Programs & Examples On #Discriminator

A discriminator is a column used in object-relational mapping problems to describe inheritance. It is often, but not exclusively, associated with the single table per class hierarchy approach.

How to emulate a BEFORE INSERT trigger in T-SQL / SQL Server for super/subtype (Inheritance) entities?

While Andriy's proposal will work well for INSERTs of a small number of records, full table scans will be done on the final join as both 'enumerated' and '@new_super' are not indexed, resulting in poor performance for large inserts.

This can be resolved by specifying a primary key on the @new_super table, as follows:

DECLARE @new_super TABLE (
  row_num INT IDENTITY(1,1) PRIMARY KEY CLUSTERED,
  super_id   int
);

This will result in the SQL optimizer scanning through the 'enumerated' table but doing an indexed join on @new_super to get the new key.

EF Code First "Invalid column name 'Discriminator'" but no inheritance

I get the error in another situation, and here are the problem and the solution:

I have 2 classes derived from a same base class named LevledItem:

public partial class Team : LeveledItem
{
   //Everything is ok here!
}
public partial class Story : LeveledItem
{
   //Everything is ok here!
}

But in their DbContext, I copied some code but forget to change one of the class name:

public class MFCTeamDbContext : DbContext
{
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        //Other codes here
        modelBuilder.Entity<LeveledItem>()
            .Map<Team>(m => m.Requires("Type").HasValue(ItemType.Team));
    }

public class ProductBacklogDbContext : DbContext
{
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        //Other codes here
        modelBuilder.Entity<LeveledItem>()
            .Map<Team>(m => m.Requires("Type").HasValue(ItemType.Story));
    }

Yes, the second Map< Team> should be Map< Story>. And it cost me half a day to figure it out!

Image vs zImage vs uImage

What is the difference between them?

Image: the generic Linux kernel binary image file.

zImage: a compressed version of the Linux kernel image that is self-extracting.

uImage: an image file that has a U-Boot wrapper (installed by the mkimage utility) that includes the OS type and loader information.
A very common practice (e.g. the typical Linux kernel Makefile) is to use a zImage file. Since a zImage file is self-extracting (i.e. needs no external decompressors), the wrapper would indicate that this kernel is "not compressed" even though it actually is.


Note that the author/maintainer of U-Boot considers the (widespread) use of using a zImage inside a uImage questionable:

Actually it's pretty stupid to use a zImage inside an uImage. It is much better to use normal (uncompressed) kernel image, compress it using just gzip, and use this as poayload for mkimage. This way U-Boot does the uncompresiong instead of including yet another uncompressor with each kernel image.

(quoted from https://lists.yoctoproject.org/pipermail/yocto/2013-October/016778.html)


Which type of kernel image do I have to use?

You could choose whatever you want to program for.
For economy of storage, you should probably chose a compressed image over the uncompressed one.
Beware that executing the kernel (presumably the Linux kernel) involves more than just loading the kernel image into memory. Depending on the architecture (e.g. ARM) and the Linux kernel version (e.g. with or without DTB), there are registers and memory buffers that may have to be prepared for the kernel. In one instance there was also hardware initialization that U-Boot performed that had to be replicated.

ADDENDUM

I know that u-boot needs a kernel in uImage format.

That is accurate for all versions of U-Boot which only have the bootm command.
But more recent versions of U-Boot could also have the bootz command that can boot a zImage.

Is this the proper way to do boolean test in SQL?

With Postgres, you may use

select * from users where active

or

select * from users where active = 't'

If you want to use integer value, you have to consider it as a string. You can't use integer value.

select * from users where active = 1   -- Does not work

select * from users where active = '1' -- Works 

How do I retrieve the number of columns in a Pandas data frame?

Surprised I haven't seen this yet, so without further ado, here is:

df.columns.size

How do I get a list of folders and sub folders without the files?

dir /ad /b /s will give the required answer.

How to lock specific cells but allow filtering and sorting

I just came up with a tricky way to get almost the same functionality. Instead of protecting the sheet the normal way, use an event handler to undo anything the user tries to do.

Add the following to the worksheet's module:

Private Sub Worksheet_Change(ByVal Target As Range)
    If Target.Locked = True Then
        Application.EnableEvents = False
        Application.Undo
        Application.EnableEvents = True
    End If
End Sub

If the user does anything to change a cell that's locked, the action will get immediately undone. The temporary disabling of events is to keep the undoing itself from triggering this event, resulting in an infinite loop.

Sorting and filtering do not trigger the Change event, so those functions remain enabled.

Note that this solution prevents changing or clearing cell contents, but does not prevent changing formats. A determined user could get around it by simply setting the cells to be unlocked.

c# Image resizing to different size while preserving aspect ratio

This should do it.

private void resizeImage(string path, string originalFilename, 
                     /* note changed names */
                     int canvasWidth, int canvasHeight, 
                     /* new */
                     int originalWidth, int originalHeight)
{
    Image image = Image.FromFile(path + originalFilename);

    System.Drawing.Image thumbnail = 
        new Bitmap(canvasWidth, canvasHeight); // changed parm names
    System.Drawing.Graphics graphic = 
                 System.Drawing.Graphics.FromImage(thumbnail);

    graphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
    graphic.SmoothingMode = SmoothingMode.HighQuality;
    graphic.PixelOffsetMode = PixelOffsetMode.HighQuality;
    graphic.CompositingQuality = CompositingQuality.HighQuality;

    /* ------------------ new code --------------- */

    // Figure out the ratio
    double ratioX = (double) canvasWidth / (double) originalWidth;
    double ratioY = (double) canvasHeight / (double) originalHeight;
    // use whichever multiplier is smaller
    double ratio = ratioX < ratioY ? ratioX : ratioY;

    // now we can get the new height and width
    int newHeight = Convert.ToInt32(originalHeight * ratio);
    int newWidth = Convert.ToInt32(originalWidth * ratio);

    // Now calculate the X,Y position of the upper-left corner 
    // (one of these will always be zero)
    int posX = Convert.ToInt32((canvasWidth - (originalWidth * ratio)) / 2);
    int posY = Convert.ToInt32((canvasHeight - (originalHeight * ratio)) / 2);

    graphic.Clear(Color.White); // white padding
    graphic.DrawImage(image, posX, posY, newWidth, newHeight);

    /* ------------- end new code ---------------- */

    System.Drawing.Imaging.ImageCodecInfo[] info =
                     ImageCodecInfo.GetImageEncoders();
    EncoderParameters encoderParameters;
    encoderParameters = new EncoderParameters(1);
    encoderParameters.Param[0] = new EncoderParameter(Encoder.Quality,
                     100L);            
    thumbnail.Save(path + newWidth + "." + originalFilename, info[1], 
                     encoderParameters);
}

Edited to add:

Those who want to improve this code should put it in the comments, or a new answer. Don't edit this code directly.

react-native: command not found

Install react-native globally by using the following command

npm i -g react-native-cli

Using :focus to style outer div?

focus-within

.box:focus-within {
  background: cyan;
}

read more here

Is there an upside down caret character?

You might be able to use the black triangles, Unicode values U+25b2 and U+25bc. Or the arrows, U+2191 and U+2193.

Spring: Returning empty HTTP Responses with ResponseEntity<Void> doesn't work

You can also not specify the type parameter which seems a bit cleaner and what Spring intended when looking at the docs:

@RequestMapping(method = RequestMethod.HEAD, value = Constants.KEY )
public ResponseEntity taxonomyPackageExists( @PathVariable final String key ){
    // ...
    return new ResponseEntity(HttpStatus.NO_CONTENT);
}

document.getElementById vs jQuery $()

One other difference: getElementById returns the first match, while $('#...') returns a collection of matches - yes, the same ID can be repeated in an HTML doc.

Further, getElementId is called from the document, while $('#...') can be called from a selector. So, in the code below, document.getElementById('content') will return the entire body but $('form #content')[0] will return inside of the form.

<body id="content">
   <h1>Header!</h1>
   <form>
      <div id="content"> My Form </div>
   </form>
</body>

It might seem odd to use duplicate IDs, but if you are using something like Wordpress, a template or plugin might use the same id as you use in the content. The selectivity of jQuery could help you out there.

How to retrieve the last autoincremented ID from a SQLite table?

One other option is to look at the system table sqlite_sequence. Your sqlite database will have that table automatically if you created any table with autoincrement primary key. This table is for sqlite to keep track of the autoincrement field so that it won't repeat the primary key even after you delete some rows or after some insert failed (read more about this here http://www.sqlite.org/autoinc.html).

So with this table there is the added benefit that you can find out your newly inserted item's primary key even after you inserted something else (in other tables, of course!). After making sure that your insert is successful (otherwise you will get a false number), you simply need to do:

select seq from sqlite_sequence where name="table_name"

Checking if an object is a number in C#

While writing my own object.IsNumeric() extension method based on Saul Dolgin's answer to this question I ran into a potential issue in that you will get an OverflowException if you try it with double.MaxValue or double.MinValue.

My "solution" was to combine the accepted answer from Noldorin with the one from Saul Dolgin and add a pattern matching switch before trying to parse anything (and use some C#7 goodness to tidy up a bit):

public static bool IsNumeric(this object obj)
{
    if (obj == null) return false;

    switch (obj)
    {
        case sbyte _: return true;
        case byte _: return true;
        case short _: return true;
        case ushort _: return true;
        case int _: return true;
        case uint _: return true;
        case long _: return true;
        case ulong _: return true;
        case float _: return true;
        case double _: return true;
        case decimal _: return true;
    }

    string s = Convert.ToString(obj, CultureInfo.InvariantCulture);

    return double.TryParse(s, NumberStyles.Any, NumberFormatInfo.InvariantInfo, out double _);
}

In jQuery, what's the best way of formatting a number to 2 decimal places?

Maybe something like this, where you could select more than one element if you'd like?

$("#number").each(function(){
    $(this).val(parseFloat($(this).val()).toFixed(2));
});

How can I use Google's Roboto font on a website?

With css:

@font-face {
  font-family: 'Roboto';
  src: url('../font/Roboto-Regular.ttf') format('truetype');
  font-weight: normal;
  font-style: normal;
}

/* etc, etc. */

With sass:

  @font-face
    font-family: 'Roboto'
    src: local('Roboto'), local('Roboto-Regular'), url('../fonts/Roboto-Regular.ttf') format('truetype')
    font-weight: normal
    font-style: normal

  @font-face
    font-family: 'Roboto'
    src: local('Roboto Bold'), local('Roboto-Bold'), url('../fonts/Roboto-Bold.ttf') format('truetype')
    font-weight: bold
    font-style: normal

  @font-face
    font-family: 'Roboto'
    src: local('Roboto Italic'), local('Roboto-Italic'), url('../fonts/Roboto-Italic.ttf') format('truetype')
    font-weight: normal
    font-style: italic

  @font-face
    font-family: 'Roboto'
    src: local('Roboto BoldItalic'), local('Roboto-BoldItalic'), url('../fonts/Roboto-BoldItalic.ttf') format('truetype')
    font-weight: bold
    font-style: italic

  @font-face
    font-family: 'Roboto'
    src: local('Roboto Light'), local('Roboto-Light'), url('../fonts/Roboto-Light.ttf') format('truetype')
    font-weight: 300
    font-style: normal

  @font-face
    font-family: 'Roboto'
    src: local('Roboto LightItalic'), local('Roboto-LightItalic'), url('../fonts/Roboto-LightItalic.ttf') format('truetype')
    font-weight: 300
    font-style: italic

  @font-face
    font-family: 'Roboto'
    src: local('Roboto Medium'), local('Roboto-Medium'), url('../fonts/Roboto-Medium.ttf') format('truetype')
    font-weight: 500
    font-style: normal

  @font-face
    font-family: 'Roboto'
    src: local('Roboto MediumItalic'), local('Roboto-MediumItalic'), url('../fonts/Roboto-MediumItalic.ttf') format('truetype')
    font-weight: 500
    font-style: italic

/* Roboto-Regular.ttf       400 */
/* Roboto-Bold.ttf          700 */
/* Roboto-Italic.ttf        400 */
/* Roboto-BoldItalic.ttf    700 */
/* Roboto-Medium.ttf        500 */
/* Roboto-MediumItalic.ttf  500 */
/* Roboto-Light.ttf         300 */
/* Roboto-LightItalic.ttf   300 */

/* https://fonts.google.com/specimen/Roboto#standard-styles */

Login to website, via C#

Sometimes, it may help switching off AllowAutoRedirect and setting both login POST and page GET requests the same user agent.

request.UserAgent = userAgent;
request.AllowAutoRedirect = false;

Formatting a number with exactly two decimals in JavaScript

I'm fix the problem the modifier. Support 2 decimal only.

_x000D_
_x000D_
$(function(){_x000D_
  //input number only._x000D_
  convertNumberFloatZero(22); // output : 22.00_x000D_
  convertNumberFloatZero(22.5); // output : 22.50_x000D_
  convertNumberFloatZero(22.55); // output : 22.55_x000D_
  convertNumberFloatZero(22.556); // output : 22.56_x000D_
  convertNumberFloatZero(22.555); // output : 22.55_x000D_
  convertNumberFloatZero(22.5541); // output : 22.54_x000D_
  convertNumberFloatZero(22222.5541); // output : 22,222.54_x000D_
_x000D_
  function convertNumberFloatZero(number){_x000D_
 if(!$.isNumeric(number)){_x000D_
  return 'NaN';_x000D_
 }_x000D_
 var numberFloat = number.toFixed(3);_x000D_
 var splitNumber = numberFloat.split(".");_x000D_
 var cNumberFloat = number.toFixed(2);_x000D_
 var cNsplitNumber = cNumberFloat.split(".");_x000D_
 var lastChar = splitNumber[1].substr(splitNumber[1].length - 1);_x000D_
 if(lastChar > 0 && lastChar < 5){_x000D_
  cNsplitNumber[1]--;_x000D_
 }_x000D_
 return Number(splitNumber[0]).toLocaleString('en').concat('.').concat(cNsplitNumber[1]);_x000D_
  };_x000D_
});
_x000D_
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
_x000D_
_x000D_
_x000D_

how to get session id of socket.io client in Client

On socket.io >=1.0, after the connect event has triggered:

var socket = io('localhost');
var id = socket.io.engine.id

How to disable right-click context-menu in JavaScript

If your page really relies on the fact that people won't be able to see that menu, you should know that modern browsers (for example Firefox) let the user decide if he really wants to disable it or not. So you have no guarantee at all that the menu would be really disabled.

Hibernate-sequence doesn't exist

This might be caused by HHH-10876 which got fixed so make sure you update to:

  • Hibernate ORM 5.2.1,
  • Hibernate ORM 5.1.1,
  • Hibernate ORM 5.0.11

How to use numpy.genfromtxt when first column is string and the remaining columns are numbers?

You can use numpy.recfromcsv(filename): the types of each column will be automatically determined (as if you use np.genfromtxt() with dtype=None), and by default delimiter=",". It's basically a shortcut for np.genfromtxt(filename, delimiter=",", dtype=None) that Pierre GM pointed at in his answer.

Converting an integer to a string in PHP

You can use the strval() function to convert a number to a string.

From a maintenance perspective its obvious what you are trying to do rather than some of the other more esoteric answers. Of course, it depends on your context.

$var = 5;

// Inline variable parsing
echo "I'd like {$var} waffles"; // = I'd like 5 waffles

// String concatenation 
echo "I'd like ".$var." waffles"; // I'd like 5 waffles

// The two examples above have the same end value...
// ... And so do the two below

// Explicit cast 
$items = (string)$var; // $items === "5";

// Function call
$items = strval($var); // $items === "5";

Transparent image - background color

If I understand you right, you can do this:

<img src="image.png" style="background-color:red;" />

In fact, you can even apply a whole background-image to the image, resulting in two "layers" without the need for multi-background support in the browser ;)

How can I temporarily disable a foreign key constraint in MySQL?

I normally only disable foreign key constraints when I want to truncate a table, and since I keep coming back to this answer this is for future me:

SET FOREIGN_KEY_CHECKS=0;
TRUNCATE TABLE table;
SET FOREIGN_KEY_CHECKS=1;

How to return a PNG image from Jersey REST service method to the browser

I built a general method for that with following features:

  • returning "not modified" if the file hasn't been modified locally, a Status.NOT_MODIFIED is sent to the caller. Uses Apache Commons Lang
  • using a file stream object instead of reading the file itself

Here the code:

import org.apache.commons.lang3.time.DateUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

private static final Logger logger = LoggerFactory.getLogger(Utils.class);

@GET
@Path("16x16")
@Produces("image/png")
public Response get16x16PNG(@HeaderParam("If-Modified-Since") String modified) {
    File repositoryFile = new File("c:/temp/myfile.png");
    return returnFile(repositoryFile, modified);
}

/**
 * 
 * Sends the file if modified and "not modified" if not modified
 * future work may put each file with a unique id in a separate folder in tomcat
 *   * use that static URL for each file
 *   * if file is modified, URL of file changes
 *   * -> client always fetches correct file 
 * 
 *     method header for calling method public Response getXY(@HeaderParam("If-Modified-Since") String modified) {
 * 
 * @param file to send
 * @param modified - HeaderField "If-Modified-Since" - may be "null"
 * @return Response to be sent to the client
 */
public static Response returnFile(File file, String modified) {
    if (!file.exists()) {
        return Response.status(Status.NOT_FOUND).build();
    }

    // do we really need to send the file or can send "not modified"?
    if (modified != null) {
        Date modifiedDate = null;

        // we have to switch the locale to ENGLISH as parseDate parses in the default locale
        Locale old = Locale.getDefault();
        Locale.setDefault(Locale.ENGLISH);
        try {
            modifiedDate = DateUtils.parseDate(modified, org.apache.http.impl.cookie.DateUtils.DEFAULT_PATTERNS);
        } catch (ParseException e) {
            logger.error(e.getMessage(), e);
        }
        Locale.setDefault(old);

        if (modifiedDate != null) {
            // modifiedDate does not carry milliseconds, but fileDate does
            // therefore we have to do a range-based comparison
            // 1000 milliseconds = 1 second
            if (file.lastModified()-modifiedDate.getTime() < DateUtils.MILLIS_PER_SECOND) {
                return Response.status(Status.NOT_MODIFIED).build();
            }
        }
    }        
    // we really need to send the file

    try {
        Date fileDate = new Date(file.lastModified());
        return Response.ok(new FileInputStream(file)).lastModified(fileDate).build();
    } catch (FileNotFoundException e) {
        return Response.status(Status.NOT_FOUND).build();
    }
}

/*** copied from org.apache.http.impl.cookie.DateUtils, Apache 2.0 License ***/

/**
 * Date format pattern used to parse HTTP date headers in RFC 1123 format.
 */
public static final String PATTERN_RFC1123 = "EEE, dd MMM yyyy HH:mm:ss zzz";

/**
 * Date format pattern used to parse HTTP date headers in RFC 1036 format.
 */
public static final String PATTERN_RFC1036 = "EEEE, dd-MMM-yy HH:mm:ss zzz";

/**
 * Date format pattern used to parse HTTP date headers in ANSI C
 * <code>asctime()</code> format.
 */
public static final String PATTERN_ASCTIME = "EEE MMM d HH:mm:ss yyyy";

public static final String[] DEFAULT_PATTERNS = new String[] {
    PATTERN_RFC1036,
    PATTERN_RFC1123,
    PATTERN_ASCTIME
};

Note that the Locale switching does not seem to be thread-safe. I think, it's better to switch the locale globally. I am not sure about the side-effects though...

How to define two angular apps / modules in one page?

You can bootstrap multiple angular applications, but:

1) You need to manually bootstrap them

2) You should not use "document" as the root, but the node where the angular interface is contained to:

var todoRootNode = jQuery('[ng-controller=TodoController]');
angular.bootstrap(todoRootNode, ['TodoApp']);

This would be safe.

IF EXIST C:\directory\ goto a else goto b problems windows XP batch files

From the help (if /?):

The ELSE clause must occur on the same line as the command after the IF.  For
example:

    IF EXIST filename. (
        del filename.
    ) ELSE (
        echo filename. missing.
    )

The following would NOT work because the del command needs to be terminated
by a newline:

    IF EXIST filename. del filename. ELSE echo filename. missing

Nor would the following work, since the ELSE command must be on the same line
as the end of the IF command:

    IF EXIST filename. del filename.
    ELSE echo filename. missing

Parse JSON from JQuery.ajax success data

From the jQuery API: with the setting of dataType, If none is specified, jQuery will try to infer it with $.parseJSON() based on the MIME type (the MIME type for JSON text is "application/json") of the response (in 1.4 JSON will yield a JavaScript object).

Or you can set the dataType to json to convert it automatically.

Python Create unix timestamp five minutes in the future

The following is based on the answers above (plus a correction for the milliseconds) and emulates datetime.timestamp() for Python 3 before 3.3 when timezones are used.

def datetime_timestamp(datetime):
    '''
    Equivalent to datetime.timestamp() for pre-3.3
    '''
    try:
        return datetime.timestamp()
    except AttributeError:
        utc_datetime = datetime.astimezone(utc)
        return timegm(utc_datetime.timetuple()) + utc_datetime.microsecond / 1e6

To strictly answer the question as asked, you'd want:

datetime_timestamp(my_datetime) + 5 * 60

datetime_timestamp is part of simple-date. But if you were using that package you'd probably type:

SimpleDate(my_datetime).timestamp + 5 * 60

which handles many more formats / types for my_datetime.

Advantages of using display:inline-block vs float:left in CSS

If you want to align the div with pixel accurate, then use float. inline-block seems to always requires you to chop off a few pixels (at least in IE)

jquery change class name

So you want to change it WHEN it's clicked...let me go through the whole process. Let's assume that your "External DOM Object" is an input, like a select:

Let's start with this HTML:

<body>
  <div>
    <select id="test">
      <option>Bob</option>
      <option>Sam</option>
      <option>Sue</option>
      <option>Jen</option>
    </select>
  </div>

  <table id="theTable">
    <tr><td id="cellToChange">Bob</td><td>Sam</td></tr>
    <tr><td>Sue</td><td>Jen</td></tr>
  </table>
</body>

Some very basic CSS:

?#theTable td {
    border:1px solid #555;
}
.activeCell {
    background-color:#F00;
}

And set up a jQuery event:

function highlightCell(useVal){
  $("#theTable td").removeClass("activeCell")
      .filter(":contains('"+useVal+"')").addClass("activeCell");
}

$(document).ready(function(){
    $("#test").change(function(e){highlightCell($(this).val())});
});

Now, whenever you pick something from the select, it will automatically find a cell with the matching text, allowing you to subvert the whole id-based process. Of course, if you wanted to do it that way, you could easily modify the script to use IDs rather than values by saying

.filter("#"+useVal)

and make sure to add the ids appropriately. Hope this helps!

How to drop a table if it exists?

IF EXISTS (SELECT NAME FROM SYS.OBJECTS WHERE object_id = OBJECT_ID(N'Scores') AND TYPE in (N'U'))
    DROP TABLE Scores
GO

Bash script to check running process

I use this one to check every 10 seconds process is running and start if not and allows multiple arguments:

#!/bin/sh

PROCESS="$1"
PROCANDARGS=$*

while :
do
    RESULT=`pgrep ${PROCESS}`

    if [ "${RESULT:-null}" = null ]; then
            echo "${PROCESS} not running, starting "$PROCANDARGS
            $PROCANDARGS &
    else
            echo "running"
    fi
    sleep 10
done    

The operation cannot be completed because the DbContext has been disposed error

This can be as simple as adding ToList() in your repository. For example:

public IEnumerable<MyObject> GetMyObjectsForId(string id)
{
    using (var ctxt = new RcContext())
    {
        // causes an error
        return ctxt.MyObjects.Where(x => x.MyObjects.Id == id);
    }
}

Will yield the Db Context disposed error in the calling class but this can be resolved by explicitly exercising the enumeration by adding ToList() on the LINQ operation:

public IEnumerable<MyObject> GetMyObjectsForId(string id)
{
    using (var ctxt = new RcContext())
    {
        return ctxt.MyObjects.Where(x => x.MyObjects.Id == id).ToList();
    }
}

PyCharm shows unresolved references error for valid code

There are many solutions to this, some more convenient than others, and they don't always work.

Here's all you can try, going from 'quick' to 'annoying':

  • Do File -> Invalidate Caches / Restart and restart PyCharm.
    • You could also do this after any of the below methods, just to be sure.
  • First, check which interpreter you're running: Run -> Edit Configurations -> Configuration -> Python Interpreter.
  • Refresh the paths of your interpreter:
    • File -> Settings
    • Project: [name] -> Project Interpreter -> 'Project Interpreter': Gear icon -> More...
    • Click the 'Show paths' button (bottom one)
    • Click the 'Refresh' button (bottom one)
  • Remove the interpreter and add it again:
    • File -> Settings
    • Project: [name] -> Project Interpreter -> 'Project Interpreter': Gear icon -> More...
    • Click the 'Remove' button
    • Click the 'Add' button and re-add your interpeter
  • Delete your project preferences
    • Delete your project's .idea folder
    • Close and re-open PyCharm
    • Open your project from scratch
  • Delete your PyCharm user preferences (but back them up first).
    • ~/.PyCharm50 on Mac
    • %homepath%/.PyCharm50 on Windows
  • Switch to another interpreter, then back again to the one you want.
  • Create a new virtual environment, and switch to that environments' interpreter.
  • Switch to another interpreter altogether, don't switch back.

If you are using Docker, take note:

Mongod complains that there is no /data/db folder

You need to create /data/db ... that is a directory called /data/ in your root (i.e. /) and subfolder in there called /db/ ...

You're getting permission errors becuase you need to use sudo to create a direcotry in your root dir in MacOS, sudo lets you run commands as an administrator.

So, run this instead ...

$ sudo mkdir -p /data/db

This will prompt you for a password, it's the same password you use to change system settings (that little dialog that opens when you try and change things in System Preferences for ecample), and likely the same as you use to login.

is it possible to add colors to python output?

If your console (like your standard ubuntu console) understands ANSI color codes, you can use those.

Here an example:

print ('This is \x1b[31mred\x1b[0m.') 

How can I convert bigint (UNIX timestamp) to datetime in SQL Server?

Like this

add the Unix (epoch) datetime to the base date in seconds

this will get it for now (2010-05-25 07:56:23.000)

 SELECT dateadd(s,1274756183,'19700101 05:00:00:000')

If you want to go reverse, take a look at this http://wiki.lessthandot.com/index.php/Epoch_Date

Convert long/lat to pixel x/y on a given picture

my approach works without a library and with cropped maps. Means it works with just parts from a Mercator image. Maybe it helps somebody: https://stackoverflow.com/a/10401734/730823

Elegant way to report missing values in a data.frame

For one more graphical solution, visdat package offers vis_miss.

library(visdat)
vis_miss(airquality)

enter image description here

Very similar to Amelia output with a small difference of giving %s on missings out of the box.

How to play YouTube video in my Android application?

Google has a YouTube Android Player API that enables you to incorporate video playback functionality into your Android applications. The API itself is very easy to use and works well. For example, here is how to create a new activity to play a video using the API.

Intent intent = YouTubeStandalonePlayer.createVideoIntent(this, "<<YOUTUBE_API_KEY>>", "<<Youtube Video ID>>", 0, true, false);   
startActivity(intent);

See this for more details.

Where does npm install packages?

Not direct answer but may help ....

The npm also has a cache folder, which can be found by running npm config get cache (%AppData%/npm-cache on Windows).

The npm modules are first downloaded here and then copied to npm global folder (%AppData%/Roaming/npm on Windows) or project specific folder (your-project/node_modules).

So if you want to track npm packages, and some how, the list of all downloaded npm packages (if the npm cache is not cleaned) have a look at this folder. The folder structure is as {cache}/{name}/{version}

This may help also https://docs.npmjs.com/cli/cache

How do I determine scrollHeight?

scrollHeight is a regular javascript property so you don't need jQuery.

var test = document.getElementById("foo").scrollHeight;

What is the difference between <jsp:include page = ... > and <%@ include file = ... >?

jGuru:

The <%@include file="abc.jsp"%> directive acts like C "#include", pulling in the text of the included file and compiling it as if it were part of the including file. The included file can be any type (including HTML or text).

The <jsp:include page="abc.jsp"> tag compiles the file as a separate JSP file, and embeds a call to it in the compiled JSP.

Some JSP engines support the non-standard tags <!--#include file="data.inc"--> (NCSA-, or .shtml-style) and <%@ vinclude="data.inc" %> (JRun-style), but these are not defined in the JSP spec and thus cannot be relied on.

See also this question in the JSP FAQ.

XPath to get all child nodes (elements, comments, and text) without parent

Use this XPath expression:

/*/*/X/node()

This selects any node (element, text node, comment or processing instruction) that is a child of any X element that is a grand-child of the top element of the XML document.

To verify what is selected, here is this XSLT transformation that outputs exactly the selected nodes:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes"/>
 <xsl:template match="/">
  <xsl:copy-of select="/*/*/X/node()"/>
 </xsl:template>
</xsl:stylesheet>

and it produces exactly the wanted, correct result:

   First Text Node #1            
    <y> Y can Have Child Nodes #                
        <child> deep to it </child>
    </y>            Second Text Node #2 
    <z />

Explanation:

  1. As defined in the W3 XPath 1.0 Spec, "child::node() selects all the children of the context node, whatever their node type." This means that any element, text-node, comment-node and processing-instruction node children are selected by this node-test.

  2. node() is an abbreviation of child::node() (because child:: is the primary axis and is used when no axis is explicitly specified).

How can I get the source directory of a Bash script from within the script itself?

pwd can be used to find the current working directory, and dirname to find the directory of a particular file (command that was run, is $0, so dirname $0 should give you the directory of the current script).

However, dirname gives precisely the directory portion of the filename, which more likely than not is going to be relative to the current working directory. If your script needs to change directory for some reason, then the output from dirname becomes meaningless.

I suggest the following:

#!/bin/bash

reldir=`dirname $0`
cd $reldir
directory=`pwd`

echo "Directory is $directory"

This way, you get an absolute, rather than a relative directory.

Since the script will be run in a separate Bash instance, there isn't any need to restore the working directory afterwards, but if you do want to change back in your script for some reason, you can easily assign the value of pwd to a variable before you change directory, for future use.

Although just

cd `dirname $0`

solves the specific scenario in the question, I find having the absolute path to more more useful generally.

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 ;)

Handle Guzzle exception and get HTTP body

Guzzle 6.x

Per the docs, the exception types you may need to catch are:

  • GuzzleHttp\Exception\ClientException for 400-level errors
  • GuzzleHttp\Exception\ServerException for 500-level errors
  • GuzzleHttp\Exception\BadResponseException for both (it's their superclass)

Code to handle such errors thus now looks something like this:

$client = new GuzzleHttp\Client;
try {
    $client->get('http://google.com/nosuchpage');    
}
catch (GuzzleHttp\Exception\ClientException $e) {
    $response = $e->getResponse();
    $responseBodyAsString = $response->getBody()->getContents();
}

How can you flush a write using a file descriptor?

fflush() only flushes the buffering added by the stdio fopen() layer, as managed by the FILE * object. The underlying file itself, as seen by the kernel, is not buffered at this level. This means that writes that bypass the FILE * layer, using fileno() and a raw write(), are also not buffered in a way that fflush() would flush.

As others have pointed out, try not mixing the two. If you need to use "raw" I/O functions such as ioctl(), then open() the file yourself directly, without using fopen<() and friends from stdio.

How to extract this specific substring in SQL Server?

Combine the SUBSTRING(), LEFT(), and CHARINDEX() functions.

SELECT LEFT(SUBSTRING(YOUR_FIELD,
                      CHARINDEX(';', YOUR_FIELD) + 1, 100),
                      CHARINDEX('[', YOUR_FIELD) - 1)
FROM YOUR_TABLE;

This assumes your field length will never exceed 100, but you can make it smarter to account for that if necessary by employing the LEN() function. I didn't bother since there's enough going on in there already, and I don't have an instance to test against, so I'm just eyeballing my parentheses, etc.

Converting between java.time.LocalDateTime and java.util.Date

The fastest way for LocalDateTime -> Date is:

Date.from(ldt.toInstant(ZoneOffset.UTC))

jQuery UI Alert Dialog as a replacement for alert()

I don't think you even need to attach it to the DOM, this seems to work for me:

$("<div>Test message</div>").dialog();

Here's a JS fiddle:

http://jsfiddle.net/TpTNL/98

What are examples of TCP and UDP in real life?

Real life examples of both TCP and UDP tcp -> a phone call, sms or anything specific to destination UDP -> a FM radio channel (AM), Wi-Fi.

How to check if that data already exist in the database during update (Mongoose And Express)

In addition to already posted examples, here is another approach using express-async-wrap and asynchronous functions (ES2017).

Router

router.put('/:id/settings/profile', wrap(async function (request, response, next) {
    const username = request.body.username
    const email = request.body.email
    const userWithEmail = await userService.findUserByEmail(email)
    if (userWithEmail) {
        return response.status(409).send({message: 'Email is already taken.'})
    }
    const userWithUsername = await userService.findUserByUsername(username)
    if (userWithUsername) {
        return response.status(409).send({message: 'Username is already taken.'})
    }
    const user = await userService.updateProfileSettings(userId, username, email)
    return response.status(200).json({user: user})
}))

UserService

async function updateProfileSettings (userId, username, email) {
    try {
        return User.findOneAndUpdate({'_id': userId}, {
            $set: {
                'username': username,
                'auth.email': email
            }
        }, {new: true})
    } catch (error) {
        throw new Error(`Unable to update user with id "${userId}".`)
    }
}

async function findUserByEmail (email) {
    try {
        return User.findOne({'auth.email': email.toLowerCase()})
    } catch (error) {
        throw new Error(`Unable to connect to the database.`)
    }
}

async function findUserByUsername (username) {
    try {
        return User.findOne({'username': username})
    } catch (error) {
        throw new Error(`Unable to connect to the database.`)
    }
}

// other methods

export default {
    updateProfileSettings,
    findUserByEmail,
    findUserByUsername,
}

Resources

async function

await

express-async-wrap

Learning Ruby on Rails

Fantastic decision! It is extremely useful to get a grounding in Ruby before going to Rails so here is my take on the best path to Rails:

Aside from books the most important thing is to get feedback on what you are doing. To do this I recommend spending time in irc.freenode.net #ruby and #rubyonrails. It is also extremely helpful to post things you are working on or having trouble with here on stackoverflow as the comments, explanations and different way of thinking about things that people provide are invaluable.

You should also definitely check out the Ruby Rogues podcast, they provide invaluable information and the commentators are all extremely respected people in the Ruby community. And for your viewing and reading pleasure (in that order,) head over to Ryan Bates's Railscasts and then Eifion Bedford's Asciicasts.

Finally, I recommend looking into different gems on github, reading the code and then contributing to them. You don't have to get overly ambitious and do massive recodes, especially at first. Just start with small things like editing and making the README files a little easier to read.

I don't use an IDE but at Railsconf I saw a demo of Rubymine from Jetbrains and it seemed pretty amazing.

Specified cast is not valid?

From your comment:

this line DateTime Date = reader.GetDateTime(0); was throwing the exception

The first column is not a valid DateTime. Most likely, you have multiple columns in your table, and you're retrieving them all by running this query:

SELECT * from INFO

Replace it with a query that retrieves only the two columns you're interested in:

SELECT YOUR_DATE_COLUMN, YOUR_TIME_COLUMN from INFO

Then try reading the values again:

var Date = reader.GetDateTime(0);
var Time = reader.GetTimeSpan(1);  // equivalent to time(7) from your database

Or:

var Date = Convert.ToDateTime(reader["YOUR_DATE_COLUMN"]);
var Time = (TimeSpan)reader["YOUR_TIME_COLUMN"];

In Python script, how do I set PYTHONPATH?

You can get and set environment variables via os.environ:

import os
user_home = os.environ["HOME"]

os.environ["PYTHONPATH"] = "..."

But since your interpreter is already running, this will have no effect. You're better off using

import sys
sys.path.append("...")

which is the array that your PYTHONPATH will be transformed into on interpreter startup.

Algorithm to find Largest prime factor of a number

#python implementation
import math
n = 600851475143
i = 2
factors=set([])
while i<math.sqrt(n):
   while n%i==0:
       n=n/i
       factors.add(i)
   i+=1
factors.add(n)
largest=max(factors)
print factors
print largest

Default settings Raspberry Pi /etc/network/interfaces

For my Raspberry Pi 3B model it was

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet manual

allow-hotplug wlan0
iface wlan0 inet manual
    wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

allow-hotplug wlan1
iface wlan1 inet manual
    wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

Click a button programmatically - JS

window.onload = function() {
    var userImage = document.getElementById('imageOtherUser');
    var hangoutButton = document.getElementById("hangoutButtonId");
    userImage.onclick = function() {
       hangoutButton.click(); // this will trigger the click event
    };
};

this will do the trick

How can I search an array in VB.NET?

If you want an efficient search that is often repeated, first sort the array (Array.Sort) and then use Array.BinarySearch.

Rebase feature branch onto another feature branch

  1. Switch to Branch2

    git checkout Branch2
    
  2. Apply the current (Branch2) changes on top of the Branch1 changes, staying in Branch2:

    git rebase Branch1
    

Which would leave you with the desired result in Branch2:

a -- b -- c                      <-- Master
           \
            d -- e               <-- Branch1
           \
            d -- e -- f' -- g'   <-- Branch2

You can delete Branch1.

How to redirect to the same page in PHP

My preferred method for reloading the same page is $_SERVER['PHP_SELF']

header('Location: '.$_SERVER['PHP_SELF']);
die;

Don't forget to die or exit after your header();

Edit: (Thanks @RafaelBarros )

If the query string is also necessary, use

header('Location:'.$_SERVER['PHP_SELF'].'?'.$_SERVER['QUERY_STRING']);
die;

Edit: (thanks @HugoDelsing)

When htaccess url manipulation is in play the value of $_SERVER['PHP_SELF'] may take you to the wrong place. In that case the correct url data will be in $_SERVER['REQUEST_URI'] for your redirect, which can look like Nabil's answer below:

header("Location: http://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]");
exit;

You can also use $_SERVER[REQUEST_URI] to assign the correct value to $_SERVER['PHP_SELF'] if desired. This can help if you use a redirect function heavily and you don't want to change it. Just set the correct vale in your request handler like this:

$_SERVER['PHP_SELF'] = 'https://sample.com/controller/etc';

How to add a new audio (not mixing) into a video using ffmpeg?

Code to add audio to video using ffmpeg.

If audio length is greater than video length it will cut the audio to video length. If you want full audio in video remove -shortest from the cmd.

String[] cmd = new String[]{"-i", selectedVideoPath,"-i",audiopath,"-map","1:a","-map","0:v","-codec","copy", ,outputFile.getPath()};

private void execFFmpegBinaryShortest(final String[] command) {



            final File outputFile = new File(Environment.getExternalStorageDirectory().getAbsolutePath()+"/videoaudiomerger/"+"Vid"+"output"+i1+".mp4");




            String[] cmd = new String[]{"-i", selectedVideoPath,"-i",audiopath,"-map","1:a","-map","0:v","-codec","copy","-shortest",outputFile.getPath()};


            try {

                ffmpeg.execute(cmd, new ExecuteBinaryResponseHandler() {
                    @Override
                    public void onFailure(String s) {
                        System.out.println("on failure----"+s);
                    }

                    @Override
                    public void onSuccess(String s) {
                        System.out.println("on success-----"+s);
                    }

                    @Override
                    public void onProgress(String s) {
                        //Log.d(TAG, "Started command : ffmpeg "+command);
                        System.out.println("Started---"+s);

                    }

                    @Override
                    public void onStart() {


                        //Log.d(TAG, "Started command : ffmpeg " + command);
                        System.out.println("Start----");

                    }

                    @Override
                    public void onFinish() {
                        System.out.println("Finish-----");


                    }
                });
            } catch (FFmpegCommandAlreadyRunningException e) {
                // do nothing for now
                System.out.println("exceptio :::"+e.getMessage());
            }


        }

C#: How to add subitems in ListView

You whack the subitems into an array and add the array as a list item.

The order in which you add values to the array dictates the column they appear under so think of your sub item headings as [0],[1],[2] etc.

Here's a code sample:

//In this example an array of three items is added to a three column listview
string[] saLvwItem = new string[3];

foreach (string wholeitem in listofitems)
{
     saLvwItem[0] = "Status Message";
     saLvwItem[1] = wholeitem;
     saLvwItem[2] = DateTime.Now.ToString("dddd dd/MM/yyyy - HH:mm:ss");

     ListViewItem lvi = new ListViewItem(saLvwItem);

     lvwMyListView.Items.Add(lvi);
}

PHP Header redirect not working

Also see your php file text encoding. Mine was UTF-8 with BOM and it prevented the script to work. But now works flawlessly after removing the BOM...

append option to select menu?

HTML

<select id="mySelect">
    <option value="volvo">Volvo</option>
    <option value="saab">Saab</option>
    <option value="mercedes">Mercedes</option>
    <option value="audi">Audi</option>
</select>

JavaScript

 var mySelect = document.getElementById('mySelect'),
    newOption = document.createElement('option');

newOption.value = 'bmw';

// Not all browsers support textContent (W3C-compliant)
// When available, textContent is faster (see http://stackoverflow.com/a/1359822/139010)
if (typeof newOption.textContent === 'undefined')
{
    newOption.innerText = 'BMW';
}
else
{
    newOption.textContent = 'BMW';
}

mySelect.appendChild(newOption);

Demo →

How to check if type is Boolean

The most reliable way to check type of a variable in JavaScript is the following:

var toType = function(obj) {
  return ({}).toString.call(obj).match(/\s([a-zA-Z]+)/)[1].toLowerCase()
}
toType(new Boolean(true)) // returns "boolean"
toType(true); // returns "boolean"

The reason for this complication is that typeof true returns "boolean" while typeof new Boolean(true) returns "object".

How do I use CREATE OR REPLACE?

CREATE OR REPLACE can only be used on functions, procedures, types, views, or packages - it will not work on tables.

Python: can't assign to literal

You should use variables to store the names.

Numbers can't store strings.

ggplot legends - change labels, order and title

You need to do two things:

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

The code:

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

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

enter image description here

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

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

enter image description here

pandas dataframe convert column type to string or categorical

To convert a column into a string type (that will be an object column per se in pandas), use astype:

df.zipcode = zipcode.astype(str)

If you want to get a Categorical column, you can pass the parameter 'category' to the function:

df.zipcode = zipcode.astype('category')

How can I do division with variables in a Linux shell?

Those variables are shell variables. To expand them as parameters to another program (ie expr), you need to use the $ prefix:

expr $x / $y

The reason it complained is because it thought you were trying to operate on alphabetic characters (ie non-integer)

If you are using the Bash shell, you can achieve the same result using expression syntax:

echo $((x / y))

Or:

z=$((x / y))
echo $z

Big-oh vs big-theta

There are a lot of good answers here but I noticed something was missing. Most answers seem to be implying that the reason why people use Big O over Big Theta is a difficulty issue, and in some cases this may be true. Often a proof that leads to a Big Theta result is far more involved than one that results in Big O. This usually holds true, but I do not believe this has a large relation to using one analysis over the other.

When talking about complexity we can say many things. Big O time complexity is just telling us what an algorithm is guarantied to run within, an upper bound. Big Omega is far less often discussed and tells us the minimum time an algorithm is guarantied to run, a lower bound. Now Big Theta tells us that both of these numbers are in fact the same for a given analysis. This tells us that the application has a very strict run time, that can only deviate by a value asymptoticly less than our complexity. Many algorithms simply do not have upper and lower bounds that happen to be asymptoticly equivalent.

So as to your question using Big O in place of Big Theta would technically always be valid, while using Big Theta in place of Big O would only be valid when Big O and Big Omega happened to be equal. For instance insertion sort has a time complexity of Big ? at n^2, but its best case scenario puts its Big Omega at n. In this case it would not be correct to say that its time complexity is Big Theta of n or n^2 as they are two different bounds and should be treated as such.

How to write character & in android strings.xml

It should be like this :

<string name="game_settings_dragNDropMove_checkBox">Move by Drag&amp;Drop</string>

HTML "overlay" which allows clicks to fall through to elements behind it

You can use an overlay with opacity set in order to the buttons/anchors in the back stay visible, but once you have that overlay over an element, you can't click it.

How do I get user IP address in django?

here is a short one liner to accomplish this:

request.META.get('HTTP_X_FORWARDED_FOR', request.META.get('REMOTE_ADDR', '')).split(',')[0].strip()

Tomcat started in Eclipse but unable to connect to http://localhost:8085/

Right-click on your project's name in Eclipse's Project Explorer, then click Run As followed by Run on Server. Click the Next button. Make sure your project's name is listed in the Configured: column on the right. If it is, then you should be able to access it with this URL:

http://localhost:8085/projectname/

Additionally, whenever you make new additions (such as new JSPs, graphics or other resources) to your project, be sure to refresh the project by clicking on its name and then hitting F5. Otherwise Eclipse does not know that those new resources are available and will not make them available to Tomcat to serve.

IntelliJ shortcut to show a popup of methods in a class that can be searched

You can type "this." and wait a second, a popup with methods and properties will display.

Not a shortcut, but it works for me.

PS: if you are in a static method, type the class name.

Positioning background image, adding padding

first off, to be a bit of a henpeck, its best NOT to use just the <background> tag. rather, use the proper, more specific, <background-image> tag.

the only way that i'm aware of to do such a thing is to build the padding into the image by extending the matte. since the empty pixels aren't stripped, you have your padding right there. so if you need a 10px border, create 10px of empty pixels all around your image. this is mui simple in Photoshop, Fireworks, GIMP, &c.

i'd also recommend trying out the PNG8 format instead of the dying GIF... much better.

there may be an alternate solution to your problem if we knew a bit more of how you're using it. :) it LOOKS like you're trying to add an accordion button. this would be best placed in the HTML because then you can target it with JavaScript/PHP; something you cannot do if it's in the background (at least not simply). in such a case, you can style the heck out of the image you currently have in CSS by using the following:

#hello img { padding: 10px; }

WR!

When to use "ON UPDATE CASCADE"

It's an excellent question, I had the same question yesterday. I thought about this problem, specifically SEARCHED if existed something like "ON UPDATE CASCADE" and fortunately the designers of SQL had also thought about that. I agree with Ted.strauss, and I also commented Noran's case.

When did I use it? Like Ted pointed out, when you are treating several databases at one time, and the modification in one of them, in one table, has any kind of reproduction in what Ted calls "satellite database", can't be kept with the very original ID, and for any reason you have to create a new one, in case you can't update the data on the old one (for example due to permissions, or in case you are searching for fastness in a case that is so ephemeral that doesn't deserve the absolute and utter respect for the total rules of normalization, simply because will be a very short-lived utility)

So, I agree in two points:

(A.) Yes, in many times a better design can avoid it; BUT

(B.) In cases of migrations, replicating databases, or solving emergencies, it's a GREAT TOOL that fortunately was there when I went to search if it existed.

How do I get information about an index and table owner in Oracle?

Below are two simple query using which you can check index created on a table in Oracle.

select index_name
  from dba_indexes
 where table_name='&TABLE_NAME'
   and owner='&TABLE_OWNER';
select index_name 
  from user_indexes 
 where table_name='&TABLE_NAME';

Please check for more details and index size below. Index on a table and its size in Oracle

Why is "cursor:pointer" effect in CSS not working

I have the same issue, when I close the chrome window popup browser inspector its working fine for me.

Unicode character in PHP string

Try Portable UTF-8:

$str = utf8_chr( 0x1000 );
$str = utf8_chr( '\u1000' );
$str = utf8_chr( 4096 );

All work exactly the same way. You can get the codepoint of a character with utf8_ord(). Read more about Portable UTF-8.

Get class name of object as string in Swift

Swift 5

Here is the extension to get the typeName as a variable (work with both value type or reference type).

protocol NameDescribable {
    var typeName: String { get }
    static var typeName: String { get }
}

extension NameDescribable {
    var typeName: String {
        return String(describing: type(of: self))
    }

    static var typeName: String {
        return String(describing: self)
    }
}

How to use:

// Extend with class/struct/enum...
extension NSObject: NameDescribable {}
extension Array: NameDescribable {}
extension UIBarStyle: NameDescribable { }

print(UITabBarController().typeName)
print(UINavigationController.typeName)
print([Int]().typeName)
print(UIBarStyle.typeName)

// Out put:
UITabBarController
UINavigationController
Array<Int>
UIBarStyle

How do I ignore all files in a folder with a Git repository in Sourcetree?

Ignore full folder on source tree.

   Just Open Repository >Repository setting > Edit git ignore File and 
   you can rite some thing like this :

 *.pdb 
*.bak 
*.dll
*.lib 
.gitignore
packages/ 
*/bin/
*/obj/ 

For bin folder and obj folder just write : */bin/ */obj/

What character represents a new line in a text area

Talking specifically about textareas in web forms, for all textareas, on all platforms, \r\n will work.

If you use anything else you will cause issues with cut and paste on Windows platforms.

The line breaks will be canonicalised by windows browsers when the form is submitted, but if you send the form down to the browser with \n linebreaks, you will find that the text will not copy and paste correctly between for example notepad and the textarea.

Interestingly, in spite of the Unix line end convention being \n, the standard in most text-based network protocols including HTTP, SMTP, POP3, IMAP, and so on is still \r\n. Yes, it may not make a lot of sense, but that's history and evolving standards for you!

Clear icon inside input text

No need to include CSS or image files. No need to include that whole heavy-artillery jQuery UI library. I wrote a lightweight jQuery plugin that does the magic for you. All you need is jQuery and the plugin. =)

jQuery InputSearch sneak peek

Fiddle here: jQuery InputSearch demo.

JPA and Hibernate - Criteria vs. JPQL or HQL

Criteria are the only way to specify natural key lookups that take advantage of the special optimization in the second level query cache. HQL does not have any way to specify the necessary hint.

You can find some more info here:

What is the MySQL JDBC driver connection string?

update for mySQL 8 :

String jdbcUrl="jdbc:mysql://localhost:3306/youdatabase?useSSL=false&serverTimezone=UTC";

How can I initialize base class member variables in derived class constructor?

Why can't you do it? Because the language doesn't allow you to initializa a base class' members in the derived class' initializer list.

How can you get this done? Like this:

class A
{
public:
    A(int a, int b) : a_(a), b_(b) {};
    int a_, b_;
};

class B : public A
{
public:
    B() : A(0,0) 
    {
    }
};

How do I detect IE 8 with jQuery?

document.documentMode is undefined if the browser is not IE8,

it returns 8 for standards mode and 7 for 'compatable to IE7'

If it is running as IE7 there are a lot of css and dom features that won't be supported.

Check if a value is in an array or not with Excel VBA

You can brute force it like this:

Public Function IsInArray(stringToBeFound As String, arr As Variant) As Boolean
    Dim i
    For i = LBound(arr) To UBound(arr)
        If arr(i) = stringToBeFound Then
            IsInArray = True
            Exit Function
        End If
    Next i
    IsInArray = False

End Function

Use like

IsInArray("example", Array("example", "someother text", "more things", "and another"))

How to remove text before | character in notepad++

To replace anything that starts with "text" until the last character:

text.+(.*)$

Example

text             hsjh sdjh sd          jhsjhsdjhsdj hsd
                                                      ^
                                                      last character


To replace anything that starts with "text" until "123"

text.+(\ 123)

Example

text fuhfh283nfnd03no3 d90d3nd 3d 123 udauhdah au dauh ej2e
^                                   ^
From here                     To here

Is Python interpreted, or compiled, or both?

Almost, we can say Python is interpreted language. But we are using some part of one time compilation process in python to convert complete source code into byte-code like java language.

how to count the total number of lines in a text file using python

One liner:

total_line_count = sum(1 for line in open("filename.txt"))

print(total_line_count)

Setting environment variables in Linux using Bash

export VAR=value will set VAR to value. Enclose it in single quotes if you want spaces, like export VAR='my val'. If you want the variable to be interpolated, use double quotes, like export VAR="$MY_OTHER_VAR".

Convert Java object to XML string

Using ByteArrayOutputStream

public static String printObjectToXML(final Object object) throws TransformerFactoryConfigurationError,
        TransformerConfigurationException, SOAPException, TransformerException
{
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    XMLEncoder xmlEncoder = new XMLEncoder(baos);
    xmlEncoder.writeObject(object);
    xmlEncoder.close();

    String xml = baos.toString();
    System.out.println(xml);

    return xml.toString();
}

How to use adb command to push a file on device without sd card

Sometimes you need the extension,

adb push file.zip /sdcard/file.zip

Angular 2.0 router not working on reloading the browser

The error you are seeing is because you are requesting http://localhost/route which doesn't exist. According to Simon.

When using html5 routing you need to map all routes in your app(currently 404) to index.html in your server side. Here are some options for you:

  1. using live-server: https://www.npmjs.com/package/live-server

    $live-server --entry-file=index.html`
    
  2. using nginx: http://nginx.org/en/docs/beginners_guide.html

    error_page 404 /index.html
    
  3. Tomcat - configuration of web.xml. From Kunin's comment

    <error-page>
          <error-code>404</error-code>
          <location>/index.html</location>
    </error-page>
    

apt-get for Cygwin?

you can always make a bash alias to setup*.exe files in $home/.bashrc

cygwin 32bit

alias cyg-get="/cygdrive/c/cygwin/setup-x86.exe -q -P"

cygwin 64bit

alias cyg-get="/cygdrive/c/cygwin64/setup-x86_64.exe -q -P"

now you can install packages with

cyg-get <package>

How to set a variable to be "Today's" date in Python/Pandas

import datetime
def today_date():
    '''
    utils:
    get the datetime of today
    '''
    date=datetime.datetime.now().date()
    date=pd.to_datetime(date)
    return date
Df['Date'] = today_date()

this could be safely used in pandas dataframes.

Copy folder structure (without files) from one location to another

This solves even the problem with whitespaces:

In the original/source dir:

find . -type d -exec echo "'{}'" \; > dirs2.txt

then recreate it in the newly created dir:

mkdir -p <../<SOURCEDIR>/dirs2.txt

Copying sets Java

The copy constructor given by @Stephen C is the way to go when you have a Set you created (or when you know where it comes from). When it comes from a Map.entrySet(), it will depend on the Map implementation you're using:

findbugs says

The entrySet() method is allowed to return a view of the underlying Map in which a single Entry object is reused and returned during the iteration. As of Java 1.6, both IdentityHashMap and EnumMap did so. When iterating through such a Map, the Entry value is only valid until you advance to the next iteration. If, for example, you try to pass such an entrySet to an addAll method, things will go badly wrong.

As addAll() is called by the copy constructor, you might find yourself with a Set of only one Entry: the last one.

Not all Map implementations do that though, so if you know your implementation is safe in that regard, the copy constructor definitely is the way to go. Otherwise, you'd have to create new Entry objects yourself:

Set<K,V> copy = new HashSet<K,V>(map.size());
for (Entry<K,V> e : map.entrySet())
    copy.add(new java.util.AbstractMap.SimpleEntry<K,V>(e));

Edit: Unlike tests I performed on Java 7 and Java 6u45 (thanks to Stephen C), the findbugs comment does not seem appropriate anymore. It might have been the case on earlier versions of Java 6 (before u45) but I don't have any to test.

How to overplot a line on a scatter plot in python?

I'm partial to scikits.statsmodels. Here an example:

import statsmodels.api as sm
import numpy as np
import matplotlib.pyplot as plt

X = np.random.rand(100)
Y = X + np.random.rand(100)*0.1

results = sm.OLS(Y,sm.add_constant(X)).fit()

print results.summary()

plt.scatter(X,Y)

X_plot = np.linspace(0,1,100)
plt.plot(X_plot, X_plot*results.params[0] + results.params[1])

plt.show()

The only tricky part is sm.add_constant(X) which adds a columns of ones to X in order to get an intercept term.

     Summary of Regression Results
=======================================
| Dependent Variable:            ['y']|
| Model:                           OLS|
| Method:                Least Squares|
| Date:               Sat, 28 Sep 2013|
| Time:                       09:22:59|
| # obs:                         100.0|
| Df residuals:                   98.0|
| Df model:                        1.0|
==============================================================================
|                   coefficient     std. error    t-statistic          prob. |
------------------------------------------------------------------------------
| x1                      1.007       0.008466       118.9032         0.0000 |
| const                 0.05165       0.005138        10.0515         0.0000 |
==============================================================================
|                          Models stats                      Residual stats  |
------------------------------------------------------------------------------
| R-squared:                     0.9931   Durbin-Watson:              1.484  |
| Adjusted R-squared:            0.9930   Omnibus:                    12.16  |
| F-statistic:                1.414e+04   Prob(Omnibus):           0.002294  |
| Prob (F-statistic):        9.137e-108   JB:                        0.6818  |
| Log likelihood:                 223.8   Prob(JB):                  0.7111  |
| AIC criterion:                 -443.7   Skew:                     -0.2064  |
| BIC criterion:                 -438.5   Kurtosis:                   2.048  |
------------------------------------------------------------------------------

example plot

How do you pull first 100 characters of a string in PHP

try this function

function summary($str, $limit=100, $strip = false) {
    $str = ($strip == true)?strip_tags($str):$str;
    if (strlen ($str) > $limit) {
        $str = substr ($str, 0, $limit - 3);
        return (substr ($str, 0, strrpos ($str, ' ')).'...');
    }
    return trim($str);
}

How to check for empty array in vba macro

As you are dealing with a string array, have you considered Join?

If Len(Join(FileNamesList)) > 0 Then

XML string to XML document

Depending on what document type you want you can use XmlDocument.LoadXml or XDocument.Load.

Cannot implicitly convert type 'string' to 'System.Threading.Tasks.Task<string>'

Beyond the problematic use of async as pointed out by @Servy, the other issue is that you need to explicitly get T from Task<T> by calling Task.Result. Note that the Result property will block async code, and should be used carefully.

Try:

private async void button1_Click(object sender, EventArgs e)
{
    var s = await methodAsync();
    MessageBox.Show(s.Result);
}

Make div 100% Width of Browser Window

If width:100% works in any cases, just use that, otherwise you can use vw in this case which is relative to 1% of the width of the viewport.

That means if you want to cover off the width, just use 100vw.

Look at the image I draw for you here:

enter image description here

Try the snippet I created for you as below:

_x000D_
_x000D_
.full-width {_x000D_
  width: 100vw;_x000D_
  height: 100px;_x000D_
  margin-bottom: 40px;_x000D_
  background-color: red;_x000D_
}_x000D_
_x000D_
.one-vw-width {_x000D_
  width: 1vw;_x000D_
  height: 100px;_x000D_
  background-color: red;_x000D_
}
_x000D_
<div class="full-width"></div>_x000D_
<div class="one-vw-width"></div>
_x000D_
_x000D_
_x000D_

How can I tell if an algorithm is efficient?

Yes you can start with the Wikipedia article explaining the Big O notation, which in a nutshell is a way of describing the "efficiency" (upper bound of complexity) of different type of algorithms. Or you can look at an earlier answer where this is explained in simple english

How do you configure HttpOnly cookies in tomcat / java webapps?

In Tomcat6, You can conditionally enable from your HTTP Listener Class:

public void contextInitialized(ServletContextEvent event) {                 
   if (Boolean.getBoolean("HTTP_ONLY_SESSION")) HttpOnlyConfig.enable(event);
}

Using this class

import java.lang.reflect.Field;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import org.apache.catalina.core.StandardContext;
public class HttpOnlyConfig
{
    public static void enable(ServletContextEvent event)
    {
        ServletContext servletContext = event.getServletContext();
        Field f;
        try
        { // WARNING TOMCAT6 SPECIFIC!!
            f = servletContext.getClass().getDeclaredField("context");
            f.setAccessible(true);
            org.apache.catalina.core.ApplicationContext ac = (org.apache.catalina.core.ApplicationContext) f.get(servletContext);
            f = ac.getClass().getDeclaredField("context");
            f.setAccessible(true);
            org.apache.catalina.core.StandardContext sc = (StandardContext) f.get(ac);
            sc.setUseHttpOnly(true);
        }
        catch (Exception e)
        {
            System.err.print("HttpOnlyConfig cant enable");
            e.printStackTrace();
        }
    }
}

Android webview launches browser when calling loadurl

I was facing the same problem and I found the solution Android's official Documentation about WebView

Here is my onCreateView() method and here i used two methods to open the urls

Method 1 is opening url in Browser and

Method 2 is opening url in your desired WebView.
And I am using Method 2 for my Application and this is my code:

public class MainActivity extends Activity {
   private WebView myWebView;

     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

      View rootView = inflater.inflate(R.layout.fragment_webpage_detail, container, false);

      // Show the dummy content as text in a TextView.
      if (mItem != null) {

         /* Method : 1
          This following line is working fine BUT when we click the menu item then it opens the URL in BROWSER not in WebView */
         //((WebView)   rootView.findViewById(R.id.detail_area)).loadUrl(mItem.url);

        // Method : 2
        myWebView = (WebView) rootView.findViewById(R.id.detail_area); // get your WebView form your xml file
        myWebView.setWebViewClient(new WebViewClient()); // set the WebViewClient
        myWebView.loadUrl(mItem.url); // Load your desired url
    }

    return rootView;
}                                                                                               }

Show Error on the tip of the Edit Text Android

With youredittext.equals("")you can know if user hasn't entered any letter.

How to code a BAT file to always run as admin mode?

I think I have a solution to the password problem. This single argument is truly amazing. It asks for the password once, and than never asks for it again. Even if you put it onto another program, it will not ask for the password. Here it is:

runas /user:Administrator /savecred Example1Server.exe

Sites not accepting wget user agent header

It seems Yahoo server does some heuristic based on User-Agent in a case Accept header is set to */*.

Accept: text/html

did the trick for me.

e.g.

wget  --header="Accept: text/html" --user-agent="Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:21.0) Gecko/20100101 Firefox/21.0"  http://yahoo.com

Note: if you don't declare Accept header then wget automatically adds Accept:*/* which means give me anything you have.

How to convert integer into date object python?

I would suggest the following simple approach for conversion:

from datetime import datetime, timedelta
s = "20120213"
# you could also import date instead of datetime and use that.
date = datetime(year=int(s[0:4]), month=int(s[4:6]), day=int(s[6:8]))

For adding/subtracting an arbitary amount of days (seconds work too btw.), you could do the following:

date += timedelta(days=10)
date -= timedelta(days=5)

And convert back using:

s = date.strftime("%Y%m%d")

To convert the integer to a string safely, use:

s = "{0:-08d}".format(i)

This ensures that your string is eight charecters long and left-padded with zeroes, even if the year is smaller than 1000 (negative years could become funny though).

Further reference: datetime objects, timedelta objects

C++ String Concatenation operator<<

For string concatenation in C++, you should use the + operator.

nametext = "Your name is" + name;

IN Clause with NULL or IS NULL

The question as answered by Daniel is perfctly fine. I wanted to leave a note regarding NULLS. We should be carefull about using NOT IN operator when a column contains NULL values. You won't get any output if your column contains NULL values and you are using the NOT IN operator. This is how it's explained over here http://www.oraclebin.com/2013/01/beware-of-nulls.html , a very good article which I came across and thought of sharing it.

Inheritance and init method in Python

Since you don't call Num.__init__ , the field "n1" never gets created. Call it and then it will be there.

How do I write a "tab" in Python?

This is the code:

f = open(filename, 'w')
f.write("hello\talex")

The \t inside the string is the escape sequence for the horizontal tabulation.

What and where are the stack and heap?

I have something to share, although the major points are already covered.

Stack

  • Very fast access.
  • Stored in RAM.
  • Function calls are loaded here along with the local variables and function parameters passed.
  • Space is freed automatically when program goes out of a scope.
  • Stored in sequential memory.

Heap

  • Slow access comparatively to Stack.
  • Stored in RAM.
  • Dynamically created variables are stored here, which later requires freeing the allocated memory after use.
  • Stored wherever memory allocation is done, accessed by pointer always.

Interesting note:

  • Should the function calls had been stored in heap, it would had resulted in 2 messy points:
    1. Due to sequential storage in stack, execution is faster. Storage in heap would have resulted in huge time consumption thus making the whole program execute slower.
    2. If functions were stored in heap (messy storage pointed by pointer), there would have been no way to return to the caller address back (which stack gives due to sequential storage in memory).

Java - How to find the redirected url of a url?

I'd actually suggest using a solid open-source library as an http client. If you take a look at http client by ASF you'll find life a lot easier. It is an easy-to-use,scalable and robust client for http.

how to set auto increment column with sql developer

You can make auto increment in SQL Modeler. In column properties window Click : General then Tick the box of Auto Increment. After that the auto increment window will be enabled for you.

VBA (Excel) Initialize Entire Array without Looping

This function works with variables for size and initial value it combines tbur & Filipe responses.

Function ArrayIniValue(iSize As Integer, iValue As Integer)
Dim sIndex As String
sIndex = "INDEX(Row(1:" & iSize & "),)"
ArrayIniValue = Evaluate("=Transpose(" & sIndex & "-" & sIndex & "+" & iValue & ")")
End Function

Called this way:

myArray = ArrayIniValue(350, 13)

Why is Python running my module when I import it, and how do I stop it?

Try just importing the functions needed from main.py? So,

from main import SomeFunction

It could be that you've named a function in batch.py the same as one in main.py, and when you import main.py the program runs the main.py function instead of the batch.py function; doing the above should fix that. I hope.

How can I parse a time string containing milliseconds in it with python?

My first thought was to try passing it '30/03/09 16:31:32.123' (with a period instead of a colon between the seconds and the milliseconds.) But that didn't work. A quick glance at the docs indicates that fractional seconds are ignored in any case...

Ah, version differences. This was reported as a bug and now in 2.6+ you can use "%S.%f" to parse it.

403 - Forbidden: Access is denied. You do not have permission to view this directory or page using the credentials that you supplied

Try this

 <allow  users="?" />

Now you are using <deny users="?" /> that means you are not allowing authenticated user to use your site.

authorization Element

How to check if a file exists in the Documents directory in Swift?

Swift 4.2

extension URL    {
    func checkFileExist() -> Bool {
        let path = self.path
        if (FileManager.default.fileExists(atPath: path))   {
            print("FILE AVAILABLE")
            return true
        }else        {
            print("FILE NOT AVAILABLE")
            return false;
        }
    }
}

Using: -

if fileUrl.checkFileExist()
   {
      // Do Something
   }

android.content.res.Resources$NotFoundException: String resource ID Fatal Exception in Main

This always can happen in DataBinding. Try to stay away from adding logic in your bindings, including appending an empty string. You can make your own custom adapter, and use it multiple times.

@BindingAdapter("numericText")
fun numericText(textView: TextView, value: Number?) {
    value?.let {
        textView.text = value.toString()
    }
}

<TextView app:numericText="@{list.size()}" .../>

Find unique lines

uniq should do fine if you're file is/can be sorted, if you can't sort the file for some reason you can use awk:

awk '{a[$0]++}END{for(i in a)if(a[i]<2)print i}'

Create a unique number with javascript time

This also should do:

(function() {
    var uniquePrevious = 0;
    uniqueId = function() {
        return uniquePrevious++;
    };
}());

mean() warning: argument is not numeric or logical: returning NA

The same error appears if you do not use the correct (numeric) format of your data in your data.frame column using mean() function. Therefore, check your data using str(data.frame&column) function to see what data type you have, and convert it to numeric format if necessary. For example, if your data is Character convert it with as.numeric(data.frame$column), or as a factor with as.numeric(as.character(data.frame$column)). The mean function does not work with types other than numeric.

How to align 3 divs (left/center/right) inside another div?

possible answer, if you want to keep the order of the html and not use flex.

HTML

<div class="a">
  <div class="c">
    the 
  </div>
  <div class="c e">
    jai ho 
  </div>
  <div class="c d">
    watsup
  </div>
</div>

CSS

.a {
  width: 500px;
  margin: 0 auto;
  border: 1px solid red;
  position: relative;
  display: table;
}

.c {
  display: table-cell;
  width:33%;
}

.d {
  text-align: right;
}

.e {
  position: absolute;
  left: 50%;
  display: inline;
  width: auto;
  transform: translateX(-50%);
}

Code Pen Link

What is a good way to handle exceptions when trying to read a file in python?

Here is a read/write example. The with statements insure the close() statement will be called by the file object regardless of whether an exception is thrown. http://effbot.org/zone/python-with-statement.htm

import sys

fIn = 'symbolsIn.csv'
fOut = 'symbolsOut.csv'

try:
   with open(fIn, 'r') as f:
      file_content = f.read()
      print "read file " + fIn
   if not file_content:
      print "no data in file " + fIn
      file_content = "name,phone,address\n"
   with open(fOut, 'w') as dest:
      dest.write(file_content)
      print "wrote file " + fOut
except IOError as e:
   print "I/O error({0}): {1}".format(e.errno, e.strerror)
except: #handle other exceptions such as attribute errors
   print "Unexpected error:", sys.exc_info()[0]
print "done"

Initializing a two dimensional std::vector

Let's say you want to initialize 2D vector, m*n, with initial value to be 0

we could do this

#include<iostream>
int main(){ 
    int m = 2, n = 5;

    vector<vector<int>> vec(m, vector<int> (n, 0));

    return 0;
}

How to import .py file from another directory?

You can add to the system-path at runtime:

import sys
sys.path.insert(0, 'path/to/your/py_file')

import py_file

This is by far the easiest way to do it.

How do you use math.random to generate random ints?

double  i = 2+Math.random()*100;
int j = (int)i;
System.out.print(j);

Http Post With Body

You can use HttpClient and HttpPost to build and send the request.

HttpClient client= new DefaultHttpClient();
HttpPost request = new HttpPost("www.example.com");

List<NameValuePair> pairs = new ArrayList<NameValuePair>();
pairs.add(new BasicNameValuePair("paramName", "paramValue"));

request.setEntity(new UrlEncodedFormEntity(pairs ));
HttpResponse resp = client.execute(request);

What's with the dollar sign ($"string")

It's the new feature in C# 6 called Interpolated Strings.

The easiest way to understand it is: an interpolated string expression creates a string by replacing the contained expressions with the ToString representations of the expressions' results.

For more details about this, please take a look at MSDN.

Now, think a little bit more about it. Why this feature is great?

For example, you have class Point:

public class Point
{
    public int X { get; set; }

    public int Y { get; set; }
}

Create 2 instances:

var p1 = new Point { X = 5, Y = 10 };
var p2 = new Point { X = 7, Y = 3 };

Now, you want to output it to the screen. The 2 ways that you usually use:

Console.WriteLine("The area of interest is bounded by (" + p1.X + "," + p1.Y + ") and (" + p2.X + "," + p2.Y + ")");

As you can see, concatenating string like this makes the code hard to read and error-prone. You may use string.Format() to make it nicer:

Console.WriteLine(string.Format("The area of interest is bounded by({0},{1}) and ({2},{3})", p1.X, p1.Y, p2.X, p2.Y));

This creates a new problem:

  1. You have to maintain the number of arguments and index yourself. If the number of arguments and index are not the same, it will generate a runtime error.

For those reasons, we should use new feature:

Console.WriteLine($"The area of interest is bounded by ({p1.X},{p1.Y}) and ({p2.X},{p2.Y})");

The compiler now maintains the placeholders for you so you don’t have to worry about indexing the right argument because you simply place it right there in the string.

For the full post, please read this blog.

ReactJS SyntheticEvent stopPropagation() only works with React events?

It is still one intersting moment:

ev.preventDefault()
ev.stopPropagation();
ev.nativeEvent.stopImmediatePropagation();

Use this construction, if your function is wrapped by tag

What is the best way to give a C# auto-property an initial value?

In the constructor. The constructor's purpose is to initialized it's data members.

Best way to extract a subvector from a vector?

The only way to project a collection that is not linear time is to do so lazily, where the resulting "vector" is actually a subtype which delegates to the original collection. For example, Scala's List#subseq method create a sub-sequence in constant time. However, this only works if the collection is immutable and if the underlying language sports garbage collection.

What is an MvcHtmlString and when should I use it?

ASP.NET 4 introduces a new code nugget syntax <%: %>. Essentially, <%: foo %> translates to <%= HttpUtility.HtmlEncode(foo) %>. The team is trying to get developers to use <%: %> instead of <%= %> wherever possible to prevent XSS.

However, this introduces the problem that if a code nugget already encodes its result, the <%: %> syntax will re-encode it. This is solved by the introduction of the IHtmlString interface (new in .NET 4). If the foo() in <%: foo() %> returns an IHtmlString, the <%: %> syntax will not re-encode it.

MVC 2's helpers return MvcHtmlString, which on ASP.NET 4 implements the interface IHtmlString. Therefore when developers use <%: Html.*() %> in ASP.NET 4, the result won't be double-encoded.

Edit:

An immediate benefit of this new syntax is that your views are a little cleaner. For example, you can write <%: ViewData["anything"] %> instead of <%= Html.Encode(ViewData["anything"]) %>.

Git Clone: Just the files, please?

git --work-tree=/tmp/files_without_dot_git clone --depth=1 \
  https://git.yourgit.your.com/myawesomerepo.git \
  /tmp/deleteme_contents_of_dot_git

Both the directories in /tmp are created on the fly. No need to pre-create these.

Call to undefined function App\Http\Controllers\ [ function name ]

say you define the static getFactorial function inside a CodeController

then this is the way you need to call a static function, because static properties and methods exists with in the class, not in the objects created using the class.

CodeController::getFactorial($index);

----------------UPDATE----------------

To best practice I think you can put this kind of functions inside a separate file so you can maintain with more easily.

to do that

create a folder inside app directory and name it as lib (you can put a name you like).

this folder to needs to be autoload to do that add app/lib to composer.json as below. and run the composer dumpautoload command.

"autoload": {
    "classmap": [
                "app/commands",
                "app/controllers",
                ............
                "app/lib"
    ]
},

then files inside lib will autoloaded.

then create a file inside lib, i name it helperFunctions.php

inside that define the function.

if ( ! function_exists('getFactorial'))
{

    /**
     * return the factorial of a number
     *
     * @param $number
     * @return string
     */
    function getFactorial($date)
    {
        $fact = 1;

        for($i = 1; $i <= $num ;$i++)
            $fact = $fact * $i;

        return $fact;

     }
}

and call it anywhere within the app as

$fatorial_value = getFactorial(225);

Java: Check the date format of current string is according to required format or not

Disclaimer

Parsing a string back to date/time value in an unknown format is inherently impossible (let's face it, what does 3/3/3 actually mean?!), all we can do is "best effort"

Important

This solution doesn't throw an Exception, it returns a boolean, this is by design. Any Exceptions are used purely as a guard mechanism.

2018

Since it's now 2018 and Java 8+ has the date/time API (and the rest have the ThreeTen backport). The solution remains basically the same, but becomes slightly more complicated, as we need to perform checks for:

  • date and time
  • date only
  • time only

This makes it look something like...

public static boolean isValidFormat(String format, String value, Locale locale) {
    LocalDateTime ldt = null;
    DateTimeFormatter fomatter = DateTimeFormatter.ofPattern(format, locale);

    try {
        ldt = LocalDateTime.parse(value, fomatter);
        String result = ldt.format(fomatter);
        return result.equals(value);
    } catch (DateTimeParseException e) {
        try {
            LocalDate ld = LocalDate.parse(value, fomatter);
            String result = ld.format(fomatter);
            return result.equals(value);
        } catch (DateTimeParseException exp) {
            try {
                LocalTime lt = LocalTime.parse(value, fomatter);
                String result = lt.format(fomatter);
                return result.equals(value);
            } catch (DateTimeParseException e2) {
                // Debugging purposes
                //e2.printStackTrace();
            }
        }
    }

    return false;
}

This makes the following...

System.out.println("isValid - dd/MM/yyyy with 20130925 = " + isValidFormat("dd/MM/yyyy", "20130925", Locale.ENGLISH));
System.out.println("isValid - dd/MM/yyyy with 25/09/2013 = " + isValidFormat("dd/MM/yyyy", "25/09/2013", Locale.ENGLISH));
System.out.println("isValid - dd/MM/yyyy with 25/09/2013 12:13:50 = " + isValidFormat("dd/MM/yyyy", "25/09/2013  12:13:50", Locale.ENGLISH));
System.out.println("isValid - yyyy-MM-dd with 2017-18--15 = " + isValidFormat("yyyy-MM-dd", "2017-18--15", Locale.ENGLISH));

output...

isValid - dd/MM/yyyy with 20130925 = false
isValid - dd/MM/yyyy with 25/09/2013 = true
isValid - dd/MM/yyyy with 25/09/2013 12:13:50 = false
isValid - yyyy-MM-dd with 2017-18--15 = false

Original Answer

Simple try and parse the String to the required Date using something like SimpleDateFormat

Date date = null;
try {
    SimpleDateFormat sdf = new SimpleDateFormat(format);
    date = sdf.parse(value);
    if (!value.equals(sdf.format(date))) {
        date = null;
    }
} catch (ParseException ex) {
    ex.printStackTrace();
}
if (date == null) {
    // Invalid date format
} else {
    // Valid date format
}

You could then simply write a simple method that performed this action and returned true when ever Date was not null...

As a suggestion...

Updated with running example

I'm not sure what you are doing, but, the following example...

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class TestDateParser {

    public static void main(String[] args) {
        System.out.println("isValid - dd/MM/yyyy with 20130925 = " + isValidFormat("dd/MM/yyyy", "20130925"));
        System.out.println("isValid - dd/MM/yyyy with 25/09/2013 = " + isValidFormat("dd/MM/yyyy", "25/09/2013"));
        System.out.println("isValid - dd/MM/yyyy with 25/09/2013 12:13:50 = " + isValidFormat("dd/MM/yyyy", "25/09/2013  12:13:50"));
    }

    public static boolean isValidFormat(String format, String value) {
        Date date = null;
        try {
            SimpleDateFormat sdf = new SimpleDateFormat(format);
            date = sdf.parse(value);
            if (!value.equals(sdf.format(date))) {
                date = null;
            }
        } catch (ParseException ex) {
            ex.printStackTrace();
        }
        return date != null;
    }

}

Outputs (something like)...

java.text.ParseException: Unparseable date: "20130925"
isValid - dd/MM/yyyy with 20130925 = false
isValid - dd/MM/yyyy with 25/09/2013 = true
isValid - dd/MM/yyyy with 25/09/2013 12:13:50 = false
    at java.text.DateFormat.parse(DateFormat.java:366)
    at javaapplication373.JavaApplication373.isValidFormat(JavaApplication373.java:28)
    at javaapplication373.JavaApplication373.main(JavaApplication373.java:19)

Not correct. For isValidFormat("yyyy-MM-dd", "2017-18--15"); not throw any Exception.

isValid - yyyy-MM-dd", "2017-18--15 = false

Seems to work as expected for me - the method doesn't rely on (nor does it throw) the exception alone to perform it's operation

How do I include image files in Django templates?

Your

<img src="/home/tony/london.jpg" />

will work for a HTML file read from disk, as it will assume the URL is file:///home/.... For a file served from a webserver though, the URL will become something like: http://www.yourdomain.com/home/tony/london.jpg, which can be an invalid URL and not what you really mean.

For about how to serve and where to place your static files, check out this document. Basicly, if you're using django's development server, you want to show him the place where your media files live, then make your urls.py serve those files (for example, by using some /static/ url prefix).

Will require you to put something like this in your urls.py:

(r'^site_media/(?P<path>.*)$', 'django.views.static.serve',
    {'document_root': '/path/to/media'}),

In production environment you want to skip this and make your http server (apache, lighttpd, etc) serve static files.

How to display list items as columns?

CSS:

#cols {
    -moz-column-count: 3;
    -moz-column-gap: 20px;
    -webkit-column-count: 3;
    -webkit-column-gap: 20px;
    column-count: 3;
    column-gap: 20px;
}

HTML

<div id="cols">
    <ul>
    <li>List item 1</li>
    <li>List item 2</li>
    <li>List item 3</li>
    <li>List item 4</li>
    <li>List item 5</li>
    <li>List item 6</li>
    <li>List item 7</li>
    <li>List item 8</li>
    <li>List item 9</li>
    <li>List item 10</li>
    <li>List item 11</li>
    <li>List item 12</li>
    <li>List item 10</li>
    <li>List item 11</li>
    <li>List item 12</li>
   
    </ul>
</div> 

Check demo : https://codepen.io/pen/

Disabling contextual LOB creation as createClob() method threw error

If you set:

hibernate.temp.use_jdbc_metadata_defaults: false

it can cause you troubles with PostgreSQL when your table name contains reserved word like user. After insert it will try to find id sequence with:

select currval('"user"_id_seq');

which will obviously fail. This at least with Hibernate 5.2.13 and Spring Boot 2.0.0.RC1. Haven't found other way to prevent this message so now just ignoring it.

How to make a GUI for bash scripts?

Please, take a look at my library: http://sites.google.com/site/easybashgui

It is intended to handle, with the same commands set, indifferently all four big tools "kdialog", "Xdialog", "cdialog" and "zenity", depending if X is running or not, if D.E. is KDE or Gnome or other. There are 15 different functions ( among them there are two called "progress" and "adjust" )...

Bye :-)

How to connect Android app to MySQL database?

Android does not support MySQL out of the box. The "normal" way to access your database would be to put a Restful server in front of it and use the HTTPS protocol to connect to the Restful front end.

Have a look at ContentProvider. It is normally used to access a local database (SQLite) but it can be used to get data from any data store.

I do recommend that you look at having a local copy of all/some of your websites data locally, that way your app will still work when the Android device hasn't got a connection. If you go down this route then a service can be used to keep the two databases in sync.

How to easily initialize a list of Tuples?

Old question, but this is what I typically do to make things a bit more readable:

Func<int, string, Tuple<int, string>> tc = Tuple.Create;

var tupleList = new List<Tuple<int, string>>
{
    tc( 1, "cow" ),
    tc( 5, "chickens" ),
    tc( 1, "airplane" )
};

Selenium 2.53 not working on Firefox 47

If you're on a Mac do brew install geckodriver and off you go!

Ant task to run an Ant target only if a file exists?

Available and Condition

<target name="check-abc">
    <available file="abc.txt" property="abc.present"/>
</target>

<target name="do-if-abc" depends="check-abc" if="abc.present">
    ...
</target> 

Git copy changes from one branch to another

This is 2 step process

  • git checkout BranchB ( destination branch is BranchB, so we need the head on this branch)
  • git merge BranchA (it will merge BranchB with BranchA. Here you have merged code in branch B)

If you want to push your branch code to remote repo then do

  • git push origin master (it will push your BranchB code to remote repo)

Get resultset from oracle stored procedure

Oracle is not sql server. Try the following in SQL Developer

variable rc refcursor;
exec testproc(:rc2);
print rc2

How do I format date and time on ssrs report?

=Replace(Format(CDate(Now()),"MM.dd.yyyy"), ".", "/")

jQuery selector to get form by name

    // this will give all the forms on the page.

    $('form')

   // If you know the name of form then.

    $('form[name="myFormName"]')

  //  If you don't know know the name but the position (starts with 0)

    $('form:eq(1)')  // 2nd form will be fetched.

How to save a plot as image on the disk?

If you want to keep seeing the plot in R, another option is to use dev.copy:

X11 ()
plot (x,y)

dev.copy(jpeg,filename="plot.jpg");
dev.off ();

If you reach a clutter of too many plot windows in R, use graphics.off() to close all of the plot windows.

How to get javax.comm API?

Another Simple way i found in Netbeans right click on your project>libraris click add jar/folder add your comm.jar and you done.

if you dont have comm.jar download it from >>> http://llk.media.mit.edu/projects/picdev/software/javaxcomm.zip

Concatenate columns in Apache Spark DataFrame

concat(*cols)

v1.5 and higher

Concatenates multiple input columns together into a single column. The function works with strings, binary and compatible array columns.

Eg: new_df = df.select(concat(df.a, df.b, df.c))


concat_ws(sep, *cols)

v1.5 and higher

Similar to concat but uses the specified separator.

Eg: new_df = df.select(concat_ws('-', df.col1, df.col2))


map_concat(*cols)

v2.4 and higher

Used to concat maps, returns the union of all the given maps.

Eg: new_df = df.select(map_concat("map1", "map2"))


Using string concat operator (||):

v2.3 and higher

Eg: df = spark.sql("select col_a || col_b || col_c as abc from table_x")

Reference: Spark sql doc

Warning: Attempt to present * on * whose view is not in the window hierarchy - swift

Swift 3.

Call this function to get the topmost view controller, then have that view controller present.

func topMostController() -> UIViewController {
    var topController: UIViewController = UIApplication.shared.keyWindow!.rootViewController!
        while (topController.presentedViewController != nil) {
            topController = topController.presentedViewController!
        }
        return topController
    }

Usage:

let topVC = topMostController()
let vcToPresent = self.storyboard!.instantiateViewController(withIdentifier: "YourVCStoryboardID") as! YourViewController
topVC.present(vcToPresent, animated: true, completion: nil)

Running Python code in Vim

  1. Go to your home directory. cd
  2. Open your .vimrc file with vim. vim .vimrc
  3. Add the next code to the file. nmap <F4> <Esc>:w<CR>:!clear;python %<CR>
  4. Save it and quit. ZZ

The next time you want to run your code, just press F4 in "normal mode". If you want to run your code in "insert mode", replace nmap with imap.

How to send a HTTP OPTIONS request from the command line?

The curl installed by default in Debian supports HTTPS since a great while back. (a long time ago there were two separate packages, one with and one without SSL but that's not the case anymore)

OPTIONS /path

You can send an OPTIONS request with curl like this:

curl -i -X OPTIONS http://example.org/path

You may also use -v instead of -i to see more output.

OPTIONS *

To send a plain * (instead of the path, see RFC 7231) with the OPTIONS method, you need curl 7.55.0 or later as then you can run a command line like:

curl -i --request-target "*" -X OPTIONS http://example.org

Getting the difference between two sets

Adding a solution which I've recently used myself and haven't seen mentioned here. If you have Apache Commons Collections available then you can use the SetUtils#difference method:

// Returns all the elements of test2 which are not in test1
SetUtils.difference(test2, test1) 

Note that according to the documentation the returned set is an unmodifiable view:

Returns a unmodifiable view containing the difference of the given Sets, denoted by a \ b (or a - b). The returned view contains all elements of a that are not a member of b.

Full documentation: https://commons.apache.org/proper/commons-collections/apidocs/org/apache/commons/collections4/SetUtils.html#difference-java.util.Set-java.util.Set-

Laravel check if collection is empty

This is the best solution I found so far.

in blade

@if($mentors->count() == 0)
    <td colspan="5" class="text-center">
        Nothing Found
    </td>
@endif

in controller

if ($mentors->count() == 0) {
    return "Nothing Found";
}

Java2D: Increase the line width

What is Stroke:

The BasicStroke class defines a basic set of rendering attributes for the outlines of graphics primitives, which are rendered with a Graphics2D object that has its Stroke attribute set to this BasicStroke.

https://docs.oracle.com/javase/7/docs/api/java/awt/BasicStroke.html

Note that the Stroke setting:

Graphics2D g2 = (Graphics2D) g;
g2.setStroke(new BasicStroke(10));

is setting the line width,since BasicStroke(float width):

Constructs a solid BasicStroke with the specified line width and with default values for the cap and join styles.

And, it also effects other methods like Graphics2D.drawLine(int x1, int y1, int x2, int y2) and Graphics2D.drawRect(int x, int y, int width, int height):

The methods of the Graphics2D interface that use the outline Shape returned by a Stroke object include draw and any other methods that are implemented in terms of that method, such as drawLine, drawRect, drawRoundRect, drawOval, drawArc, drawPolyline, and drawPolygon.

Converting String to Int using try/except in Python

It is important to be specific about what exception you're trying to catch when using a try/except block.

string = "abcd"
try:
    string_int = int(string)
    print(string_int)
except ValueError:
    # Handle the exception
    print('Please enter an integer')

Try/Excepts are powerful because if something can fail in a number of different ways, you can specify how you want the program to react in each fail case.

How to get height of Keyboard?

The method by ZAFAR007 updated for Swift 5 in Xcode 10

override func viewDidLoad() {
    super.viewDidLoad()

    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)

}




@objc func keyboardWillShow(notification: NSNotification) {

    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        let keyboardHeight : Int = Int(keyboardSize.height)
        print("keyboardHeight",keyboardHeight)
    }

}

Detect whether a Python string is a number or a letter

For a string of length 1 you can simply perform isdigit() or isalpha()

If your string length is greater than 1, you can make a function something like..

def isinteger(a):
    try:
        int(a)
        return True
    except ValueError:
        return False

Allowing Java to use an untrusted certificate for SSL/HTTPS connection

Here is some relevant code:

// Create a trust manager that does not validate certificate chains
TrustManager[] trustAllCerts = new TrustManager[]{
    new X509TrustManager() {
        public java.security.cert.X509Certificate[] getAcceptedIssuers() {
            return null;
        }
        public void checkClientTrusted(
            java.security.cert.X509Certificate[] certs, String authType) {
        }
        public void checkServerTrusted(
            java.security.cert.X509Certificate[] certs, String authType) {
        }
    }
};

// Install the all-trusting trust manager
try {
    SSLContext sc = SSLContext.getInstance("SSL");
    sc.init(null, trustAllCerts, new java.security.SecureRandom());
    HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
} catch (Exception e) {
}

// Now you can access an https URL without having the certificate in the truststore
try {
    URL url = new URL("https://hostname/index.html");
} catch (MalformedURLException e) {
}

This will completely disable SSL checking—just don't learn exception handling from such code!

To do what you want, you would have to implement a check in your TrustManager that prompts the user.

Where to declare variable in react js

Assuming that onMove is an event handler, it is likely that its context is something other than the instance of MyContainer, i.e. this points to something different.

You can manually bind the context of the function during the construction of the instance via Function.bind:

class MyContainer extends Component {
  constructor(props) {
    super(props);

    this.onMove = this.onMove.bind(this);

    this.test = "this is a test";
  }

  onMove() {
    console.log(this.test);
  }
}

Also, test !== testVariable.

Want custom title / image / description in facebook share link from a flash app

I actually have a similar problem. I have a page with multiple radio buttons; each button will set the title and description meta tags of the page, via JavaScript upon change.

For example, if users select the first button, the meta tags will say:

<meta name="title" content="First Title">
<meta name="description" content="First Description">

If the user select the second button, this changes the meta tags to:

<meta name="title" content="Second Title">
<meta name="description" content="Second Description">

... and so on. I have confirmed that the code is working fine via Firebug (i.e. I can see that those two tags were properly changed).

Apparently, Facebook Share only pulls in the title and description meta tags that are available upon page load. The changes to those two tags post page load are completely ignored.

Does anybody have any ideas on how to solve this? That is, to force Facebook to get the latest values that are change after the page loads.

How to convert any date format to yyyy-MM-dd

Convert your string to DateTime and then use DateTime.ToString("yyyy-MM-dd");

DateTime temp = DateTime.ParseExact(sourceDate, "dd-MM-yyyy", CultureInfo.InvariantCulture);
string str = temp.ToString("yyyy-MM-dd");

Google Maps API v3: How do I dynamically change the marker icon?

You can also use a circle as a marker icon, for example:

var oMarker = new google.maps.Marker({
    position: latLng,
    sName: "Marker Name",
    map: map,
    icon: {
        path: google.maps.SymbolPath.CIRCLE,
        scale: 8.5,
        fillColor: "#F00",
        fillOpacity: 0.4,
        strokeWeight: 0.4
    },
});

and then, if you want to change the marker dynamically (like on mouseover), you can, for example:

oMarker.setIcon({
            path: google.maps.SymbolPath.CIRCLE,
            scale: 10,
            fillColor: "#00F",
            fillOpacity: 0.8,
            strokeWeight: 1
        })

Vue.js getting an element within a component

In Vue2 be aware that you can access this.$refs.uniqueName only after mounting the component.

How to upload a file to directory in S3 bucket using boto

Using boto3

import logging
import boto3
from botocore.exceptions import ClientError


def upload_file(file_name, bucket, object_name=None):
    """Upload a file to an S3 bucket

    :param file_name: File to upload
    :param bucket: Bucket to upload to
    :param object_name: S3 object name. If not specified then file_name is used
    :return: True if file was uploaded, else False
    """

    # If S3 object_name was not specified, use file_name
    if object_name is None:
        object_name = file_name

    # Upload the file
    s3_client = boto3.client('s3')
    try:
        response = s3_client.upload_file(file_name, bucket, object_name)
    except ClientError as e:
        logging.error(e)
        return False
    return True

For more:- https://boto3.amazonaws.com/v1/documentation/api/latest/guide/s3-uploading-files.html

How to get the sizes of the tables of a MySQL database?

Calculate the total size of the database at the end:

(SELECT 
  table_name AS `Table`, 
  round(((data_length + index_length) / 1024 / 1024), 2) `Size in MB` 
  FROM information_schema.TABLES 
  WHERE table_schema = "$DB_NAME"
)
UNION ALL
(SELECT 
  'TOTAL:',
  SUM(round(((data_length + index_length) / 1024 / 1024), 2) )
  FROM information_schema.TABLES 
  WHERE table_schema = "$DB_NAME"
)

What causes "Unable to access jarfile" error?

None of the provided answers worked for me on macOS 11 Big Sur. The problem turned out to be that programs require special permission to access the Desktop, Documents, and Downloads folders, and Java breaks both the exception for directly opened files and the permission request popup.

Fixes:

  • Move the .jar into a folder that isn’t (and isn’t under) Documents, Desktop, or Downloads.
  • Manually grant the permission. Go to System Preferences ? Security and Privacy ? Privacy ? Files and Folders ? java, and check the appropriate folders.

git pull fails "unable to resolve reference" "unable to update local ref"

I just would like to add how it may happen that a reference breaks.

Possible root cause

On my system (Windows 7 64-bit), when a BSOD happens, some of the stored reference files (most likely currently opened/being written into when BSOD happened) are overwritten with NULL characters (ASCII 0).

As others mentioned, to fix it, it's enough to just delete those invalid reference files and re-fetch or re-pull the repository.

Example

Error: cannot lock ref 'refs/remotes/origin/some/branch': unable to resolve reference 'refs/remotes/origin/some/branch': reference broken

Solution: delete the file %repo_root%/.git/refs/remotes/origin/some/branch

Use a JSON array with objects with javascript

This isn't a single JSON object. You have an array of JSON objects. You need to loop over array first and then access each object. Maybe the following kickoff example is helpful:

var arrayOfObjects = [{
  "id": 28,
  "Title": "Sweden"
}, {
  "id": 56,
  "Title": "USA"
}, {
  "id": 89,
  "Title": "England"
}];

for (var i = 0; i < arrayOfObjects.length; i++) {
  var object = arrayOfObjects[i];
  for (var property in object) {
    alert('item ' + i + ': ' + property + '=' + object[property]);
  }
  // If property names are known beforehand, you can also just do e.g.
  // alert(object.id + ',' + object.Title);
}

If the array of JSON objects is actually passed in as a plain vanilla string, then you would indeed need eval() here.

var string = '[{"id":28,"Title":"Sweden"}, {"id":56,"Title":"USA"}, {"id":89,"Title":"England"}]';
var arrayOfObjects = eval(string);
// ...

To learn more about JSON, check MDN web docs: Working with JSON .

How to undo the last commit in git

I think you haven't messed up yet. Try:

git reset HEAD^

This will bring the dir to state before you've made the commit, HEAD^ means the parent of the current commit (the one you don't want anymore), while keeping changes from it (unstaged).

How to run multiple DOS commands in parallel?

I suggest you to see "How do I run a bat file in the background from another bat file?"

Also, good answer (of using start command) was given in "Parallel execution of shell processes" question page here;

But my recommendation is to use PowerShell. I believe it will perfectly suit your needs.

Doctrine findBy 'does not equal'

There is now a an approach to do this, using Doctrine's Criteria.

A full example can be seen in How to use a findBy method with comparative criteria, but a brief answer follows.

use \Doctrine\Common\Collections\Criteria;

// Add a not equals parameter to your criteria
$criteria = new Criteria();
$criteria->where(Criteria::expr()->neq('prize', 200));

// Find all from the repository matching your criteria
$result = $entityRepository->matching($criteria);

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

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

Step1: add in AndroidManifest.xml file

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

Step2: Request permission.

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

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

Step3: Handle callback when you request permission.

@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
    switch (requestCode) {
        case REQUEST_READ_PHONE_STATE:
            if ((grantResults.length > 0) && (grantResults[0] == PackageManager.PERMISSION_GRANTED)) {
                //TODO
            }
            break;

        default:
            break;
    }
}

Edit: Read official guide here Requesting Permissions at Run Time

Nodejs - Redirect url

The logic of determining a "wrong" url is specific to your application. It could be a simple file not found error or something else if you are doing a RESTful app. Once you've figured that out, sending a redirect is as simple as:

response.writeHead(302, {
  'Location': 'your/404/path.html'
  //add other headers here...
});
response.end();

How do I filter date range in DataTables?

Using other posters code with some tweaks:

<table id="MainContent_tbFilterAsp" style="margin-top:-15px;">
        <tbody>
            <tr>
                <td style="vertical-align:initial;"><label for="datepicker_from" id="MainContent_datepicker_from_lbl" style="margin-top:7px;">From date:</label>&nbsp;
                </td>
                
                <td style="padding-right: 20px;"><input name="ctl00$MainContent$datepicker_from" type="text" id="datepicker_from" class="datepick form-control hasDatepicker" autocomplete="off" style="cursor:pointer; background-color: #FFFFFF">&nbsp;&nbsp;&nbsp;
                </td>
                
                <td style="vertical-align:initial"><label for="datepicker_to" id="MainContent_datepicker_to_lbl" style="margin-top:7px;">To date:</label>&nbsp;
                </td>
                
                <td style="padding-right: 20px;"><input name="ctl00$MainContent$datepicker_to" type="text" id="datepicker_to" class="datepick form-control hasDatepicker" autocomplete="off" style="cursor:pointer; background-color: #FFFFFF">&nbsp;&nbsp;&nbsp;                        
                </td>
                
                <td style="vertical-align:initial"><a onclick="$('#datepicker_from').val(''); $('#datepicker_to').val(''); return false;" id="datepicker_clear_lnk" style="margin-top:7px;">Clear</a></td>
            </tr>
        </tbody>
    </table>
    
    <script>
        $(document).ready(function() {
            $(function() {
                var oTable = $('#tbAD').DataTable({
                "oLanguage": {
                    "sSearch": "Filter Data"
                },
                "iDisplayLength": -1,
                "sPaginationType": "full_numbers",
                "pageLength": 50, 
                });

                $("#datepicker_from").datepicker();
                $("#datepicker_to").datepicker();

                $('#datepicker_from').change(function (e) {
                    oTable.draw();
                });
                $('#datepicker_to').change(function (e) {
                    oTable.draw();
                });
                $('#datepicker_clear_lnk').click(function (e) {
                    oTable.draw();
                });
            });   

            $.fn.dataTable.ext.search.push(
                function (settings, data, dataIndex) {
                var min = $('#datepicker_from').datepicker("getDate") == null ? null : $('#datepicker_from').datepicker("getDate").setHours(0,0,0,0);
                var max = $('#datepicker_to').datepicker("getDate") == null ? null : $('#datepicker_to').datepicker("getDate").setHours(0,0,0,0);
                var startDate = new Date(data[9]).setHours(0,0,0,0);
                if (min == null && max == null) { return true; }
                if (min == null && startDate <= max) { return true; }
                if (max == null && startDate >= min) { return true; }
                if (startDate <= max && startDate >= min) { return true; }                    
                return false;
                }
            );
        });
</script>

only integers, slices (`:`), ellipsis (`...`), numpy.newaxis (`None`) and integer or boolean arrays are valid indices

put a int infront of the all the voxelCoord's...Like this below :

patch = numpyImage [int(voxelCoord[0]),int(voxelCoord[1])- int(voxelWidth/2):int(voxelCoord[1])+int(voxelWidth/2),int(voxelCoord[2])-int(voxelWidth/2):int(voxelCoord[2])+int(voxelWidth/2)]

Finish all previous activities

If you are using startActivityForResult() in your previous activities, just override OnActivityResult() and call the finish(); method inside it in all activities.. This will do the job...

Generate a random number in the range 1 - 10

The correct version of hythlodayr's answer.

-- ERROR:  operator does not exist: double precision % integer
-- LINE 1: select (trunc(random() * 10) % 10) + 1

The output from trunc has to be converted to INTEGER. But it can be done without trunc. So it turns out to be simple.

select (random() * 9)::INTEGER + 1

Generates an INTEGER output in range [1, 10] i.e. both 1 & 10 inclusive.

For any number (floats), see user80168's answer. i.e just don't convert it to INTEGER.

Configuring diff tool with .gitconfig

Others have done a 99% answer on this, but there is one step left out. (My answer will be coming from OS X so you will have to change file paths accordingly.)

You make these changes to your ~/.gitconfig:

[diff]
    tool = diffmerge
[difftool "diffmerge"]
    cmd = /Applications/Diffmerge.app/Contents/MacOS/diffmerge $LOCAL $REMOTE

This will fix the diff tool. You can also fix this without editing the ~/.gitconfig directly by entering these commands from the terminal:

git config --global diff.tool diffmerge
git config --global difftool.diffmerge.cmd "/Applications/DiffMerge.appContents/MacOS/diffmerge \$LOCAL \$REMOTE"

The 1% that everyone else failed to mention is when using this you can't just run git diff myfile.txt; you need to run git difftool myfile.txt.

Calling async method on button click

You're the victim of the classic deadlock. task.Wait() or task.Result is a blocking call in UI thread which causes the deadlock.

Don't block in the UI thread. Never do it. Just await it.

private async void Button_Click(object sender, RoutedEventArgs 
{
      var task = GetResponseAsync<MyObject>("my url");
      var items = await task;
}

Btw, why are you catching the WebException and throwing it back? It would be better if you simply don't catch it. Both are same.

Also I can see you're mixing the asynchronous code with synchronous code inside the GetResponse method. StreamReader.ReadToEnd is a blocking call --you should be using StreamReader.ReadToEndAsync.

Also use "Async" suffix to methods which returns a Task or asynchronous to follow the TAP("Task based Asynchronous Pattern") convention as Jon says.

Your method should look something like the following when you've addressed all the above concerns.

public static async Task<List<T>> GetResponseAsync<T>(string url)
{
    HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);
    var response = (HttpWebResponse)await Task.Factory.FromAsync<WebResponse>(request.BeginGetResponse, request.EndGetResponse, null);

    Stream stream = response.GetResponseStream();
    StreamReader strReader = new StreamReader(stream);
    string text = await strReader.ReadToEndAsync();

    return JsonConvert.DeserializeObject<List<T>>(text);
}

How to read a text file into a string variable and strip newlines?

file = open("myfile.txt", "r")
lines = file.readlines()
str = ''                                     #string declaration

for i in range(len(lines)):
    str += lines[i].rstrip('\n') + ' '

print str

How to use Sublime over SSH

I'm on Windows and have used 4 methods: SFTP, WinSCP, Unison and Sublime Text on Linux with X11 forwarding over SSH to Windows (yes you can do this without messy configs and using a free tool).

The fourth way is the best if you can install software on your Linux machine.

The fourth way:

MobaXterm

  1. Install MobaXterm on Windows
  2. SSH to your Linux box from MobaXterm
  3. On your linux box, install Sublime Text 3. Here's how to on Ubuntu
  4. At the command prompt, start sublime with subl
  5. That's it! You now have sublime text running on Linux, but with its window running on your Windows desktop. This is possible because MobaXterm handles the X11 forwarding over SSH for you so you don't have to do anything funky to get it going. There might be a teeny amount of a delay, but your files will never be out of sync, because you're editing them right on the Linux machine.

Note: When invoking subl if it complains for a certain library - ensure you install them to successfully invoke sublimetext from mobaxterm.

If you can't install software on your Linux box, the best is Unison. Why?

  • It's free
  • It's fast
  • It's reliable and doesn't care which editor you use
  • You can create custom ignore lists

SFTP

Setup: Install the SFTP Sublime Text package. This package requires a license.

  1. Create a new folder
  2. Open it as a Sublime Text Project.
  3. In the sidebar, right click on the folder and select Map Remote.
  4. Edit the sftp-config.json file
  5. Right click the folder in step 1 select download.
  6. Work locally.

In the sftp-config, I usually set:

"upload_on_save": true,
"sync_down_on_open": true,

This, in addition to an SSH terminal to the machine gives me a fairly seamless remote editing experience.

WinSCP

  1. Install and run WinSCP
  2. Go to Preferences (Ctrl+Alt+P) and click on Transfer, then on Add. Name the preset.
  3. Set the transfer mode to binary (you don't want line conversions)
  4. Set file modification to "No change"
  5. Click the Edit button next to File Mask and setup your include and exclude files and folders (useful for when you have a .git/.svn folder present or you want to exclude build products from being synchronized).
  6. Click OK
  7. Connect to your remote server and navigate to the folder of interest
  8. Choose an empty folder on your local machine.
  9. Select your newly created Transfer settings preset.
  10. Finally, hit Ctrl+U (Commands > Keep remote directory up to date) and make sure "Synchronize on start" and "Update subdirectories" are checked.

From then on, WinSCP will keep your changes synchronized.

Work in the local folder using SublimeText. Just make sure that Sublime Text is set to guess the line endings from the file that is being edited.

Unison

I have found that if source tree is massive (around a few hundred MB with a deep hierarchy), then the WinSCP method described above might be a bit slow. You can get much better performance using Unison. The down side is that Unison is not automatic (you need to trigger it with a keypress) and requires a server component to be running on your linux machine. The up side is that the transfers are incredibly fast, it is very reliable and ignoring files, folders and extensions are incredibly easy to setup.

Footnotes for tables in LaTeX

\begin{figure}[H]
\centering
{\includegraphics[width=1.0\textwidth]{image}}
\caption{captiontext\protect\footnotemark}
\label{fig:}
\end{figure}
\footnotetext{Footnotetext} 

IIS Manager in Windows 10

I arrived here because I was having the same issue.

If you are here and everything above didn't work, it's likely that you butchered your path somehow.

Go to System -> Advanced System Settings -> Advanced -> Environment Variables -> Machine or User and add the following entry to the end, or append to the existing, separating with a semi-colon:

C:\Windows\System32\inetsrv

After closing and opening your shell, you should now be able to access inetmgr from the command line.