_dateadd.asp

Send values from one form to another form

After a series of struggle for passing the data from one form to another i finally found a stable answer. It works like charm.

All you need to do is declare a variable as public static datatype 'variableName' in one form and assign the value to this variable which you want to pass to another form and call this variable in another form using directly the form name (Don't create object of this form as static variables can be accessed directly) and access this variable value.

Example of such is,

Form1

public static int quantity;
quantity=TextBox1.text; \\Value which you want to pass

Form2

TextBox2.Text=Form1.quantity;\\ Data will be placed in TextBox2

JWT refresh token flow

Below are the steps to do revoke your JWT access token:

When you do log in, send 2 tokens (Access token, Refresh token) in response to the client.
The access token will have less expiry time and Refresh will have long expiry time.
The client (Front end) will store refresh token in his local storage and access token in cookies.
The client will use an access token for calling APIs. But when it expires, pick the refresh token from local storage and call auth server API to get the new token.
Your auth server will have an API exposed which will accept refresh token and checks for its validity and return a new access token.
Once the refresh token is expired, the User will be logged out.

Please let me know if you need more details, I can share the code (Java + Spring boot) as well.

For your questions:

Q1: It's another JWT with fewer claims put in with long expiry time.

Q2: It won't be in a database. The backend will not store anywhere. They will just decrypt the token with private/public key and validate it with its expiry time also.

Q3: Yes, Correct

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

As said, JsonMappingException: out of START_ARRAY token exception is thrown by Jackson object mapper as it's expecting an Object {} whereas it found an Array [{}] in response.

A simpler solution could be replacing the method getLocations with:

public static List<Location> getLocations(InputStream inputStream) {
    ObjectMapper objectMapper = new ObjectMapper();
    try {
        TypeReference<List<Location>> typeReference = new TypeReference<>() {};
        return objectMapper.readValue(inputStream, typeReference);
    } catch (IOException e) {
        e.printStackTrace();
    }
    return null;
}

On the other hand, if you don't have a pojo like Location, you could use:

TypeReference<List<Map<String, Object>>> typeReference = new TypeReference<>() {};
return objectMapper.readValue(inputStream, typeReference);

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

I solved the problem by covering the download button of a audio controller with a transparent div that changes the symbol of the mouse-cursor to "not-allowed".

The div blocks the activation of the download button.

Height: 50px, Width: 35px, Left: (document-right -60), Top: (same as the audio controller).

You must set the z-index style of the div above the z-index of the audio-controller.

See sapplic.com/jive66 for an example that works for chrome on win7 and on win8.

Node.js spawn child process and get terminal output live

PHP-like passthru

import { spawn } from 'child_process';

export default async function passthru(exe, args, options) {
    return new Promise((resolve, reject) => {
        const env = Object.create(process.env);
        const child = spawn(exe, args, {
            ...options,
            env: {
                ...env,
                ...options.env,
            },
        });
        child.stdout.setEncoding('utf8');
        child.stderr.setEncoding('utf8');
        child.stdout.on('data', data => console.log(data));
        child.stderr.on('data', data => console.log(data));
        child.on('error', error => reject(error));
        child.on('close', exitCode => {
            console.log('Exit code:', exitCode);
            resolve(exitCode);
        });
    });
}

Usage

const exitCode = await passthru('ls', ['-al'], { cwd: '/var/www/html' })

Check if a specific tab page is selected (active)

Assuming you are looking out in Winform, there is a SelectedIndexChanged event for the tab

Now in it you could check for your specific tab and proceed with the logic

private void tab1_SelectedIndexChanged(object sender, EventArgs e)
{
     if (tab1.SelectedTab == tab1.TabPages["tabname"])//your specific tabname
     {
         // your stuff
     }
}

Best way to change font colour halfway through paragraph?

wrap a <span> around those words and style with the appropriate color

now is the time for <span style='color:orange'>all good men</span> to come to the

How to Clear Console in Java?

You can easily implement clrscr() using simple for loop printing "\b".

How do I set up IntelliJ IDEA for Android applications?

I had some issues that this didn't address in getting this environment set up on OSX. It had to do with the solution that I was maintaining having additional dependencies on some of the Google APIs. It wasn't enough to just download and install the items listed in the first response.

You have to download these.

Run Terminal
Navigate to the android/sdk directory
Type "android" You will get a gui. Check the "Tools" directory and the latest Android API (at this time, it's 4.3 (API 18)).
Click "Install xx packages" and go watch an episode of Breaking Bad or something. It'll take a while.
Go back to IntelliJ and open the "Project Structure..." dialog (Cmd+;).
In the left panel of the dialog, under "Project Settings," select Project. In the right panel, under "Project SDK," click "New..." > Android SDK and navigate to your android/sdk directory. Choose this and you will be presented with a dialog with which you can add the "Google APIs" build target. This is what I needed. You may need to do this more than once if you have multiple version targets.
Now, under the left pane "Modules," with your project selected in the center pane, select the appropriate module under the "Dependencies" tab in the right pane.

How to solve ERR_CONNECTION_REFUSED when trying to connect to localhost running IISExpress - Error 502 (Cannot debug from Visual Studio)?

This issue may be because in the recent past you have used IP address binding in your application configuration.

Steps to Solve the issue:

Run below command in administrator access command terminal

netsh http show iplisten

If you see some thing like below then this solution may not help you.

IP addresses present in the IP listen to list:

0.0.0.0

If you see something different than 0.0.0.0 then try below steps to fix this.

Run following shell command in order with elevated command terminal

netsh http delete iplisten ipaddress=11.22.33.44

netsh http add iplisten ipaddress=0.0.0.0

iisreset

(Here 11.22.33.44 is the actual IP that needs to be removed)

And now your issexpress is set to listen to any ping coming to localhost binding.

IF - ELSE IF - ELSE Structure in Excel

Say P7 is a Cell then you can use the following Syntex to check the value of the cell and assign appropriate value to another cell based on this following nested if:

=IF(P7=0,200,IF(P7=1,100,IF(P7=2,25,IF(P7=3,10,IF((P7=4),5,0)))))

Understanding the set() function

After reading the other answers, I still had trouble understanding why the set comes out un-ordered.

Mentioned this to my partner and he came up with this metaphor: take marbles. You put them in a tube a tad wider than marble width : you have a list. A set, however, is a bag. Even though you feed the marbles one-by-one into the bag; when you pour them from a bag back into the tube, they will not be in the same order (because they got all mixed up in a bag).

How to submit a form with JavaScript by clicking a link?

this works well without any special function needed. Much easier to write with php as well. <input onclick="this.form.submit()"/>

Implement specialization in ER diagram

So I assume your permissions table has a foreign key reference to admin_accounts table. If so because of referential integrity you will only be able to add permissions for account ids exsiting in the admin accounts table. Which also means that you wont be able to enter a user_account_id [assuming there are no duplicates!]

Re-assign host access permission to MySQL user

For reference, the solution is:

UPDATE mysql.user SET host = '10.0.0.%' WHERE host = 'internalfoo' AND user != 'root';
UPDATE mysql.db SET host = '10.0.0.%' WHERE host = 'internalfoo' AND user != 'root';
FLUSH PRIVILEGES;

Angular.js ng-repeat filter by property having one of multiple values (OR of values)

For me, it worked as given below:

<div ng-repeat="product in products | filter: { color: 'red'||'blue' }">

<div ng-repeat="product in products | filter: { color: 'red'} | filter: { color:'blue' }">

IF...THEN...ELSE using XML

Personally, I would prefer

<IF>
  <TIME from="5pm" to="9pm" />
  <THEN>
    <!-- action -->
  </THEN>
  <ELSE>
    <!-- action -->
  </ELSE>
</IF>

In this way you don't need an id attribute to tie together the IF, THEN, ELSE tags

Executing another application from Java

You could simply use Runtime.exec()

best way to get folder and file list in Javascript

I don't like adding new package into my project just to handle this simple task.

And also, I try my best to avoid RECURSIVE algorithm.... since, for most cases it is slower compared to non Recursive one.

So I made a function to get all the folder content (and its sub folder).... NON-Recursively

var getDirectoryContent = function(dirPath) {
    /* 
        get list of files and directories from given dirPath and all it's sub directories
        NON RECURSIVE ALGORITHM
        By. Dreamsavior
    */
    var RESULT = {'files':[], 'dirs':[]};

    var fs = fs||require('fs');
    if (Boolean(dirPath) == false) {
        return RESULT;
    }
    if (fs.existsSync(dirPath) == false) {
        console.warn("Path does not exist : ", dirPath);
        return RESULT;
    }

    var directoryList = []
    var DIRECTORY_SEPARATOR = "\\";
    if (dirPath[dirPath.length -1] !== DIRECTORY_SEPARATOR) dirPath = dirPath+DIRECTORY_SEPARATOR;

    directoryList.push(dirPath); // initial

    while (directoryList.length > 0) {
        var thisDir  = directoryList.shift(); 
        if (Boolean(fs.existsSync(thisDir) && fs.lstatSync(thisDir).isDirectory()) == false) continue;

        var thisDirContent = fs.readdirSync(thisDir);
        while (thisDirContent.length > 0) { 
            var thisFile  = thisDirContent.shift(); 
            var objPath = thisDir+thisFile

            if (fs.existsSync(objPath) == false) continue;
            if (fs.lstatSync(objPath).isDirectory()) { // is a directory
                let thisDirPath = objPath+DIRECTORY_SEPARATOR; 
                directoryList.push(thisDirPath);
                RESULT['dirs'].push(thisDirPath);

            } else  { // is a file
                RESULT['files'].push(objPath); 

            } 
        } 

    }
    return RESULT;
}

the only drawback of this function is that this is Synchronous function... You have been warned ;)

Add CSS to iFrame

Based on solution You've already found How to apply CSS to iframe?:

var cssLink = document.createElement("link") 
cssLink.href = "file://path/to/style.css"; 
cssLink .rel = "stylesheet"; 
cssLink .type = "text/css"; 
frames['iframe'].document.body.appendChild(cssLink);

or more jqueryish (from Append a stylesheet to an iframe with jQuery):

var $head = $("iframe").contents().find("head");                
$head.append($("<link/>", 
    { rel: "stylesheet", href: "file://path/to/style.css", type: "text/css" }));

as for security issues: Disabling same-origin policy in Safari

Selecting pandas column by location

You could use label based using .loc or index based using .iloc method to do column-slicing including column ranges:

In [50]: import pandas as pd

In [51]: import numpy as np

In [52]: df = pd.DataFrame(np.random.rand(4,4), columns = list('abcd'))

In [53]: df
Out[53]: 
          a         b         c         d
0  0.806811  0.187630  0.978159  0.317261
1  0.738792  0.862661  0.580592  0.010177
2  0.224633  0.342579  0.214512  0.375147
3  0.875262  0.151867  0.071244  0.893735

In [54]: df.loc[:, ["a", "b", "d"]] ### Selective columns based slicing
Out[54]: 
          a         b         d
0  0.806811  0.187630  0.317261
1  0.738792  0.862661  0.010177
2  0.224633  0.342579  0.375147
3  0.875262  0.151867  0.893735

In [55]: df.loc[:, "a":"c"] ### Selective label based column ranges slicing
Out[55]: 
          a         b         c
0  0.806811  0.187630  0.978159
1  0.738792  0.862661  0.580592
2  0.224633  0.342579  0.214512
3  0.875262  0.151867  0.071244

In [56]: df.iloc[:, 0:3] ### Selective index based column ranges slicing
Out[56]: 
          a         b         c
0  0.806811  0.187630  0.978159
1  0.738792  0.862661  0.580592
2  0.224633  0.342579  0.214512
3  0.875262  0.151867  0.071244

How do I programmatically force an onchange event on an input?

ugh don't use eval for anything. Well, there are certain things, but they're extremely rare. Rather, you would do this:

document.getElementById("test").onchange()

Look here for more options: http://jehiah.cz/archive/firing-javascript-events-properly

How to set zoom level in google map

For zooming your map two level then just add this small code of line map.setZoom(map.getZoom() + 2);

How do you specify table padding in CSS? ( table, not cell padding )

You can't... Maybe if you posted a picture of the desired effect there's another way to achieve it.

For example, you can wrap the entire table in a DIV and set the padding to the div.

Cannot install packages using node package manager in Ubuntu

For me the fix was removing the node* packages and also the npm packages.

Then a fresh install as:

sudo apt-get install autoclean
sudo apt-get install nodejs-legacy
npm install

Easiest way to copy a table from one database to another?

I use Navicat for MySQL...

It makes all database manipulation easy !

You simply select both databases in Navicat and then use.

 INSERT INTO Database2.Table1 SELECT * from Database1.Table1

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

I arrived here because I thought I should check in SO if there are adequate answers, after a syntax error that gave me this error, or if I could possibly post an answer myself.

OK, the answers here explain what this error is, so not much more to say, but nevertheless I will give my 2 cents using my words:

This error is caused by the fact that you basically generate a new table with your subquery for the FROM command.

That's what a derived table is, and as such, it needs to have an alias (actually a name reference to it).

So given the following hypothetical query:

SELECT id, key1
FROM (
    SELECT t1.ID id, t2.key1 key1, t2.key2 key2, t2.key3 key3
    FROM table1 t1 
    LEFT JOIN table2 t2 ON t1.id = t2.id
    WHERE t2.key3 = 'some-value'
) AS tt

So, at the end, the whole subquery inside the FROM command will produce the table that is aliased as tt and it will have the following columns id, key1, key2, key3.

So, then with the initial SELECT from that table we finally select the id and key1 from the tt.

Execution failed for task ':app:processDebugResources' even with latest build tools

as a quick fix to this question, make sure your compile Sdk verion, your buildtoolsversion, your appcompat, and finally your support library are all running on the same sdk version, for further clarity take a look at the image i just uploaded. Cheers. Follow the red annotations and get rid of that trouble.

Java maximum memory on Windows XP

Everyone seems to be answering about contiguous memory, but have neglected to acknowledge a more pressing issue.

Even with 100% contiguous memory allocation, you can't have a 2 GiB heap size on a 32-bit Windows OS (*by default). This is because 32-bit Windows processes cannot address more than 2 GiB of space.

The Java process will contain perm gen (pre Java 8), stack size per thread, JVM / library overhead (which pretty much increases with each build) all in addition to the heap.

Furthermore, JVM flags and their default values change between versions. Just run the following and you'll get some idea:

 java -XX:+PrintFlagsFinal

Lots of the options affect memory division in and out of the heap. Leaving you with more or less of that 2 GiB to play with...

To reuse portions of this answer of mine (about Tomcat, but applies to any Java process):

The Windows OS limits the memory allocation of a 32-bit process to 2 GiB in total (by default).

[You will only be able] to allocate around 1.5 GiB heap space because there is also other memory allocated to the process (the JVM / library overhead, perm gen space etc.).

Why does 32-bit Windows impose a 2 GB process address space limit, but 64-bit Windows impose a 4GB limit?

Other modern operating systems [cough Linux] allow 32-bit processes to use all (or most) of the 4 GiB addressable space.

That said, 64-bit Windows OS's can be configured to increase the limit of 32-bit processes to 4 GiB (3 GiB on 32-bit):

http://msdn.microsoft.com/en-us/library/windows/desktop/aa366778(v=vs.85).aspx

Range with step of type float

Here is a special case that might be good enough:

 [ (1.0/divStep)*x for x in range(start*divStep, stop*divStep)]

In your case this would be:

#for(float x = 0; x < 10; x += 0.5f) { /* ... */ } ==>
start = 0
stop  = 10
divstep = 1/.5 = 2 #This needs to be int, thats why I said 'special case'

and so:

>>> [ .5*x for x in range(0*2, 10*2)]
[0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5]

How to resolve "Error: bad index – Fatal: index file corrupt" when using Git

This is ridiculous but I just have rebooted my machine (mac) and the problem was gone like it has never happened. I hate to sound like a support guy...

Integer value in TextView

If you want it to display on your layout you should

For example:

activity_layout.XML file

    <TextView
        android:id="@+id/example_tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

On the activity.java file

    final TextView textView = findViewById(R.id.example_tv);
    textView.setText(Integer.toString(yourNumberHere));

In the first line on the XML file you can see:

android:id="@+id/example_tv"

That's where you get the id to change in the .java file for the findViewById(R.id.example_tv)

Hope I made myself clear, I just went with this explanation because a lot of times people seem to know the ".setText()" method, they just can't change the text in the "UI".

EDIT Since this is a fairly old answer, and Kotlin is the preferred language for Android development, here's its counterpart.

With the same XML layout:

You can either use the findViewbyId() or use Kotlin synthetic properties:

findViewById<TextView>(R.id.example_tv).text = yourNumberHere.toString()

// Or

example_tv?.text = yourNumberHere.toString()

The toString() is from Kotlin's Any object (comparable to the Java Object):

The root of the Kotlin class hierarchy. Every Kotlin class has Any as a superclass.

java.io.StreamCorruptedException: invalid stream header: 54657374

Clearly you aren't sending the data with ObjectOutputStream: you are just writing the bytes.

If you read with readObject() you must write with writeObject().
If you read with readUTF() you must write with writeUTF().
If you read with readXXX() you must write with writeXXX(), for most values of XXX.

What does hash do in python?

You can use the Dictionary data type in python. It's very very similar to the hash—and it also supports nesting, similar to the to nested hash.

Example:

dict = {'Name': 'Zara', 'Age': 7, 'Class': 'First'}
dict['Age'] = 8; # update existing entry
dict['School'] = "DPS School" # Add new entry

print ("dict['Age']: ", dict['Age'])
print ("dict['School']: ", dict['School'])

For more information, please reference this tutorial on the dictionary data type.

Specified cast is not valid.. how to resolve this

If you are expecting double, decimal, float, integer why not use the one which accomodates all namely decimal (128 bits are enough for most numbers you are looking at).

instead of (double)value use decimal.Parse(value.ToString()) or Convert.ToDecimal(value)

Capture HTML Canvas as gif/jpg/png/pdf?

If you are using jQuery, which quite a lot of people do, then you would implement the accepted answer like so:

var canvas = $("#mycanvas")[0];
var img = canvas.toDataURL("image/png");

$("#elememt-to-write-to").html('<img src="'+img+'"/>');

The 'json' native gem requires installed build tools

Followed the steps.

Extract DevKit to path C:\Ruby193\DevKit
cd C:\Ruby192\DevKit
ruby dk.rb init
ruby dk.rb review
ruby dk.rb install

Then I wrote the command

gem install rails -r -y

Circular (or cyclic) imports in Python

There was a really good discussion on this over at comp.lang.python last year. It answers your question pretty thoroughly.

Imports are pretty straightforward really. Just remember the following:

'import' and 'from xxx import yyy' are executable statements. They execute when the running program reaches that line.

If a module is not in sys.modules, then an import creates the new module entry in sys.modules and then executes the code in the module. It does not return control to the calling module until the execution has completed.

If a module does exist in sys.modules then an import simply returns that module whether or not it has completed executing. That is the reason why cyclic imports may return modules which appear to be partly empty.

Finally, the executing script runs in a module named __main__, importing the script under its own name will create a new module unrelated to __main__.

Take that lot together and you shouldn't get any surprises when importing modules.

Facebook Android Generate Key Hash

SIMPLEST SOLUTION OUT THERE FOR THIS PROBLEM:

I have had this Problem for two months now. My key hashes have been pyling up to 9. Today i finally found the simple solution:

STEP 1:

Install the facebook sdk you downloaded from the facebook developer page on your phone. Don´t install the normal facebook app. Make sure you can log into facebook. Then log out.

STEP 2:

Export your app with your final release key as an apk, like you would when uploading it to the playstore.

STEP 3:

Put the Apk file on your phone via usb cable or usb stick.

STEP 4:

Install your app, using a file manager: Example

STEP 5:

Launch your app and try to log in with facebook. A dialog will open and tell you: "the key YOURHASHKEY has not been found in the facebook developer console"

STEP 6:

Write down the key.

STEP 7:

Put it into your facebook developer console and save. Now you are done. Anyone that downloads your app, published with earlier used keystore can log into facebook.

Enjoy

Preprocessing in scikit learn - single sample - Depreciation warning

I faced the same issue and got the same deprecation warning. I was using a numpy array of [23, 276] when I got the message. I tried reshaping it as per the warning and end up in nowhere. Then I select each row from the numpy array (as I was iterating over it anyway) and assigned it to a list variable. It worked then without any warning.

array = []
array.append(temp[0])

Then you can use the python list object (here 'array') as an input to sk-learn functions. Not the most efficient solution, but worked for me.

How do I set the proxy to be used by the JVM

I think configuring WINHTTP will also work.

Many programs including Windows Updates are having problems behind proxy. By setting up WINHTTP will always fix this kind of problems

How to move all HTML element children to another parent using JavaScript?

If you not use - in id's names then you can do this

_x000D_

oldParent.id='xxx';_x000D_
newParent.id='oldParent';_x000D_
xxx.id='newParent';_x000D_
oldParent.parentNode.insertBefore(oldParent,newParent);

_x000D_

#newParent { color: red }

_x000D_

<div id="oldParent">_x000D_
    <span>Foo</span>_x000D_
    <b>Bar</b>_x000D_
    Hello World_x000D_
</div>_x000D_
<div id="newParent"></div>

_x000D_

How to open a folder in Windows Explorer from VBA?

You can use command prompt to open explorer with path.

here example with batch or command prompt:

start "" explorer.exe (path)

so In VBA ms.access you can write with:

Dim Path
Path="C:\Example"
shell "cmd /c start """" explorer.exe " & Path ,vbHide

curl: (35) error:1408F10B:SSL routines:ssl3_get_record:wrong version number

More simply in one line:

proxy=192.168.2.1:8080;curl -v example.com

eg. $proxy=192.168.2.1:8080;curl -v example.com

xxxxxxxxx-ASUS:~$ proxy=192.168.2.1:8080;curl -v https://google.com|head -c 15 % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0

Trying 172.217.163.46:443...
TCP_NODELAY set
Connected to google.com (172.217.163.46) port 443 (#0)
ALPN, offering h2
ALPN, offering http/1.1
successfully set certificate verify locations:
CAfile: /etc/ssl/certs/ca-certificates.crt CApath: /etc/ssl/certs } [5 bytes data]
TLSv1.3 (OUT), TLS handshake, Client hello (1): } [512 bytes data]

Display SQL query results in php

You need to fetch the data from each row of the resultset obtained from the query. You can use mysql_fetch_array() for this.

// Process all rows
while($row = mysql_fetch_array($result)) {
    echo $row['column_name']; // Print a single column data
    echo print_r($row);       // Print the entire row data
}

Change your code to this :

require_once('db.php');  
$sql="SELECT * FROM  modul1open WHERE idM1O>=(SELECT FLOOR( MAX( idM1O ) * RAND( ) )  FROM  modul1open) 
ORDER BY idM1O LIMIT 1"

$result = mysql_query($sql);
while($row = mysql_fetch_array($result)) {
    echo $row['fieldname']; 
}

Making authenticated POST requests with Spring RestTemplate for Android

Ok found the answer. exchange() is the best way. Oddly the HttpEntity class doesn't have a setBody() method (it has getBody()), but it is still possible to set the request body, via the constructor.

// Create the request body as a MultiValueMap
MultiValueMap<String, String> body = new LinkedMultiValueMap<String, String>();     

body.add("field", "value");

// Note the body object as first parameter!
HttpEntity<?> httpEntity = new HttpEntity<Object>(body, requestHeaders);

ResponseEntity<MyModel> response = restTemplate.exchange("/api/url", HttpMethod.POST, httpEntity, MyModel.class);

Lambda function in list comprehensions

The big difference is that the first example actually invokes the lambda f(x), while the second example doesn't.

Your first example is equivalent to [(lambda x: x*x)(x) for x in range(10)] while your second example is equivalent to [f for x in range(10)].

Javascript to set hidden form value on drop down change

$(function() {
$('#myselect').change(function() {
   $('#myhidden').val =$("#myselect option:selected").text();
    });
});

-didSelectRowAtIndexPath: not being called

I just had this and as has happened to me in the past it didn't work because I didn't pay attention to the autocomplete when trying to add the method and I actually end up implementing tableView:didDeselectRowAtIndexPath: instead of tableView:didSelectRowAtIndexPath:.

ReferenceError: describe is not defined NodeJs

if you are using vscode, want to debug your files

I used tdd before, it throw ReferenceError: describe is not defined

But, when I use bdd, it works!

waste half day to solve it....

    {
      "type": "node",
      "request": "launch",
      "name": "Mocha Tests",
      "program": "${workspaceFolder}/node_modules/mocha/bin/_mocha",
      "args": [
        "-u",
        "bdd",// set to bdd, not tdd
        "--timeout",
        "999999",
        "--colors",
        "${workspaceFolder}/test/**/*.js"
      ],
      "internalConsoleOptions": "openOnSessionStart"
},

How to select different app.config for several build configurations

SlowCheetah and FastKoala from the VisualStudio Gallery seem to be very good tools that help out with this problem.

However, if you want to avoid addins or use the principles they implement more extensively throughout your build/integration processes then adding this to your msbuild *proj files is a shorthand fix.

Note: this is more or less a rework of the No. 2 of @oleksii's answer.

This works for .exe and .dll projects:

  <Target Name="TransformOnBuild" BeforeTargets="PrepareForBuild">
    <TransformXml Source="App_Config\app.Base.config" Transform="App_Config\app.$(Configuration).config" Destination="app.config" />
  </Target>

This works for web projects:

  <Target Name="TransformOnBuild" BeforeTargets="PrepareForBuild">
    <TransformXml Source="App_Config\Web.Base.config" Transform="App_Config\Web.$(Configuration).config" Destination="Web.config" />
  </Target>

Note that this step happens even before the build proper begins. The transformation of the config file happens in the project folder. So that the transformed web.config is available when you are debugging (a drawback of SlowCheetah).

Do remember that if you create the App_Config folder (or whatever you choose to call it), the various intermediate config files should have a Build Action = None, and Copy to Output Directory = Do not copy.

This combines both options into one block. The appropriate one is executed based on conditions. The TransformXml task is defined first though:

<Project>
<UsingTask TaskName="TransformXml" AssemblyFile="$(MSBuildExtensionsPath)\Microsoft\VisualStudio\v$(VisualStudioVersion)\Web\Microsoft.Web.Publishing.Tasks.dll" />
<Target Name="TransformOnBuild" BeforeTargets="PrepareForBuild">
    <TransformXml Condition="Exists('App_Config\app.Base.config')" Source="App_Config\app.Base.config" Transform="App_Config\app.$(Configuration).config" Destination="app.config" />
    <TransformXml Condition="Exists('App_Config\Web.Base.config')" Source="App_Config\Web.Base.config" Transform="App_Config\Web.$(Configuration).config" Destination="Web.config" />
</Target>

From a Sybase Database, how I can get table description ( field names and types)?

For Sybase ASE, sp_columns table_name will return all the table metadata you are looking for.

How to list all the files in a commit?

List all files in a commit tree:

git ls-tree --name-only --full-tree a21e610

How to change Android version and code version number?

Open your build.gradle file and make sure you have versionCode and versionName inside defaultConfig element. If not, add them. Refer to this link for more details.

Edit Crystal report file without Crystal Report software

My dad moved his office after 30 year and they need to update the address in the header of their Crystal Reports 7 (1997!) based billing system.

After buying old copies of Access 97 and Visual Studio 2003 Pro, I found out that both programs were too new - they could open the RPT files, but they saved them with an updated version that would not open in the billing system.

I ended up being able to make the changes using this life-saver program...

http://www.softwareforces.com/Products/rpt-inspector-professional-suite-for-crystal-reports

It was available with a 10 day free trial, and I only needed about 10 minutes to make my changes. That said, I would have happily paid whatever they asked for it. :)

Some hints:

When I opened my RPT files, I got an error saving the database could not be found. I ignored this error and everything worked fine.
Because my RPT files were Crystal Reports version 7, I had to go into Options->Misc and tell the program to save in the old format...

How change List<T> data to IQueryable<T> data

var list = new List<string>();
var queryable = list.AsQueryable();

Add a reference to: System.Linq

Manually install Gradle and use it in Android Studio

Like @ said

https://services.gradle.org/distributions/

Download The Latest Gradle Distribution File and Extract It, Then Copy all Files and Paste it Under:

C:\Users\{USERNAME}\.gradle\wrapper\dists\

but you have to first make Android Studio try downloading the zip file and cancel it.

That way you can get the hash and copy the file and put it under the hash

ReactJS - .JS vs .JSX

In most of the cases it’s only a need for the transpiler/bundler, which might not be configured to work with JSX files, but with JS! So you are forced to use JS files instead of JSX.

And since react is just a library for javascript, it makes no difference for you to choose between JSX or JS. They’re completely interchangeable!

In some cases users/developers might also choose JSX over JS, because of code highlighting, but the most of the newer editors are also viewing the react syntax correctly in JS files.

How to open a new form from another form

In my opinion the main form should be responsible for opening both child form. Here is some pseudo that explains what I would do:

// MainForm
private ChildForm childForm;
private MoreForm moreForm;

ButtonThatOpenTheFirstChildForm_Click()
{
    childForm = CreateTheChildForm();
    childForm.MoreClick += More_Click;
    childForm.Show();
}

More_Click()
{
    childForm.Close();
    moreForm = new MoreForm();
    moreForm.Show();
}

You will just need to create a simple event MoreClick in the first child. The main benefit of this approach is that you can replicate it as needed and you can very easily model some sort of basic workflow.

The entity name must immediately follow the '&' in the entity reference

Just in case someone from Blogger arrives, I had this problem when using Beautify extension in VSCode. Don´t use it, don´t beautify it.

How to make an introduction page with Doxygen

As of v1.8.8 there is also the option USE_MDFILE_AS_MAINPAGE. So make sure to add your index file, e.g. README.md, to INPUT and set it as this option's value:

INPUT += README.md
USE_MDFILE_AS_MAINPAGE = README.md

get and set in TypeScript

It is very similar to creating common methods, simply put the keyword reserved get or set at the beginning.

class Name{
    private _name: string;

    getMethod(): string{
        return this._name;
    }

    setMethod(value: string){
        this._name = value
    }

    get getMethod1(): string{
        return this._name;
    }

    set setMethod1(value: string){
        this._name = value
    }
}

class HelloWorld {

    public static main(){

        let test = new Name();

        test.setMethod('test.getMethod() --- need ()');
            console.log(test.getMethod());

        test.setMethod1 = 'test.getMethod1 --- no need (), and used = for set ';
            console.log(test.getMethod1);
    }
}
HelloWorld.main();

In this case you can skip return type in get getMethod1() {

    get getMethod1() {
        return this._name;
    }

What is the difference between dynamic and static polymorphism in Java?

Polymorphism refers to the ability of an object to behave differently for the same trigger.

Static polymorphism (Compile-time Polymorphism)

Static Polymorphism decides which method to execute during compile time.
Method Overloading is an example of static polymorphism, and it is requred to happens static polymorphism.
Static Polymorphism achieved through static binding.
Static Polymorphism happens in the same class.
Object assignment is not required for static polymorphism.
Inheritance not involved for static polymorphism.

Dynamic Polymorphism (Runtime Polymorphism)

Dynamic Polymorphism decides which method to execute in runtime.
Method Overriding is an example of dynamic polymorphism, and it is requred to happens dynamic polymorphism.
Dynamic Polymorphism achieved through dynamic binding.
Dynamic Polymorphism happens between different classes.
It is required where a subclass object is assigned to super class object for dynamic polymorphism.
Inheritance involved for dynamic polymorphism.

php Replacing multiple spaces with a single space

Use preg_replace() and instead of [ \t\n\r] use \s:

$output = preg_replace('!\s+!', ' ', $input);

From Regular Expression Basic Syntax Reference:

\d, \w and \s

Shorthand character classes matching digits, word characters (letters, digits, and underscores), and whitespace (spaces, tabs, and line breaks). Can be used inside and outside character classes.

Explain the different tiers of 2 tier & 3 tier architecture?

First, we must make a distinction between layers and tiers. Layers are the way to logically break code into components and tiers are the physical nodes to place the components on. This question explains it better: What's the difference between "Layers" and "Tiers"?

A two layer architecture is usually just a presentation layer and data store layer. These can be on 1 tier (1 machine) or 2 tiers (2 machines) to achieve better performance by distributing the work load.

A three layer architecture usually puts something between the presentation and data store layers such as a business logic layer or service layer. Again, you can put this into 1,2, or 3 tiers depending on how much money you have for hardware and how much load you expect.

Putting multiple machines in a tier will help with the robustness of the system by providing redundancy.

Below is a good example of a layered architecture:

_{(source: microsoft.com)}

A good reference for all of this can be found here on MSDN: http://msdn.microsoft.com/en-us/library/ms978678.aspx

printf() formatting for hex

The # part gives you a 0x in the output string. The 0 and the x count against your "8" characters listed in the 08 part. You need to ask for 10 characters if you want it to be the same.

int i = 7;

printf("%#010x\n", i);  // gives 0x00000007
printf("0x%08x\n", i);  // gives 0x00000007
printf("%#08x\n", i);   // gives 0x000007

Also changing the case of x, affects the casing of the outputted characters.

printf("%04x", 4779); // gives 12ab
printf("%04X", 4779); // gives 12AB

Color picker utility (color pipette) in Ubuntu

You can install the package gcolor2 for this:

sudo apt-get install gcolor2

Then:

Applications -> Graphics -> GColor2

Read a file line by line assigning the value to a variable

Use:

filename=$1
IFS=$'\n'
for next in `cat $filename`; do
    echo "$next read from $filename" 
done
exit 0

If you have set IFS differently you will get odd results.

Change value of variable with dplyr

We can use replace to change the values in 'mpg' to NA that corresponds to cyl==4.

mtcars %>%
     mutate(mpg=replace(mpg, cyl==4, NA)) %>%
     as.data.frame()

Tensorflow installation error: not a supported wheel on this platform

The pip wheel contains the python version in its name (cp34-cp34m). If you download the whl file and rename it to say py3-none or instead, it should work. Can you try that?

The installation won't work for anaconda users that choose python 3 support because the installation procedure is asking to create a python 3.5 environment and the file is currently called cp34-cp34m. So renaming it would do the job for now.

sudo pip3 install --upgrade https://storage.googleapis.com/tensorflow/linux/gpu/tensorflow-0.7.0-cp34-cp34m-linux_x86_64.whl

This will produced the exact error message you got above. However, when you will downloaded the file yourself and rename it to "tensorflow-0.7.0-py3-none-linux_x86_64.whl", then execute the command again with changed filename, it should work fine.

HTML <input type='file'> File Selection Event

When you have to reload the file, you can erase the value of input. Next time you add a file, 'on change' event will trigger.

document.getElementById('my_input').value = null;
// ^ that just erase the file path but do the trick

Adding to the classpath on OSX

In OSX, you can set the classpath from scratch like this:

export CLASSPATH=/path/to/some.jar:/path/to/some/other.jar

Or you can add to the existing classpath like this:

export CLASSPATH=$CLASSPATH:/path/to/some.jar:/path/to/some/other.jar

This is answering your exact question, I'm not saying it's the right or wrong thing to do; I'll leave that for others to comment upon.

How to generate a create table script for an existing table in phpmyadmin?

Use the following query in sql tab:

SHOW CREATE TABLE tablename

To view full query There is this Hyperlink named +Options left above, There select Full Texts

How to set <iframe src="..."> without causing `unsafe value` exception?

constructor(
 public sanitizer: DomSanitizer, ) {

 }

I had been struggling for 4 hours. the problem was in img tag. When you use square bracket to 'src' ex: [src]. you can not use this angular expression {{}}. you just give directly from an object example below. if you give angular expression {{}}. you will get interpolation error.

first i used ngFor to iterate the countries
```
*ngFor="let country of countries"
```

second you put this in the img tag. this is it.

<img [src]="sanitizer.bypassSecurityTrustResourceUrl(country.flag)"
height="20" width="20" alt=""/>

NSRange from Swift Range?

For me this works perfectly:

let font = UIFont.systemFont(ofSize: 12, weight: .medium)
let text = "text"
let attString = NSMutableAttributedString(string: "exemple text :)")

attString.addAttributes([.font: font], range:(attString.string as NSString).range(of: text))

label.attributedText = attString

How to tar certain file types in all subdirectories?

find ./someDir -name "*.php" -o -name "*.html" | tar -cf my_archive -T -

How to keep the local file or the remote file during merge using Git and the command line?

This approach seems more straightforward, avoiding the need to individually select each file:

# keep remote files
git merge --strategy-option theirs
# keep local files
git merge --strategy-option ours

# keep remote files
git pull -Xtheirs
# keep local files
git pull -Xours

Copied directly from: Resolve Git merge conflicts in favor of their changes during a pull

C++ sorting and keeping track of indexes

Make a std::pair in function then sort pair :

generic version :

template< class RandomAccessIterator,class Compare >
auto sort2(RandomAccessIterator begin,RandomAccessIterator end,Compare cmp) ->
   std::vector<std::pair<std::uint32_t,RandomAccessIterator>>
{
    using valueType=typename std::iterator_traits<RandomAccessIterator>::value_type;
    using Pair=std::pair<std::uint32_t,RandomAccessIterator>;

    std::vector<Pair> index_pair;
    index_pair.reserve(std::distance(begin,end));

    for(uint32_t idx=0;begin!=end;++begin,++idx){
        index_pair.push_back(Pair(idx,begin));
    }

    std::sort( index_pair.begin(),index_pair.end(),[&](const Pair& lhs,const Pair& rhs){
          return cmp(*lhs.second,*rhs.second);
    });

    return index_pair;
}

ideone

Press enter in textbox to and execute button command

If you're just gonna click the button when Enter was pressed how about this?

private void textbox1_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.Enter)
        {
            buttonSearch.PerformClick();
        }

Getting URL hash location, and using it in jQuery

I'm using this to address the security implications noted in @CMS's answer.

// example 1: www.example.com/index.html#foo

// load correct subpage from URL hash if it exists
$(window).on('load', function () {
    var hash = window.location.hash;
    if (hash) {
        hash = hash.replace('#',''); // strip the # at the beginning of the string
        hash = hash.replace(/([^a-z0-9]+)/gi, '-'); // strip all non-alphanumeric characters
        hash = '#' + hash; // hash now equals #foo with example 1

        // do stuff with hash
        $( 'ul' + hash + ':first' ).show();
        // etc...
    }
});

How do I find out which process is locking a file using .NET?

simpler with linq:

public void KillProcessesAssociatedToFile(string file)
    {
        GetProcessesAssociatedToFile(file).ForEach(x =>
        {
            x.Kill();
            x.WaitForExit(10000);
        });
    }

    public List<Process> GetProcessesAssociatedToFile(string file)
    {
        return Process.GetProcesses()
            .Where(x => !x.HasExited
                && x.Modules.Cast<ProcessModule>().ToList()
                    .Exists(y => y.FileName.ToLowerInvariant() == file.ToLowerInvariant())
                ).ToList();
    }

How do you style a TextInput in react native for password input

An TextInput must include secureTextEntry={true}, note that the docs of React state that you must not use multiline={true} at the same time, as that combination is not supported.

You can also set textContentType={'password'} to allow the field to retrieve credentials from the keychain stored on your mobile, an alternative way to enter credentials if you got biometric input on your mobile to quickly insert credentials. Such as FaceId on iPhone X or fingerprint touch input on other iPhone models and Android.

 <TextInput value={this.state.password} textContentType={'password'} multiline={false} secureTextEntry={true} onChangeText={(text) => { this._savePassword(text); this.setState({ password: text }); }} style={styles.input} placeholder='Github password' />

Invalid column name sql error

Always try to use parametrized sql query to keep safe from malicious occurrence, so you could rearrange you code as below:

Also make sure that your table has column name matches to Name, PhoneNo ,Address.

using (SqlConnection connection = new SqlConnection(connectionString))
{
    SqlCommand cmd = new SqlCommand("INSERT INTO Data (Name, PhoneNo, Address) VALUES (@Name, @PhoneNo, @Address)");
    cmd.CommandType = CommandType.Text;
    cmd.Connection = connection;
    cmd.Parameters.AddWithValue("@Name", txtName.Text);
    cmd.Parameters.AddWithValue("@PhoneNo", txtPhone.Text);
    cmd.Parameters.AddWithValue("@Address", txtAddress.Text);
    connection.Open();
    cmd.ExecuteNonQuery();
}

Java: Multiple class declarations in one file

Yes you can, with public static members on an outer public class, like so:

public class Foo {

    public static class FooChild extends Z {
        String foo;
    }

    public static class ZeeChild extends Z {

    }

}

and another file that references the above:

public class Bar {

    public static void main(String[] args){

        Foo.FooChild f = new Foo.FooChild();
        System.out.println(f);

    }
}

put them in the same folder. Compile with:

javac folder/*.java

and run with:

 java -cp folder Bar

How to set image to fit width of the page using jsPDF?

i faced same problem but i solve using this code

html2canvas(body,{
                onrendered:function(canvas){
                    var pdf=new jsPDF("p", "mm", "a4");
                    var width = pdf.internal.pageSize.getWidth();    
                    var height = pdf.internal.pageSize.getHeight();
                    pdf.addImage(canvas, 'JPEG', 0, 0,width,height);
                    pdf.save('test11.pdf');
                }
            })

What is an opaque response, and what purpose does it serve?

Consider the case in which a service worker acts as an agnostic cache. Your only goal is serve the same resources that you would get from the network, but faster. Of course you can't ensure all the resources will be part of your origin (consider libraries served from CDNs, for instance). As the service worker has the potential of altering network responses, you need to guarantee you are not interested in the contents of the response, nor on its headers, nor even on the result. You're only interested on the response as a black box to possibly cache it and serve it faster.

This is what { mode: 'no-cors' } was made for.

How to create .pfx file from certificate and private key?

I got a link with your requirement.Combine CRT and KEY Files into a PFX with OpenSSL

Extracts from the above link:

First we need to extract the root CA certificate from the existing .crt file, because we need this later. So open up the .crt and click on the Certification Path tab.

Click the topmost certificate (In this case VeriSign) and hit View Certificate. Select the Details tab and hit Copy to File…

Select Base-64 encoded X.509 (.CER) certificate Save it as rootca.cer or something similar. Place it in the same folder as the other files.

Rename it from rootca.cer to rootca.crt Now we should have 3 files in our folder from which we can create a PFX file.

Here is where we need OpenSSL. We can either download and install it on Windows, or simply open terminal on OSX.

EDIT:

There is a support link with step by step information on how to do install the certificate.
After successfully install, export the certificate, choose .pfx format, include private key.

Important Note: : To export the certificate in .pfx format you need to follow the steps on the same machine from which you have requested the certificate.
The imported file can be uploaded to server.

How to fix Cannot find module 'typescript' in Angular 4?

For me just running the below command is not enough (though a valid first step):

npm install -g typescript

The following command is what you need (I think deleting node_modules works too, but the below command is quicker)

npm link typescript

What are the differences between 'call-template' and 'apply-templates' in XSL?

To add to the good answer by @Tomalak:

Here are some unmentioned and important differences:

xsl:apply-templates is much richer and deeper than xsl:call-templates and even from xsl:for-each, simply because we don't know what code will be applied on the nodes of the selection -- in the general case this code will be different for different nodes of the node-list.
The code that will be applied can be written way after the xsl:apply templates was written and by people that do not know the original author.

The FXSL library's implementation of higher-order functions (HOF) in XSLT wouldn't be possible if XSLT didn't have the <xsl:apply-templates> instruction.

Summary: Templates and the <xsl:apply-templates> instruction is how XSLT implements and deals with polymorphism.

Reference: See this whole thread: http://www.biglist.com/lists/lists.mulberrytech.com/xsl-list/archives/200411/msg00546.html

java.net.ConnectException: Connection refused

I had the same issue, and it turned out to be due to permission of the catalina.out file not being correct. It was not writable by the tomcat user. Once I fixed the permissions, the issue got resolved. I got to know that it is a permissions issue from the logs in the tomcat8-initd.log file:

/usr/sbin/tomcat8: line 40: /usr/share/tomcat8/logs/catalina.out: Permission denied

'^M' character at end of lines

Try using dos2unix to strip off the ^M.

Javascript event handler with parameters

Short answer:

x.addEventListener("click", function(e){myfunction(e, param1, param2)});

... 

function myfunction(e, param1, param1) {
    ... 
}

CSS Outside Border

I shared two solutions depending on your needs:

<style type="text/css" ref="stylesheet">
  .border-inside-box {
    border: 1px solid black;
  }
  .border-inside-box-v1 {
    outline: 1px solid black; /* 'border-radius' not available */
  }
  .border-outside-box-v2 {
    box-shadow: 0 0 0 1px black; /* 'border-style' not available (dashed, solid, etc) */
  }
</style>

example: https://codepen.io/danieldd/pen/gObEYKj

What is Java String interning?

Update for Java 8 or plus. In Java 8, PermGen (Permanent Generation) space is removed and replaced by Meta Space. The String pool memory is moved to the heap of JVM.

Compared with Java 7, the String pool size is increased in the heap. Therefore, you have more space for internalized Strings, but you have less memory for the whole application.

One more thing, you have already known that when comparing 2 (referrences of) objects in Java, '==' is used for comparing the reference of object, 'equals' is used for comparing the contents of object.

Let's check this code:

String value1 = "70";
String value2 = "70";
String value3 = new Integer(70).toString();

Result:

value1 == value2 ---> true

value1 == value3 ---> false

value1.equals(value3) ---> true

value1 == value3.intern() ---> true

That's why you should use 'equals' to compare 2 String objects. And that's is how intern() is useful.

Checking for the correct number of arguments

You can check the total number of arguments which are passed in command line with "$#" Say for Example my shell script name is hello.sh

sh hello.sh hello-world
# I am passing hello-world as argument in command line which will b considered as 1 argument 
if [ $# -eq 1 ] 
then
    echo $1
else
    echo "invalid argument please pass only one argument "
fi

Output will be hello-world

How to iterate through a table rows and get the cell values using jQuery

Hello every one thanks for the help below is the working code for my question

$("#TableView tr.item").each(function() { 
    var quantity1=$(this).find("input.name").val(); 
    var quantity2=$(this).find("input.id").val(); 
});

what is the basic difference between stack and queue?

Queue

Queue is a ordered collection of items.

Items are deleted at one end called ‘front’ end of the queue.

Items are inserted at other end called ‘rear’ of the queue.

The first item inserted is the first to be removed (FIFO).

Stack

Stack is a collection of items.

It allows access to only one data item: the last item inserted.

Items are inserted & deleted at one end called ‘Top of the stack’.

It is a dynamic & constantly changing object.

All the data items are put on top of the stack and taken off the top

This structure of accessing is known as Last in First out structure (LIFO)

What does the percentage sign mean in Python

What does the percentage sign mean?

It's an operator in Python that can mean several things depending on the context. A lot of what follows was already mentioned (or hinted at) in the other answers but I thought it could be helpful to provide a more extensive summary.

`%` for Numbers: Modulo operation / Remainder / Rest

The percentage sign is an operator in Python. It's described as:

x % y       remainder of x / y

So it gives you the remainder/rest that remains if you "floor divide" x by y. Generally (at least in Python) given a number x and a divisor y:

x == y * (x // y) + (x % y)

For example if you divide 5 by 2:

>>> 5 // 2
2
>>> 5 % 2
1

>>> 2 * (5 // 2) + (5 % 2)
5

In general you use the modulo operation to test if a number divides evenly by another number, that's because multiples of a number modulo that number returns 0:

>>> 15 % 5  # 15 is 3 * 5
0

>>> 81 % 9  # 81 is 9 * 9
0

That's how it's used in your example, it cannot be a prime if it's a multiple of another number (except for itself and one), that's what this does:

if n % x == 0:
    break

If you feel that n % x == 0 isn't very descriptive you could put it in another function with a more descriptive name:

def is_multiple(number, divisor):
    return number % divisor == 0

...

if is_multiple(n, x):
    break

Instead of is_multiple it could also be named evenly_divides or something similar. That's what is tested here.

Similar to that it's often used to determine if a number is "odd" or "even":

def is_odd(number):
    return number % 2 == 1

def is_even(number):
    return number % 2 == 0

And in some cases it's also used for array/list indexing when wrap-around (cycling) behavior is wanted, then you just modulo the "index" by the "length of the array" to achieve that:

>>> l = [0, 1, 2]
>>> length = len(l)
>>> for index in range(10):
...     print(l[index % length])
0
1
2
0
1
2
0
1
2
0

Note that there is also a function for this operator in the standard library operator.mod (and the alias operator.__mod__):

>>> import operator
>>> operator.mod(5, 2)  # equivalent to 5 % 2
1

But there is also the augmented assignment %= which assigns the result back to the variable:

>>> a = 5
>>> a %= 2  # identical to: a = a % 2
>>> a
1

`%` for strings: `printf`-style String Formatting

For strings the meaning is completely different, there it's one way (in my opinion the most limited and ugly) for doing string formatting:

>>> "%s is %s." % ("this", "good") 
'this is good'

Here the % in the string represents a placeholder followed by a formatting specification. In this case I used %s which means that it expects a string. Then the string is followed by a % which indicates that the string on the left hand side will be formatted by the right hand side. In this case the first %s is replaced by the first argument this and the second %s is replaced by the second argument (good).

Note that there are much better (probably opinion-based) ways to format strings:

>>> "{} is {}.".format("this", "good")
'this is good.'

`%` in Jupyter/IPython: magic commands

To quote the docs:

To Jupyter users: Magics are specific to and provided by the IPython kernel. Whether magics are available on a kernel is a decision that is made by the kernel developer on a per-kernel basis. To work properly, Magics must use a syntax element which is not valid in the underlying language. For example, the IPython kernel uses the % syntax element for magics as % is not a valid unary operator in Python. While, the syntax element has meaning in other languages.

This is regularly used in Jupyter notebooks and similar:

In [1]:  a = 10
         b = 20
         %timeit a + b   # one % -> line-magic

54.6 ns ± 2.7 ns per loop (mean ± std. dev. of 7 runs, 10000000 loops each)

In [2]:  %%timeit  # two %% -> cell magic 
         a ** b

362 ns ± 8.4 ns per loop (mean ± std. dev. of 7 runs, 1000000 loops each)

The `%` operator on arrays (in the NumPy / Pandas ecosystem)

The % operator is still the modulo operator when applied to these arrays, but it returns an array containing the remainder of each element in the array:

>>> import numpy as np
>>> a = np.arange(10)
>>> a
array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

>>> a % 2
array([0, 1, 0, 1, 0, 1, 0, 1, 0, 1])

Customizing the `%` operator for your own classes

Of course you can customize how your own classes work when the % operator is applied to them. Generally you should only use it to implement modulo operations! But that's a guideline, not a hard rule.

Just to provide a simple example that shows how it works:

class MyNumber(object):
    def __init__(self, value):
        self.value = value

    def __mod__(self, other):
        print("__mod__ called on '{!r}'".format(self))
        return self.value % other

    def __repr__(self):
        return "{self.__class__.__name__}({self.value!r})".format(self=self)

This example isn't really useful, it just prints and then delegates the operator to the stored value, but it shows that __mod__ is called when % is applied to an instance:

>>> a = MyNumber(10)
>>> a % 2
__mod__ called on 'MyNumber(10)'
0

Note that it also works for %= without explicitly needing to implement __imod__:

>>> a = MyNumber(10)
>>> a %= 2
__mod__ called on 'MyNumber(10)'

>>> a
0

However you could also implement __imod__ explicitly to overwrite the augmented assignment:

class MyNumber(object):
    def __init__(self, value):
        self.value = value

    def __mod__(self, other):
        print("__mod__ called on '{!r}'".format(self))
        return self.value % other

    def __imod__(self, other):
        print("__imod__ called on '{!r}'".format(self))
        self.value %= other
        return self

    def __repr__(self):
        return "{self.__class__.__name__}({self.value!r})".format(self=self)

Now %= is explicitly overwritten to work in-place:

>>> a = MyNumber(10)
>>> a %= 2
__imod__ called on 'MyNumber(10)'

>>> a
MyNumber(0)

Get filename in batch for loop

The answer by @AKX works on the command line, but not within a batch file. Within a batch file, you need an extra %, like this:

@echo off
for /R TutorialSteps %%F in (*.py) do echo %%~nF

MySql Query Replace NULL with Empty String in Select

Try this, this should also get rid of those empty lines also:

SELECT prereq FROM test WHERE prereq IS NOT NULL;

Unexpected character encountered while parsing value

I solved the problem with these online tools:

To check if the Json structure is OKAY: http://jsonlint.com/
To generate my Object class from my Json structure: https://www.jsonutils.com/

The simple code:

RootObject rootObj= JsonConvert.DeserializeObject<RootObject>(File.ReadAllText(pathFile));

How to redirect to a different domain using NGINX?

Why use the rewrite module if you can do return? Technically speaking, return is part of the rewrite module as you can read here but this snippet is easier to read imho.

server {
    server_name  .domain.com;

    return 302 $scheme://forwarded-domain.com;
}

You can also give it a 301 redirect.

Switch statement for string matching in JavaScript

Self-contained version that increases job security:

switch((s.match(r)||[null])[0])

_x000D_

function identifyCountry(hostname,only_gov=false){
    const exceptionRe = /^(?:uk|ac|eu)$/ ; //https://en.wikipedia.org/wiki/Country_code_top-level_domain#ASCII_ccTLDs_not_in_ISO_3166-1
    const h = hostname.split('.');
    const len = h.length;
    const tld = h[len-1];
    const sld = len >= 2 ? h[len-2] : null;

    if( tld.length == 2 ) {
        if( only_gov && sld != 'gov' ) return null;
        switch(  ( tld.match(exceptionRe) || [null] )[0]  ) {
         case 'uk':
            //Britain owns+uses this one
            return 'gb';
         case 'ac':
            //Ascension Island is part of the British Overseas territory
            //"Saint Helena, Ascension and Tristan da Cunha"
            return 'sh';
         case null:
            //2-letter TLD *not* in the exception list;
            //it's a valid ccTLD corresponding to its country
            return tld;
         default:
            //2-letter TLD *in* the exception list (e.g.: .eu);
            //it's not a valid ccTLD and we don't know the country
            return null;
        }
    } else if( tld == 'gov' ) {
        //AMERICAAA
        return 'us';
    } else {
        return null;
    }
}

_x000D_

<p>Click the following domains:</p>
<ul onclick="console.log(`${identifyCountry(event.target.textContent)} <= ${event.target.textContent}`);">
    <li>example.com</li>
    <li>example.co.uk</li>
    <li>example.eu</li>
    <li>example.ca</li>
    <li>example.ac</li>
    <li>example.gov</li>
</ul>

_x000D_

Honestly, though, you could just do something like

function switchableMatch(s,r){
    //returns the FIRST match of r on s; otherwise, null
    const m = s.match(r);
    if(m) return m[0];
    else return null;
}

and then later switch(switchableMatch(s,r)){…}

SQL Data Reader - handling Null column values

None of these was quite what i wanted:

 public static T GetFieldValueOrDefault<T>(this SqlDataReader reader, string name)
 {
     int index = reader.GetOrdinal(name);
     T value = reader.IsDBNull(index) ? default(T) : reader.GetFieldValue<T>(index);
     return value;
 }

Sqlite in chrome

You can use Web SQL API which is an ordinary SQLite database in your browser and you can open/modify it like any other SQLite databases for example with Lita.

Chrome locates databases automatically according to domain names or extension id. A few months ago I posted on my blog short article on how to delete Chrome's database because when you're testing some functionality it's quite useful.

Various ways to remove local Git changes

1. When you don't want to keep your local changes at all.

git reset --hard

This command will completely remove all the local changes from your local repository. This is the best way to avoid conflicts during pull command, only if you don't want to keep your local changes at all.

2. When you want to keep your local changes

If you want to pull the new changes from remote and want to ignore the local changes during this pull then,

git stash

It will stash all the local changes, now you can pull the remote changes,

git pull

Now, you can bring back your local changes by,

git stash pop

Simple way to copy or clone a DataRow?

But to make sure that your new row is accessible in the new table, you need to close the table:

DataTable destination = new DataTable(source.TableName);
destination = source.Clone();
DataRow sourceRow = source.Rows[0];
destination.ImportRow(sourceRow);

alert a variable value

A couple of things:

You can't use new as a variable name, it's a reserved word.
On input elements, you can just use the value property directly, you don't have to go through getAttribute. The attribute is "reflected" as a property.
Same for name.

So:

var inputs, input, newValue, i;

inputs = document.getElementsByTagName('input');
for (i=0; i<inputs.length; i++) {
    input = inputs[i];
    if (input.name == "ans") {   
        newValue = input.value;
        alert(newValue);
    }
}

Determine a string's encoding in C#

The SimpleHelpers.FileEncoding Nuget package wraps a C# port of the Mozilla Universal Charset Detector into a dead-simple API:

var encoding = FileEncoding.DetectFileEncoding(txtFile);

Perl regular expression (using a variable as a search string with Perl operator characters included)

You can use quotemeta (\Q \E) if your Perl is version 5.16 or later, but if below you can simply avoid using a regular expression at all.

For example, by using the index command:

if (index($text_to_search, $search_string) > -1) {
    print "wee";
}

C++: variable 'std::ifstream ifs' has initializer but incomplete type

This seems to be answered - #include <fstream>.

The message means :-

incomplete type - the class has not been defined with a full class. The compiler has seen statements such as class ifstream; which allow it to understand that a class exists, but does not know how much memory the class takes up.

The forward declaration allows the compiler to make more sense of :-

void BindInput( ifstream & inputChannel );

It understands the class exists, and can send pointers and references through code without being able to create the class, see any data within the class, or call any methods of the class.

The has initializer seems a bit extraneous, but is saying that the incomplete object is being created.

form_for with nested resources

Be sure to have both objects created in controller: @post and @comment for the post, eg:

@post = Post.find params[:post_id]
@comment = Comment.new(:post=>@post)

Then in view:

<%= form_for([@post, @comment]) do |f| %>

Be sure to explicitly define the array in the form_for, not just comma separated like you have above.

Android Emulator Error Message: "PANIC: Missing emulator engine program for 'x86' CPUS."

This worked for me on macOS:

echo 'export PATH=$PATH:'$HOME'/Library/Android/sdk/emulator:'$HOME'/Library/Android/sdk/tools:'$HOME'/Library/Android/sdk/platform-tools' >> ~/.bash_profile
source ~/.bash_profile

Collections.emptyList() vs. new instance

Use Collections.emptyList() if you want to make sure that the returned list is never modified.

This is what is returned on calling emptyList():

/**
 * The empty list (immutable). 
 */
public static final List EMPTY_LIST = new EmptyList();

How to add an image to the emulator gallery in android studio?

As of API 28 at least:

Open Settings app in emulator
Search for "Storage" select search result for it
Select Photos & Videos in Storage
Select Images
Drag an image onto the emulator, it won't immediately show up
From the AVD Manager in Android Studio, cold boot the emulator

The photos you've dragged in are now available.

How to use <md-icon> in Angular Material?

The simplest way today would be to simply request the Material Icons font from Google Fonts, for example in your HTML header tag:

<link href="https://fonts.googleapis.com/icon?family=Material+Icons" rel="stylesheet">

or in your stylesheet:

@import url(https://fonts.googleapis.com/icon?family=Material+Icons);

and then use as font icon with ligatures as explained in the md-icon directive. For example:

<md-icon aria-label="Menu" class="material-icons">menu</md-icon>

The complete list of icons/ligatures is at https://www.google.com/design/icons/

How do you clear a slice in Go?

Setting the slice to nil is the best way to clear a slice. nil slices in go are perfectly well behaved and setting the slice to nil will release the underlying memory to the garbage collector.

See playground

package main

import (
    "fmt"
)

func dump(letters []string) {
    fmt.Println("letters = ", letters)
    fmt.Println(cap(letters))
    fmt.Println(len(letters))
    for i := range letters {
        fmt.Println(i, letters[i])
    }
}

func main() {
    letters := []string{"a", "b", "c", "d"}
    dump(letters)
    // clear the slice
    letters = nil
    dump(letters)
    // add stuff back to it
    letters = append(letters, "e")
    dump(letters)
}

Prints

letters =  [a b c d]
4
4
0 a
1 b
2 c
3 d
letters =  []
0
0
letters =  [e]
1
1
0 e

Note that slices can easily be aliased so that two slices point to the same underlying memory. The setting to nil will remove that aliasing.

This method changes the capacity to zero though.

How do I prevent Eclipse from hanging on startup?

Windows -> Preferences -> General -> Startup and Shutdown

Is Refresh workspace on startup checked?

Encrypt and Decrypt in Java

Here is a solution using the javax.crypto library and the apache commons codec library for encoding and decoding in Base64 that I was looking for:

import java.security.spec.KeySpec;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESedeKeySpec;
import org.apache.commons.codec.binary.Base64;

public class TrippleDes {

    private static final String UNICODE_FORMAT = "UTF8";
    public static final String DESEDE_ENCRYPTION_SCHEME = "DESede";
    private KeySpec ks;
    private SecretKeyFactory skf;
    private Cipher cipher;
    byte[] arrayBytes;
    private String myEncryptionKey;
    private String myEncryptionScheme;
    SecretKey key;

    public TrippleDes() throws Exception {
        myEncryptionKey = "ThisIsSpartaThisIsSparta";
        myEncryptionScheme = DESEDE_ENCRYPTION_SCHEME;
        arrayBytes = myEncryptionKey.getBytes(UNICODE_FORMAT);
        ks = new DESedeKeySpec(arrayBytes);
        skf = SecretKeyFactory.getInstance(myEncryptionScheme);
        cipher = Cipher.getInstance(myEncryptionScheme);
        key = skf.generateSecret(ks);
    }


    public String encrypt(String unencryptedString) {
        String encryptedString = null;
        try {
            cipher.init(Cipher.ENCRYPT_MODE, key);
            byte[] plainText = unencryptedString.getBytes(UNICODE_FORMAT);
            byte[] encryptedText = cipher.doFinal(plainText);
            encryptedString = new String(Base64.encodeBase64(encryptedText));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return encryptedString;
    }


    public String decrypt(String encryptedString) {
        String decryptedText=null;
        try {
            cipher.init(Cipher.DECRYPT_MODE, key);
            byte[] encryptedText = Base64.decodeBase64(encryptedString);
            byte[] plainText = cipher.doFinal(encryptedText);
            decryptedText= new String(plainText);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return decryptedText;
    }


    public static void main(String args []) throws Exception
    {
        TrippleDes td= new TrippleDes();

        String target="imparator";
        String encrypted=td.encrypt(target);
        String decrypted=td.decrypt(encrypted);

        System.out.println("String To Encrypt: "+ target);
        System.out.println("Encrypted String:" + encrypted);
        System.out.println("Decrypted String:" + decrypted);

    }

}

Running the above program results with the following output:

String To Encrypt: imparator
Encrypted String:FdBNaYWfjpWN9eYghMpbRA==
Decrypted String:imparator

Adding a JAR to an Eclipse Java library

You might also consider using a build tool like Maven to manage your dependencies. It is very easy to setup and helps manage those dependencies automatically in eclipse. Definitely worth the effort if you have a large project with a lot of external dependencies.

div hover background-color change?

if you want the color to change when you have simply add the :hover pseudo

div.e:hover {
    background-color:red;
}

Copy a file list as text from Windows Explorer

In Windows 7 and later, this will do the trick for you

Select the file/files.
Hold the shift key and then right-click on the selected file/files.
You will see Copy as Path. Click that.
Open a Notepad file and paste and you will be good to go.

The menu item Copy as Path is not available in Windows XP.

MySQL Trigger after update only if row has changed

I cant comment, so just beware, that if your column supports NULL values, OLD.x<>NEW.x isnt enough, because

SELECT IF(1<>NULL,1,0)

returns 0 as same as

NULL<>NULL 1<>NULL 0<>NULL 'AAA'<>NULL

So it will not track changes FROM and TO NULL

The correct way in this scenario is

((OLD.x IS NULL AND NEW.x IS NOT NULL) OR (OLD.x IS NOT NULL AND NEW.x IS NULL) OR (OLD.x<>NEW.x))

tmux set -g mouse-mode on doesn't work

Just a quick heads-up to anyone else who is losing their mind right now:

https://github.com/tmux/tmux/blob/310f0a960ca64fa3809545badc629c0c166c6cd2/CHANGES#L12

so that's just

 :setw -g mouse

Splitting a string at every n-th character

Java does not provide very full-featured splitting utilities, so the Guava libraries do:

Iterable<String> pieces = Splitter.fixedLength(3).split(string);

Check out the Javadoc for Splitter; it's very powerful.

iOS detect if user is on an iPad

In Swift you can use the following equalities to determine the kind of device on Universal apps:

UIDevice.current.userInterfaceIdiom == .phone
// or
UIDevice.current.userInterfaceIdiom == .pad

Usage would then be something like:

if UIDevice.current.userInterfaceIdiom == .pad {
    // Available Idioms - .pad, .phone, .tv, .carPlay, .unspecified
    // Implement your logic here
}

Insert a row to pandas dataframe

We can use numpy.insert. This has the advantage of flexibility. You only need to specify the index you want to insert to.

s1 = pd.Series([5, 6, 7])
s2 = pd.Series([7, 8, 9])

df = pd.DataFrame([list(s1), list(s2)],  columns =  ["A", "B", "C"])

pd.DataFrame(np.insert(df.values, 0, values=[2, 3, 4], axis=0))

    0   1   2
0   2   3   4
1   5   6   7
2   7   8   9

For np.insert(df.values, 0, values=[2, 3, 4], axis=0), 0 tells the function the place/index you want to place the new values.

Is there a way to automatically build the package.json file for Node.js projects

1. Choice

If you git and GitHub user:

generate-package more simply, than npm init.

else

and/or you don't like package.json template, that generate-package or npm init generate:

you can generate your own template via scaffolding apps as generate, sails or yeoman.

2. Relevance

This answer is relevant for March 2018. In the future, the data from this answer may be obsolete.

Author of this answer personally used generate-package at March 2018.

3. Limitations

You need use git and GitHub for using generate-package.

4. Demonstration

For example, I create blank folder sasha-npm-init-vs-generate-package.

4.1. generate-package

Command:

D:\SashaDemoRepositories\sasha-npm-init-vs-generate-package>gen package
[16:58:52] starting generate
[16:59:01] v running tasks: [ 'package' ]
[16:59:04] starting package
? Project description? generate-package demo
? Author's name? Sasha Chernykh
? Author's URL? https://vk.com/hair_in_the_wind
[17:00:19] finished package v 1m

package.json:

{
  "name": "sasha-npm-init-vs-generate-package",
  "description": "generate-package demo",
  "version": "0.1.0",
  "homepage": "https://github.com/Kristinita/sasha-npm-init-vs-generate-package",
  "author": "Sasha Chernykh (https://vk.com/hair_in_the_wind)",
  "repository": "Kristinita/sasha-npm-init-vs-generate-package",
  "bugs": {
    "url": "https://github.com/Kristinita/sasha-npm-init-vs-generate-package/issues"
  },
  "license": "MIT",
  "engines": {
    "node": ">=4"
  },
  "scripts": {
    "test": "mocha"
  },
  "keywords": [
    "generate",
    "init",
    "npm",
    "package",
    "sasha",
    "vs"
  ]
}

4.2. npm init

D:\SashaDemoRepositories\sasha-npm-init-vs-generate-package>npm init
This utility will walk you through creating a package.json file.
It only covers the most common items, and tries to guess sensible defaults.

See `npm help json` for definitive documentation on these fields
and exactly what they do.

Use `npm install <pkg>` afterwards to install a package and
save it as a dependency in the package.json file.

Press ^C at any time to quit.
package name: (sasha-npm-init-vs-generate-package)
version: (1.0.0) 0.1.0
description: npm init demo
entry point: (index.js)
test command: mocha
git repository: https://github.com/Kristinita/sasha-npm-init-vs-generate-package
keywords: generate, package, npm, package, sasha, vs
author: Sasha Chernykh
license: (ISC) MIT
About to write to D:\SashaDemoRepositories\sasha-npm-init-vs-generate-package\package.json:

{
  "name": "sasha-npm-init-vs-generate-package",
  "version": "0.1.0",
  "description": "npm init demo",
  "main": "index.js",
  "scripts": {
    "test": "mocha"
  },
  "repository": {
    "type": "git",
    "url": "git+https://github.com/Kristinita/sasha-npm-init-vs-generate-package.git"
  },
  "keywords": [
    "generate",
    "package",
    "npm",
    "package",
    "sasha",
    "vs"
  ],
  "author": "Sasha Chernykh",
  "license": "MIT",
  "bugs": {
    "url": "https://github.com/Kristinita/sasha-npm-init-vs-generate-package/issues"
  },
  "homepage": "https://github.com/Kristinita/sasha-npm-init-vs-generate-package#readme"
}


Is this ok? (yes) y

{
  "name": "sasha-npm-init-vs-generate-package",
  "version": "0.1.0",
  "description": "npm init demo",
  "main": "index.js",
  "scripts": {
    "test": "mocha"
  },
  "repository": {
    "type": "git",
    "url": "git+https://github.com/Kristinita/sasha-npm-init-vs-generate-package.git"
  },
  "keywords": [
    "generate",
    "package",
    "npm",
    "package",
    "sasha",
    "vs"
  ],
  "author": "Sasha Chernykh",
  "license": "MIT",
  "bugs": {
    "url": "https://github.com/Kristinita/sasha-npm-init-vs-generate-package/issues"
  },
  "homepage": "https://github.com/Kristinita/sasha-npm-init-vs-generate-package#readme"
}

I think, that generate-package more simply, that npm init.

5. Customizing

That create your own package.json template, see generate and yeoman examples.

How to sort an array based on the length of each element?

<script>
         arr = []
         arr[0] = "ab"
         arr[1] = "abcdefgh"
         arr[2] = "sdfds"
         arr.sort(function(a,b){
            return a.length<b.length
         })
         document.write(arr)

</script>

The anonymous function that you pass to sort tells it how to sort the given array.hope this helps.I know this is confusing but you can tell the sort function how to sort the elements of the array by passing it a function as a parameter telling it what to do

How to get the groups of a user in Active Directory? (c#, asp.net)

GetAuthorizationGroups() does not find nested groups. To really get all groups a given user is a member of (including nested groups), try this:

using System.Security.Principal

private List<string> GetGroups(string userName)
{
    List<string> result = new List<string>();
    WindowsIdentity wi = new WindowsIdentity(userName);

    foreach (IdentityReference group in wi.Groups)
    {
        try
        {
            result.Add(group.Translate(typeof(NTAccount)).ToString());
        }
        catch (Exception ex) { }
    }
    result.Sort();
    return result;
}

I use try/catch because I had some exceptions with 2 out of 200 groups in a very large AD because some SIDs were no longer available. (The Translate() call does a SID -> Name conversion.)

Efficiently getting all divisors of a given number

#include<bits/stdc++.h> 
using namespace std;
typedef long long int ll;
#define MOD 1000000007
#define fo(i,k,n) for(int i=k;i<=n;++i)
#define endl '\n'
ll etf[1000001];
ll spf[1000001];
void sieve(){
    ll i,j;
    for(i=0;i<=1000000;i++) {etf[i]=i;spf[i]=i;}
    for(i=2;i<=1000000;i++){
        if(etf[i]==i){
            for(j=i;j<=1000000;j+=i){
                etf[j]/=i;
                etf[j]*=(i-1);
                if(spf[j]==j)spf[j]=i;
            }
        }
    }
}
void primefacto(ll n,vector<pair<ll,ll>>& vec){
    ll lastprime = 1,k=0;
    while(n>1){
        if(lastprime!=spf[n])vec.push_back(make_pair(spf[n],0));
        vec[vec.size()-1].second++;
        lastprime=spf[n];
        n/=spf[n];
    }
}
void divisors(vector<pair<ll,ll>>& vec,ll idx,vector<ll>& divs,ll num){
    if(idx==vec.size()){
        divs.push_back(num);
        return;
    }
    for(ll i=0;i<=vec[idx].second;i++){
        divisors(vec,idx+1,divs,num*pow(vec[idx].first,i));
    }
}
void solve(){
    ll n;
    cin>>n;
    vector<pair<ll,ll>> vec;
    primefacto(n,vec);
    vector<ll> divs;
    divisors(vec,0,divs,1);
    for(auto it=divs.begin();it!=divs.end();it++){
        cout<<*it<<endl;
    }
}
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    sieve();
    ll t;cin>>t;
    while(t--) solve();
    return 0;
}

How can I remove leading and trailing quotes in SQL Server?

Try this:

SELECT left(right(cast(SampleText as nVarchar),LEN(cast(sampleText as nVarchar))-1),LEN(cast(sampleText as nVarchar))-2)
  FROM TableName

Update multiple rows using select statement

If you have ids in both tables, the following works:

update table2
    set value = (select value from table1 where table1.id = table2.id)

Perhaps a better approach is a join:

update table2
    set value = table1.value
    from table1
    where table1.id = table2.id

Note that this syntax works in SQL Server but may be different in other databases.

How do I see all foreign keys to a table or column?

A quick way to list your FKs (Foreign Key references) using the

KEY_COLUMN_USAGE view:

SELECT CONCAT( table_name, '.',
column_name, ' -> ',
referenced_table_name, '.',
referenced_column_name ) AS list_of_fks
FROM information_schema.KEY_COLUMN_USAGE
WHERE REFERENCED_TABLE_SCHEMA = (your schema name here)
AND REFERENCED_TABLE_NAME is not null
ORDER BY TABLE_NAME, COLUMN_NAME;

This query does assume that the constraints and all referenced and referencing tables are in the same schema.

Add your own comment.

Source: the official mysql manual.

Pandas split column of lists into multiple columns

Based on the previous answers, here is another solution which returns the same result as df2.teams.apply(pd.Series) with a much faster run time:

pd.DataFrame([{x: y for x, y in enumerate(item)} for item in df2['teams'].values.tolist()], index=df2.index)

Timings:

In [1]:
import pandas as pd
d1 = {'teams': [['SF', 'NYG'],['SF', 'NYG'],['SF', 'NYG'],
                ['SF', 'NYG'],['SF', 'NYG'],['SF', 'NYG'],['SF', 'NYG']]}
df2 = pd.DataFrame(d1)
df2 = pd.concat([df2]*1000).reset_index(drop=True)

In [2]: %timeit df2['teams'].apply(pd.Series)

8.27 s ± 2.73 s per loop (mean ± std. dev. of 7 runs, 1 loop each)

In [3]: %timeit pd.DataFrame([{x: y for x, y in enumerate(item)} for item in df2['teams'].values.tolist()], index=df2.index)

35.4 ms ± 5.22 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)

How do I display a ratio in Excel in the format A:B?

Try this formula:

=SUBSTITUTE(TEXT(A1/B1,"?/?"),"/",":")

Result:

A   B   C
33  11  3:1
25  5   5:1
6   4   3:2

Explanation:

TEXT(A1/B1,"?/?") turns A/B into an improper fraction
SUBSTITUTE(...) replaces the "/" in the fraction with a colon

This doesn't require any special toolkits or macros. The only downside might be that the result is considered text--not a number--so you can easily use it for further calculations.

Note: as @Robin Day suggested, increase the number of question marks (?) as desired to reduce rounding (thanks Robin!).

How to get selected value of a dropdown menu in ReactJS

It is as simple as that. You just need to use "value" attributes instead of "defaultValue" or you can keep both if a pre-selected feature is there.

 ....
const [currentValue, setCurrentValue] = useState(2);
<select id = "dropdown" value={currentValue} defaultValue={currentValue}>
     <option value="N/A">N/A</option>
     <option value="1">1</option>
     <option value="2">2</option>
     <option value="3">3</option>
     <option value="4">4</option>
  </select>
.....

setTimeut(()=> {
 setCurrentValue(4);
}, 4000);

In this case, after 4 secs the dropdown will be auto-selected with option 4.

Creating email templates with Django

From the docs, to send HTML e-mail you want to use alternative content-types, like this:

from django.core.mail import EmailMultiAlternatives

subject, from_email, to = 'hello', '[email protected]', '[email protected]'
text_content = 'This is an important message.'
html_content = '<p>This is an <strong>important</strong> message.</p>'
msg = EmailMultiAlternatives(subject, text_content, from_email, [to])
msg.attach_alternative(html_content, "text/html")
msg.send()

You'll probably want two templates for your e-mail - a plain text one that looks something like this, stored in your templates directory under email.txt:

Hello {{ username }} - your account is activated.

and an HTMLy one, stored under email.html:

Hello <strong>{{ username }}</strong> - your account is activated.

You can then send an e-mail using both those templates by making use of get_template, like this:

from django.core.mail import EmailMultiAlternatives
from django.template.loader import get_template
from django.template import Context

plaintext = get_template('email.txt')
htmly     = get_template('email.html')

d = Context({ 'username': username })

subject, from_email, to = 'hello', '[email protected]', '[email protected]'
text_content = plaintext.render(d)
html_content = htmly.render(d)
msg = EmailMultiAlternatives(subject, text_content, from_email, [to])
msg.attach_alternative(html_content, "text/html")
msg.send()

Render partial view with dynamic model in Razor view engine and ASP.NET MVC 3

There's another reason that this can be thrown, even if you're not using dynamic/ExpandoObject. If you are doing a loop, like this:

@foreach (var folder in ViewBag.RootFolder.ChildFolders.ToList())
{
    @Html.Partial("ContentFolderTreeViewItems", folder)
}

In that case, the "var" instead of the type declaration will throw the same error, despite the fact that RootFolder is of type "Folder. By changing the var to the actual type, the problem goes away.

@foreach (ContentFolder folder in ViewBag.RootFolder.ChildFolders.ToList())
{
    @Html.Partial("ContentFolderTreeViewItems", folder)
}

error: No resource identifier found for attribute 'adSize' in package 'com.google.example' main.xml

I had the same problem. I copied the example code from Google code, and could not compile.

xmlns:ads="http://schemas.android.com/apk/res/com.google.example"

Finally, I figured it out. The last part of the code "com.google.example", is their package name, so you need to replace it with your project package.

For example, my project package is "com.jms.AdmobExample", so my ads naming space is:

xmlns:ads="http://schemas.android.com/apk/res/com.jms.AdmobExample"

Check my example, it works fine. You can download the APK to try. I also put my source code here: Add Google Admob in Android Application

MySQL query finding values in a comma separated string

This will work for sure, and I actually tried it out:

lwdba@localhost (DB test) :: DROP TABLE IF EXISTS shirts;
Query OK, 0 rows affected (0.08 sec)

lwdba@localhost (DB test) :: CREATE TABLE shirts
    -> (<BR>
    -> id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
    -> ticketnumber INT,
    -> colors VARCHAR(30)
    -> );<BR>
Query OK, 0 rows affected (0.19 sec)

lwdba@localhost (DB test) :: INSERT INTO shirts (ticketnumber,colors) VALUES
    -> (32423,'1,2,5,12,15'),
    -> (32424,'1,5,12,15,30'),
    -> (32425,'2,5,11,15,28'),
    -> (32426,'1,2,7,12,15'),
    -> (32427,'2,4,8,12,15');
Query OK, 5 rows affected (0.06 sec)
Records: 5  Duplicates: 0  Warnings: 0

lwdba@localhost (DB test) :: SELECT * FROM shirts WHERE LOCATE(CONCAT(',', 1 ,','),CONCAT(',',colors,',')) > 0;
+----+--------------+--------------+
| id | ticketnumber | colors       |
+----+--------------+--------------+
|  1 |        32423 | 1,2,5,12,15  |
|  2 |        32424 | 1,5,12,15,30 |
|  4 |        32426 | 1,2,7,12,15  |
+----+--------------+--------------+
3 rows in set (0.00 sec)

Give it a Try !!!

Why can't I use background image and color together?

To tint an image, you can use CSS3 background to stack images and a linear-gradient. In the example below, I use a linear-gradient with no actual gradient. The browser treats gradients as images (I think it actually generates a bitmap and overlays it) and thus, is actually stacking multiple images.

background: linear-gradient(0deg, rgba(2,173,231,0.5), rgba(2,173,231,0.5)), url(images/mba-grid-5px-bg.png) repeat;

Will yield a graph-paper with light blue tint, if you had the png. Note that the stacking order might work in reverse to your mental model, with the first item being on top.

Excellent documentation by Mozilla, here:

https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Using_multiple_backgrounds

Tool for building the gradients:

http://www.colorzilla.com/gradient-editor/

Note - doesn't work in IE11! I'll post an update when I find out why, since its supposed to.

What is an .inc and why use it?

Just to add. Another disadvantage would be, .inc files are not recognized by IDE thus, you could not take advantage of auto-complete or code prediction features.

Pip "Could not find a that satisfies the requirement"

pygame is not distributed via pip. See this link which provides windows binaries ready for installation.

Install python
Make sure you have python on your PATH
Download the appropriate wheel from this link
Install pip using this tutorial
Finally, use these commands to install pygame wheel with pip
- Python 2 (usually called pip)
  - pip install file.whl
- Python 3 (usually called pip3)
  - pip3 install file.whl

Another tutorial for installing pygame for windows can be found here. Although the instructions are for 64bit windows, it can still be applied to 32bit

dplyr change many data types

Since Nick's answer is deprecated by now and Rafael's comment is really useful, I want to add this as an Answer. If you want to change all factor columns to character use mutate_if:

dat %>% mutate_if(is.factor, as.character)

Also other functions are allowed. I for instance used iconv to change the encoding of all character columns:

dat %>% mutate_if(is.character, function(x){iconv(x, to = "ASCII//TRANSLIT")})

or to substitute all NA by 0 in numeric columns:

dat %>% mutate_if(is.numeric, function(x){ifelse(is.na(x), 0, x)})

Execute cmd command from VBScript

Can also invoke oShell.Exec in order to be able to read STDIN/STDOUT/STDERR responses. Perfect for error checking which it seems you're doing with your sanity .BAT.

How to use the start command in a batch file?

I think this other Stack Overflow answer would solve your problem: How do I run a bat file in the background from another bat file?

Basically, you use the /B and /C options:

START /B CMD /C CALL "foo.bat" [args [...]] >NUL 2>&1

fatal: The current branch master has no upstream branch

Apparently you also get this error message when you forget the --all parameter when pushing for the first time. I wrote

git push -u origin

which gave this error, it should have been

git push -u origin --all

Oh how I love these copy-paste errors ...

How to keep the spaces at the end and/or at the beginning of a String?

Even if you use string formatting, sometimes you still need white spaces at the beginning or the end of your string. For these cases, neither escaping with \, nor xml:space attribute helps. You must use HTML entity   for a whitespace.

Use   for non-breakable whitespace.
Use   for regular space.

Passing an array as an argument to a function in C

You are not passing the array as copy. It is only a pointer pointing to the address where the first element of the array is in memory.

Print Html template in Angular 2 (ng-print in Angular 2)

If you need to print some custom HTML, you can use this method:

ts:

    let control_Print;

    control_Print = document.getElementById('__printingFrame');

    let doc = control_Print.contentWindow.document;
    doc.open();
    doc.write("<div style='color:red;'>I WANT TO PRINT THIS, NOT THE CURRENT HTML</div>");
    doc.close();

    control_Print = control_Print.contentWindow;
    control_Print.focus();
    control_Print.print();

html:

<iframe title="Lets print" id="__printingFrame" style="width: 0; height: 0; border: 0"></iframe>

Multithreading in Bash

Sure, just add & after the command:

read_cfg cfgA &
read_cfg cfgB &
read_cfg cfgC &
wait

all those jobs will then run in the background simultaneously. The optional wait command will then wait for all the jobs to finish.

Each command will run in a separate process, so it's technically not "multithreading", but I believe it solves your problem.

(.text+0x20): undefined reference to `main' and undefined reference to function

This rule

main: producer.o consumer.o AddRemove.o
   $(COMPILER) -pthread $(CCFLAGS) -o producer.o consumer.o AddRemove.o

is wrong. It says to create a file named producer.o (with -o producer.o), but you want to create a file named main. Please excuse the shouting, but ALWAYS USE $@ TO REFERENCE THE TARGET:

main: producer.o consumer.o AddRemove.o
   $(COMPILER) -pthread $(CCFLAGS) -o $@ producer.o consumer.o AddRemove.o

As Shahbaz rightly points out, the gmake professionals would also use $^ which expands to all the prerequisites in the rule. In general, if you find yourself repeating a string or name, you're doing it wrong and should use a variable, whether one of the built-ins or one you create.

main: producer.o consumer.o AddRemove.o
   $(COMPILER) -pthread $(CCFLAGS) -o $@ $^

In Visual Studio Code How do I merge between two local branches?

You can do it without using plugins.

In the latest version of vscode that I'm using (1.17.0) you can simply open the branch that you want (from the bottom left menu) then press ctrl+shift+p and type Git: Merge branch and then choose the other branch that you want to merge from (to the current one)

JAX-WS - Adding SOAP Headers

The best option (for my of course) is do it yourserfl. It means you can modify programattly all parts of the SOAP message

Binding binding = prov.getBinding();
   List<Handler> handlerChain = binding.getHandlerChain();
    handlerChain.add( new ModifyMessageHandler() );
    binding.setHandlerChain( handlerChain );

And the ModifyMessageHandler source could be

@Override
public boolean handleMessage( SOAPMessageContext context )
{
    SOAPMessage msg = context.getMessage(); 
    try
    {

        SOAPEnvelope envelope = msg.getSOAPPart().getEnvelope();
        SOAPHeader header = envelope.addHeader();
        SOAPElement ele = header.addChildElement( new QName( "http://uri", "name_of_header" ) );
        ele.addTextNode( "value_of_header" );
        ele = header.addChildElement( new QName( "http://uri", "name_of_header" ) );
        ele.addTextNode( "value_of_header" );
        ele = header.addChildElement( new QName( "http://uri", "name_of_header" ) );
        ele.addTextNode( "value_of_header" );

...

I hope this helps you

Change background color of edittext in android

I create color.xml file, for naming my color name (black, white...)

 <?xml version="1.0" encoding="utf-8"?>
 <resources>
    <color name="white">#ffffff</color>
    <color name="black">#000000</color>
 </resources>

And in your EditText, set color

<EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="asdsadasdasd"
        android:textColor="@color/black"
        android:background="@color/white"
        />

or use style in you style.xml:

<style name="EditTextStyleWhite" parent="android:style/Widget.EditText">
    <item name="android:textColor">@color/black</item>
    <item name="android:background">@color/white</item>
</style>

and add ctreated style to EditText:

 <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="asdsadasdasd"
        style="@style/EditTextStyleWhite"
        />

Collection was modified; enumeration operation may not execute

This way should cover a situation of concurrency when the function is called again while is still executing (and items need used only once):

 while (list.Count > 0)
 {
    string Item = list[0];
    list.RemoveAt(0);
 
    // do here what you need to do with item
 
 }

If the function get called while is still executing items will not reiterate from the first again as they get deleted as soon as they get used. Should not affect performance much for small lists.

How do I send a file as an email attachment using Linux command line?

From source machine

mysqldump --defaults-extra-file=sql.cnf database | gzip | base64 | mail [email protected]

On Destination machine. Save the received mail body as db.sql.gz.b64; then..

base64 -D -i db.sql.gz.b64 | gzip -d | mysql --defaults-extra-file=sql.cnf

How to stop (and restart) the Rails Server?

Now in rails 5 yu can do:

rails restart

This print by rails --tasks

Restart app by touching tmp/restart.txt

I think that is usefully if you run rails as a demon

Retrieving Dictionary Value Best Practices

I imagine that trygetvalue is doing something more like:

if(myDict.ReallyOptimisedVersionofContains(someKey))
{ 
  someVal = myDict[someKey];
  return true;
}
return false;

So hopefully no try/catch anywhere.

I think it is just a method of convenience really. I generally use it as it saves a line of code or two.

CUSTOM_ELEMENTS_SCHEMA added to NgModule.schemas still showing Error

Just wanted to add a little bit more on this.

With the new angular 2.0.0 final release (sept 14, 2016), if you use custom html tags then it will report that Template parse errors. A custom tag is a tag you use in your HTML that's not one of these tags.

It looks like the line schemas: [ CUSTOM_ELEMENTS_SCHEMA ] need to be added to each component where you are using custom HTML tags.

EDIT: The schemas declaration needs to be in a @NgModule decorator. The example below shows a custom module with a custom component CustomComponent which allows any html tag in the html template for that one component.

custom.module.ts

import { NgModule, CUSTOM_ELEMENTS_SCHEMA } from '@angular/core';
import { CommonModule } from '@angular/common';

import { CustomComponent } from './custom.component';

@NgModule({
  declarations: [ CustomComponent ],
  exports: [ CustomComponent ],
  imports: [ CommonModule ],
  schemas: [ CUSTOM_ELEMENTS_SCHEMA ]
})
export class CustomModule {}

custom.component.ts

import { Component, OnInit } from '@angular/core';

@Component({
  selector: 'my-custom-component',
  templateUrl: 'custom.component.html'
})
export class CustomComponent implements OnInit {
  constructor () {}
  ngOnInit () {}
}

custom.component.html

In here you can use any HTML tag you want.

<div class="container">
  <boogey-man></boogey-man>
  <my-minion class="one-eyed">
    <job class="plumber"></job>
  </my-minion>
</div>

Git: How to pull a single file from a server repository in Git?

Try using:

git checkout branchName -- fileName

Ex:

git checkout master -- index.php

how to set default method argument values?

You can overload the method with different parameters:

public int doSomething(int arg1, int arg2)
{
//some logic here
        return 0;
}

public int doSomething(
{
doSomething(0,0)
}

datetime.parse and making it work with a specific format

DateTime.ParseExact(input,"yyyyMMdd HH:mm",null);

assuming you meant to say that minutes followed the hours, not seconds - your example is a little confusing.

The ParseExact documentation details other overloads, in case you want to have the parse automatically convert to Universal Time or something like that.

As @Joel Coehoorn mentions, there's also the option of using TryParseExact, which will return a Boolean value indicating success or failure of the operation - I'm still on .Net 1.1, so I often forget this one.

If you need to parse other formats, you can check out the Standard DateTime Format Strings.

Node.js res.setHeader('content-type', 'text/javascript'); pushing the response javascript as file download

Use application/javascript as content type instead of text/javascript

text/javascript is mentioned obsolete. See reference docs.

http://www.iana.org/assignments/media-types/application

Also see this question on SO.

UPDATE:

I have tried executing the code you have given and the below didn't work.

res.setHeader('content-type', 'text/javascript');
res.send(JS_Script);

This is what worked for me.

res.setHeader('content-type', 'text/javascript');
res.end(JS_Script);

As robertklep has suggested, please refer to the node http docs, there is no response.send() there.

What is the path that Django uses for locating and loading templates?

In django 2.2 this is explained here

https://docs.djangoproject.com/en/2.2/howto/overriding-templates/

import os

BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))

INSTALLED_APPS = [
    ...,
    'blog',
    ...,
]

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [os.path.join(BASE_DIR, 'templates')],
        'APP_DIRS': True,
        ...
    },
]

jQuery attr('onclick')

As @Richard pointed out above, the onClick needs to have a capital 'C'.

$('#stop').click(function() {
     $('next').attr('onClick','stopMoving()');
}

IE6/IE7 css border on select element

It solves to me, for my purposes:

.select-container {
  position:relative;
  width:200px;
  height:18px;
  overflow:hidden;
  border:1px solid white !important
}
.select-container select {
  position:relative;
  left:-2px;
  top:-2px
}

To put more style will be necessary to use nested divs .

Android load from URL to Bitmap

fun getBitmap(url : String?) : Bitmap? {
    var bmp : Bitmap ? = null
    Picasso.get().load(url).into(object : com.squareup.picasso.Target {
        override fun onBitmapLoaded(bitmap: Bitmap?, from: Picasso.LoadedFrom?) {
            bmp =  bitmap
        }

        override fun onPrepareLoad(placeHolderDrawable: Drawable?) {}

        override fun onBitmapFailed(e: Exception?, errorDrawable: Drawable?) {}
    })
    return bmp
}

Try this with picasso

"TypeError: (Integer) is not JSON serializable" when serializing JSON in Python?

You have Numpy Data Type, Just change to normal int() or float() data type. it will work fine.

How to get date in BAT file

%date% will give you the date.

%time% will give you the time.

The date and time /t commands may give you more detail.

No suitable driver found for 'jdbc:mysql://localhost:3306/mysql

In this particular case (assuming that the Class#forName() didn't throw an exception; your code is namely continuing with running instead of throwing the exception), this SQLException means that Driver#acceptsURL() has returned false for any of the loaded drivers.

And indeed, your JDBC URL is wrong:

String url = "'jdbc:mysql://localhost:3306/mysql";

Remove the singlequote:

String url = "jdbc:mysql://localhost:3306/mysql";

Twitter Bootstrap tabs not working: when I click on them nothing happens

Since i'm working with Bootstrap Javascript Modules instead of loading the entire Bootstrap Javascript, my tabs were not working because i forgot to load load/include/ the node_modules/bootstrap/js/tab.js file.

After including it, it worked...

Good Luck

What is the difference between up-casting and down-casting with respect to class variable

Upcasting and downcasting are important part of Java, which allow us to build complicated programs using simple syntax, and gives us great advantages, like Polymorphism or grouping different objects. Java permits an object of a subclass type to be treated as an object of any superclass type. This is called upcasting. Upcasting is done automatically, while downcasting must be manually done by the programmer, and i'm going to give my best to explain why is that so.

Upcasting and downcasting are NOT like casting primitives from one to other, and i believe that's what causes a lot of confusion, when programmer starts to learn casting objects.

Polymorphism: All methods in java are virtual by default. That means that any method can be overridden when used in inheritance, unless that method is declared as final or static.

You can see the example below how getType(); works according to the object(Dog,Pet,Police Dog) type.

Assume you have three dogs

Dog - This is the super Class.
Pet Dog - Pet Dog extends Dog.

Police Dog - Police Dog extends Pet Dog.

public class Dog{ 
   public String getType () {
      System.out.println("NormalDog");
      return "NormalDog";
   }
 }

/**
 * Pet Dog has an extra method dogName()
 */   
public class PetDog extends Dog{ 
   public String getType () {
      System.out.println("PetDog");
      return "PetDog";
   }
   public String dogName () {
      System.out.println("I don't have Name !!");
      return "NO Name";
   }
 }

/**
 * Police Dog has an extra method secretId()
 */
public class PoliceDog extends PetDog{

 public String secretId() {
    System.out.println("ID");
    return "ID";
 }

 public String getType () {
     System.out.println("I am a Police Dog");
     return "Police Dog";
 }
}

Polymorphism : All methods in java are virtual by default. That means that any method can be overridden when used in inheritance, unless that method is declared as final or static.(Explanation Belongs to Virtual Tables Concept)

Virtual Table / Dispatch Table : An object's dispatch table will contain the addresses of the object's dynamically bound methods. Method calls are performed by fetching the method's address from the object's dispatch table. The dispatch table is the same for all objects belonging to the same class, and is therefore typically shared between them.

public static void main (String[] args) {
      /**
       * Creating the different objects with super class Reference
       */
     Dog obj1 = new Dog();
`         /**
           *  Object of Pet Dog is created with Dog Reference since                
           *  Upcasting is done automatically for us we don't have to worry about it 
           *  
           */
     Dog obj2 = new PetDog();
`         /**
           *  Object of Police Dog is created with Dog Reference since                
           *  Upcasting is done automatically for us we don't have to worry       
           *  about it here even though we are extending PoliceDog with PetDog 
           *  since PetDog is extending Dog Java automatically upcast for us 
           */
      Dog obj3 = new PoliceDog();
}



 obj1.getType();

Prints Normal Dog

  obj2.getType();

Prints Pet Dog

 obj3.getType();

Prints Police Dog

Downcasting need to be done by the programmer manually

When you try to invoke the secretID(); method on obj3 which is PoliceDog object but referenced to Dog which is a super class in the hierarchy it throws error since obj3 don't have access to secretId() method.In order to invoke that method you need to Downcast that obj3 manually to PoliceDog

  ( (PoliceDog)obj3).secretID();

which prints ID

In the similar way to invoke the dogName();method in PetDog class you need to downcast obj2 to PetDog since obj2 is referenced to Dog and don't have access to dogName(); method

  ( (PetDog)obj2).dogName();

Why is that so, that upcasting is automatical, but downcasting must be manual? Well, you see, upcasting can never fail. But if you have a group of different Dogs and want to downcast them all to a to their types, then there's a chance, that some of these Dogs are actually of different types i.e., PetDog, PoliceDog, and process fails, by throwing ClassCastException.

This is the reason you need to downcast your objects manually if you have referenced your objects to the super class type.

Note: Here by referencing means you are not changing the memory address of your ojects when you downcast it it still remains same you are just grouping them to particular type in this case Dog

Clear input fields on form submit

Still using empty strings you can use:

document.getElementById("name").value = '';
document.getElementById("review").value = '';

How/when to generate Gradle wrapper files?

This is the command to use to tell Gradle to upgrade the wrapper such that it will grab the distribution versions of libraries that includes source code:

./gradlew wrapper --gradle-version <version> --distribution-type all

Specifying the distribution-type with "all" will make sure Gradle downloads source files for use by your development environment.

Pros:

IDEs will have immediate access to source code. For example, Intellij IDEA won't prompt you to update your build scripts to include the source distro (because this command already did that)

Cons:

Longer/Bigger build process because it's downloading source code. This is a waste of time/space on a build or CI server where the source code is not necessary.

Please comment or provide another answer if you know of any command line option to tell Gradle not to download sources on a build server.

How can I convert string date to NSDate?

 func convertDateFormatter(date: String) -> String
 {

    let dateFormatter = NSDateFormatter()
    dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"//this your string date format
    dateFormatter.timeZone = NSTimeZone(name: "UTC")
    let date = dateFormatter.dateFromString(date)


    dateFormatter.dateFormat = "yyyy MMM EEEE HH:mm"///this is what you want to convert format
    dateFormatter.timeZone = NSTimeZone(name: "UTC")
    let timeStamp = dateFormatter.stringFromDate(date!)


    return timeStamp
}

Updated for Swift 3.

func convertDateFormatter(date: String) -> String
{

    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"//this your string date format
    dateFormatter.timeZone = NSTimeZone(name: "UTC") as TimeZone!
    let date = dateFormatter.date(from: date)


    dateFormatter.dateFormat = "yyyy MMM EEEE HH:mm"///this is what you want to convert format
    dateFormatter.timeZone = NSTimeZone(name: "UTC") as TimeZone!
    let timeStamp = dateFormatter.string(from: date!)


    return timeStamp
}

How to restart a node.js server

Using "kill -9 [PID]" or "killall -9 node" worked for me where "kill -2 [PID]" did not work.

How to declare and use 1D and 2D byte arrays in Verilog?

Verilog thinks in bits, so reg [7:0] a[0:3] will give you a 4x8 bit array (=4x1 byte array). You get the first byte out of this with a[0]. The third bit of the 2nd byte is a[1][2].

For a 2D array of bytes, first check your simulator/compiler. Older versions (pre '01, I believe) won't support this. Then reg [7:0] a [0:3] [0:3] will give you a 2D array of bytes. A single bit can be accessed with a[2][0][7] for example.

reg [7:0] a [0:3];
reg [7:0] b [0:3] [0:3];

reg [7:0] c;
reg d;

initial begin

   for (int i=0; i<=3; i++) begin
      a[i] = i[7:0];
   end

   c = a[0];
   d = a[1][2]; 


   // using 2D
   for (int i=0; i<=3; i++)
      for (int j=0; j<=3; j++)
          b[i][j] = i*j;  // watch this if you're building hardware

end

Compare objects in Angular

Assuming that the order is the same in both objects, just stringify them both and compare!

JSON.stringify(obj1) == JSON.stringify(obj2);

SQL Server: How to check if CLR is enabled?

This is @Jason's answer but with simplified output

SELECT name, CASE WHEN value = 1 THEN 'YES' ELSE 'NO' END AS 'Enabled'
FROM sys.configurations WHERE name = 'clr enabled'

The above returns the following:

| name        | Enabled |
-------------------------
| clr enabled | YES     |

Tested on SQL Server 2017

Easiest way to convert a Blob into a byte array

the mySql blob class has the following function :

blob.getBytes

use it like this:

//(assuming you have a ResultSet named RS)
Blob blob = rs.getBlob("SomeDatabaseField");

int blobLength = (int) blob.length();  
byte[] blobAsBytes = blob.getBytes(1, blobLength);

//release the blob and free up memory. (since JDBC 4.0)
blob.free();

How can I auto increment the C# assembly version via our CI platform (Hudson)?

My solution doesn't require the addition of external tools or scripting languages --it's pretty much guaranteed to work on your build machine. I solve this problem in several parts. First, I have created a BUILD.BAT file that converts the Jenkins BUILD_NUMBER parameter into an environment variable. I use Jenkins's "Execute Windows batch command" function to run the build batch file by entering the following information for the Jenkins build:

     ./build.bat --build_id %BUILD_ID% -build_number %BUILD_NUMBER%

In the build environment, I have a build.bat file that starts as follows:

     rem build.bat
     set BUILD_ID=Unknown
     set BUILD_NUMBER=0
     :parse_command_line
     IF NOT "%1"=="" (
         IF "%1"=="-build_id" (
             SET BUILD_ID=%2
             SHIFT
             )
         IF "%1"=="-build_number" (
             SET BUILD_NUMBER=%2
             SHIFT
         )
         SHIFT
         GOTO :parse_command_line
     )
     REM your build continues with the environmental variables set
     MSBUILD.EXE YourProject.sln

Once I did that, I right-clicked on the project to be built in Visual Studio's Solution Explorer pane and selected Properties, select Build Events, and entered the following information as the Pre-Build Event Command Line, which automatically creates a .cs file containing build number information based on current environment variable settings:

     set VERSION_FILE=$(ProjectDir)\Properties\VersionInfo.cs
     if !%BUILD_NUMBER%==! goto no_buildnumber_set
     goto buildnumber_set
     :no_buildnumber_set
     set BUILD_NUMBER=0
     :buildnumber_set
     if not exist %VERSION_FILE% goto no_version_file
     del /q %VERSION_FILE%
     :no_version_file
     echo using System.Reflection; >> %VERSION_FILE%
     echo using System.Runtime.CompilerServices; >> %VERSION_FILE%
     echo using System.Runtime.InteropServices; >> %VERSION_FILE%
     echo [assembly: AssemblyVersion("0.0.%BUILD_NUMBER%.1")] >> %VERSION_FILE%
     echo [assembly: AssemblyFileVersion("0.0.%BUILD_NUMBER%.1")] >> %VERSION_FILE%

You may need to adjust to your build taste. I build the project manually once to generate an initial Version.cs file in the Properties directory of the main project. Lastly, I manually include the Version.cs file into the Visual Studio solution by dragging it into the Solution Explorer pane, underneath the Properties tab for that project. In future builds, Visual Studio then reads that .cs file at Jenkins build time and gets the correct build number information out of it.

How can I use the python HTMLParser library to extract data from a specific div tag?

Little correction at Line 3

HTMLParser.HTMLParser.__init__(self)

it should be

HTMLParser.__init__(self)

The following worked for me though

import urllib2 

from HTMLParser import HTMLParser  

class MyHTMLParser(HTMLParser):

  def __init__(self):
    HTMLParser.__init__(self)
    self.recording = 0 
    self.data = []
  def handle_starttag(self, tag, attrs):
    if tag == 'required_tag':
      for name, value in attrs:
        if name == 'somename' and value == 'somevale':
          print name, value
          print "Encountered the beginning of a %s tag" % tag 
          self.recording = 1 


  def handle_endtag(self, tag):
    if tag == 'required_tag':
      self.recording -=1 
      print "Encountered the end of a %s tag" % tag 

  def handle_data(self, data):
    if self.recording:
      self.data.append(data)

 p = MyHTMLParser()
 f = urllib2.urlopen('http://www.someurl.com')
 html = f.read()
 p.feed(html)
 print p.data
 p.close()

Android SDK folder taking a lot of disk space. Do we need to keep all of the System Images?

I had 20.8 GB in the C:\Users\ggo\AppData\Local\Android\Sdk\system-images folder (6 android images: - android-10 - android-15 - android-21 - android-23 - android-25 - android-26 ).

I have compressed the C:\Users\ggo\AppData\Local\Android\Sdk\system-images folder.

Now it takes only 4.65 GB.

$C:\Users\ggo\AppData\Local\Android\Sdk\system-images$

I did not encountered any problem up to now...

Compression seems to vary from 2/3 to 6, sometimes much more:

Collection was modified; enumeration operation may not execute in ArrayList

Here's an example (sorry for any typos)

var itemsToRemove = new ArrayList();  // should use generic List if you can

foreach (var item in originalArrayList) {
  if (...) {
    itemsToRemove.Add(item);
  }
}

foreach (var item in itemsToRemove) {
  originalArrayList.Remove(item);
}

OR if you're using 3.5, Linq makes the first bit easier:

itemsToRemove = originalArrayList
  .Where(item => ...)
  .ToArray();

foreach (var item in itemsToRemove) {
  originalArrayList.Remove(item);
}

Replace "..." with your condition that determines if item should be removed.

Why do we need middleware for async flow in Redux?

You don't.

But... you should use redux-saga :)

Dan Abramov's answer is right about redux-thunk but I will talk a bit more about redux-saga that is quite similar but more powerful.

Imperative VS declarative

DOM: jQuery is imperative / React is declarative
Monads: IO is imperative / Free is declarative
Redux effects: redux-thunk is imperative / redux-saga is declarative

When you have a thunk in your hands, like an IO monad or a promise, you can't easily know what it will do once you execute. The only way to test a thunk is to execute it, and mock the dispatcher (or the whole outside world if it interacts with more stuff...).

If you are using mocks, then you are not doing functional programming.

Seen through the lens of side-effects, mocks are a flag that your code is impure, and in the functional programmer's eye, proof that something is wrong. Instead of downloading a library to help us check the iceberg is intact, we should be sailing around it. A hardcore TDD/Java guy once asked me how you do mocking in Clojure. The answer is, we usually don't. We usually see it as a sign we need to refactor our code.

Source

The sagas (as they got implemented in redux-saga) are declarative and like the Free monad or React components, they are much easier to test without any mock.

Confusion: actions/events/commands...

There is a lot of confusion in the frontend world on how some backend concepts like CQRS / EventSourcing and Flux / Redux may be related, mostly because in Flux we use the term "action" which can sometimes represent both imperative code (LOAD_USER) and events (USER_LOADED). I believe that like event-sourcing, you should only dispatch events.

Using sagas in practice

Imagine an app with a link to a user profile. The idiomatic way to handle this with each middleware would be:

`redux-thunk`

<div onClick={e => dispatch(actions.loadUserProfile(123)}>Robert</div>

function loadUserProfile(userId) {
  return dispatch => fetch(`http://data.com/${userId}`)
    .then(res => res.json())
    .then(
      data => dispatch({ type: 'USER_PROFILE_LOADED', data }),
      err => dispatch({ type: 'USER_PROFILE_LOAD_FAILED', err })
    );
}

`redux-saga`

<div onClick={e => dispatch({ type: 'USER_NAME_CLICKED', payload: 123 })}>Robert</div>


function* loadUserProfileOnNameClick() {
  yield* takeLatest("USER_NAME_CLICKED", fetchUser);
}

function* fetchUser(action) {
  try {
    const userProfile = yield fetch(`http://data.com/${action.payload.userId }`)
    yield put({ type: 'USER_PROFILE_LOADED', userProfile })
  } 
  catch(err) {
    yield put({ type: 'USER_PROFILE_LOAD_FAILED', err })
  }
}

This saga translates to:

every time a username gets clicked, fetch the user profile and then dispatch an event with the loaded profile.

As you can see, there are some advantages of redux-saga.

The usage of takeLatest permits to express that you are only interested to get the data of the last username clicked (handle concurrency problems in case the user click very fast on a lot of usernames). This kind of stuff is hard with thunks. You could have used takeEvery if you don't want this behavior.

You keep action creators pure. Note it's still useful to keep actionCreators (in sagas put and components dispatch), as it might help you to add action validation (assertions/flow/typescript) in the future.

Your code becomes much more testable as the effects are declarative

You don't need anymore to trigger rpc-like calls like actions.loadUser(). Your UI just needs to dispatch what HAS HAPPENED. We only fire events (always in the past tense!) and not actions anymore. This means that you can create decoupled "ducks" or Bounded Contexts and that the saga can act as the coupling point between these modular components.

This means that your views are more easy to manage because they don't need anymore to contain that translation layer between what has happened and what should happen as an effect

For example imagine an infinite scroll view. CONTAINER_SCROLLED can lead to NEXT_PAGE_LOADED, but is it really the responsibility of the scrollable container to decide whether or not we should load another page? Then he has to be aware of more complicated stuff like whether or not the last page was loaded successfully or if there is already a page that tries to load, or if there is no more items left to load? I don't think so: for maximum reusability the scrollable container should just describe that it has been scrolled. The loading of a page is a "business effect" of that scroll

Some might argue that generators can inherently hide state outside of redux store with local variables, but if you start to orchestrate complex things inside thunks by starting timers etc you would have the same problem anyway. And there's a select effect that now permits to get some state from your Redux store.

Sagas can be time-traveled and also enables complex flow logging and dev-tools that are currently being worked on. Here is some simple async flow logging that is already implemented:

Decoupling

Sagas are not only replacing redux thunks. They come from backend / distributed systems / event-sourcing.

It is a very common misconception that sagas are just here to replace your redux thunks with better testability. Actually this is just an implementation detail of redux-saga. Using declarative effects is better than thunks for testability, but the saga pattern can be implemented on top of imperative or declarative code.

In the first place, the saga is a piece of software that permits to coordinate long running transactions (eventual consistency), and transactions across different bounded contexts (domain driven design jargon).

To simplify this for frontend world, imagine there is widget1 and widget2. When some button on widget1 is clicked, then it should have an effect on widget2. Instead of coupling the 2 widgets together (ie widget1 dispatch an action that targets widget2), widget1 only dispatch that its button was clicked. Then the saga listen for this button click and then update widget2 by dispaching a new event that widget2 is aware of.

This adds a level of indirection that is unnecessary for simple apps, but make it more easy to scale complex applications. You can now publish widget1 and widget2 to different npm repositories so that they never have to know about each others, without having them to share a global registry of actions. The 2 widgets are now bounded contexts that can live separately. They do not need each others to be consistent and can be reused in other apps as well. The saga is the coupling point between the two widgets that coordinate them in a meaningful way for your business.

Some nice articles on how to structure your Redux app, on which you can use Redux-saga for decoupling reasons:

A concrete usecase: notification system

I want my components to be able to trigger the display of in-app notifications. But I don't want my components to be highly coupled to the notification system that has its own business rules (max 3 notifications displayed at the same time, notification queueing, 4 seconds display-time etc...).

I don't want my JSX components to decide when a notification will show/hide. I just give it the ability to request a notification, and leave the complex rules inside the saga. This kind of stuff is quite hard to implement with thunks or promises.

I've described here how this can be done with saga

Why is it called a Saga?

The term saga comes from the backend world. I initially introduced Yassine (the author of Redux-saga) to that term in a long discussion.

Initially, that term was introduced with a paper, the saga pattern was supposed to be used to handle eventual consistency in distributed transactions, but its usage has been extended to a broader definition by backend developers so that it now also covers the "process manager" pattern (somehow the original saga pattern is a specialized form of process manager).

Today, the term "saga" is confusing as it can describe 2 different things. As it is used in redux-saga, it does not describe a way to handle distributed transactions but rather a way to coordinate actions in your app. redux-saga could also have been called redux-process-manager.

Alternatives

If you don't like the idea of using generators but you are interested by the saga pattern and its decoupling properties, you can also achieve the same with redux-observable which uses the name epic to describe the exact same pattern, but with RxJS. If you're already familiar with Rx, you'll feel right at home.

const loadUserProfileOnNameClickEpic = action$ =>
  action$.ofType('USER_NAME_CLICKED')
    .switchMap(action =>
      Observable.ajax(`http://data.com/${action.payload.userId}`)
        .map(userProfile => ({
          type: 'USER_PROFILE_LOADED',
          userProfile
        }))
        .catch(err => Observable.of({
          type: 'USER_PROFILE_LOAD_FAILED',
          err
        }))
    );

Some redux-saga useful resources

2017 advises

Don't overuse Redux-saga just for the sake of using it. Testable API calls only are not worth it.
Don't remove thunks from your project for most simple cases.
Don't hesitate to dispatch thunks in yield put(someActionThunk) if it makes sense.

If you are frightened of using Redux-saga (or Redux-observable) but just need the decoupling pattern, check redux-dispatch-subscribe: it permits to listen to dispatches and trigger new dispatches in listener.

const unsubscribe = store.addDispatchListener(action => {
  if (action.type === 'ping') {
    store.dispatch({ type: 'pong' });
  }
});

How do I convert a PDF document to a preview image in PHP?

You need ImageMagick and GhostScript

<?php
$im = new imagick('file.pdf[0]');
$im->setImageFormat('jpg');
header('Content-Type: image/jpeg');
echo $im;
?>

The [0] means page 1.

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