Programs & Examples On #Security policy

Refused to load the font 'data:font/woff.....'it violates the following Content Security Policy directive: "default-src 'self'". Note that 'font-src'

To fix this specific error, CSP should include this:

font-src 'self' data:;

So, index.html meta should read:

<meta http-equiv="Content-Security-Policy" content="font-src 'self' data:; img-src 'self' data:; default-src 'self' http://121.0.0:3000/">

Content Security Policy: The page's settings blocked the loading of a resource

With my ASP.NET Core Angular project running in Visual Studio 2019, sometimes I get this error message in the Firefox console:

Content Security Policy: The page’s settings blocked the loading of a resource at inline (“default-src”).

In Chrome, the error message is instead:

Failed to load resource: the server responded with a status of 404 ()

In my case it had nothing to do with my Content Security Policy, but instead was simply the result of a TypeScript error on my part.

Check your IDE output window for a TypeScript error, like:

> ERROR in src/app/shared/models/person.model.ts(8,20): error TS2304: Cannot find name 'bool'.
> i ?wdm?: Failed to compile.

Note: Since this question is the first result on Google for this error message.

What is the "Upgrade-Insecure-Requests" HTTP header?

This explains the whole thing:

The HTTP Content-Security-Policy (CSP) upgrade-insecure-requests directive instructs user agents to treat all of a site's insecure URLs (those served over HTTP) as though they have been replaced with secure URLs (those served over HTTPS). This directive is intended for web sites with large numbers of insecure legacy URLs that need to be rewritten.

The upgrade-insecure-requests directive is evaluated before block-all-mixed-content and if it is set, the latter is effectively a no-op. It is recommended to set one directive or the other, but not both.

The upgrade-insecure-requests directive will not ensure that users visiting your site via links on third-party sites will be upgraded to HTTPS for the top-level navigation and thus does not replace the Strict-Transport-Security (HSTS) header, which should still be set with an appropriate max-age to ensure that users are not subject to SSL stripping attacks.


Refused to load the script because it violates the following Content Security Policy directive

For anyone looking for a complete explanation, I recommend you to take a look at Content Security Policy:

"Code from should only have access to’s data, and should certainly never be allowed access. Each origin is kept isolated from the rest of the web"

XSS attacks are based on the browser's inability to distinguish your app's code from code downloaded from another website. So you must whitelist the content origins that you consider safe to download content from, using the Content-Security-Policy HTTP header.

This policy is described using a series of policy directives, each of which describes the policy for a certain resource type or policy area. Your policy should include a default-src policy directive, which is a fallback for other resource types when they don't have policies of their own.

So, if you modify your tag to:

<meta http-equiv="Content-Security-Policy" content="default-src 'self' data: gap: 'unsafe-eval'; style-src 'self' 'unsafe-inline'; media-src *;**script-src 'self' 'unsafe-inline' 'unsafe-eval';** ">

You are saying that you are authorizing the execution of JavaScript code (script-src) from the origins 'self',, 'unsafe-inline', 'unsafe-eval'.

I guess that the first two are perfectly valid for your use case, I am a bit unsure about the other ones. 'unsafe-line' and 'unsafe-eval' pose a security problem, so you should not be using them unless you have a very specific need for them:

"If eval and its text-to-JavaScript brethren are completely essential to your application, you can enable them by adding 'unsafe-eval' as an allowed source in a script-src directive. But, again, please don’t. Banning the ability to execute strings makes it much more difficult for an attacker to execute unauthorized code on your site." (Mike West, Google)

How does Content Security Policy (CSP) work?

Apache 2 mod_headers

You could also enable Apache 2 mod_headers. On Fedora it's already enabled by default. If you use Ubuntu/Debian, enable it like this:

# First enable headers module for Apache 2,
# and then restart the Apache2 service
a2enmod headers
apache2 -k graceful

On Ubuntu/Debian you can configure headers in the file /etc/apache2/conf-enabled/security.conf

# Setting this header will prevent MSIE from interpreting files as something
# else than declared by the content type in the HTTP headers.
# Requires mod_headers to be enabled.
#Header set X-Content-Type-Options: "nosniff"

# Setting this header will prevent other sites from embedding pages from this
# site as frames. This defends against clickjacking attacks.
# Requires mod_headers to be enabled.
Header always set X-Frame-Options: "sameorigin"
Header always set X-Content-Type-Options nosniff
Header always set X-XSS-Protection "1; mode=block"
Header always set X-Permitted-Cross-Domain-Policies "master-only"
Header always set Cache-Control "no-cache, no-store, must-revalidate"
Header always set Pragma "no-cache"
Header always set Expires "-1"
Header always set Content-Security-Policy: "default-src 'none';"
Header always set Content-Security-Policy: "script-src 'self';"
Header always set Content-Security-Policy: "style-src 'self';"

Note: This is the bottom part of the file. Only the last three entries are CSP settings.

The first parameter is the directive, the second is the sources to be white-listed. I've added Google analytics and an adserver, which you might have. Furthermore, I found that if you have aliases, e.g, and configured in Apache 2 you should add them to the white-list as well.

Inline code is considered harmful, and you should avoid it. Copy all the JavaScript code and CSS to separate files and add them to the white-list.

While you're at it you could take a look at the other header settings and install mod_security

Further reading:

"No Content-Security-Policy meta tag found." error in my phonegap application

For me the problem was that I was using obsolete versions of the cordova android and ios platforms. So upgrading to [email protected] and [email protected] solved it.

You can upgrade to these specific versions:

cordova platforms rm android
cordova platforms add [email protected]
cordova platforms rm ios
cordova platforms add [email protected]

Content Security Policy "data" not working for base64 Images in Chrome 28

Try this

data to load:

<svg xmlns='' viewBox='0 0 4 5'><path fill='#343a40' d='M2 0L0 2h4zm0 5L0 3h4z'/></svg>

get a utf8 to base64 convertor and convert the "svg" string to:


and the CSP is

img-src data: image/svg+xml;base64,PHN2ZyB4bWxucz0naHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmcnIHZpZXdCb3g9JzAgMCA0IDUn

Converting an integer to a hexadecimal string in Ruby

Here's another approach:

sprintf("%02x", 10).upcase

see the documentation for sprintf here:

How do I get a TextBox to only accept numeric input in WPF?

Add in a VALIDATION RULE so that when the text changes, check to determine if the data is numeric, and if it is, allows processing to continue, and if it is not, prompts the user that only numeric data is accepted in that field.

Read more in Validation in Windows Presentation Foundation

How to fix Python Numpy/Pandas installation?

This worked for me under 10.7.5 with EPD_free-7.3-2 from Enthought:

Install EPD free, then follow the step in the following link to create .bash_profile file.

And add the following to the file.

export PATH

Execute the following command in Terminal

$ sudo easy_install pandas

When finished, launch PyLab and type:

In [1]: import pandas

In [2]: plot(arange(10))

This should open a plot with a diagonal straight line.

Execute a shell function with timeout

function foo(){
    for i in {1..100};
        echo $i;  
        sleep 1;

cat <( foo ) # Will work 
timeout 3 cat <( foo ) # Will Work 
timeout 3 cat <( foo ) | sort # Wont work, As sort will fail 
cat <( timeout 3 cat <( foo ) ) | sort -r # Will Work 

How to decode viewstate

Here's another decoder that works well as of 2014:

This worked on an input on which the Ignatu decoder failed with "The serialized data is invalid" (although it leaves the BinaryFormatter-serialized data undecoded, showing only its length).

Test if element is present using Selenium WebDriver?

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

object SeleniumFacade {

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

so then,

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

Programmatically go back to previous ViewController in Swift

For questions regarding how to embed your viewController to a navigationController in the storyboard:

  1. Open your storyboard where your different viewController are located
  2. Tap the viewController you would like your navigation controller to start from
  3. On the top of Xcode, tap "Editor"
  4. -> Tap embed in
  5. -> Tap "Navigation Controller

How to get the HTML's input element of "file" type to only accept pdf files?

To get the HTML file input form element to only accept PDFs, you can use the accept attribute in modern browsers such as Firefox 9+, Chrome 16+, Opera 11+ and IE10+ like such:

<input name="file1" type="file" accept="application/pdf">

You can string together multiple mime types with a comma.

The following string will accept JPG, PNG, GIF, PDF, and EPS files:

<input name="foo" type="file" accept="image/jpeg,image/gif,image/png,application/pdf,image/x-eps">

In older browsers the native OS file dialog cannot be restricted – you'd have to use Flash or a Java applet or something like that to handle the file transfer.

And of course it goes without saying that this doesn't do anything to verify the validity of the file type. You'll do that on the server-side once the file has uploaded.

A little update – with javascript and the FileReader API you could do more validation client-side before uploading huge files to your server and checking them again.

Troubleshooting "Illegal mix of collations" error in mysql

Solution if literals are involved.

I am using Pentaho Data Integration and dont get to specify the sql syntax. Using a very simple DB lookup gave the error "Illegal mix of collations (cp850_general_ci,COERCIBLE) and (latin1_swedish_ci,COERCIBLE) for operation '='"

The generated code was "SELECT DATA_DATE AS latest_DATA_DATE FROM hr_cc_normalised_data_date_v WHERE PSEUDO_KEY = ?"

Cutting the story short the lookup was to a view and when I issued

mysql> show full columns from hr_cc_normalised_data_date_v;
| Field      | Type       | Collation         | Null | Key |
| PSEUDO_KEY | varchar(1) | cp850_general_ci  | NO   |     |
| DATA_DATE  | varchar(8) | latin1_general_cs | YES  |     |

which explains where the 'cp850_general_ci' comes from.

The view was simply created with 'SELECT 'X',......' According to the manual literals like this should inherit their character set and collation from server settings which were correctly defined as 'latin1' and 'latin1_general_cs' as this clearly did not happen I forced it in the creation of the view

CREATE OR REPLACE VIEW hr_cc_normalised_data_date_v AS
SELECT convert('X' using latin1) COLLATE latin1_general_cs        AS PSEUDO_KEY
    ,  DATA_DATE

now it shows latin1_general_cs for both columns and the error has gone away. :)

Why are arrays of references illegal?

Actually, this is a mixture of C and C++ syntax.

You should either use pure C arrays, which cannot be of references, since reference are part of C++ only. Or you go the C++ way and use the std::vector or std::array class for your purpose.

As for the edited part: Even though the struct is an element from C, you define a constructor and operator functions, which make it a C++ class. Consequently, your struct would not compile in pure C!

How to make a JTable non-editable

table.setDefaultEditor(Object.class, null);

error: resource android:attr/fontVariationSettings not found

I have soled the problem by changing target android version to 28 in (target=android-28) and installed cordova-plugin-androidx and cordova-plugin-androidx-adapter.

Regex Explanation ^.*$

  • ^ matches position just before the first character of the string
  • $ matches position just after the last character of the string
  • . matches a single character. Does not matter what character it is, except newline
  • * matches preceding match zero or more times

So, ^.*$ means - match, from beginning to end, any character that appears zero or more times. Basically, that means - match everything from start to end of the string. This regex pattern is not very useful.

Let's take a regex pattern that may be a bit useful. Let's say I have two strings The bat of Matt Jones and Matthew's last name is Jones. The pattern ^Matt.*Jones$ will match Matthew's last name is Jones. Why? The pattern says - the string should start with Matt and end with Jones and there can be zero or more characters (any characters) in between them.

Feel free to use an online tool like to test out regex patterns and strings.

Force browser to refresh css, javascript, etc

The accepted answer above is correct. If, however, you only want to reload the cache periodically, and you are using Firefox, the Web Developer tools (under the Tools menu item as of November 2015) provides a Network option. This includes a Reload button. Select the Reload for a once off cache reset.

'^M' character at end of lines

The SQL script was originally created on a Windows OS. The '^M' characters are a result of Windows and Unix having different ideas about what to use for an end-of-line character. You can use perl at the command line to fix this.

perl -pie 's/\r//g' filename.txt

Get bytes from std::string in C++

Normally, encryption functions take

encrypt(const void *ptr, size_t bufferSize);

as arguments. You can pass c_str and length directly:

encrypt(strng.c_str(), strng.length());

This way, extra space is allocated or wasted.

How to compare two JSON objects with the same elements in a different order equal?

You can write your own equals function:

  • dicts are equal if: 1) all keys are equal, 2) all values are equal
  • lists are equal if: all items are equal and in the same order
  • primitives are equal if a == b

Because you're dealing with json, you'll have standard python types: dict, list, etc., so you can do hard type checking if type(obj) == 'dict':, etc.

Rough example (not tested):

def json_equals(jsonA, jsonB):
    if type(jsonA) != type(jsonB):
        # not equal
        return False
    if type(jsonA) == dict:
        if len(jsonA) != len(jsonB):
            return False
        for keyA in jsonA:
            if keyA not in jsonB or not json_equal(jsonA[keyA], jsonB[keyA]):
                return False
    elif type(jsonA) == list:
        if len(jsonA) != len(jsonB):
            return False
        for itemA, itemB in zip(jsonA, jsonB):
            if not json_equal(itemA, itemB):
                return False
        return jsonA == jsonB

How can I read inputs as numbers?

For multiple integer in a single line, map might be better.

arr = map(int, raw_input().split())

If the number is already known, (like 2 integers), you can use

num1, num2 = map(int, raw_input().split())

What is the difference between Task.Run() and Task.Factory.StartNew()

See this blog article that describes the difference. Basically doing:


Is the same as doing:

Task.Factory.StartNew(A, CancellationToken.None, TaskCreationOptions.DenyChildAttach, TaskScheduler.Default);   

Export and import table dump (.sql) using pgAdmin

Using PgAdmin step 1: select schema and right click and go to Backup..enter image description here

step 2: Give the file name and click the backup button.

enter image description here

step 3: In detail message copy the backup file path.

enter image description here

step 4:

Go to other schema and right click and go to Restore. (see step 1)

step 5:

In popup menu paste aboved file path to filename category and click Restore button.

enter image description here

Connect Android Studio with SVN

Go to File->Settings->Version Control->Subversion enter the path for your SVN executable in the General tab under Subversion configuration directory. Also, you can download a latest SVN client such as VisualSVN and point the path to the executable as mentioned above. That will most likely solve your problem.

Calculating width from percent to pixel then minus by pixel in LESS CSS

Or, you could use the margin attribute like this:

    margin-left: 10px;
    margin-right: 10px;

Redirecting to authentication dialog - "An error occurred. Please try again later"

I had this exact problem on a Page Tab app and for the life of me couldn't work out what the problem was. It worked on my test page but as soon as I made it live it wouldn't work. I found in the end that I fixed the problem by putting the actual URL to the Page Tab (i.e.<"page_name">/app_<"app_id">) into "Site URL" under "Website". This doesn't make any sense. But it worked :-)

Convert string to datetime

    <script type="text/javascript">
        var d = Date.parse("Jul 8, 2005");

C# Select elements in list as List of string

List<string> empnames = (from e in emplist select e.Enaame).ToList();


string[] empnames = (from e in emplist select e.Enaame).ToArray();


Removing object from array in Swift 3

var a = ["one", "two", "three", "four", "five"]

// Remove/filter item with value 'three'
a = a.filter { $0 != "three" }

Combining two expressions (Expression<Func<T, bool>>)

Well, you can use Expression.AndAlso / OrElse etc to combine logical expressions, but the problem is the parameters; are you working with the same ParameterExpression in expr1 and expr2? If so, it is easier:

var body = Expression.AndAlso(expr1.Body, expr2.Body);
var lambda = Expression.Lambda<Func<T,bool>>(body, expr1.Parameters[0]);

This also works well to negate a single operation:

static Expression<Func<T, bool>> Not<T>(
    this Expression<Func<T, bool>> expr)
    return Expression.Lambda<Func<T, bool>>(
        Expression.Not(expr.Body), expr.Parameters[0]);

Otherwise, depending on the LINQ provider, you might be able to combine them with Invoke:

// OrElse is very similar...
static Expression<Func<T, bool>> AndAlso<T>(
    this Expression<Func<T, bool>> left,
    Expression<Func<T, bool>> right)
    var param = Expression.Parameter(typeof(T), "x");
    var body = Expression.AndAlso(
            Expression.Invoke(left, param),
            Expression.Invoke(right, param)
    var lambda = Expression.Lambda<Func<T, bool>>(body, param);
    return lambda;

Somewhere, I have got some code that re-writes an expression-tree replacing nodes to remove the need for Invoke, but it is quite lengthy (and I can't remember where I left it...)

Generalized version that picks the simplest route:

static Expression<Func<T, bool>> AndAlso<T>(
    this Expression<Func<T, bool>> expr1,
    Expression<Func<T, bool>> expr2)
    // need to detect whether they use the same
    // parameter instance; if not, they need fixing
    ParameterExpression param = expr1.Parameters[0];
    if (ReferenceEquals(param, expr2.Parameters[0]))
        // simple version
        return Expression.Lambda<Func<T, bool>>(
            Expression.AndAlso(expr1.Body, expr2.Body), param);
    // otherwise, keep expr1 "as is" and invoke expr2
    return Expression.Lambda<Func<T, bool>>(
            Expression.Invoke(expr2, param)), param);

Starting from .NET 4.0, there is the ExpressionVisitor class which allows you to build expressions that are EF safe.

    public static Expression<Func<T, bool>> AndAlso<T>(
        this Expression<Func<T, bool>> expr1,
        Expression<Func<T, bool>> expr2)
        var parameter = Expression.Parameter(typeof (T));

        var leftVisitor = new ReplaceExpressionVisitor(expr1.Parameters[0], parameter);
        var left = leftVisitor.Visit(expr1.Body);

        var rightVisitor = new ReplaceExpressionVisitor(expr2.Parameters[0], parameter);
        var right = rightVisitor.Visit(expr2.Body);

        return Expression.Lambda<Func<T, bool>>(
            Expression.AndAlso(left, right), parameter);

    private class ReplaceExpressionVisitor
        : ExpressionVisitor
        private readonly Expression _oldValue;
        private readonly Expression _newValue;

        public ReplaceExpressionVisitor(Expression oldValue, Expression newValue)
            _oldValue = oldValue;
            _newValue = newValue;

        public override Expression Visit(Expression node)
            if (node == _oldValue)
                return _newValue;
            return base.Visit(node);

How to upload multiple files using PHP, jQuery and AJAX

Finally I have found the solution by using the following code:

$('body').on('click', '#upload', function(e){
        var formData = new FormData($(this).parents('form')[0]);

            url: 'upload.php',
            type: 'POST',
            xhr: function() {
                var myXhr = $.ajaxSettings.xhr();
                return myXhr;
            success: function (data) {
                alert("Data Uploaded: "+data);
            data: formData,
            cache: false,
            contentType: false,
            processData: false
        return false;

Visual Studio Code cannot detect installed git

I faced this problem on MacOS High Sierra 10.13.5 after upgrading Xcode.

When I run git command, I received below message:

Agreeing to the Xcode/iOS license requires admin privileges, please run “sudo xcodebuild -license” and then retry this command.

After running sudo xcodebuild -license command, below message appears:

You have not agreed to the Xcode license agreements. You must agree to both license agreements below in order to use Xcode.

Hit the Enter key to view the license agreements at '/Applications/'

Typing Enter key to open license agreements and typing space key to review details of it, until below message appears:

By typing 'agree' you are agreeing to the terms of the software license agreements. Type 'print' to print them or anything else to cancel, [agree, print, cancel]

The final step is simply typing agree to sign with the license agreement.

After typing git command, we can check that VSCode detected git again.

How can I export tables to Excel from a webpage

Far and away, the cleanest, easiest export from tables to Excel is Jquery DataTables Table Tools plugin. You get a grid that sorts, filters, orders, and pages your data, and with just a few extra lines of code and two small files included, you get export to Excel, PDF, CSV, to clipboard and to the printer.

This is all the code that's required:

  $(document).ready( function () {
    $('#example').dataTable( {
        "sDom": 'T<"clear">lfrtip',
        "oTableTools": {
            "sSwfPath": "/swf/copy_cvs_xls_pdf.swf"
    } );
} );

So, quick to deploy, no browser limitations, no server-side language required, and most of all very EASY to understand. It's a win-win. The one thing it does have limits on, though, is strict formatting of columns.

If formatting and colors are absolute dealbreakers, the only 100% reliable, cross browser method I've found is to use a server-side language to process proper Excel files from your code. My solution of choice is PHPExcel It is the only one I've found so far that positively handles export with formatting to a MODERN version of Excel from any browser when you give it nothing but HTML. Let me clarify though, it's definitely not as easy as the first solution, and also is a bit of a resource hog. However, on the plus side it also can output direct to PDF as well. And, once you get it configured, it just works, every time.

UPDATE - September 15, 2016: TableTools has been discontinued in favor of a new plugin called "buttons" These tools perform the same functions as the old TableTools extension, but are FAR easier to install and they make use of HTML5 downloads for modern browsers, with the capability to fallback to the original Flash download for browsers that don't support the HTML5 standard. As you can see from the many comments since I posted this response in 2011, the main weakness of TableTools has been addressed. I still can't recommend DataTables enough for handling large amounts of data simply, both for the developer and the user.

How do I drop table variables in SQL-Server? Should I even do this?

Just Like TempTables, a local table variable is also created in TempDB. The scope of table variable is the batch, stored procedure and statement block in which it is declared. They can be passed as parameters between procedures. They are automatically dropped when you close that session on which you create them.

How to construct a REST API that takes an array of id's for the resources

I find another way of doing the same thing by using @PathParam. Here is the code sample.

public Object getData(@PathParam("zrssIds") String Ids)
  System.out.println("zrssIds = " + Ids);
  //Here you need to use String tokenizer to make the array from the string.

Call the service by using following url.



http://localhost:8080/[War File Name]/[Servlet Mapping]/[Class Path]/data/xml/12,13,56,76

Referenced Project gets "lost" at Compile Time

Check your build types of each project under project properties - I bet one or the other will be set to build against .NET XX - Client Profile.

With inconsistent versions, specifically with one being Client Profile and the other not, then it works at design time but fails at compile time. A real gotcha.

There is something funny going on in Visual Studio 2010 for me, which keeps setting projects seemingly randomly to Client Profile, sometimes when I create a project, and sometimes a few days later. Probably some keyboard shortcut I'm accidentally hitting...

Select a row from html table and send values onclick of a button

This below code will give selected row, you can parse the values from it and send to the AJAX call.

$(".selected").click(function () {
var row = $(this).parent().parent().parent().html();            

How to run multiple DOS commands in parallel?

You can execute commands in parallel with start like this:

start "" ping myserver
start "" nslookup myserver
start "" morecommands

They will each start in their own command prompt and allow you to run multiple commands at the same time from one batch file.

Hope this helps!

jQuery Set Cursor Position in Text Area

Set the focus before you have inserted the text into the textarea thus?


What does HTTP/1.1 302 mean exactly?

In the term of SEO , 301 and 302 both are good it is depend on situation,

If only one version can be returned (i.e., the other redirects to it), that’s great! This behavior is beneficial because it reduces duplicate content. In the particular case of redirects to trailing slash URLs, our search results will likely show the version of the URL with the 200 response code (most often the trailing slash URL) -- regardless of whether the redirect was a 301 or 302.

How to Convert the value in DataTable into a string array in c#

            string[] result = new string[table.Columns.Count];
            DataRow dr = table.Rows[0];
            for (int i = 0; i < dr.ItemArray.Length; i++)
                result[i] = dr[i].ToString();
            foreach (string str in result)

Get year, month or day from numpy datetime64

There's no direct way to do it yet, unfortunately, but there are a couple indirect ways:

[dt.year for dt in dates.astype(object)]


[datetime.datetime.strptime(repr(d), "%Y-%m-%d %H:%M:%S").year for d in dates]

both inspired by the examples here.

Both of these work for me on Numpy 1.6.1. You may need to be a bit more careful with the second one, since the repr() for the datetime64 might have a fraction part after a decimal point.

MVC - Set selected value of SelectList

The below code solves two problems: 1) dynamically set the selected value of the dropdownlist and 2) more importantly to create a dropdownlistfor for an indexed array in the model. the problem here is that everyone uses one instance of the selectlist which is the ViewBoag.List, while the array needs one Selectlist instance for each dropdownlistfor to be able to set the selected value.

create the ViewBag variable as List (not SelectList) int he controller

//controller code
ViewBag.Role = db.LUT_Role.ToList();

//in the view @Html.DropDownListFor(m => m.Contacts[i].Role, new SelectList(ViewBag.Role,"ID","Role",Model.Contacts[i].Role))

How to normalize an array in NumPy to a unit vector?

This might also work for you

import numpy as np
normalized_v = v / np.sqrt(np.sum(v**2))

but fails when v has length 0.

In that case, introducing a small constant to prevent the zero division solves this.

text-align: right on <select> or <option>

I was facing the same issue in which I need to align selected placeholder value to the right of the select box & also need to align options to right but when I have used direction: rtl; to select & applied some right padding to select then all options also getting shift to the right by padding as I only want to apply padding to selected placeholder.

I have fixed the issue by the following the style:

  text-indent: 24%;
  direction: rtl;
  padding-right: 7px;

select option{
  direction: rtl;

You can change text-indent as per your requirement. Hope it will help you.

public static const in TypeScript

Here's what's this TS snippet compiled into (via TS Playground):

define(["require", "exports"], function(require, exports) {
    var Library = (function () {
        function Library() {
        Library.BOOK_SHELF_NONE = "None";
        Library.BOOK_SHELF_FULL = "Full";
        return Library;
    exports.Library = Library;

As you see, both properties defined as public static are simply attached to the exported function (as its properties); therefore they should be accessible as long as you properly access the function itself.

How to fix 'Microsoft Excel cannot open or save any more documents'

Go to this key on Registry Editor (Run | Regedit) HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders

change key Cache to something like C:\Windows\Temp

My similar problem was solved like this.



How to initialize a dict with keys from a list and empty value in Python?

You could use dict.fromkeys as follows:

dict.fromkeys([1, 2, 3, 4], list())

This will create a list object for each key. If you change value for any specific key it won't affect other keys (as most people would want, I presume).

How can I check if a value is a json object?

I don't really like the accepted answer. First and foremost it requires jQuery, which is not always available or required. Secondly, it does a full stringification of the object which to me is overkill. Here's a simple function that thoroughly detects whether a value is JSON-like, using nothing more than a few parts of the lodash library for genericity.

import * as isNull from 'lodash/isNull'
import * as isPlainObject from 'lodash/isPlainObject'
import * as isNumber from 'lodash/isNumber'
import * as isBoolean from 'lodash/isBoolean'
import * as isString from 'lodash/isString'
import * as isArray from 'lodash/isArray'

function isJSON(val) {
  if (isNull(val)
   || isBoolean(val)
   || isString(val))
    return true;
  if (isNumber(val)) 
     return !isNaN(val) && isFinite(val)
  if (isArray(val))
    return, isJSON)
  if (isPlainObject(val)) {
    for (const key of Object.keys(val)) {
      if (!isJSON(val[key]))
        return false
    return true
  return false

I've even taken the time to put it up in npm as a package: Use it together with something like Webpack to get it in the browser.

Hope this helps someone!

Add disabled attribute to input element using Javascript

Just use jQuery's attr() method

$(this).closest("tr").next().show().find('.longboxsmall').attr('disabled', 'disabled');

Select every Nth element in CSS

As the name implies, :nth-child() allows you to construct an arithmetic expression using the n variable in addition to constant numbers. You can perform addition (+), subtraction (-) and coefficient multiplication (an where a is an integer, including positive numbers, negative numbers and zero).

Here's how you would rewrite the above selector list:


For an explanation on how these arithmetic expressions work, see my answer to this question, as well as the spec.

Note that this answer assumes that all of the child elements within the same parent element are of the same element type, div. If you have any other elements of different types such as h1 or p, you will need to use :nth-of-type() instead of :nth-child() to ensure you only count div elements:

  <div>1</div>  <div>2</div>
  <div>3</div>  <div>4</div>
  <div>5</div>  <div>6</div>
  <div>7</div>  <div>8</div>
  <div>9</div>  <div>10</div>
  <div>11</div> <div>12</div>
  <div>13</div> <div>14</div>
  <div>15</div> <div>16</div>

For everything else (classes, attributes, or any combination of these), where you're looking for the nth child that matches an arbitrary selector, you will not be able to do this with a pure CSS selector. See my answer to this question.

By the way, there's not much of a difference between 4n and 4n + 4 with regards to :nth-child(). If you use the n variable, it starts counting at 0. This is what each selector would match:


4(0) = 0
4(1) = 4
4(2) = 8
4(3) = 12
4(4) = 16


4(0) + 4 = 0  + 4 = 4
4(1) + 4 = 4  + 4 = 8
4(2) + 4 = 8  + 4 = 12
4(3) + 4 = 12 + 4 = 16
4(4) + 4 = 16 + 4 = 20

As you can see, both selectors will match the same elements as above. In this case, there is no difference.

Cannot open database "test" requested by the login. The login failed. Login failed for user 'xyz\ASPNET'

In my case the application can usually connect to database without any problems. I noticed such message in logs. I turn on the SQL server logs and I find out this message:

2016-10-28 10:27:10.86 Logon       Login failed for user '****'. Reason: Failed to open the explicitly specified database '****'. [CLIENT: <local machine>]
2016-10-28 10:27:13.22 Server      SQL Server is terminating because of a system shutdown. This is an informational message only. No user action is required.

So it seems that server was restarting and that SQL server whad been shutting down a bit earlier then ASP.NET application and the database was not available for few seconds before server restart.

Bloomberg Open API

Since the data is not free, you can use this Bloomberg API Emulator (disclaimer: it's my project) to learn how to send requests and make subscriptions. This emulator looks and acts just like the real Bloomberg API, although it doesn't return real data. In my time developing applications that use the Bloomberg API, I rarely care about the actual data that I'm handling; I care about how to retrieve data.

If you want to learn how to use the Bloomberg API give it a try. If you want to test out your code without an account, use this. A Bloomberg account costs about $2,000 a month, so you can save a lot with this project.

The emulator now supports Java and C++ in addition to C#.

C#, C++, and Java:

  • Intraday Tick Requests
  • Intraday Bar Requests
  • Reference Data Requests
  • Historical Data Requests
  • Market Data Subscriptions

Edit: Updated Project link, moved to github

HTML&CSS + Twitter Bootstrap: full page layout or height 100% - Npx

if you use Bootstrap 2.2.1 then maybe is this what you are looking for.

Sample file index.html

<!DOCTYPE html>_x000D_
<html xmlns="">_x000D_
    <link href="Content/bootstrap.min.css" rel="stylesheet" />_x000D_
    <link href="Content/Site.css" rel="stylesheet" />_x000D_
        <div class="navbar navbar-default navbar-fixed-top">_x000D_
            <div class="container">_x000D_
                <div class="navbar-header">_x000D_
                    <button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">_x000D_
                        <span class="icon-bar"></span>_x000D_
                        <span class="icon-bar"></span>_x000D_
                        <span class="icon-bar"></span>_x000D_
                    <a class="navbar-brand" href="/">Application name</a>_x000D_
                <div class="navbar-collapse collapse">_x000D_
                    <ul class="nav navbar-nav">_x000D_
                        <li><a href="/">Home</a></li>_x000D_
                        <li><a href="/Home/About">About</a></li>_x000D_
                        <li><a href="/Home/Contact">Contact</a></li>_x000D_
                    <ul class="nav navbar-nav navbar-right">_x000D_
                        <li><a href="/Account/Register" id="registerLink">Register</a></li>_x000D_
                        <li><a href="/Account/Login" id="loginLink">Log in</a></li>_x000D_
        <div class="col-md-2">_x000D_
            <a href="#" class="btn btn-block btn-info">Some Menu</a>_x000D_
            <a href="#" class="btn btn-block btn-info">Some Menu</a>_x000D_
            <a href="#" class="btn btn-block btn-info">Some Menu</a>_x000D_
            <a href="#" class="btn btn-block btn-info">Some Menu</a>_x000D_
       <div class="col-md-10">_x000D_
               <h3>Your application description page.</h3>_x000D_
               <p>Use this area to provide additional information.</p>_x000D_
               <p>Use this area to provide additional information.</p>_x000D_
               <p>Use this area to provide additional information.</p>_x000D_
               <p>Use this area to provide additional information.</p>_x000D_
               <p>Use this area to provide additional information.</p>_x000D_
               <p>Use this area to provide additional information.</p>_x000D_
               <hr />_x000D_
        <div class="navbar navbar-default navbar-fixed-bottom">_x000D_
            <div class="container" style="font-size: .8em">_x000D_
                <p class="navbar-text">_x000D_
                    &copy; Some info_x000D_
_x000D_ File Content/Site.css
body {_x000D_
    padding-bottom: 70px;_x000D_
    padding-top: 70px;_x000D_

C# Call a method in a new thread

As far as I understand you need mean terminate as Thread.Abort() right? In this case, you can just exit the Foo(). Or you can use Process to catch the thread.

Thread myThread = new Thread(DoWork);



Process example:

using System;
using System.Diagnostics;
using System.ComponentModel;
using System.Threading;
using Microsoft.VisualBasic;

class PrintProcessClass

    private Process myProcess = new Process();
    private int elapsedTime;
    private bool eventHandled;

    // Print a file with any known extension.
    public void PrintDoc(string fileName)

        elapsedTime = 0;
        eventHandled = false;

            // Start a process to print a file and raise an event when done.
            myProcess.StartInfo.FileName = fileName;
            myProcess.StartInfo.Verb = "Print";
            myProcess.StartInfo.CreateNoWindow = true;
            myProcess.EnableRaisingEvents = true;
            myProcess.Exited += new EventHandler(myProcess_Exited);

        catch (Exception ex)
            Console.WriteLine("An error occurred trying to print \"{0}\":" + "\n" + ex.Message, fileName);

        // Wait for Exited event, but not more than 30 seconds.
        const int SLEEP_AMOUNT = 100;
        while (!eventHandled)
            elapsedTime += SLEEP_AMOUNT;
            if (elapsedTime > 30000)

    // Handle Exited event and display process information.
    private void myProcess_Exited(object sender, System.EventArgs e)

        eventHandled = true;
        Console.WriteLine("Exit time:    {0}\r\n" +
            "Exit code:    {1}\r\nElapsed time: {2}", myProcess.ExitTime, myProcess.ExitCode, elapsedTime);

    public static void Main(string[] args)

        // Verify that an argument has been entered.
        if (args.Length <= 0)
            Console.WriteLine("Enter a file name.");

        // Create the process and print the document.
        PrintProcessClass myPrintProcess = new PrintProcessClass();

Various ways to remove local Git changes

Reason for adding an answer at this moment:

So far I was adding the conclusion and ‘answers’ to my initial question itself, making the question very lengthy, hence moving to separate answer.

I have also added more frequently used git commands that helps me on git, to help someone else too.

Basically to clean all local commits $ git reset --hard and $ git clean -d -f

First step before you do any commits is to configure your username and email that appears along with your commit.

#Sets the name you want attached to your commit transactions

$ git config --global "[name]"

#Sets the email you want atached to your commit transactions

$ git config --global "[email address]"

#List the global config

$ git config --list

#List the remote URL

$ git remote show origin

#check status

git status

#List all local and remote branches

git branch -a

#create a new local branch and start working on this branch

git checkout -b "branchname" 

or, it can be done as a two step process

create branch: git branch branchname work on this branch: git checkout branchname

#commit local changes [two step process:- Add the file to the index, that means adding to the staging area. Then commit the files that are present in this staging area]

git add <path to file>

git commit -m "commit message"

#checkout some other local branch

git checkout "local branch name"

#remove all changes in local branch [Suppose you made some changes in local branch like adding new file or modifying existing file, or making a local commit, but no longer need that] git clean -d -f and git reset --hard [clean all local changes made to the local branch except if local commit]

git stash -u also removes all changes

Note: It's clear that we can use either (1) combination of git clean –d –f and git reset --hard OR (2) git stash -u to achieve the desired result.

Note 1: Stashing, as the word means 'Store (something) safely and secretly in a specified place.' This can always be retreived using git stash pop. So choosing between the above two options is developer's call.

Note 2: git reset --hard will delete working directory changes. Be sure to stash any local changes you want to keep before running this command.

# Switch to the master branch and make sure you are up to date.

git checkout master

git fetch [this may be necessary (depending on your git config) to receive updates on origin/master ]

git pull

# Merge the feature branch into the master branch.

git merge feature_branch

# Reset the master branch to origin's state.

git reset origin/master

#Accidentally deleted a file from local , how to retrieve it back? Do a git status to get the complete filepath of the deleted resource

git checkout branchname <file path name>

that's it!

#Merge master branch with someotherbranch

git checkout master
git merge someotherbranchname

#rename local branch

git branch -m old-branch-name new-branch-name

#delete local branch

git branch -D branch-name

#delete remote branch

git push origin --delete branchname


git push origin :branch-name

#revert a commit already pushed to a remote repository

git revert hgytyz4567

#branch from a previous commit using GIT

git branch branchname <sha1-of-commit>

#Change commit message of the most recent commit that's already been pushed to remote

git commit --amend -m "new commit message"
git push --force origin <branch-name>

# Discarding all local commits on this branch [Removing local commits]

In order to discard all local commits on this branch, to make the local branch identical to the "upstream" of this branch, simply run

git reset --hard @{u}

Reference: or do git reset --hard origin/master [if local branch is master]

# Revert a commit already pushed to a remote repository?

$ git revert ab12cd15

#Delete a previous commit from local branch and remote branch

Use-Case: You just commited a change to your local branch and immediately pushed to the remote branch, Suddenly realized , Oh no! I dont need this change. Now do what?

git reset --hard HEAD~1 [for deleting that commit from local branch. 1 denotes the ONE commit you made]

git push origin HEAD --force [both the commands must be executed. For deleting from remote branch]. Currently checked out branch will be referred as the branch where you are making this operation.

#Delete some of recent commits from local and remote repo and preserve to the commit that you want. ( a kind of reverting commits from local and remote)

Let's assume you have 3 commits that you've pushed to remote branch named 'develop'

commitid-1 done at 9am
commitid-2 done at 10am
commitid-3 done at 11am. // latest commit. HEAD is current here.

To revert to old commit ( to change the state of branch)

git log --oneline --decorate --graph // to see all your commitids

git clean -d -f // clean any local changes

git reset --hard commitid-1 // locally reverting to this commitid

git push -u origin +develop // push this state to remote. + to do force push

# Remove local git merge: Case: I am on master branch and merged master branch with a newly working branch phase2

$ git status

On branch master

$ git merge phase2 $ git status

On branch master

Your branch is ahead of 'origin/master' by 8 commits.

Q: How to get rid of this local git merge? Tried git reset --hard and git clean -d -f Both didn't work. The only thing that worked are any of the below ones:

$ git reset --hard origin/master


$ git reset --hard HEAD~8


$ git reset --hard 9a88396f51e2a068bb7 [sha commit code - this is the one that was present before all your merge commits happened]

#create gitignore file

touch .gitignore // create the file in mac or unix users

sample .gitignore contents:


Reference link to GIT cheat sheet:

How to switch databases in psql?

Though not explicitly stated in the question, the purpose is to connect to a specific schema/database.

Another option is to directly connect to the schema. Example:

sudo -u postgres psql -d my_database_name

Source from man psql:

-d dbname
   Specifies the name of the database to connect to. This is equivalent to specifying dbname as the first non-option argument on the command line.

   If this parameter contains an = sign or starts with a valid URI prefix (postgresql:// or postgres://), it is treated as a conninfo string. See Section 31.1.1, “Connection Strings”, in the
   documentation for more information.

Is there any way to configure multiple registries in a single npmrc file

As of 13 April 2020 there is no such functionality unless you are able to use different scopes, but you may use the postinstall script as a workaround. It is always executed, well, after each npm install:

Say you have your .npmrc configured to install @foo-org/foo-pack-private from your private github repo, but the @foo-org/foo-pack-public public package is on npm (under the same scope: foo-org).

Your postinstall might look like this:

"scripts": {
    "postinstall": "mv .npmrc .npmrcc && npm i @foo-org/foo-pack --dry-run && mv .npmrcc .npmrc".

Don't forget to remove @foo-pack/foo-org from the dependencies array to make sure npm install does not try and get it from github and to add the --dry-run flag that makes sure package.json and package-lock.json stay unchanged after npm install.

Getting the value of an attribute in XML

This is more of an xpath question, but like this, assuming the context is the parent element:

<xsl:value-of select="name/@attribute1" />

How to serialize Joda DateTime with Jackson JSON processor?

The easy solution

I have encountered similar problem and my solution is much clear than above.

I simply used the pattern in @JsonFormat annotation

Basically my class has a DateTime field, so I put an annotation around the getter:

@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss")
public DateTime getDate() {
    return date;

I serialize the class with ObjectMapper

    ObjectMapper mapper = new ObjectMapper();
    mapper.registerModule(new JodaModule());
    ObjectWriter ow = mapper.writer();
    try {
        String logStr = ow.writeValueAsString(log);;
    } catch (IOException e) {
        logger.warn("JSON mapping exception", e);

We use Jackson 2.5.4

socket.shutdown vs socket.close

Explanation of shutdown and close: Graceful shutdown (msdn)

Shutdown (in your case) indicates to the other end of the connection there is no further intention to read from or write to the socket. Then close frees up any memory associated with the socket.

Omitting shutdown may cause the socket to linger in the OSs stack until the connection has been closed gracefully.

IMO the names 'shutdown' and 'close' are misleading, 'close' and 'destroy' would emphasise their differences.

How to clear react-native cache?

try this

react-native start --reset-cache

duplicate 'row.names' are not allowed error

This related question points out a part of the ?read.table documentation that explains your problem:

If there is a header and the first row contains one fewer field than the number of columns, the first column in the input is used for the row names. Otherwise if row.names is missing, the rows are numbered.

Your header row likely has 1 fewer column than the rest of the file and so read.table assumes that the first column is the row.names (which must all be unique), not a column (which can contain duplicated values). You can fix this by using one of the following two Solutions:

  1. adding a delimiter (ie \t or ,) to the front or end of your header row in the source file, or,
  2. removing any trailing delimiters in your data

The choice will depend on the structure of your data.

Here the header row is interpreted as having one fewer column than the data because the delimiters don't match:

v1,v2,v3   # 3 items!!
a1,a2,a3,  # 4 items
b1,b2,b3,  # 4 items

This is how it is interpreted by default:

   v1,v2,v3   # 3 items!!
a1,a2,a3,  # 4 items
b1,b2,b3,  # 4 items

The first column (with no header) values are interpreted as row.names: a1 and b1. If this column contains duplicates, which is entirely possible, then you get the duplicate 'row.names' are not allowed error.

If you set row.names = FALSE, the shift doesn't happen, but you still have a mismatching number of items in the header and in the data because the delimiters don't match.

Solution 1 Add trailing delimiter to header:

v1,v2,v3,  # 4 items!!
a1,a2,a3,  # 4 items
b1,b2,b3,  # 4 items

Solution 2 Remove excess trailing delimiter from non-header rows:

v1,v2,v3   # 3 items
a1,a2,a3   # 3 items!!
b1,b2,b3   # 3 items!!

Do copyright dates need to be updated?

Copyright should be up to the date of publish.

So, if it's a static content (such as the Times article you linked to), it should probably be statically copyrighted.

If it's dynamically generated content, it should be copyrighted to the current year

How to modify existing, unpushed commit messages?

git commit --amend -m "your new message"

How to make picturebox transparent?

I've had a similar problem like this. You can not make Transparent picturebox easily such as picture that shown at top of this page, because .NET Framework and VS .NET objects are created by INHERITANCE! (Use Parent Property).

I solved this problem by RectangleShape and with the below code I removed background, if difference between PictureBox and RectangleShape is not important and doesn't matter, you can use RectangleShape easily.

private void CreateBox(int X, int Y, int ObjectType)
    ShapeContainer canvas = new ShapeContainer();
    RectangleShape box = new RectangleShape();
    box.Parent = canvas;
    box.Size = new System.Drawing.Size(100, 90);
    box.Location = new System.Drawing.Point(X, Y);
    box.Name = "Box" + ObjectType.ToString();
    box.BackColor = Color.Transparent;
    box.BorderColor = Color.Transparent;
    box.BackgroundImage = img.Images[ObjectType];// Load from imageBox Or any resource
    box.BackgroundImageLayout = ImageLayout.Stretch;
    box.BorderWidth = 0;
    canvas.Controls.Add(box);   // For feature use 

How to post JSON to PHP with curl

You need to set a few extra flags so that curl sends the data as JSON.


$ curl -H "Content-Type: application/json" \
       -X POST \
       -d '{"JSON": "HERE"}' \


  • -H: custom header, next argument is expected to be header
  • -X: custom HTTP verb, next argument is expected to be verb
  • -d: sends the next argument as data in an HTTP POST request


How do I populate a JComboBox with an ArrayList?

DefaultComboBoxModel dml= new DefaultComboBoxModel();
for (int i = 0; i < <ArrayList>.size(); i++) {


Understandable code.Edit<> with type as required.

urlencode vs rawurlencode?

echo rawurlencode(' asd');



echo urlencode(' asd');


The difference being the asd%20asd vs asd+asd

urlencode differs from RFC 1738 by encoding spaces as + instead of %20

Show a message box from a class in c#?

using System.Windows.Forms;

public class message
    static void Main()
        MessageBox.Show("Hello World!"); 

Is there a way to only install the mysql client (Linux)?

Maybe try this:

yum -y groupinstall "MYSQL Database Client"

Jenkins Pipeline Wipe Out Workspace

You can use deleteDir() as the last step of the pipeline Jenkinsfile (assuming you didn't change the working directory).

Omitting one Setter/Getter in Lombok

According to @Data description you can use:

All generated getters and setters will be public. To override the access level, annotate the field or class with an explicit @Setter and/or @Getter annotation. You can also use this annotation (by combining it with AccessLevel.NONE) to suppress generating a getter and/or setter altogether.

CardView not showing Shadow in Android L

Card view can't show shadow because of your RelativeLayout is on the card view's shadow. To show the shadow add margins on your Card view. For example:

<RelativeLayout xmlns:android=""




Facebook Like-Button - hide count?

Facebook now supports hiding the count, use this in the markup:


How do ACID and database transactions work?

ACID are desirable properties of any transaction processing engine.

A DBMS is (if it is any good) a particular kind of transaction processing engine that exposes, usually to a very large extent but not quite entirely, those properties.

But other engines exist that can also expose those properties. The kind of software that used to be called "TP monitors" being a case in point (nowadays' equivalent mostly being web servers).

Such TP monitors can access resources other than a DBMS (e.g. a printer), and still guarantee ACID toward their users. As an example of what ACID might mean when a printer is involved in a transaction:

  • Atomicity: an entire document gets printed or nothing at all
  • Consistency: at end-of-transaction, the paper feed is positioned at top-of-page
  • Isolation: no two documents get mixed up while printing
  • Durability: the printer can guarantee that it was not "printing" with empty cartridges.

Web scraping with Python

Here is a simple web crawler, i used BeautifulSoup and we will search for all the links(anchors) who's class name is _3NFO0d. I used, it is an online retailing store.

import requests
from bs4 import BeautifulSoup
def crawl_flipkart():
    url = ''
    source_code = requests.get(url)
    plain_text = source_code.text
    soup = BeautifulSoup(plain_text, "lxml")
    for link in soup.findAll('a', {'class': '_3NFO0d'}):
        href = link.get('href')


Cannot use a CONTAINS or FREETEXT predicate on table or indexed view because it is not full-text indexed

Select * from table
where CONTAINS([Column], '"A00*"')  

will act as % same as

where [Column] Like 'A00%'

How to run specific test cases in GoogleTest

You could use advanced options to run Google tests.

To run only some unit tests you could use --gtest_filter=Test_Cases1* command line option with value that accepts the * and ? wildcards for matching with multiple tests. I think it will solve your problem.


Well, the question was how to run specific test cases. Integration of gtest with your GUI is another thing, which I can't really comment, because you didn't provide details of your approach. However I believe the following approach might be a good start:

  1. Get all testcases by running tests with --gtest_list_tests
  2. Parse this data into your GUI
  3. Select test cases you want ro run
  4. Run test executable with option --gtest_filter

FIX CSS <!--[if lt IE 8]> in IE

If you want this to work in IE 8 and below, use

<!--[if lte IE 8]>

lte meaning "Less than or equal".

For more on conditional comments, see e.g. the page.

twitter bootstrap navbar fixed top overlapping site

For handling wrapping lines in menu-bar, apply an id to the navbar, like this:

<div class="navbar navbar-default navbar-fixed-top" role="navigation" id="topnavbar">

and add this small script in the head after including the jquery, like this:

        $(document.body).css('padding-top', $('#topnavbar').height() + 10);
            $(document.body).css('padding-top', $('#topnavbar').height() + 10);

That way, the top-padding of the body gets automatically adjusted.

converting a javascript string to a html object

In addition to Gaby aka's method, we can find elements inside htmlObject in this way -


Fiddle is available here -

Calling C/C++ from Python?

I love cppyy, it makes it very easy to extend Python with C++ code, dramatically increasing performance when needed.

It is powerful and frankly very simple to use,

here it is an example of how you can create a numpy array and pass it to a class member function in C++.

import cppyy
import numpy as np

s = cppyy.gbl.Buffer()
numpy_array = np.empty(32000, np.float64)
s.get_numpy_array(, numpy_array.size)


struct Buffer {
  void get_numpy_array(double *ad, int size) {
    for( long i=0; i < size; i++)

You can also create a Python module very easily (with CMake), this way you will avoid recompile the C++ code all the times.

Make A List Item Clickable (HTML/CSS)

HTML and CSS only.

#leftsideMenu ul li {_x000D_
  border-bottom: 1px dashed lightgray;_x000D_
  background-color: cadetblue;_x000D_
#leftsideMenu ul li a {_x000D_
  padding: 8px 20px 8px 20px;_x000D_
  color: white;_x000D_
  display: block;_x000D_
#leftsideMenu ul li a:hover {_x000D_
  background-color: lightgreen;_x000D_
  transition: 0.5s;_x000D_
  padding-left: 30px;_x000D_
  padding-right: 10px;_x000D_
<div id="leftsideMenu">_x000D_
  <ul style="list-style-type:none">_x000D_
    <li><a href="#">India</a></li>_x000D_
    <li><a href="#">USA</a></li>_x000D_
    <li><a href="#">Russia</a></li>_x000D_
    <li><a href="#">China</a></li>_x000D_
    <li><a href="#">Afganistan</a></li>_x000D_
    <li><a href="#">Landon</a></li>_x000D_
    <li><a href="#">Scotland</a></li>_x000D_
    <li><a href="#">Ireland</a></li>_x000D_

Email Address Validation for ASP.NET

Preventing XSS is a different issue from validating input.

Regarding XSS: You should not try to check input for XSS or related exploits. You should prevent XSS exploits, SQL injection and so on by escaping correctly when inserting strings into a different language where some characters are "magic", eg, when inserting strings in HTML or SQL. For example a name like O'Reilly is perfectly valid input, but could cause a crash or worse if inserted unescaped into SQL. You cannot prevent that kind of problems by validating input.

Validation of user input makes sense to prevent missing or malformed data, eg. a user writing "asdf" in the zip-code field and so on. Wrt. e-mail adresses, the syntax is so complex though, that it doesnt provide much benefit to validate it using a regex. Just check that it contains a "@".

How to draw vectors (physical 2D/3D vectors) in MATLAB?

a = [2 3 5];
b = [1 1 0];
c = a+b;

starts = zeros(3,3);
ends = [a;b;c];

quiver3(starts(:,1), starts(:,2), starts(:,3), ends(:,1), ends(:,2), ends(:,3))
axis equal

How do I write a Windows batch script to copy the newest file from a directory?


 find -type f -printf "%T@ %p \n" \
     | sort  \
     | tail -n 1  \
     | sed -r "s/^\S+\s//;s/\s*$//" \
     | xargs -iSTR cp STR newestfile

where "newestfile" will become the newestfile

alternatively, you could do newdir/STR or just newdir


  1. list all files in {time} {file} format.
  2. sort them by time
  3. get the last one
  4. cut off the time, and whitespace from the start/end
  5. copy resulting value


After running this once, the newest file will be whatever you just copied :p ( assuming they're both in the same search scope that is ). So you may have to adjust which filenumber you copy if you want this to work more than once.

Stacked bar chart

You need to transform your data to long format and shouldn't use $ inside aes:

DF <- read.table(text="Rank F1     F2     F3
1    500    250    50
2    400    100    30
3    300    155    100
4    200    90     10", header=TRUE)

DF1 <- melt(DF, id.var="Rank")

ggplot(DF1, aes(x = Rank, y = value, fill = variable)) + 
  geom_bar(stat = "identity")

enter image description here

What is the minimum I have to do to create an RPM file?

If you are familiar with Maven there also rpm-maven-plugin which simplifies making RPMs: you have to write only pom.xml which will be then used to build RPM. RPM build environment is created implicitly by the plugin.

What is the difference between ArrayList.clear() and ArrayList.removeAll()?

clear() will go through the underlying Array and set each entry to null;

removeAll(collection) will go through the ArrayList checking for collection and remove(Object) it if it exists.

I would imagine that clear() is way faster then removeAll because it's not comparing, etc.

Add Variables to Tuple

In Python 3, you can use * to create a new tuple of elements from the original tuple along with the new element.

>>> tuple1 = ("foo", "bar")
>>> tuple2 = (*tuple1, "baz")
>>> tuple2
('foo', 'bar', 'baz')

The byte code is almost the same as tuple1 + ("baz",)

Python 3.7.5 (default, Oct 22 2019, 10:35:10) 
[Clang 10.0.1 (clang-1001.0.46.4)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> def f():
...     tuple1 = ("foo", "bar")
...     tuple2 = (*tuple1, "baz")
...     return tuple2
>>> def g():
...     tuple1 = ("foo", "bar")
...     tuple2 = tuple1 + ("baz",)
...     return tuple2
>>> from dis import dis
>>> dis(f)
  2           0 LOAD_CONST               1 (('foo', 'bar'))
              2 STORE_FAST               0 (tuple1)

  3           4 LOAD_FAST                0 (tuple1)
              6 LOAD_CONST               3 (('baz',))
              8 BUILD_TUPLE_UNPACK       2
             10 STORE_FAST               1 (tuple2)

  4          12 LOAD_FAST                1 (tuple2)
             14 RETURN_VALUE
>>> dis(g)
  2           0 LOAD_CONST               1 (('foo', 'bar'))
              2 STORE_FAST               0 (tuple1)

  3           4 LOAD_FAST                0 (tuple1)
              6 LOAD_CONST               2 (('baz',))
              8 BINARY_ADD
             10 STORE_FAST               1 (tuple2)

  4          12 LOAD_FAST                1 (tuple2)
             14 RETURN_VALUE

The only difference is BUILD_TUPLE_UNPACK vs BINARY_ADD. The exact performance depends on the Python interpreter implementation, but it's natural to implement BUILD_TUPLE_UNPACK faster than BINARY_ADD because BINARY_ADD is a polymorphic operator, requiring additional type calculation and implicit conversion.

How to parse/read a YAML file into a Python object?

If your YAML file looks like this:

# tree format
        name: Node 1
            name: Node 1-1
        name: Node 2
            name: Node 2-1

And you've installed PyYAML like this:

pip install PyYAML

And the Python code looks like this:

import yaml
with open('tree.yaml') as f:
    # use safe_load instead load
    dataMap = yaml.safe_load(f)

The variable dataMap now contains a dictionary with the tree data. If you print dataMap using PrettyPrint, you will get something like:

    'treeroot': {
        'branch1': {
            'branch1-1': {
                'name': 'Node 1-1'
            'name': 'Node 1'
        'branch2': {
            'branch2-1': {
                'name': 'Node 2-1'
            'name': 'Node 2'

So, now we have seen how to get data into our Python program. Saving data is just as easy:

with open('newtree.yaml', "w") as f:
    yaml.dump(dataMap, f)

You have a dictionary, and now you have to convert it to a Python object:

class Struct:
    def __init__(self, **entries): 

Then you can use:

>>> args = your YAML dictionary
>>> s = Struct(**args)
>>> s
<__main__.Struct instance at 0x01D6A738>
>>> s...

and follow "Convert Python dict to object".

For more information you can look at and this.

Try/catch does not seem to have an effect

Edit: As stated in the comments, the following solution applies to PowerShell V1 only.

See this blog post on "Technical Adventures of Adam Weigert" for details on how to implement this.

Example usage (copy/paste from Adam Weigert's blog):

Try {
    echo " ::Do some work..."
    echo " ::Try divide by zero: $(0/0)"
} -Catch {
    echo "  ::Cannot handle the error (will rethrow): $_"
    #throw $_
} -Finally {
    echo " ::Cleanup resources..."

Otherwise you'll have to use exception trapping.

How to preview git-pull without doing fetch?

After doing a git fetch, do a git log HEAD..origin/master to show the log entries between your last common commit and the origin's master branch. To show the diffs, use either git log -p HEAD..origin/master to show each patch, or git diff HEAD...origin/master (three dots not two) to show a single diff.

There normally isn't any need to undo a fetch, because doing a fetch only updates the remote branches and none of your branches. If you're not prepared to do a pull and merge in all the remote commits, you can use git cherry-pick to accept only the specific remote commits you want. Later, when you're ready to get everything, a git pull will merge in the rest of the commits.

Update: I'm not entirely sure why you want to avoid the use of git fetch. All git fetch does is update your local copy of the remote branches. This local copy doesn't have anything to do with any of your branches, and it doesn't have anything to do with uncommitted local changes. I have heard of people who run git fetch in a cron job because it's so safe. (I wouldn't normally recommend doing that, though.)

Remove multiple objects with rm()

Another variation you can try is(expanding @mnel's answer) if you have many temp'x'.

here "n" could be the number of temp variables present

rm(list = c(paste("temp",c(1:n),sep="")))

How to disable the parent form when a child form is active?


Sorry for this is not C# code but this is what you would want, besides translating this should be easy.


Private Sub Form1_MouseEnter(sender As Object, e As EventArgs) Handles MyBase.MouseEnter
    Me.Enabled = True
    Form2.Enabled = False
End Sub

Private Sub Form1_MouseLeave(sender As Object, e As EventArgs) Handles MyBase.MouseLeave
    Form2.Enabled = True
End Sub


Private Sub Form2_MouseEnter(sender As Object, e As EventArgs) Handles MyBase.MouseEnter
    Me.Enabled = True
    Form1.Enabled = False
End Sub

Private Sub Form2_MouseLeave(sender As Object, e As EventArgs) Handles MyBase.MouseLeave
    Form1.Enabled = True
End Sub

Hope this helps

Get Element value with minidom with Python

Here is a slightly modified answer of Henrik's for multiple nodes (ie. when getElementsByTagName returns more than one instance)

images = xml.getElementsByTagName("imageUrl")
for i in images:
    print " ".join(t.nodeValue for t in i.childNodes if t.nodeType == t.TEXT_NODE)

How to check permissions of a specific directory?

This displays files with its permisions

stat -c '%a - %n' directory/*

getting file size in javascript

To get the file size of pages on the web I built a javascript bookmarklet to do the trick. It alerts the size in kb's. Change the alert to a prompt if you want to copy the filesize.

Here's the bookmarklet code for the alert.

<a href="javascript:a=document.getElementsByTagName('HTML')[0].outerHTML;b=a.length/1024;c=Math.round(b);alert(c+' kb');">Doc Size</a>

Here's the bookmarklet code for the prompt.

<a href="javascript:a=document.getElementsByTagName('HTML')[0].outerHTML;b=a.length/1024;c=Math.round(b);prompt('Page Size',c+' kb');">Doc Size</a>

See it in action at

How do I change Bootstrap 3's glyphicons to white?

You can just create your own .white class and add it to the glyphicon element.

.white, .white a {
  color: #fff;
<i class="glyphicon glyphicon-home white"></i>

Is there any WinSCP equivalent for linux?

Filezilla is available for Linux. If you are using Ubuntu:

sudo apt-get install filezilla

Otherwise, you can download it from the Filezilla website.

Display TIFF image in all web browser

I found this resource that details the various methods: How to embed TIFF files in HTML documents

As mentioned, it will very much depend on browser support for the format. Viewing that page in Chrome on Windows didn't display any of the images.

It would also be helpful if you posted the code you've tried already.

Spring boot: Unable to start embedded Tomcat servlet container

If you are running on a linux environment, basically your app does not have rights for the default port.

Try 8181 by giving the following option on VM.


Add querystring parameters to link_to

In case you want to pass in a block, say, for a glyphicon button, as in the following:

<%= link_to my_url, class: "stuff" do %>
  <i class="glyphicon glyphicon-inbox></i> Nice glyph-button
<% end %>

Then passing querystrings params could be accomplished through:

<%= link_to url_for(params.merge(my_params: "value")), class: "stuff" do %>
  <i class="glyphicon glyphicon-inbox></i> Nice glyph-button
<% end %>

Creating a Facebook share button with customized url, title and image

This is the code as 2017:

<i class="fa fa-facebook-square"></i>
<a href="#" onclick="''+encodeURIComponent(location.href),'facebook-share-dialog','width=626,height=436');return false;">Share on Facebook</a>

Facebook now takes all data from OG metatags.

NOTE: This code assumes you have OG metatags on in site's code.


How to get just the date part of getdate()?


In laymans terms, what does 'static' mean in Java?

Another great example of when static attributes and operations are used when you want to apply the Singleton design pattern. In a nutshell, the Singleton design pattern ensures that one and only one object of a particular class is ever constructeed during the lifetime of your system. to ensure that only one object is ever constructed, typical implemenations of the Singleton pattern keep an internal static reference to the single allowed object instance, and access to that instance is controlled using a static operation

Import a file from a subdirectory?

  • Create a subdirectory named lib.
  • Create an empty file named lib\
  • In lib\, write a function foo() like this:

    def foo():
        print "foo!"
  • In your client code in the directory above lib, write:

    from lib import BoxTime
  • Run your client code. You will get:


Much later -- in linux, it would look like this:

% cd ~/tmp
% mkdir lib
% touch lib/
% cat > lib/ << EOF
heredoc> def foo():
heredoc>     print "foo!"
heredoc> EOF
% tree lib

0 directories, 2 files
% python 
Python 2.7.6 (default, Mar 22 2014, 22:59:56) 
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from lib import BoxTime

Java Refuses to Start - Could not reserve enough space for object heap

ulimit max memory size and virtual memory set to unlimited?

Getting a slice of keys from a map


package main

import (

func main() {
    mapEg := map[string]string{"c":"a","a":"c","b":"b"}
    keys := make([]string, 0, len(mapEg))
    for k := range mapEg {
        keys = append(keys, k)

How do I install opencv using pip?

run the following command by creating a virtual enviroment using python 3 and run

pip3 install opencv-python

to check it has installed correctly run

python3 -c "import cv2"

Regex for checking if a string is strictly alphanumeric

To check if a String is alphanumeric, you can use a method that goes through every character in the string and checks if it is alphanumeric.

    public static boolean isAlphaNumeric(String s){
            for(int i = 0; i < s.length(); i++){
                    char c = s.charAt(i);
                    if(!Character.isDigit(c) && !Character.isLetter(c))
                            return false;
            return true;

How to make primary key as autoincrement for Room Persistence lib

You can add @PrimaryKey(autoGenerate = true) like this:

data class Food(
        var foodName: String, 
        var foodDesc: String, 
        var protein: Double, 
        var carbs: Double, 
        var fat: Double
    @PrimaryKey(autoGenerate = true)
    var foodId: Int = 0 // or foodId: Int? = null
    var calories: Double = 0.toDouble()

Git, fatal: The remote end hung up unexpectedly

had same problem and try all answer not work, just try another account and that work for me .

How to present UIAlertController when not in a view controller?

@agilityvision's answer is so good. I have sense used in swift projects so I thought I would share my take on his answer using swift 3.0

fileprivate class MyUIAlertController: UIAlertController {

  typealias Handler = () -> Void

  struct AssociatedKeys {
    static var alertWindowKey = "alertWindowKey"

  dynamic var _alertWindow: UIWindow?

  var alertWindow: UIWindow? {
    return objc_getAssociatedObject(self, &AssociatedKeys.alertWindowKey) as? UIWindow

  func setAlert(inWindow window: UIWindow) {
    objc_setAssociatedObject(self, &AssociatedKeys.alertWindowKey, _alertWindow, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)

  func show(completion: Handler? = nil) {
    show(animated: true, completion: completion)

  func show(animated: Bool, completion: Handler? =  nil) {
    _alertWindow = UIWindow(frame: UIScreen.main.bounds)
    _alertWindow?.rootViewController = UIViewController()

    if let delegate: UIApplicationDelegate = UIApplication.shared.delegate, let window = delegate.window {
      _alertWindow?.tintColor = window?.tintColor


    let topWindow =
    _alertWindow?.windowLevel = topWindow?.windowLevel ?? 0 + 1
    _alertWindow?.rootViewController?.present(self, animated: animated, completion: completion)

  fileprivate override func viewDidDisappear(_ animated: Bool) {
    _alertWindow?.isHidden = true
    _alertWindow = nil

Inline labels in Matplotlib

@Jan Kuiken's answer is certainly well-thought and thorough, but there are some caveats:

  • it does not work in all cases
  • it requires a fair amount of extra code
  • it may vary considerably from one plot to the next

A much simpler approach is to annotate the last point of each plot. The point can also be circled, for emphasis. This can be accomplished with one extra line:

from matplotlib import pyplot as plt

for i, (x, y) in enumerate(samples):
    plt.plot(x, y)
    plt.text(x[-1], y[-1], 'sample {i}'.format(i=i))

A variant would be to use ax.annotate.

using if else with eval in aspx page

 <%if (System.Configuration.ConfigurationManager.AppSettings["OperationalMode"] != "live") {%>

Count number of files within a directory in Linux?

this is one:

ls -l . | egrep -c '^-'


ls -1 | wc -l

Which means: ls: list files in dir

-1: (that's a ONE) only one entry per line. Change it to -1a if you want hidden files too

|: pipe output onto...

wc: "wordcount"

-l: count lines.

Dependency injection with Jersey 2.0

The selected answer dates from a while back. It is not practical to declare every binding in a custom HK2 binder. I'm using Tomcat and I just had to add one dependency. Even though it was designed for Glassfish it fits perfectly into other containers.


Make sure your container is properly configured too (see the documentation).

Dealing with timestamps in R

You want the (standard) POSIXt type from base R that can be had in 'compact form' as a POSIXct (which is essentially a double representing fractional seconds since the epoch) or as long form in POSIXlt (which contains sub-elements). The cool thing is that arithmetic etc are defined on this -- see help(DateTimeClasses)

Quick example:

R> now <- Sys.time()
R> now
[1] "2009-12-25 18:39:11 CST"
R> as.numeric(now)
[1] 1.262e+09
R> now + 10  # adds 10 seconds
[1] "2009-12-25 18:39:21 CST"
R> as.POSIXlt(now)
[1] "2009-12-25 18:39:11 CST"
R> str(as.POSIXlt(now))
 POSIXlt[1:9], format: "2009-12-25 18:39:11"
R> unclass(as.POSIXlt(now))
[1] 11.79

[1] 39

[1] 18

[1] 25

[1] 11

[1] 109

[1] 5

[1] 358

[1] 0

[1] "America/Chicago" "CST"             "CDT"            

As for reading them in, see help(strptime)

As for difference, easy too:

R> Jan1 <- strptime("2009-01-01 00:00:00", "%Y-%m-%d %H:%M:%S")
R> difftime(now, Jan1, unit="week")
Time difference of 51.25 weeks

Lastly, the zoo package is an extremely versatile and well-documented container for matrix with associated date/time indices.

MVC 4 Edit modal form using Bootstrap

You should use partial views. I use the following approach:

Use a view model so you're not passing your domain models to your views:

public class EditPersonViewModel
    public int Id { get; set; }   // this is only used to retrieve record from Db
    public string Name { get; set; }
    public string Age { get; set; }

In your PersonController:

[HttpGet] // this action result returns the partial containing the modal
public ActionResult EditPerson(int id)
    var viewModel = new EditPersonViewModel();
    viewModel.Id = id;
    return PartialView("_EditPersonPartial", viewModel);

[HttpPost] // this action takes the viewModel from the modal
public ActionResult EditPerson(EditPersonViewModel viewModel)
    if (ModelState.IsValid)
        var toUpdate = personRepo.Find(viewModel.Id);
        toUpdate.Name = viewModel.Name;
        toUpdate.Age = viewModel.Age;
        return View("Index");

Next create a partial view called _EditPersonPartial. This contains the modal header, body and footer. It also contains the Ajax form. It's strongly typed and takes in our view model.

@model Namespace.ViewModels.EditPersonViewModel
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-hidden="true">×</button>
    <h3 id="myModalLabel">Edit group member</h3>
@using (Ajax.BeginForm("EditPerson", "Person", FormMethod.Post,
                    new AjaxOptions
                        InsertionMode = InsertionMode.Replace,
                        HttpMethod = "POST",
                        UpdateTargetId = "list-of-people"
    <div class="modal-body">
        @Html.Bootstrap().ControlGroup().TextBoxFor(x => x.Name)
        @Html.Bootstrap().ControlGroup().TextBoxFor(x => x.Age)
    <div class="modal-footer">
        <button class="btn btn-inverse" type="submit">Save</button>

Now somewhere in your application, say another partial _peoplePartial.cshtml etc:

   @foreach(var person in Model.People)
        <button class="btn btn-primary edit-person" data-id="@person.PersonId">Edit</button>
// this is the modal definition
<div class="modal hide fade in" id="edit-person">
    <div id="edit-person-container"></div>

    <script type="text/javascript">
    $(document).ready(function () {
        $('.edit-person').click(function () {
            var url = "/Person/EditPerson"; // the url to the controller
            var id = $(this).attr('data-id'); // the id that's given to each button in the list
            $.get(url + '/' + id, function (data) {

How to add a button dynamically using jquery

the $("body").append(r) statement should be within the test function, also there was misplaced " in the test method

function test() {
    var r=$('<input/>').attr({
        type: "button",
        id: "field",
        value: 'new'

Demo: Fiddle

In that case try a more jQuery-ish solution

<!DOCTYPE html>
        <script src=""></script>
        <script type="text/javascript">
              $('#mybutton').one('click', function(){
                  var r=$('<input/>').attr({
                      type: "button",
                      id: "field",
                      value: 'new'
        <button id="mybutton">Insert after</button> 

Demo: Plunker

UnicodeDecodeError: 'utf8' codec can't decode byte 0x9c

str = unicode(str, errors='replace')


str = unicode(str, errors='ignore')

Note: This will strip out (ignore) the characters in question returning the string without them.

For me this is ideal case since I'm using it as protection against non-ASCII input which is not allowed by my application.

Alternatively: Use the open method from the codecs module to read in the file:

import codecs
with, 'r', encoding='utf-8',
                 errors='ignore') as fdata:

java.lang.NoClassDefFoundError: org.slf4j.LoggerFactory

You have to provide one of the various SLF4J implementation .jar files in the classpath, as well as the interface .jar file. This is documented.

Is there a PowerShell "string does not contain" cmdlet or syntax?

You can use the -notmatch operator to get the lines that don't have the characters you are interested in.

     Get-Content $FileName | foreach-object { 
     if ($_ -notmatch $arrayofStringsNotInterestedIn) { $) }

How to deal with "data of class uneval" error from ggplot2?

This could also occur if you refer to a variable in the data.frame that doesn't exist. For example, recently I forgot to tell ddply to summarize by one of my variables that I used in geom_line to specify line color. Then, ggplot didn't know where to find the variable I hadn't created in the summary table, and I got this error.

Wait one second in running program

use dataGridView1.Refresh(); :)

How to query all the GraphQL type fields without writing a long query?

Unfortunately what you'd like to do is not possible. GraphQL requires you to be explicit about specifying which fields you would like returned from your query.

Compilation error: stray ‘\302’ in program etc

With me this error ocurred when I copied and pasted a code in text format to my editor (gedit). The code was in a text document (.odt) and I copied it and pasted it into gedit. If you did the same, you have manually rewrite the code.

Detach (move) subdirectory into separate Git repository

The Easy Way™

It turns out that this is such a common and useful practice that the overlords of Git made it really easy, but you have to have a newer version of Git (>= 1.7.11 May 2012). See the appendix for how to install the latest Git. Also, there's a real-world example in the walkthrough below.

  1. Prepare the old repo

     cd <big-repo>
     git subtree split -P <name-of-folder> -b <name-of-new-branch>

Note: <name-of-folder> must NOT contain leading or trailing characters. For instance, the folder named subproject MUST be passed as subproject, NOT ./subproject/

Note for Windows users: When your folder depth is > 1, <name-of-folder> must have *nix style folder separator (/). For instance, the folder named path1\path2\subproject MUST be passed as path1/path2/subproject

  1. Create the new repo

     mkdir ~/<new-repo> && cd ~/<new-repo>
     git init
     git pull </path/to/big-repo> <name-of-new-branch>
  2. Link the new repo to GitHub or wherever

     git remote add origin <[email protected]:user/new-repo.git>
     git push -u origin master
  3. Cleanup inside <big-repo>, if desired

     git rm -rf <name-of-folder>

Note: This leaves all the historical references in the repository. See the Appendix below if you're actually concerned about having committed a password or you need to decreasing the file size of your .git folder.


These are the same steps as above, but following my exact steps for my repository instead of using <meta-named-things>.

Here's a project I have for implementing JavaScript browser modules in node:

tree ~/node-browser-compat

+-- ArrayBuffer
+-- Audio
+-- Blob
+-- FormData
+-- atob
+-- btoa
+-- location
+-- navigator

I want to split out a single folder, btoa, into a separate Git repository

cd ~/node-browser-compat/
git subtree split -P btoa -b btoa-only

I now have a new branch, btoa-only, that only has commits for btoa and I want to create a new repository.

mkdir ~/btoa/ && cd ~/btoa/
git init
git pull ~/node-browser-compat btoa-only

Next, I create a new repo on GitHub or Bitbucket, or whatever and add it as the origin

git remote add origin [email protected]:node-browser-compat/btoa.git
git push -u origin master

Happy day!

Note: If you created a repo with a, .gitignore and LICENSE, you will need to pull first:

git pull origin master
git push origin master

Lastly, I'll want to remove the folder from the bigger repo

git rm -rf btoa


Latest Git on macOS

To get the latest version of Git using Homebrew:

brew install git

Latest Git on Ubuntu

sudo apt-get update
sudo apt-get install git
git --version

If that doesn't work (you have a very old version of Ubuntu), try

sudo add-apt-repository ppa:git-core/ppa
sudo apt-get update
sudo apt-get install git

If that still doesn't work, try

sudo chmod +x /usr/share/doc/git/contrib/subtree/
sudo ln -s \
/usr/share/doc/git/contrib/subtree/ \

Thanks to rui.araujo from the comments.

Clearing your history

By default removing files from Git doesn't actually remove them, it just commits that they aren't there anymore. If you want to actually remove the historical references (i.e. you committed a password), you need to do this:

git filter-branch --prune-empty --tree-filter 'rm -rf <name-of-folder>' HEAD

After that, you can check that your file or folder no longer shows up in the Git history at all

git log -- <name-of-folder> # should show nothing

However, you can't "push" deletes to GitHub and the like. If you try, you'll get an error and you'll have to git pull before you can git push - and then you're back to having everything in your history.

So if you want to delete history from the "origin" - meaning to delete it from GitHub, Bitbucket, etc - you'll need to delete the repo and re-push a pruned copy of the repo. But wait - there's more! - if you're really concerned about getting rid of a password or something like that you'll need to prune the backup (see below).

Making .git smaller

The aforementioned delete history command still leaves behind a bunch of backup files - because Git is all too kind in helping you to not ruin your repo by accident. It will eventually delete orphaned files over the days and months, but it leaves them there for a while in case you realize that you accidentally deleted something you didn't want to.

So if you really want to empty the trash to reduce the clone size of a repo immediately you have to do all of this really weird stuff:

rm -rf .git/refs/original/ && \
git reflog expire --all && \
git gc --aggressive --prune=now

git reflog expire --all --expire-unreachable=0
git repack -A -d
git prune

That said, I'd recommend not performing these steps unless you know that you need to - just in case you did prune the wrong subdirectory, y'know? The backup files shouldn't get cloned when you push the repo, they'll just be in your local copy.


How to list records with date from the last 10 days?

Yes this does work in PostgreSQL (assuming the column "date" is of datatype date) Why don't you just try it?

The standard ANSI SQL format would be:

FROM Table 
WHERE date > current_date - interval '10' day;

I prefer that format as it makes things easier to read (but it is the same as current_date - 10).

How to install MySQLi on MacOS

sudo apt-get -y -f install php7.0-mysql

Child with max-height: 100% overflows parent

You can use the property object-fit

.cover {
    object-fit: cover;
    width: 150px;
    height: 100px;

Like suggested here

A full explanation of this property by Chris Mills in Dev.Opera

And an even better one in CSS-Tricks

It's supported in

  • Chrome 31+
  • Safari 7.1+
  • Firefox 36+
  • Opera 26+
  • Android 4.4.4+
  • iOS 8+

I just checked that vivaldi and chromium support it as well (no surprise here)

It's currently not supported on IE, but... who cares ? Also, iOS supports object-fit, but not object-position, but it will soon.

Angularjs: Get element in controller

You can pass in the element to the controller, just like the scope:

function someControllerFunc($scope, $element){


Why does the C++ STL not provide any "tree" containers?

This one looks promising and seems to be what you're looking for:

ascending/descending in LINQ - can one change the order via parameter?

You can easily create your own extension method on IEnumerable or IQueryable:

public static IOrderedEnumerable<TSource> OrderByWithDirection<TSource,TKey>
    (this IEnumerable<TSource> source,
     Func<TSource, TKey> keySelector,
     bool descending)
    return descending ? source.OrderByDescending(keySelector)
                      : source.OrderBy(keySelector);

public static IOrderedQueryable<TSource> OrderByWithDirection<TSource,TKey>
    (this IQueryable<TSource> source,
     Expression<Func<TSource, TKey>> keySelector,
     bool descending)
    return descending ? source.OrderByDescending(keySelector)
                      : source.OrderBy(keySelector);

Yes, you lose the ability to use a query expression here - but frankly I don't think you're actually benefiting from a query expression anyway in this case. Query expressions are great for complex things, but if you're only doing a single operation it's simpler to just put that one operation:

var query = dataList.OrderByWithDirection(x => x.Property, direction);

Rails: Default sort order for a rails model?

A quick update to Michael's excellent answer above.

For Rails 4.0+ you need to put your sort in a block like this:

class Book < ActiveRecord::Base
  default_scope { order('created_at DESC') }

Notice that the order statement is placed in a block denoted by the curly braces.

They changed it because it was too easy to pass in something dynamic (like the current time). This removes the problem because the block is evaluated at runtime. If you don't use a block you'll get this error:

Support for calling #default_scope without a block is removed. For example instead of default_scope where(color: 'red'), please use default_scope { where(color: 'red') }. (Alternatively you can just redefine self.default_scope.)

As @Dan mentions in his comment below, you can do a more rubyish syntax like this:

class Book < ActiveRecord::Base
  default_scope { order(created_at: :desc) }

or with multiple columns:

class Book < ActiveRecord::Base
  default_scope { order({begin_date: :desc}, :name) }

Thanks @Dan!

iOS app 'The application could not be verified' only on one device

just delete the app and try again, it happens to me when i try to launch over a device that has the same app but generated by an ipa file.

Java program to find the largest & smallest number in n numbers without using arrays

import java.util.Scanner;

public class LargestSmallestNum {

    public void findLargestSmallestNo() {

        int smallest = Integer.MAX_VALUE;
        int large = 0;
        int num;

        System.out.println("enter the number");

        Scanner input = new Scanner(;

        int n = input.nextInt();

        for (int i = 0; i < n; i++) {

            num = input.nextInt();

            if (num > large)
                large = num;

            if (num < smallest)
                smallest = num;

            System.out.println("the largest is:" + large);
            System.out.println("Smallest no is : "  + smallest);

    public static void main(String...strings){
        LargestSmallestNum largestSmallestNum = new LargestSmallestNum();

Java: method to get position of a match in a String?

int match_position=text.indexOf(match);

How to configure welcome file list in web.xml

I saw a nice solution in this stackoverflow link that may help the readers of the defulat servlet handling issue by using the empty string URL pattern "" :



    <url-pattern></url-pattern> <!-- Yes, empty string! -->

How to generate a Dockerfile from an image?

A bash solution :

docker history --no-trunc $argv  | tac | tr -s ' ' | cut -d " " -f 5- | sed 's,^/bin/sh -c #(nop) ,,g' | sed 's,^/bin/sh -c,RUN,g' | sed 's, && ,\n  & ,g' | sed 's,\s*[0-9]*[\.]*[0-9]*\s*[kMG]*B\s*$,,g' | head -n -1

Step by step explanations:

tac : reverse the file
tr -s ' '                                       trim multiple whitespaces into 1
cut -d " " -f 5-                                remove the first fields (until X months/years ago)
sed 's,^/bin/sh -c #(nop) ,,g'                  remove /bin/sh calls for ENV,LABEL...
sed 's,^/bin/sh -c,RUN,g'                       remove /bin/sh calls for RUN
sed 's, && ,\n  & ,g'                           pretty print multi command lines following Docker best practices
sed 's,\s*[0-9]*[\.]*[0-9]*\s*[kMG]*B\s*$,,g'      remove layer size information
head -n -1                                      remove last line ("SIZE COMMENT" in this case)


 ~ ? dih ubuntu:18.04
ADD file:28c0771e44ff530dba3f237024acc38e8ec9293d60f0e44c8c78536c12f13a0b in /
RUN set -xe
   &&  echo '#!/bin/sh' > /usr/sbin/policy-rc.d
   &&  echo 'exit 101' >> /usr/sbin/policy-rc.d
   &&  chmod +x /usr/sbin/policy-rc.d
   &&  dpkg-divert --local --rename --add /sbin/initctl
   &&  cp -a /usr/sbin/policy-rc.d /sbin/initctl
   &&  sed -i 's/^exit.*/exit 0/' /sbin/initctl
   &&  echo 'force-unsafe-io' > /etc/dpkg/dpkg.cfg.d/docker-apt-speedup
   &&  echo 'DPkg::Post-Invoke { "rm -f /var/cache/apt/archives/*.deb /var/cache/apt/archives/partial/*.deb /var/cache/apt/*.bin || true"; };' > /etc/apt/apt.conf.d/docker-clean
   &&  echo 'APT::Update::Post-Invoke { "rm -f /var/cache/apt/archives/*.deb /var/cache/apt/archives/partial/*.deb /var/cache/apt/*.bin || true"; };' >> /etc/apt/apt.conf.d/docker-clean
   &&  echo 'Dir::Cache::pkgcache ""; Dir::Cache::srcpkgcache "";' >> /etc/apt/apt.conf.d/docker-clean
   &&  echo 'Acquire::Languages "none";' > /etc/apt/apt.conf.d/docker-no-languages
   &&  echo 'Acquire::GzipIndexes "true"; Acquire::CompressionTypes::Order:: "gz";' > /etc/apt/apt.conf.d/docker-gzip-indexes
   &&  echo 'Apt::AutoRemove::SuggestsImportant "false";' > /etc/apt/apt.conf.d/docker-autoremove-suggests
RUN rm -rf /var/lib/apt/lists/*
RUN sed -i 's/^#\s*\(deb.*universe\)$/\1/g' /etc/apt/sources.list
RUN mkdir -p /run/systemd
   &&  echo 'docker' > /run/systemd/container
CMD ["/bin/bash"]

Convert String array to ArrayList

Use this code for that,

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

public class StringArrayTest {

   public static void main(String[] args) {  
      String[] words = {"ace", "boom", "crew", "dog", "eon"};  

      List<String> wordList = Arrays.asList(words);  

      for (String e : wordList) {  

Radio button checked event handling

Update in 2017: Hey. This is a terrible answer. Don't use it. Back in the old days this type of jQuery use was common. And it probably worked back then. Just read it, realize it's terrible, then move on (or downvote or, whatever) to one of the other answers that are better for today's jQuery.

    alert( $("input[type=radio][name="+ + "]").val() );

Windows Application has stopped working :: Event Name CLR20r3

Make sure the client computer has the same or higher version of the .NET framework that you built your program to., '_blank'); not working on iMac/Safari

window.location.assign(url) this fixs the issue in ios devices

Deck of cards JAVA

public class shuffleCards{

    public static void main(String[] args) {

        String[] cardsType ={"club","spade","heart","diamond"};
        String [] cardValue = {"Ace","2","3","4","5","6","7","8","9","10","King", "Queen", "Jack" };

        List<String> cards = new ArrayList<String>();
        for(int i=0;i<=(cardsType.length)-1;i++){
            for(int j=0;j<=(cardValue.length)-1;j++){
                cards.add(cardsType[i] + " " + "of" + " " + cardValue[j]) ;

        System.out.print("Enter the number of cards within:" + cards.size() + " = ");

        Scanner data = new Scanner(;
        Integer inputString = data.nextInt();
        for(int l=0;l<= inputString -1;l++){
            System.out.print( cards.get(l)) ;

Python error: AttributeError: 'module' object has no attribute

My solution is put those imports in of lib:

in file:
import mod1


import lib

would work fine.

import android packages cannot be resolved

RightClick on the Project > Properties > Android > Fix project properties

This solved it for me. easy.

Find kth smallest element in a binary search tree in Optimum way

A simpler solution would be to do an inorder traversal and keep track of the element currently to be printed (without printing it). When we reach k, print the element and skip rest of tree traversal.

void findK(Node* p, int* k) {
  if(!p || k < 0) return;
  findK(p->left, k);
  if(k == 0) { 
    print p->data;
  findK(p->right, k); 

How to fix warning from date() in PHP"

You need to set the default timezone smth like this :


More info about this in

Or you could use @ in front of date to suppress the warning however as the warning states it's not safe to rely on the servers default timezone

Iptables setting multiple multiports in one rule

You need to use multiple rules to implement OR-like semantics, since matches are always AND-ed together within a rule. Alternatively, you can do matching against port-indexing ipsets (ipset create blah bitmap:port).

How to get json response using in c#?

You need to explicitly ask for the content type.

Add this line:

 request.ContentType = "application/json; charset=utf-8";
At the appropriate place

How to sum all the values in a dictionary?

As you'd expect:


Vue 2 - Mutating props vue-warn

Vue.component('task', {
    template: '#task-template',
    props: ['list'],
    computed: {
      middleData() {
        return this.list
    watch: {
      list(newVal, oldVal) {
        this.newList = newVal
    data() {
      return {
        newList: {}
new Vue({
    el: '.container'

Maybe this will meet your needs.

How do I create a comma delimited string from an ArrayList?

The solutions so far are all quite complicated. The idiomatic solution should doubtless be:

String.Join(",", x.Cast(Of String)().ToArray())

There's no need for fancy acrobatics in new framework versions. Supposing a not-so-modern version, the following would be easiest:

Console.WriteLine(String.Join(",", CType(x.ToArray(GetType(String)), String())))

mspmsp's second solution is a nice approach as well but it's not working because it misses the AddressOf keyword. Also, Convert.ToString is rather inefficient (lots of unnecessary internal evaluations) and the Convert class is generally not very cleanly designed. I tend to avoid it, especially since it's completely redundant.

Why No such provider: BC?

My experience with this was that when I had this in every execution it was fine using the provider as a string like this

Security.addProvider(new BounctCastleProvider());
new JcaPEMKeyConverter().setProvider("BC");

But when I optimized and put the following in the constructor:

   if(bounctCastleProvider == null) {
      bounctCastleProvider = new BouncyCastleProvider();

    if(Security.getProvider(bouncyCastleProvider.getName()) == null) {

Then I had to use provider like this or I would get the above error:

new JcaPEMKeyConverter().setProvider(bouncyCastleProvider);

I am using bcpkix-jdk15on version 1.65

How to chain scope queries with OR instead of AND?

Rails 4 + Scope + Arel

class Creature < ActiveRecord::Base
    scope :is_good_pet, -> {

I tried chaining named scopes with .or and no luck, but this worked for finding anything with those booleans set. Generates SQL like

SELECT 'CREATURES'.* FROM 'CREATURES' WHERE ((('CREATURES'.'is_cat' = 1 OR 'CREATURES'.'is_dog' = 1) OR 'CREATURES'.'eats_children' = 0))

How to extract text from the PDF document?

Download the class.pdf2text.php @ or (Registration required)


$a = new PDF2Text();
echo $a->output(); 

  • class.pdf2text.php Project Home

  • pdf2textclass doesn't work with all the PDF's I've tested, If it doesn't work for you, try PDF Parser

Print a div using javascript in angularJS single page application

Two conditional functions are needed: one for Google Chrome, and a second for the remaining browsers.

$scope.printDiv = function (divName) {

    var printContents = document.getElementById(divName).innerHTML; 

    if (navigator.userAgent.toLowerCase().indexOf('chrome') > -1) {
        var popupWin ='', '_blank', 'width=600,height=600,scrollbars=no,menubar=no,toolbar=no,location=no,status=no,titlebar=no');
        popupWin.document.write('<!DOCTYPE html><html><head>' +
            '<link rel="stylesheet" type="text/css" href="style.css" />' +
            '</head><body onload="window.print()"><div class="reward-body">' + printContents + '</div></body></html>');
        popupWin.onbeforeunload = function (event) {
            return '.\n';
        popupWin.onabort = function (event) {
    } else {
        var popupWin ='', '_blank', 'width=800,height=600');;
        popupWin.document.write('<html><head><link rel="stylesheet" type="text/css" href="style.css" /></head><body onload="window.print()">' + printContents + '</body></html>');

    return true;

One-liner if statements, how to convert this if-else-statement

Since expression is boolean:

return expression;

How do I put text on ProgressBar?


The solution provided by Barry above is excellent, but there's is the "flicker-problem".

As soon as the Value is above zero the OnPaint will be envoked repeatedly and the text will flicker.

There is a solution to this. We do not need VisualStyles for the object since we will be drawing it with our own code.

Add the following code to the custom object Barry wrote and you will avoid the flicker:

    private static extern int SetWindowTheme(IntPtr hWnd, string appname, string idlist);

    protected override void OnHandleCreated(EventArgs e)
        SetWindowTheme(this.Handle, "", "");

I did not write this myself. It found it here:

I've testet it and it works.

Handling ExecuteScalar() when no results are returned

Always have a check before reading row.

if (SqlCommand.ExecuteScalar() == null)


How can I force users to access my page over HTTPS instead of HTTP?

// Require https
if ($_SERVER['HTTPS'] != "on") {
    $url = "https://". $_SERVER['SERVER_NAME'] . $_SERVER['REQUEST_URI'];
    header("Location: $url");

That easy.

how to set imageview src?

Each image has a resource-number, which is an integer. Pass this number to "setImageResource" and you should be ok.

Check this link for further information:



Highcharts - redraw() vs. new Highcharts.chart

@RobinL as mentioned in previous comments, you can use chart.series[n].setData(). First you need to make sure you’ve assigned a chart instance to the chart variable, that way it adopts all the properties and methods you need to access and manipulate the chart.

I’ve also used the second parameter of setData() and had it false, to prevent automatic rendering of the chart. This was because I have multiple data series, so I’ll rather update each of them, with render=false, and then running chart.redraw(). This multiplied performance (I’m having 10,000-100,000 data points and refreshing the data set every 50 milliseconds).

Resolving ORA-4031 "unable to allocate x bytes of shared memory"

Don't forget about fragmentation. If you have a lot of traffic, your pools can be fragmented and even if you have several MB free, there could be no block larger than 4KB. Check size of largest free block with a query like:

  10*trunc(KSMCHSIZ/10) "From",
  count(*) "Count" ,
  max(KSMCHSIZ) "Biggest",
  trunc(avg(KSMCHSIZ)) "AvgSize",
  trunc(sum(KSMCHSIZ)) "Total"
group by
  '1 (140-267)' BUCKET,
  20*trunc(KSMCHSIZ/20) ,
  count(*) ,
  max(KSMCHSIZ) ,
  trunc(avg(KSMCHSIZ)) "AvgSize",
  trunc(sum(KSMCHSIZ)) "Total"
  KSMCHSIZ between 140 and 267
group by
  '2 (268-523)' BUCKET,
  50*trunc(KSMCHSIZ/50) ,
  count(*) ,
  max(KSMCHSIZ) ,
  trunc(avg(KSMCHSIZ)) "AvgSize",
  trunc(sum(KSMCHSIZ)) "Total"
  KSMCHSIZ between 268 and 523
group by
  '3-5 (524-4107)' BUCKET,
  500*trunc(KSMCHSIZ/500) ,
  count(*) ,
  max(KSMCHSIZ) ,
  trunc(avg(KSMCHSIZ)) "AvgSize",
  trunc(sum(KSMCHSIZ)) "Total"
  KSMCHSIZ between 524 and 4107
group by
  '6+ (4108+)' BUCKET,
  1000*trunc(KSMCHSIZ/1000) ,
  count(*) ,
  max(KSMCHSIZ) ,
  trunc(avg(KSMCHSIZ)) "AvgSize",
  trunc(sum(KSMCHSIZ)) "Total"
  KSMCHSIZ >= 4108
group by
  KSMCHCLS, KSMCHIDX, 1000*trunc(KSMCHSIZ/1000);

Code from

How do I format date and time on ssrs report?

Hope this helps:

SELECT convert(varchar, getdate(), 100) -- mon dd yyyy hh:mmAM

SELECT convert(varchar, getdate(), 101) -- mm/dd/yyyy – 10/02/2008                  

SELECT convert(varchar, getdate(), 102) -- – 2008.10.02           

SELECT convert(varchar, getdate(), 103) -- dd/mm/yyyy

SELECT convert(varchar, getdate(), 104) --

SELECT convert(varchar, getdate(), 105) -- dd-mm-yyyy

SELECT convert(varchar, getdate(), 106) -- dd mon yyyy

SELECT convert(varchar, getdate(), 107) -- mon dd, yyyy

SELECT convert(varchar, getdate(), 108) -- hh:mm:ss

SELECT convert(varchar, getdate(), 109) -- mon dd yyyy hh:mm:ss:mmmAM (or PM)

SELECT convert(varchar, getdate(), 110) -- mm-dd-yyyy

SELECT convert(varchar, getdate(), 111) -- yyyy/mm/dd

SELECT convert(varchar, getdate(), 112) -- yyyymmdd

SELECT convert(varchar, getdate(), 113) -- dd mon yyyy hh:mm:ss:mmm

SELECT convert(varchar, getdate(), 114) -- hh:mm:ss:mmm(24h)

SELECT convert(varchar, getdate(), 120) -- yyyy-mm-dd hh:mm:ss(24h)

SELECT convert(varchar, getdate(), 121) -- yyyy-mm-dd hh:mm:ss.mmm

SELECT convert(varchar, getdate(), 126) -- yyyy-mm-ddThh:mm:ss.mmm

How can I grep for a string that begins with a dash/hyphen?

you can use nawk

$ nawk '/-X/{print}' file

ComboBox.SelectedText doesn't give me the SelectedText

To get selected item, you have to use SELECTEDITEM property of comboBox. And since this is an Object, if you wanna assign it to a string, you have to convert it to string, by using ToString() method:

string myItem = comboBox1.SelectedItem.ToString(); //this does the trick

Spring schemaLocation fails when there is no internet connection

I had ran into this similar problem as well. In my case, my resolution is quite different. Here's my spring context xml file:

<beans xmlns=""

I'm not specifying any xsd version as I want spring to use the latest xsd version inside spring dependencies. The spring version my application used was spring-beans-4.3.1.RELEASE.jar:4.3.1.RELEASE and when I assembly my application into jar, all spring dependencies exist in my classpath. However, I received following error during startup of my spring application context:

org.xml.sax.SAXParseException: schema_reference.4: Failed to read schema document '', because 1) could not find the document; 2) the document could not be read; 3) the root element of the document is not <xsd:schema>.

After some hard time troubleshooting, I found the issue is due to the index.list inside the META-INF folder of my jar file. With index.list file, spring namespace handlers cannot be located to parse the spring application context xml correctly. You can read more about this spring issue SPR-5705

By removing indexing from my maven-jar-plugin, I manage to resolve the issue. Hope this will save some times for people having the same problem.

PHP: Return all dates between two dates in an array

Short function. PHP 5.3 and up. Can take optional third param of any date format that strtotime can understand. Automatically reverses direction if end < start.

function getDatesFromRange($start, $end, $format='Y-m-d') {
    return array_map(function($timestamp) use($format) {
        return date($format, $timestamp);
    range(strtotime($start) + ($start < $end ? 4000 : 8000), strtotime($end) + ($start < $end ? 8000 : 4000), 86400));


print_r(getDatesFromRange( '2016-7-28','2016-8-2' ));
print_r(getDatesFromRange( '2016-8-2','2016-7-28' ));
print_r(getDatesFromRange( '2016-10-28','2016-11-2' ));
print_r(getDatesFromRange( '2016-11-2','2016-10-28' ));
print_r(getDatesFromRange( '2016-4-2','2016-3-25' ));
print_r(getDatesFromRange( '2016-3-25','2016-4-2' ));
print_r(getDatesFromRange( '2016-8-2','2016-7-25' ));
print_r(getDatesFromRange( '2016-7-25','2016-8-2' ));


Array ( [0] => 2016-07-28 [1] => 2016-07-29 [2] => 2016-07-30 [3] => 2016-07-31 [4] => 2016-08-01 [5] => 2016-08-02 ) 
Array ( [0] => 2016-08-02 [1] => 2016-08-01 [2] => 2016-07-31 [3] => 2016-07-30 [4] => 2016-07-29 [5] => 2016-07-28 ) 
Array ( [0] => 2016-10-28 [1] => 2016-10-29 [2] => 2016-10-30 [3] => 2016-10-31 [4] => 2016-11-01 [5] => 2016-11-02 ) 
Array ( [0] => 2016-11-02 [1] => 2016-11-01 [2] => 2016-10-31 [3] => 2016-10-30 [4] => 2016-10-29 [5] => 2016-10-28 ) 
Array ( [0] => 2016-04-02 [1] => 2016-04-01 [2] => 2016-03-31 [3] => 2016-03-30 [4] => 2016-03-29 [5] => 2016-03-28 [6] => 2016-03-27 [7] => 2016-03-26 [8] => 2016-03-25 ) 
Array ( [0] => 2016-03-25 [1] => 2016-03-26 [2] => 2016-03-27 [3] => 2016-03-28 [4] => 2016-03-29 [5] => 2016-03-30 [6] => 2016-03-31 [7] => 2016-04-01 [8] => 2016-04-02 ) 
Array ( [0] => 2016-08-02 [1] => 2016-08-01 [2] => 2016-07-31 [3] => 2016-07-30 [4] => 2016-07-29 [5] => 2016-07-28 [6] => 2016-07-27 [7] => 2016-07-26 [8] => 2016-07-25 ) 
Array ( [0] => 2016-07-25 [1] => 2016-07-26 [2] => 2016-07-27 [3] => 2016-07-28 [4] => 2016-07-29 [5] => 2016-07-30 [6] => 2016-07-31 [7] => 2016-08-01 [8] => 2016-08-02 )

Root password inside a Docker container

In some cases you need to be able to do things like that under a user with sudo (e.g. the application running in the container provides a shell to users). Simply add this into you Dockerfile:

RUN apt-get update         # If necessary
RUN apt-get install sudo   # If your base image does not contain sudo.
RUN useradd -m -N -s /bin/bash -u 1000 -p '$1$miTOHCYy$K.c4Yw.edukWJ7z9rbpTZ0' user && \
    usermod -aG sudo user  # Grant sudo to the user
USER user

Now under the default image user user you will be able to sudo with the password set on line 3.

See how to generate password hash for useradd here or here.

How to find which version of Oracle is installed on a Linux server (In terminal)

Login as sys user in sql*plus. Then do this query:

select * from v$version; 


select * from product_component_version;

How to read the Stock CPU Usage data

From High Performance Android Apps book (page 157):

  • what we see is equivalent of adb shell dumpsys cpuinfo command
  • Numbers are showing CPU load over 1 minute, 5 minutes and 15 minutes (from the left)
  • Colors are showing time spent by CPU in user space (green), kernel (red) and IO interrupt (blue)

How to do a regular expression replace in MySQL?

I think there is an easy way to achieve this and It's working fine for me.

To SELECT rows using REGEX

SELECT * FROM `table_name` WHERE `column_name_to_find` REGEXP 'string-to-find'

To UPDATE rows using REGEX

UPDATE `table_name` SET column_name_to_find=REGEXP_REPLACE(column_name_to_find, 'string-to-find', 'string-to-replace') WHERE column_name_to_find REGEXP 'string-to-find'

REGEXP Reference:

How to validate phone number using PHP?

Here's how I find valid 10-digit US phone numbers. At this point I'm assuming the user wants my content so the numbers themselves are trusted. I'm using in an app that ultimately sends an SMS message so I just want the raw numbers no matter what. Formatting can always be added later

//eliminate every char except 0-9
$justNums = preg_replace("/[^0-9]/", '', $string);

//eliminate leading 1 if its there
if (strlen($justNums) == 11) $justNums = preg_replace("/^1/", '',$justNums);

//if we have 10 digits left, it's probably valid.
if (strlen($justNums) == 10) $isPhoneNum = true;

Edit: I ended up having to port this to Java, if anyone's interested. It runs on every keystroke so I tried to keep it fairly light:

boolean isPhoneNum = false;
if (str.length() >= 10 && str.length() <= 14 ) { 
  //14: (###) ###-####
  //eliminate every char except 0-9
  str = str.replaceAll("[^0-9]", "");

  //remove leading 1 if it's there
  if (str.length() == 11) str = str.replaceAll("^1", "");

  isPhoneNum = str.length() == 10;
Log.d("ISPHONENUM", String.valueOf(isPhoneNum));

Python - add PYTHONPATH during command line module run

For Mac/Linux;

PYTHONPATH=/foo/bar/baz python somecommand

For Windows, setup a wrapper pythonpath.bat;

python %2 %3

and call pythonpath.bat script file like;

pythonpath.bat /foo/bar/baz somecommand

MySQL SELECT WHERE datetime matches day (and not necessarily time)

SELECT * FROM table where Date(col) = 'date'

What's the correct way to communicate between controllers in AngularJS?

Regarding the original code - it appears you want to share data between scopes. To share either Data or State between $scope the docs suggest using a service:

  • To run stateless or stateful code shared across controllers — Use angular services instead.
  • To instantiate or manage the life-cycle of other components (for example, to create service instances).

Ref: Angular Docs link here

How can I expand and collapse a <div> using javascript?

Check out Jed Foster's Readmore.js library.

It's usage is as simple as:

$(document).ready(function() {_x000D_
  $('article').readmore({collapsedHeight: 100});_x000D_
<script src=""></script>_x000D_
<script src="" type="text/javascript"></script>_x000D_
  <p>From this distant vantage point, the Earth might not seem of any particular interest. But for us, it's different. Consider again that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every "superstar," every "supreme leader," every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.</p>_x000D_
  <p>Space, the final frontier. These are the voyages of the starship Enterprise. Its five year mission: to explore strange new worlds, to seek out new life and new civilizations, to boldly go where no man has gone before!</p>_x000D_
  <p>Here's how it is: Earth got used up, so we terraformed a whole new galaxy of Earths, some rich and flush with the new technologies, some not so much. Central Planets, them was formed the Alliance, waged war to bring everyone under their rule; a few idiots tried to fight it, among them myself. I'm Malcolm Reynolds, captain of Serenity. Got a good crew: fighters, pilot, mechanic. We even picked up a preacher, and a bona fide companion. There's a doctor, too, took his genius sister out of some Alliance camp, so they're keeping a low profile. You got a job, we can do it, don't much care what it is.</p>_x000D_
  <p>Space, the final frontier. These are the voyages of the starship Enterprise. Its five year mission: to explore strange new worlds, to seek out new life and new civilizations, to boldly go where no man has gone before!</p>_x000D_

Here are the available options to configure your widget:

  speed: 100,_x000D_
  collapsedHeight: 200,_x000D_
  heightMargin: 16,_x000D_
  moreLink: '<a href="#">Read More</a>',_x000D_
  lessLink: '<a href="#">Close</a>',_x000D_
  embedCSS: true,_x000D_
  blockCSS: 'display: block; width: 100%;',_x000D_
  startOpen: false,_x000D_
  // callbacks_x000D_
  blockProcessed: function() {},_x000D_
  beforeToggle: function() {},_x000D_
  afterToggle: function() {}_x000D_

Use can use it like:

  collapsedHeight: 100,_x000D_
  moreLink: '<a href="#" class="you-can-also-add-classes-here">Continue reading...</a>',_x000D_

I hope it helps.

Align an element to bottom with flexbox

You can use display: flex to position an element to the bottom, but I do not think you want to use flex in this case, as it will affect all of your elements.

To position an element to the bottom using flex try this:

.container {
  display: flex;

.button {
  align-self: flex-end;

Your best bet is to set position: absolute to the button and set it to bottom: 0, or you can place the button outside the container and use negative transform: translateY(-100%) to bring it in the container like this:

.content {
    height: 400px;
    background: #000;
    color: #fff;
.button {
    transform: translateY(-100%);
    display: inline-block;

Check this JSFiddle

How to correct "TypeError: 'NoneType' object is not subscriptable" in recursive function?

What is a when you call Ancestors('A',a)? If a['A'] is None, or if a['A'][0] is None, you'd receive that exception.

how to upload a file to my server using html

You need enctype="multipart/form-data" otherwise you will load only the file name and not the data.

ClassNotFoundException com.mysql.jdbc.Driver

I too struggled with the same problem and finally got the solution for it. Just copy the MySql-Connector.jar into Tomcat's lib folder, and then remove the jar from the webapp's lib folder, and then, run the project.

How do I expand the output display to see more columns of a pandas DataFrame?

Try this:

pd.set_option('display.expand_frame_repr', False)

From the documentation:

display.expand_frame_repr : boolean

Whether to print out the full DataFrame repr for wide DataFrames across multiple lines, max_columns is still respected, but the output will wrap-around across multiple “pages” if it’s width exceeds display.width. [default: True] [currently: True]


How do you find out the caller function in JavaScript?

heystewart's answer and JiarongWu's answer both mentioned that the Error object has access to the stack.

Here's an example:

function main() {

function Hello() {
  var stack = new Error().stack;
  // N.B. stack === "Error\n  at Hello ...\n  at main ... \n...."
  var m = stack.match(/.*?Hello.*?\n(.*?)\n/);
  if (m) {
    var caller_name = m[1];
    console.log("Caller is:", caller_name)


Different browsers shows the stack in different string formats:

Safari  : Caller is: main@
Firefox : Caller is: main@
Chrome  : Caller is:     at main (
IE Edge : Caller is:    at main (
IE      : Caller is:    at main (

Most browsers will set the stack with var stack = (new Error()).stack. In Internet Explorer the stack will be undefined - you have to throw a real exception to retrieve the stack.

Conclusion: It's possible to determine "main" is the caller to "Hello" using the stack in the Error object. In fact it will work in cases where the callee / caller approach doesn't work. It will also show you context, i.e. source file and line number. However effort is required to make the solution cross platform.

Can Powershell Run Commands in Parallel?

This has been answered thoroughly. Just want to post this method i have created based on Powershell-Jobs as a reference.

Jobs are passed on as a list of script-blocks. They can be parameterized. Output of the jobs is color-coded and prefixed with a job-index (just like in a vs-build-process, as this will be used in a build) Can be used to startup multiple servers at a time or running build steps in parallel or so..

function Start-Parallel {
        [Parameter(Position = 0)]


    $jobs = $ScriptBlock | ForEach-Object { Start-Job -ScriptBlock $_ -ArgumentList $parameters }
    $colors = "Blue", "Red", "Cyan", "Green", "Magenta"
    $colorCount = $colors.Length

    try {
        while (($jobs | Where-Object { $_.State -ieq "running" } | Measure-Object).Count -gt 0) {
            $jobs | ForEach-Object { $i = 1 } {
                $fgColor = $colors[($i - 1) % $colorCount]
                $out = $_ | Receive-Job
                $out = $out -split [System.Environment]::NewLine
                $out | ForEach-Object {
                    Write-Host "$i> "-NoNewline -ForegroundColor $fgColor
                    Write-Host $_
    } finally {
        Write-Host "Stopping Parallel Jobs ..." -NoNewline
        $jobs | Stop-Job
        $jobs | Remove-Job -Force
        Write-Host " done."

sample output:

sample output

How do I fix certificate errors when running wget on an HTTPS URL in Cygwin?

If the problem is that a known root CA is missing and when you are using ubuntu or debian, then you can solve the problem with this one line:

sudo apt-get install ca-certificates

Android appcompat v7:23

Latest published version of the Support Library is 24.1.1, So you can use it like this,

compile ''
compile ''

Same as for other support components.

You can see the revisions here,

How do you dynamically add elements to a ListView on Android?

        This is the simple answer how to add datas dynamically in listview android kotlin

class MainActivity : AppCompatActivity(){
            var listItems = arrayListOf<String>()
            val array = arrayOf("a","b","c","d","e")
            var listView: ListView? = null
            private lateinit var adapter: listViewAdapter
            override fun onCreate(savedInstanceState: Bundle?) {
                //if you want to add array items to a list you can try this for each loop
                for(items in array)
                //check the result in console
                Log.e("TAG","listItems array: $listItems")
            adapter = ListViewAdapter()

//Here is the adapter class
    class ListviewAdapter : BaseAdapter(){
    private var itemsList = arrayListOf<String>()
    override fun getView(position: Int, container: View?, parent: ViewGroup?): View {
            var view  = container
            val inflater = context.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater
            if (view == null)
                view = inflater.inflate(R.layout.list_pc_summary, parent, false)
    return view
    override fun getItem(position: Int): Any  = itemsList[position]
    override fun getItemId(position: Int): Long = position.toLong()
    override fun getCount(): Int = itemsList.size
    fun updateList(listItems: ArrayList<String>()){
        this.itemsList = listItems
    //Here I just explained two ways, we can do this many ways.

Django check for any exists for a query

As of Django 1.2, you can use exists():

if some_queryset.filter(pk=entity_id).exists():
    print("Entry contained in queryset")

How to revert a "git rm -r ."?


Since git rm . deletes all files in this and child directories in the working checkout as well as in the index, you need to undo each of these changes:

git reset HEAD . # This undoes the index changes
git checkout .   # This checks out files in this and child directories from the HEAD

This should do what you want. It does not affect parent folders of your checked-out code or index.

Old answer that wasn't:

reset HEAD

will do the trick, and will not erase any uncommitted changes you have made to your files.

after that you need to repeat any git add commands you had queued up.

How can I add raw data body to an axios request?

You can use the below for passing the raw text.
        baseUrl + 'applications/' + appName + '/dataexport/plantypes' + plan, 
            headers: { 
                'Authorization': 'Basic xxxxxxxxxxxxxxxxxxx',
                'Content-Type' : 'text/plain' 
).then(response => {

Just have your raw text within body or pass it directly within quotes as 'raw text to be sent' in place of body.

The signature of the axios post is[, data[, config]]), so the data is where you pass your request body.

Locate Git installation folder on Mac OS X

Mostly in /usr/local/git (there are also /etc/paths.d/git and /etc/manpaths.d/git items).

Print array to a file


return [


// Read array from file
$my_arr = include './test.php';

$my_arr["my_key_1"] = "3333333";

echo write_arr_to_file($my_arr, "./test.php");

* @param array $arr <p>array</p>
* @param string $path <p>path to file</p>
* example :: "./test.php"
* @return bool <b>FALSE</b> occurred error
* more info: about "file_put_contents"
function write_arr_to_file($arr, $path){
    $data = "\n";
    foreach ($arr as $key => $value) {
        $data = $data."   '".$key."'=>'".$value."',\n";
    return file_put_contents($path, "<?php  \nreturn [".$data."];");

How do I set the request timeout for one controller action in an mvc application

I had to add "Current" using .NET 4.5:

HttpContext.Current.Server.ScriptTimeout = 300;

How to draw a circle with given X and Y coordinates as the middle spot of the circle?

The only thing that worked for me:

g.drawOval((getWidth()-200)/2,(getHeight()-200)/2, 200, 200);    

Best method to download image from url in Android

Step 1: Declaring Permission in Android Manifest

First thing to do in your first Android Project is you declare required permissions in your ‘AndroidManifest.xml’ file.

For Android Download Image from URL, we need permission to access the internet to download file and read and write internal storage to save image to internal storage.

Add following lines of code at the top of tag of AndroidManifest.xml file:

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

Step 2: Request required permission from user

Android allows every app to run in a sandbox. If an app needs to access certain resources or information outside that sandbox, it needs to request permission from user.

From Android 6.0 onward, Google wants developers to request permission from user from within the app, for more details on permissions read this.

Therefore for Android Download Image from URL, you’ll need to request Read Storage and Write

For this, we will use the following lines of code to first check if the required permission is already granted by the user, if not then we will request permission for storage read and write permission.

We’re creating a method ‘Downlaod Image’, you can simple call this wherever you need to download the image.

void DownloadImage(String ImageUrl) {

    if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED &&
            ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 123);
        ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 123);
        showToast("Need Permission to access storage for Downloading Image");
    } else {
        showToast("Downloading Image...");
       //Asynctask to create a thread to downlaod image in the background 
        new DownloadsImage().execute(ImageUrl);

Now that we have requested and been granted the user permission, to start with android download image from url, we will create an AsyncTask, as you are not allowed to run a background process in the main thread.

class DownloadsImage extends AsyncTask<String, Void,Void>{

    protected Void doInBackground(String... strings) {
        URL url = null;
        try {
            url = new URL(strings[0]);
        } catch (MalformedURLException e) {
        Bitmap bm = null;
        try {
            bm =    BitmapFactory.decodeStream(url.openConnection().getInputStream());
        } catch (IOException e) {

        //Create Path to save Image
        File path = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES+ "/AndroidDvlpr"); //Creates app specific folder

        if(!path.exists()) {

        File imageFile = new File(path, String.valueOf(System.currentTimeMillis())+".png"); // Imagename.png
        FileOutputStream out = null;
        try {
            out = new FileOutputStream(imageFile);
        } catch (FileNotFoundException e) {
            bm.compress(Bitmap.CompressFormat.PNG, 100, out); // Compress Image
            // Tell the media scanner about the new file so that it is
            // immediately available to the user.
            MediaScannerConnection.scanFile(MainActivity.this,new String[] { imageFile.getAbsolutePath() }, null,new MediaScannerConnection.OnScanCompletedListener() {
                public void onScanCompleted(String path, Uri uri) {
                    // Log.i("ExternalStorage", "Scanned " + path + ":");
                    //    Log.i("ExternalStorage", "-> uri=" + uri);
        } catch(Exception e) {
        return null;

    protected void onPostExecute(Void aVoid) {
        showToast("Image Saved!");

In the above give lines of code, a URL and Bitmap is created, using BitmapFactory.decodeStream, file is downloaded.

The File path is created to save the image (We have created a folder named ‘AndroidDvlpr’ in DIRECTORY_PICTURES) and download is initialized.

After downloading the file MediaScannerConnection, is called to read metadata from the file and add the file to the media content provider so the image is available for the user.

In the above lines of code, we have also created a method, showToast() to show Toast. complete code here:

void showToast(String msg){

Read more here