Programs & Examples On #Invalidation

Invalidating JSON Web Tokens

Kafka message queue and local black lists

I thought about using a messaging system like kafka. Let me explain:

You could have one micro service (let call it userMgmtMs service) for example which is responsible for the login and logout and to produce the JWT token. This token then gets passed to the client.

Now the client can use this token to call different micro services (lets call it pricesMs), within pricesMs there will be NO database check to the users table from which the initial token creation was triggered. This database has only to exist in userMgmtMs. Also the JWT token should include the permissions / roles so that the pricesMs do not need to lookup anything from the DB to allow spring security to work.

Instead of going to the DB in the pricesMs the JwtRequestFilter could provide a UserDetails object created by the data provided in the JWT token (without the password obviously).

So, how to logout or invalidate a token? Since we do not wanna call the database of userMgmtMs with every request for priecesMs (which would introduce quite a lot of unwanted dependencies) a solution could be to use this token blacklist.

Instead of keeping this blacklist central and haveing a dependency on one table from all microservices, I propose to use a kafka message queue.

The userMgmtMs is still responsible for the logout and once this is done it puts it into its own blacklist (a table NOT shared among microservices). In addition it sends a kafka event with the content of this token to a internal kafka service where all other microservices are subscribed to.

Once the other microservices receive the kafka event they will put it as well in their internal blacklist.

Even if some microservices are down at the time of logout they will eventually go up again and will receive the message at a later state.

Since kafka is developed so that clients have their own reference which messages they did read it is ensured that no client, down or up will miss any of this invalid tokens.

The only issue again what I can think of is that the kafka messaging service will again introduce a single point of failure. But it is kind of reversed because if we have one global table where all invalid JWT tokens are saved and this db or micro service is down nothing works. With the kafka approach + client side deletion of JWT tokens for a normal user logout a downtime of kafka would in most cases not even be noticeable. Since the black lists are distributed among all microservies as an internal copy.

In the off case that you need to invalidate a user which was hacked and kafka is down this is where the problems start. In this case changing the secret as a last resort could help. Or just make sure kafka is up before doing so.

Disclaimer: I did not implement this solution yet but somehow I feel that most of the proposed solution negate the idea of the JWT tokens with having a central database lookup. So I was thinking about another solution.

Please let me know what you think, does it make sense or is there an obvious reason why it cant?

500.21 Bad module "ManagedPipelineHandler" in its module list

I got this error on my ASP.Net 4.5 app on Windows Server 2012 R2.

Go to start menu -> "Turn windows features on or off". A wizard popped up for me.

Click Next to Server Roles

I had to check these to get this to work, located under Web Server IIS->Web Server-> Application Development (these are based on Jeremy Cook's answer above):

enter image description here

Then click next to Features and make sure the following is checked:

enter image description here

Then click next and Install. At this point, the error went away for me. Good luck!

Iterator invalidation rules

C++17 (All references are from the final working draft of CPP17 - n4659)


Sequence Containers

  • vector: The functions insert, emplace_back, emplace, push_back cause reallocation if the new size is greater than the old capacity. Reallocation invalidates all the references, pointers, and iterators referring to the elements in the sequence. If no reallocation happens, all the iterators and references before the insertion point remain valid. []
    With respect to the reserve function, reallocation invalidates all the references, pointers, and iterators referring to the elements in the sequence. No reallocation shall take place during insertions that happen after a call to reserve() until the time when an insertion would make the size of the vector greater than the value of capacity(). []

  • deque: An insertion in the middle of the deque invalidates all the iterators and references to elements of the deque. An insertion at either end of the deque invalidates all the iterators to the deque, but has no effect on the validity of references to elements of the deque. []

  • list: Does not affect the validity of iterators and references. If an exception is thrown there are no effects. [].
    The insert, emplace_front, emplace_back, emplace, push_front, push_back functions are covered under this rule.

  • forward_list: None of the overloads of insert_after shall affect the validity of iterators and references []

  • array: As a rule, iterators to an array are never invalidated throughout the lifetime of the array. One should take note, however, that during swap, the iterator will continue to point to the same array element, and will thus change its value.

Associative Containers

  • All Associative Containers: The insert and emplace members shall not affect the validity of iterators and references to the container [26.2.6/9]

Unordered Associative Containers

  • All Unordered Associative Containers: Rehashing invalidates iterators, changes ordering between elements, and changes which buckets elements appear in, but does not invalidate pointers or references to elements. [26.2.7/9]
    The insert and emplace members shall not affect the validity of references to container elements, but may invalidate all iterators to the container. [26.2.7/14]
    The insert and emplace members shall not affect the validity of iterators if (N+n) <= z * B, where N is the number of elements in the container prior to the insert operation, n is the number of elements inserted, B is the container’s bucket count, and z is the container’s maximum load factor. [26.2.7/15]

  • All Unordered Associative Containers: In case of a merge operation (e.g., a.merge(a2)), iterators referring to the transferred elements and all iterators referring to a will be invalidated, but iterators to elements remaining in a2 will remain valid. (Table 91 — Unordered associative container requirements)

Container Adaptors

  • stack: inherited from underlying container
  • queue: inherited from underlying container
  • priority_queue: inherited from underlying container


Sequence Containers

  • vector: The functions erase and pop_back invalidate iterators and references at or after the point of the erase. []

  • deque: An erase operation that erases the last element of a deque invalidates only the past-the-end iterator and all iterators and references to the erased elements. An erase operation that erases the first element of a deque but not the last element invalidates only iterators and references to the erased elements. An erase operation that erases neither the first element nor the last element of a deque invalidates the past-the-end iterator and all iterators and references to all the elements of the deque. [ Note: pop_front and pop_back are erase operations. —end note ] []

  • list: Invalidates only the iterators and references to the erased elements. []. This applies to erase, pop_front, pop_back, clear functions.
    remove and remove_if member functions: Erases all the elements in the list referred by a list iterator i for which the following conditions hold: *i == value, pred(*i) != false. Invalidates only the iterators and references to the erased elements [].
    unique member function - Erases all but the first element from every consecutive group of equal elements referred to by the iterator i in the range [first + 1, last) for which *i == *(i-1) (for the version of unique with no arguments) or pred(*i, *(i - 1)) (for the version of unique with a predicate argument) holds. Invalidates only the iterators and references to the erased elements. []

  • forward_list: erase_after shall invalidate only iterators and references to the erased elements. [].
    remove and remove_if member functions - Erases all the elements in the list referred by a list iterator i for which the following conditions hold: *i == value (for remove()), pred(*i) is true (for remove_if()). Invalidates only the iterators and references to the erased elements. [].
    unique member function - Erases all but the first element from every consecutive group of equal elements referred to by the iterator i in the range [first + 1, last) for which *i == *(i-1) (for the version with no arguments) or pred(*i, *(i - 1)) (for the version with a predicate argument) holds. Invalidates only the iterators and references to the erased elements. []

  • All Sequence Containers: clear invalidates all references, pointers, and iterators referring to the elements of a and may invalidate the past-the-end iterator (Table 87 — Sequence container requirements). But for forward_list, clear does not invalidate past-the-end iterators. []

  • All Sequence Containers: assign invalidates all references, pointers and iterators referring to the elements of the container. For vector and deque, also invalidates the past-the-end iterator. (Table 87 — Sequence container requirements)

Associative Containers

  • All Associative Containers: The erase members shall invalidate only iterators and references to the erased elements [26.2.6/9]

  • All Associative Containers: The extract members invalidate only iterators to the removed element; pointers and references to the removed element remain valid [26.2.6/10]

Container Adaptors

  • stack: inherited from underlying container
  • queue: inherited from underlying container
  • priority_queue: inherited from underlying container

General container requirements relating to iterator invalidation:

  • Unless otherwise specified (either explicitly or by defining a function in terms of other functions), invoking a container member function or passing a container as an argument to a library function shall not invalidate iterators to, or change the values of, objects within that container. [26.2.1/12]

  • no swap() function invalidates any references, pointers, or iterators referring to the elements of the containers being swapped. [ Note: The end() iterator does not refer to any element, so it may be invalidated. —end note ] [26.2.1/(11.6)]

As examples of the above requirements:

  • transform algorithm: The op and binary_op functions shall not invalidate iterators or subranges, or modify elements in the ranges [28.6.4/1]

  • accumulate algorithm: In the range [first, last], binary_op shall neither modify elements nor invalidate iterators or subranges [29.8.2/1]

  • reduce algorithm: binary_op shall neither invalidate iterators or subranges, nor modify elements in the range [first, last]. [29.8.3/5]

and so on...

Retrieve the commit log for a specific line in a file?

Try using below command implemented in Git 1.8.4.

git log -u -L <upperLimit>,<lowerLimit>:<path_to_filename>

So, in your case upperLimit & lowerLimit is the touched line_number

More info -

Import error: No module name urllib2

Some tab completions to show the contents of the packages in Python 2 vs Python 3.

In Python 2:

In [1]: import urllib

In [2]: urllib.
urllib.ContentTooShortError      urllib.ftpwrapper                urllib.socket                    urllib.test1
urllib.FancyURLopener            urllib.getproxies                urllib.splitattr                 urllib.thishost
urllib.MAXFTPCACHE               urllib.getproxies_environment    urllib.splithost                 urllib.time
urllib.URLopener                 urllib.i                         urllib.splitnport                urllib.toBytes
urllib.addbase                   urllib.localhost                 urllib.splitpasswd               urllib.unquote
urllib.addclosehook              urllib.noheaders                 urllib.splitport                 urllib.unquote_plus
urllib.addinfo                   urllib.os                        urllib.splitquery                urllib.unwrap
urllib.addinfourl                urllib.pathname2url              urllib.splittag                  urllib.url2pathname
urllib.always_safe               urllib.proxy_bypass              urllib.splittype                 urllib.urlcleanup
urllib.base64                    urllib.proxy_bypass_environment  urllib.splituser                 urllib.urlencode
urllib.basejoin                  urllib.quote                     urllib.splitvalue                urllib.urlopen
urllib.c                         urllib.quote_plus                urllib.ssl                       urllib.urlretrieve
urllib.ftpcache                                urllib.string                    
urllib.ftperrors                 urllib.reporthook                urllib.sys  

In Python 3:

In [2]: import urllib.
urllib.error        urllib.parse        urllib.request      urllib.response     urllib.robotparser

In [2]: import urllib.error.
urllib.error.ContentTooShortError  urllib.error.HTTPError             urllib.error.URLError

In [2]: import urllib.parse.
urllib.parse.parse_qs          urllib.parse.quote_plus        urllib.parse.urldefrag         urllib.parse.urlsplit
urllib.parse.parse_qsl         urllib.parse.unquote           urllib.parse.urlencode         urllib.parse.urlunparse
urllib.parse.quote             urllib.parse.unquote_plus      urllib.parse.urljoin           urllib.parse.urlunsplit
urllib.parse.quote_from_bytes  urllib.parse.unquote_to_bytes  urllib.parse.urlparse

In [2]: import urllib.request.
urllib.request.AbstractBasicAuthHandler         urllib.request.HTTPSHandler
urllib.request.AbstractDigestAuthHandler        urllib.request.OpenerDirector
urllib.request.BaseHandler                      urllib.request.ProxyBasicAuthHandler
urllib.request.CacheFTPHandler                  urllib.request.ProxyDigestAuthHandler
urllib.request.DataHandler                      urllib.request.ProxyHandler
urllib.request.FTPHandler                       urllib.request.Request
urllib.request.FancyURLopener                   urllib.request.URLopener
urllib.request.FileHandler                      urllib.request.UnknownHandler
urllib.request.HTTPBasicAuthHandler             urllib.request.build_opener
urllib.request.HTTPCookieProcessor              urllib.request.getproxies
urllib.request.HTTPDefaultErrorHandler          urllib.request.install_opener
urllib.request.HTTPDigestAuthHandler            urllib.request.pathname2url
urllib.request.HTTPErrorProcessor               urllib.request.url2pathname
urllib.request.HTTPHandler                      urllib.request.urlcleanup
urllib.request.HTTPPasswordMgr                  urllib.request.urlopen
urllib.request.HTTPPasswordMgrWithDefaultRealm  urllib.request.urlretrieve

In [2]: import urllib.response.
urllib.response.addbase       urllib.response.addclosehook  urllib.response.addinfo       urllib.response.addinfourl

Regex for password must contain at least eight characters, at least one number and both lower and uppercase letters and special characters


this the simple way to use it while validate atleast 1 uppercase 1 lowercase and 1 number

and this is the example while I use in express validation

    .withMessage('Password cannot be null')
    .isLength({ min: 6 })
    .withMessage('Password must be at least 6 characters')
      'Must have atleast 1 uppercase, 1 lowercase letter and 1 number'

How to read if a checkbox is checked in PHP?

A minimalistic boolean check with switch position retaining


$checked = ($_POST['foo'] == ' checked');


<input type="checkbox" name="foo" value=" checked"<?=$_POST['foo']?>>

split string only on first instance of specified character

I avoid RegExp at all costs. Here is another thing you can do:


Java: Enum parameter in method

You can use an enum in said parameters like this:

public enum Alignment { LEFT, RIGHT }
private static String drawCellValue(
int maxCellLength, String cellValue, Alignment align) {}

then you can use either a switch or if statement to actually do something with said parameter.

switch(align) {
case LEFT: //something
case RIGHT: //something
default: //something

if(align == Alignment.RIGHT) { /*code*/}

Replace image src location using CSS

Here is another dirty hack :)

.application-title > img {
display: none;

.application-title::before {
content: url(path/example.jpg);

What is Scala's yield?

Consider the following for-comprehension

val A = for (i <- Int.MinValue to Int.MaxValue; if i > 3) yield i

It may be helpful to read it out loud as follows

"For each integer i, if it is greater than 3, then yield (produce) i and add it to the list A."

In terms of mathematical set-builder notation, the above for-comprehension is analogous to


which may be read as

"For each integer i, if it is greater than 3, then it is a member of the set A."

or alternatively as

"A is the set of all integers i, such that each i is greater than 3."

Viewing PDF in Windows forms using C#

i think the easiest way is to use the Adobe PDF reader COM Component

  1. right click on your toolbox & select "Choose Items"
  2. Select the "COM Components" tab
  3. Select "Adobe PDF Reader" then click ok
  4. Drag & Drop the control on your form & modify the "src" Property to the PDF files you want to read

i hope this helps

JavaScript: IIF like statement

If your end goal is to add elements to your page, just manipulate the DOM directly. Don't use string concatenation to try to create HTML - what a pain! See how much more straightforward it is to just create your element, instead of the HTML that represents your element:

var x = document.createElement("option");
x.value = col;
x.text = "Very roomy";
x.selected = col == "screwdriver";

Then, later when you put the element in your page, instead of setting the innerHTML of the parent element, call appendChild():


TypeError: expected a character buffer object - while trying to save integer to textfile

Just try the code below:

As I see you have inserted 'r+' or this command open the file in read mode so you are not able to write into it, so you have to open file in write mode 'w' if you want to overwrite the file contents and write new data, otherwise you can append data to file by using 'a'

I hope this will help ;)

f = open('testfile.txt', 'w')# just put 'w' if you want to write to the file 

x = f.readlines() #this command will read file lines

y = int(x)+1

print y
z = str(y) #making data as string to avoid buffer error


How can I set a css border on one side only?

    /* set green border independently on each side */
    border-left: solid green 2px;
    border-right: solid green 2px;
    border-bottom: solid green 2px;
    border-top: solid green 2px;

How to create file execute mode permissions in Git on Windows?

Indeed, it would be nice if git-add had a --mode flag

git 2.9.x/2.10 (Q3 2016) actually will allow that (thanks to Edward Thomson):

git add --chmod=+x -- afile
git commit -m"Executable!"

That makes the all process quicker, and works even if core.filemode is set to false.

See commit 4e55ed3 (31 May 2016) by Edward Thomson (ethomson).
Helped-by: Johannes Schindelin (dscho).
(Merged by Junio C Hamano -- gitster -- in commit c8b080a, 06 Jul 2016)

add: add --chmod=+x / --chmod=-x options

The executable bit will not be detected (and therefore will not be set) for paths in a repository with core.filemode set to false, though the users may still wish to add files as executable for compatibility with other users who do have core.filemode functionality.
For example, Windows users adding shell scripts may wish to add them as executable for compatibility with users on non-Windows.

Although this can be done with a plumbing command (git update-index --add --chmod=+x foo), teaching the git-add command allows users to set a file executable with a command that they're already familiar with.

Check if user is using IE

I think it will help you Here

function checkIsIE() {
    var isIE = false;
    if (navigator.userAgent.indexOf('MSIE') !== -1 || navigator.appVersion.indexOf('Trident/') > 0) {
        isIE = true;
    if (isIE)  // If Internet Explorer, return version number
        kendo.ui.Window.fn._keydown = function (originalFn) {
            var KEY_ESC = 27;
            return function (e) {
                if (e.which !== KEY_ESC) {
          , e);

        var windowBrowser = $("#windowBrowser").kendoWindow({
            modal: true,
            id: 'dialogBrowser',
            visible: false,
            width: "40%",
            title: "Thông báo",
            scrollable: false,
            resizable: false,
            deactivate: false,
            position: {
                top: 100,
                left: '30%'
        var html = '<br /><div style="width:100%;text-align:center"><p style="color:red;font-weight:bold">Please use the browser below to use the tool</p>';
        html += '<img src="/Scripts/IPTVClearFeePackage_Box/Images/firefox.png"/>';
        html += ' <img src="/Scripts/IPTVClearFeePackage_Box/Images/chrome.png" />';
        html += ' <img src="/Scripts/IPTVClearFeePackage_Box/Images/opera.png" />';
        html += '<hr /><form><input type="button" class="btn btn-danger" value="Ðóng trình duy?t" onclick="window.close()"></form><div>';

    else  // If another browser, return 0
        return false;

java.lang.ClassNotFoundException: org.eclipse.core.runtime.adaptor.EclipseStarter

In your config.ini file of eclipse eclipse\configuration\config.ini check this three things:


And check whether these jars are in place or not, the jar files depend upon your version of eclipse .

How to set a parameter in a HttpServletRequest?

Sorry, but why not use the following construction:

request.getParameterMap().put(parameterName, new String[] {parameterValue});

an htop-like tool to display disk activity in linux

Use collectl which has extensive process I/O monitoring including monitoring threads.

Be warned that there are I/O counters for I/O being written to cache and I/O going to disk. collectl reports them separately. If you're not careful you can misinterpret the data. See

Of course, it shows a lot more than just process stats because you'd want one tool to provide everything rather than a bunch of different one that displays everything in different formats, right?

org.hibernate.MappingException: Could not determine type for: java.util.List, at table: College, for columns: [org.hibernate.mapping.Column(students)]

Don't worry! This problem occurs because of the annotation. Instead of Field based access, Property based access solves this problem. The code as follows:

package onetomanymapping;

import java.util.List;

import javax.persistence.*;

public class College {
private int collegeId;
private String collegeName;
private List<Student> students;

@OneToMany(targetEntity = Student.class, mappedBy = "college", 
    cascade = CascadeType.ALL, fetch = FetchType.EAGER)
public List<Student> getStudents() {
    return students;

public void setStudents(List<Student> students) {
    this.students = students;

public int getCollegeId() {
    return collegeId;

public void setCollegeId(int collegeId) {
    this.collegeId = collegeId;

public String getCollegeName() {
    return collegeName;

public void setCollegeName(String collegeName) {
    this.collegeName = collegeName;


CSS background-size: cover replacement for Mobile Safari

I found a working solution, the following CSS code example is targeting the iPad:

@media only screen and (min-device-width : 768px) and (max-device-width : 1024px) {

    html {  
        height: 100%;
        overflow: hidden;
        background: url('') no-repeat top center fixed;
        background-size: cover; 

    body {  
        overflow: scroll;
        -webkit-overflow-scrolling: touch;


Reference link:

Combining "LIKE" and "IN" for SQL Server

Effectively, the IN statement creates a series of OR statements... so

SELECT * FROM table WHERE column IN (1, 2, 3)

Is effectively

SELECT * FROM table WHERE column = 1 OR column = 2 OR column = 3

And sadly, that is the route you'll have to take with your LIKE statements

WHERE column LIKE 'Text%' OR column LIKE 'Hello%' OR column LIKE 'That%'

Create a new cmd.exe window from within another cmd.exe prompt

start cmd.exe 

opens a separate window

start file.cmd 

opens the batch file and executes it in another command prompt

Invalid use side-effecting operator Insert within a function

Functions cannot be used to modify base table information, use a stored procedure.

Remove the title bar in Windows Forms

if by Blue Border thats on top of the Window Form you mean titlebar, set Forms ControlBox property to false and Text property to empty string ("").

here's a snippet:

this.ControlBox = false;
this.Text = String.Empty;

Are parameters in strings.xml possible?

There is many ways to use it and i recomend you to see this documentation about String Format.

But, if you need only one variable, you'll need to use %[type] where [type] could be any Flag (see Flag types inside site above). (i.e. "My name is %s" or to set my name UPPERCASE, use this "My name is %S")

<string name="welcome_messages">Hello, %1$S! You have %2$d new message(s) and your quote is %3$.2f%%.</string>

Hello, ANDROID! You have 1 new message(s) and your quote is 80,50%.

How to stop line breaking in vim

You may find set lbr useful; with set wrap on this will wrap but only cutting the line on whitespace and not in the middle of a word.


without lbr the li
ne can be split on
a word


with lbr on the
line will be
split on 
whitespace only

How do I get SUM function in MySQL to return '0' if no values are found?

Use COALESCE to avoid that outcome.

FROM   table
WHERE  ...

To see it in action, please see this sql fiddle:!2/d1542/3/0

More Information:

Given three tables (one with all numbers, one with all nulls, and one with a mixture):

SQL Fiddle

MySQL 5.5.32 Schema Setup:

  val   INT


  val   INT


  val   INT


Query 1:

SELECT  'foo'                   as table_name,
        'mixed null/non-null'   as description,
        21                      as expected_sum,
        COALESCE(SUM(val), 0)   as actual_sum
FROM    foo

SELECT  'bar'                   as table_name,
        'all non-null'          as description,
        21                      as expected_sum,
        COALESCE(SUM(val), 0)   as actual_sum
FROM    bar

SELECT  'baz'                   as table_name,
        'all null'              as description,
        0                       as expected_sum,
        COALESCE(SUM(val), 0)   as actual_sum
FROM    baz


|        foo | mixed null/non-null |           21 |         21 |
|        bar |        all non-null |           21 |         21 |
|        baz |            all null |            0 |          0 |

Using pg_dump to only get insert statements from one table within database

If you want to DUMP your inserts into an .sql file:

  1. cd to the location which you want to .sql file to be located
  2. pg_dump --column-inserts --data-only --table=<table> <database> > my_dump.sql

Note the > my_dump.sql command. This will put everything into a sql file named my_dump

HashMap to return default value for non-found keys?

I needed to read the results returned from a server in JSON where I couldn't guarantee the fields would be present. I'm using class org.json.simple.JSONObject which is derived from HashMap. Here are some helper functions I employed:

public static String getString( final JSONObject response, 
                                final String key ) 
{ return getString( response, key, "" ); }  
public static String getString( final JSONObject response, 
                                final String key, final String defVal ) 
{ return response.containsKey( key ) ? (String)response.get( key ) : defVal; }

public static long getLong( final JSONObject response, 
                            final String key ) 
{ return getLong( response, key, 0 ); } 
public static long getLong( final JSONObject response, 
                            final String key, final long defVal ) 
{ return response.containsKey( key ) ? (long)response.get( key ) : defVal; }

public static float getFloat( final JSONObject response, 
                              final String key ) 
{ return getFloat( response, key, 0.0f ); } 
public static float getFloat( final JSONObject response, 
                              final String key, final float defVal ) 
{ return response.containsKey( key ) ? (float)response.get( key ) : defVal; }

public static List<JSONObject> getList( final JSONObject response, 
                                        final String key ) 
{ return getList( response, key, new ArrayList<JSONObject>() ); }   
public static List<JSONObject> getList( final JSONObject response, 
                                        final String key, final List<JSONObject> defVal ) { 
    try { return response.containsKey( key ) ? (List<JSONObject>) response.get( key ) : defVal; }
    catch( ClassCastException e ) { return defVal; }

using mailto to send email with an attachment

If you are using c# on the desktop, you can use SimpleMapi. That way it will be sent using the default mail client, and the user has the option of reviewing the message before sending, just like mailto:.

To use it you add the Simple-MAPI.NET package (it's 13Kb), and run:

var mapi = new SimpleMapi();
mapi.AddRecipient(null, address, false);
//mapi.Logon(ParentForm.Handle);    //not really necessary
mapi.Send(subject, body, true);

Launch Android application without main Activity and start Service on launching application

Android Studio Version 2.3

You can create a Service without a Main Activity by following a few easy steps. You'll be able to install this app through Android Studio and debug it like a normal app.

First, create a project in Android Studio without an activity. Then create your Service class and add the service to your AndroidManifest.xml

<application android:allowBackup="true"
    <service android:name="com.whatever.myservice.MyService">
            <action android:name="com.whatever.myservice.MyService" />

Now, in the drop down next to the "Run" button(green arrow), go to "edit configurations" and within the "Launch Options" choose "Nothing". This will allow you to install your Service without Android Studio complaining about not having a Main Activity.

Once installed, the service will NOT be running but you will be able to start it with this adb shell command...

am startservice -n com.whatever.myservice/.MyService

Can check it's running with...

ps | grep whatever

I haven't tried yet but you can likely have Android Studio automatically start the service too. This would be done in that "Edit Configurations" menu.

Redirect all to index.php using htaccess

You can use something like this:

RewriteEngine on
RewriteRule ^.+$ /index.php [L]

This will redirect every query to the root directory's index.php. Note that it will also redirect queries for files that exist, such as images, javascript files or style sheets.

How can I debug a HTTP POST in Chrome?

You can use Canary version of Chrome to see request payload of POST requests.

Request payload

onMeasure custom view explanation

onMeasure() is your opportunity to tell Android how big you want your custom view to be dependent the layout constraints provided by the parent; it is also your custom view's opportunity to learn what those layout constraints are (in case you want to behave differently in a match_parent situation than a wrap_content situation). These constraints are packaged up into the MeasureSpec values that are passed into the method. Here is a rough correlation of the mode values:

  • EXACTLY means the layout_width or layout_height value was set to a specific value. You should probably make your view this size. This can also get triggered when match_parent is used, to set the size exactly to the parent view (this is layout dependent in the framework).
  • AT_MOST typically means the layout_width or layout_height value was set to match_parent or wrap_content where a maximum size is needed (this is layout dependent in the framework), and the size of the parent dimension is the value. You should not be any larger than this size.
  • UNSPECIFIED typically means the layout_width or layout_height value was set to wrap_content with no restrictions. You can be whatever size you would like. Some layouts also use this callback to figure out your desired size before determine what specs to actually pass you again in a second measure request.

The contract that exists with onMeasure() is that setMeasuredDimension() MUST be called at the end with the size you would like the view to be. This method is called by all the framework implementations, including the default implementation found in View, which is why it is safe to call super instead if that fits your use case.

Granted, because the framework does apply a default implementation, it may not be necessary for you to override this method, but you may see clipping in cases where the view space is smaller than your content if you do not, and if you lay out your custom view with wrap_content in both directions, your view may not show up at all because the framework doesn't know how large it is!

Generally, if you are overriding View and not another existing widget, it is probably a good idea to provide an implementation, even if it is as simple as something like this:

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

    int desiredWidth = 100;
    int desiredHeight = 100;

    int widthMode = MeasureSpec.getMode(widthMeasureSpec);
    int widthSize = MeasureSpec.getSize(widthMeasureSpec);
    int heightMode = MeasureSpec.getMode(heightMeasureSpec);
    int heightSize = MeasureSpec.getSize(heightMeasureSpec);

    int width;
    int height;

    //Measure Width
    if (widthMode == MeasureSpec.EXACTLY) {
        //Must be this size
        width = widthSize;
    } else if (widthMode == MeasureSpec.AT_MOST) {
        //Can't be bigger than...
        width = Math.min(desiredWidth, widthSize);
    } else {
        //Be whatever you want
        width = desiredWidth;

    //Measure Height
    if (heightMode == MeasureSpec.EXACTLY) {
        //Must be this size
        height = heightSize;
    } else if (heightMode == MeasureSpec.AT_MOST) {
        //Can't be bigger than...
        height = Math.min(desiredHeight, heightSize);
    } else {
        //Be whatever you want
        height = desiredHeight;

    setMeasuredDimension(width, height);

Hope that Helps.

Selecting multiple columns in a Pandas dataframe

One different and easy approach: iterating rows

Using iterows

 df1 = pd.DataFrame() # Creating an empty dataframe
 for index,i in df.iterrows():
    df1.loc[index, 'A'] = df.loc[index, 'A']
    df1.loc[index, 'B'] = df.loc[index, 'B']

How does ApplicationContextAware work in Spring?

Interface to be implemented by any object that wishes to be notified of the ApplicationContext that it runs in.

above is excerpted from the Spring doc website

So, it seemed to be invoked when Spring container has started, if you want to do something at that time.

It just has one method to set the context, so you will get the context and do something to sth now already in context I think.

Can overridden methods differ in return type?

Yes. It is possible for overridden methods to have different return type .

But the limitations are that the overridden method must have a return type that is more specific type of the return type of the actual method.

All the answers have given examples of the overridden method to have a return type which is a subclass of the return type of the actual method.

For example :

public class Foo{

   //method which returns Foo
  Foo getFoo(){
      //your code         


 public class subFoo extends Foo{

  //Overridden method which returns subclass of Foo
  subFoo getFoo(){
      //your code         


But this is not only limited to subclass.Even classes that implement an interface are a specific type of the interface and thus can be a return type where the interface is expected.

For example :

public interface Foo{

   //method which returns Foo
  Foo getFoo();


 public class Fizz implements Foo{

  //Overridden method which returns Fizz(as it implements Foo)
  Fizz getFoo(){
      //your code         


Insert line break inside placeholder attribute of a textarea?

I modified @Richard Bronosky's fiddle like this.

It's better approach to use data-* attribute rather than a custom attribute. I replaced <textarea placeholdernl> to <textarea data-placeholder> and some other styles as well.

Here is the Richard's original answer which contains full code snippet.

Maintain/Save/Restore scroll position when returning to a ListView

CAUTION!! There is a bug in AbsListView that doesn't allow the onSaveState() to work correctly if the ListView.getFirstVisiblePosition() is 0.

So If you have large images that take up most of the screen, and you scroll to the second image, but a little of the first is showing, the scroll position Won't be saved...

from (comments mine)

// this will be false when the firstPosition IS 0
if (haveChildren && mFirstPosition > 0) {
} else {
    ss.viewTop = 0;
    ss.firstId = INVALID_POSITION;
    ss.position = 0;

But in this situation, the 'top' in the code below will be a negative number which causes other issues that prevent the state to be restored correctly. So when the 'top' is negative, get the next child

// save index and top position
int index = getFirstVisiblePosition();
View v = getChildAt(0);
int top = (v == null) ? 0 : v.getTop();

if (top < 0 && getChildAt(1) != null) {
    v = getChildAt(1);
    top = v.getTop();
// parcel the index and top

// when restoring, unparcel index and top
listView.setSelectionFromTop(index, top);

NULL values inside NOT IN clause

The title of this question at the time of writing is

SQL NOT IN constraint and NULL values

From the text of the question it appears that the problem was occurring in a SQL DML SELECT query, rather than a SQL DDL CONSTRAINT.

However, especially given the wording of the title, I want to point out that some statements made here are potentially misleading statements, those along the lines of (paraphrasing)

When the predicate evaluates to UNKNOWN you don't get any rows.

Although this is the case for SQL DML, when considering constraints the effect is different.

Consider this very simple table with two constraints taken directly from the predicates in the question (and addressed in an excellent answer by @Brannon):

 true CHAR(4) DEFAULT 'true' NOT NULL, 
 CHECK ( 3 IN (1, 2, 3, NULL )), 
 CHECK ( 3 NOT IN (1, 2, NULL ))



As per @Brannon's answer, the first constraint (using IN) evaluates to TRUE and the second constraint (using NOT IN) evaluates to UNKNOWN. However, the insert succeeds! Therefore, in this case it is not strictly correct to say, "you don't get any rows" because we have indeed got a row inserted as a result.

The above effect is indeed the correct one as regards the SQL-92 Standard. Compare and contrast the following section from the SQL-92 spec

7.6 where clause

The result of the is a table of those rows of T for which the result of the search condition is true.

4.10 Integrity constraints

A table check constraint is satisfied if and only if the specified search condition is not false for any row of a table.

In other words:

In SQL DML, rows are removed from the result when the WHERE evaluates to UNKNOWN because it does not satisfy the condition "is true".

In SQL DDL (i.e. constraints), rows are not removed from the result when they evaluate to UNKNOWN because it does satisfy the condition "is not false".

Although the effects in SQL DML and SQL DDL respectively may seem contradictory, there is practical reason for giving UNKNOWN results the 'benefit of the doubt' by allowing them to satisfy a constraint (more correctly, allowing them to not fail to satisfy a constraint): without this behaviour, every constraints would have to explicitly handle nulls and that would be very unsatisfactory from a language design perspective (not to mention, a right pain for coders!)

p.s. if you are finding it as challenging to follow such logic as "unknown does not fail to satisfy a constraint" as I am to write it, then consider you can dispense with all this simply by avoiding nullable columns in SQL DDL and anything in SQL DML that produces nulls (e.g. outer joins)!

How to get the 'height' of the screen using jquery

use with responsive website (view in mobile or ipad)

jQuery(window).height();   // return height of browser viewport
jQuery(window).width();    // return width of browser viewport

rarely use

jQuery(document).height(); // return height of HTML document
jQuery(document).width();  // return width of HTML document

SQL Delete Records within a specific Range

you can also just change your delete to a select *

and test your selection

the records selected will be the same as the ones deleted

you can also wrap your statement in a begin / rollback if you are not sure - test the statement then if all is good remove rollback

for example


will show all the records matching the where if they are the wants you 'really' want to delete then use


You can also create a trigger / which catches deletes and puts them into a history table

so if you delete something by mistake you can always get it back

(keep your history table records no older than say 6 months or whatever business rules say)

How can I use PHP to dynamically publish an ical file to be read by Google Calendar?

  1. Exact ical format:
  2. According to the spec, it has to end in .ics

Edit: actually I'm not sure - line 6186 gives an example in .ics naming format, but it also states you can use url parameters. I don't think it matters, so long as the MIME type is correct.

Edit: Example from wikipedia:

PRODID:-//hacksw/handcal//NONSGML v1.0//EN
SUMMARY:Bastille Day Party

MIME type is configured on the server.

Flatten List in LINQ

With query syntax:

var values =
from inner in outer
from value in inner
select value;

Extracting date from a string in Python

If you know the position of the date object in the string (for example in a log file), you can use .split()[index] to extract the date without fully knowing the format.

For example:

>>> string = 'monkey 2010-07-10 love banana'
>>> date = string.split()[1]
>>> date

How to convert a string to utf-8 in Python

  • First, str in Python is represented in Unicode.
  • Second, UTF-8 is an encoding standard to encode Unicode string to bytes. There are many encoding standards out there (e.g. UTF-16, ASCII, SHIFT-JIS, etc.).

When the client sends data to your server and they are using UTF-8, they are sending a bunch of bytes not str.

You received a str because the "library" or "framework" that you are using, has implicitly converted some random bytes to str.

Under the hood, there is just a bunch of bytes. You just need ask the "library" to give you the request content in bytes and you will handle the decoding yourself (if library can't give you then it is trying to do black magic then you shouldn't use it).

  • Decode UTF-8 encoded bytes to str: bs.decode('utf-8')
  • Encode str to UTF-8 bytes: s.encode('utf-8')

Have Excel formulas that return 0, make the result blank

=if(b2 = "", "", b2)

This worked for me

How to run html file on localhost?

You can try installing one of the following localhost softwares:

  1. xampp
  2. wamp
  3. ammps server
  4. laragon

There are many more such softwares but the best among them are the ones mentioned above. they also allow domain names (for example:

How to resolve 'npm should be run outside of the node repl, in your normal shell'

enter image description here

Just open Node.js commmand promt as run as administrator

Why does the Visual Studio editor show dots in blank spaces?

In visual studio 2015, goto->view->formatting marks, unselect show

Stretch child div height to fill parent that has dynamic height

The solution is to use display: table-cell to bring those elements inline instead of using display: inline-block or float: left.

div#container {_x000D_
  padding: 20px;_x000D_
  background: #F1F1F1_x000D_
.content {_x000D_
  width: 150px;_x000D_
  background: #ddd;_x000D_
  padding: 10px;_x000D_
  display: table-cell;_x000D_
  vertical-align: top;_x000D_
.text {_x000D_
  font-family: 12px Tahoma, Geneva, sans-serif;_x000D_
  color: #555;_x000D_
<div id="container">_x000D_
  <div class="content">_x000D_
    <h1>Title 1</h1>_x000D_
    <div class="text">Sample Text. Sample Text. Sample Text. Sample Text. Sample Text. Sample Text. Sample Text. Sample Text. Sample Text._x000D_
      <br>Sample Text. Sample Text. Sample Text._x000D_
      <br>Sample Text._x000D_
  <div class="content">_x000D_
    <h1>Title 2</h1>_x000D_
    <div class="text">Sample Text. Sample Text. Sample Text. Sample Text. Sample Text. Sample Text. Sample Text. Sample Text. Sample Text.</div>_x000D_

Working Fiddle

Regex to validate date format dd/mm/yyyy

Here is another version of regex to match any of the following date formats and allow leading zeros to be omitted:

Regex: ^[0-3]?[0-9].[0-3]?[0-9].(?:[0-9]{2})?[0-9]{2}$


1/1/11 or 1.1.11 or 1-1-11 : true 01/01/11 or 01.01.11 or 01-01-11 : true 01/01/2011 or 01.01.2011 or 01-01-2011 : true 01/1/2011 or 01.1.2011 or 01-1-2011 : true 1/11/2011 or 1.11.2011 or 1-11-2011 : true 1/11/11 or 1.11.11 or 1-11-11 : true 11/1/11 or 11.1.11 or 11-1-11 : true

Regular expression visualization

Debuggex Demo

ReCaptcha API v2 Styling

In case someone struggling with the recaptcha of contact form 7 (wordpress) here is a solution working for me

clear: both;
float: left;
margin-right: 6px;
width: 206px;
height: 65px;
overflow: hidden;
border-right: 1px solid #D3D3D3;
.wpcf7-recaptcha iframe{
padding-bottom: 15px;
border-bottom: 1px solid #D3D3D3;
background: #F9F9F9;
border-left: 1px solid #d3d3d3;

enter image description here

How to get the last row of an Oracle a table

There is no such thing as the "last" row in a table, as an Oracle table has no concept of order.

However, assuming that you wanted to find the last inserted primary key and that this primary key is an incrementing number, you could do something like this:

select *
  from ( select a.*, max(pk) over () as max_pk
           from my_table a
 where pk = max_pk

If you have the date that each row was created this would become, if the column is named created:

select *
  from ( select a.*, max(created) over () as max_created
           from my_table a
 where created = max_created

Alternatively, you can use an aggregate query, for example:

select *
  from my_table
 where pk = ( select max(pk) from my_table )

Here's a little SQL Fiddle to demonstrate.

PDO support for multiple queries (PDO_MYSQL, PDO_MYSQLND)

After half a day of fiddling with this, found out that PDO had a bug where...


//This would run as expected:
$pdo->exec("valid-stmt1; valid-stmt2;");


//This would error out, as expected:
$pdo->exec("non-sense; valid-stmt1;");


//Here is the bug:
$pdo->exec("valid-stmt1; non-sense; valid-stmt3;");

It would execute the "valid-stmt1;", stop on "non-sense;" and never throw an error. Will not run the "valid-stmt3;", return true and lie that everything ran good.

I would expect it to error out on the "non-sense;" but it doesn't.

Here is where I found this info: Invalid PDO query does not return an error

Here is the bug:

So, I tried doing this with mysqli and haven't really found any solid answer on how it works so I thought I's just leave it here for those who want to use it..

    // db connection
    $mysqli = new mysqli("host", "user" , "password", "database");
        throw new Exception("Connection Failed: [".$mysqli->connect_errno. "] : ".$mysqli->connect_error );

    // read file.
    // This file has multiple sql statements.
    $file_sql = file_get_contents("filename.sql");

    if($file_sql == "null" || empty($file_sql) || strlen($file_sql) <= 0){
        throw new Exception("File is empty. I wont run it..");

    //run the sql file contents through the mysqli's multi_query function.
    // here is where it gets complicated...
    // if the first query has errors, here is where you get it.
    $sqlFileResult = $mysqli->multi_query($file_sql);
    // this returns false only if there are errros on first sql statement, it doesn't care about the rest of the sql statements.

    $sqlCount = 1;
    if( $sqlFileResult == false ){
        throw new Exception("File: '".$fullpath."' , Query#[".$sqlCount."], [".$mysqli->errno."]: '".$mysqli->error."' }");

    // so handle the errors on the subsequent statements like this.
    // while I have more results. This will start from the second sql statement. The first statement errors are thrown above on the $mysqli->multi_query("SQL"); line
        // load the next result set into mysqli's active buffer. if this fails the $mysqli->error, $mysqli->errno will have appropriate error info.
        if($mysqli->next_result() == false){
            throw new Exception("File: '".$fullpath."' , Query#[".$sqlCount."], Error No: [".$mysqli->errno."]: '".$mysqli->error."' }");
catch(Exception $e){
    echo $e->getMessage(). " <pre>".$e->getTraceAsString()."</pre>";

How to get current local date and time in Kotlin

Another solution is changing the api level of your project in build.gradle and this will work.

MatPlotLib: Multiple datasets on the same scatter plot

You can also do this easily in Pandas, if your data is represented in a Dataframe, as described here:

Angular @ViewChild() error: Expected 2 arguments, but got 1

In Angular 8, ViewChild always takes 2 param, and second params always has static: true or static: false

You can try like this:

@ViewChild('nameInput', {static: false}) component

Also,the static: false is going to be the default fallback behaviour in Angular 9.

What are static false/true: So as a rule of thumb you can go for the following:

  • { static: true } needs to be set when you want to access the ViewChild in ngOnInit.

    { static: false } can only be accessed in ngAfterViewInit. This is also what you want to go for when you have a structural directive (i.e. *ngIf) on your element in your template.

Laravel Advanced Wheres how to pass variable into function?

@kajetons' answer is fully functional.

You can also pass multiple variables by passing them like: use($var1, $var2)

DB::table('users')->where(function ($query) use ($activated,$var2) {
    $query->where('activated', '=', $activated);
    $query->where('var2', '>', $var2);

Bring a window to the front in WPF

I built an extension method to make for easy reuse.

using System.Windows.Forms;
    namespace YourNamespace{
        public static class WindowsFormExtensions {
            public static void PutOnTop(this Form form) {
            }// END PutOnTop()       
        }// END class
    }// END namespace

Call in the Form Constructor

namespace YourNamespace{
       public partial class FormName : Form {
       public FormName(){
        }// END Constructor
    } // END Form            
}// END namespace

Java JSON serialization - best practice

Have your tried json-io (

This library allows you to serialize / deserialize any Java object graph, including object graphs with cycles in them (e.g., A->B, B->A). It does not require your classes to implement any particular interface or inherit from any particular Java class.

In addition to serialization of Java to JSON (and JSON to Java), you can use it to format (pretty print) JSON:

String niceFormattedJson = JsonWriter.formatJson(jsonString)

Using "Object.create" instead of "new"

Another possible usage of Object.create is to clone immutable objects in a cheap and effective way.

var anObj = {
    a: "test",
    b: "jest"

var bObj = Object.create(anObj);

bObj.b = "gone"; // replace an existing (by masking prototype)
bObj.c = "brand"; // add a new to demonstrate it is actually a new obj

// now bObj is {a: test, b: gone, c: brand}

Notes: The above snippet creates a clone of an source object (aka not a reference, as in cObj = aObj). It benefits over the copy-properties method (see 1), in that it does not copy object member properties. Rather it creates another -destination- object with it's prototype set on the source object. Moreover when properties are modified on the dest object, they are created "on the fly", masking the prototype's (src's) properties.This constitutes a fast an effective way of cloning immutable objects.

The caveat here is that this applies to source objects that should not be modified after creation (immutable). If the source object is modified after creation, all the clone's unmasked properties will be modified, too.

Fiddle here( (needs Object.create capable browser).

Return value from exec(@sql)

that's my procedure

CREATE PROC sp_count
    @CompanyId sysname,
    @codition sysname
    ( NumRows int )

    DECLARE @intCount int
         , @vcSQL varchar(255)

    SELECT    @vcSQL = ' INSERT #ctr FROM dbo.Comm_Services 
                       WHERE CompanyId = '+@CompanyId+' and '+@condition+')'
    EXEC      (@vcSQL)

    IF @@ERROR = 0
         SELECT    @intCount = NumRows
         FROM #ctr

         DROP TABLE #ctr
         RETURN @intCount
         DROP TABLE #ctr
         RETURN -1

Error when deploying an artifact in Nexus

I had the same problem today with the addition "Return code is: 400, ReasonPhrase: Bad Request." which turned out to be the "artifact is already deployed with that version if it is a release" problem from answer above enter link description here

One solution not mentioned yet is to configure Nexus to allow redeployment into a Release repository. Maybe not a best practice, because this is set for a reason, you nevertheless could go to "Access Settings" in your Nexus repositories´ "Configuration"-Tab and set the "Deployment Policy" to "Allow Redeploy".

phpMyAdmin ERROR: mysqli_real_connect(): (HY000/1045): Access denied for user 'pma'@'localhost' (using password: NO)

Add this line to the file xampp\phpMyAdmin\

$cfg['Servers'][$i]['port'] = '3307';

Here, my port is 3307, you can change it to yours.

How to get the Power of some Integer in Swift language?

The other answers are great but if preferred, you can also do it with an Int extension so long as the exponent is positive.

extension Int {   
    func pow(toPower: Int) -> Int {
        guard toPower > 0 else { return 0 }
        return Array(repeating: self, count: toPower).reduce(1, *)

2.pow(toPower: 8) // returns 256

Kotlin Error : Could not find org.jetbrains.kotlin:kotlin-stdlib-jre7:1.0.7

After fixing the build.gradle version, It started working 4.0.0 to 3.5.0

Resize height with Highcharts

According to the API Reference:

By default the height is calculated from the offset height of the containing element. Defaults to null.

So, you can control it's height according to the parent div using redraw event, which is called when it changes it's size.


Adding image inside table cell in HTML

You have a TH floating at the top of your table which isn't within a TR. Fix that.

With regards to your image problem you;re referencing the image absolutely from your computer's hard drive. Don't do that.

You also have a closing tag which shouldn't be there.

It should be:

<img src="h.gif" alt="" border="3" height="100" width="100" />

Also this:

<table border = 5 bordercolor = red align = center>

Your colspans are also messed up. You only seem to have three columns but have colspans of 14 and 4 in your code.

Should be:

<table border="5" bordercolor="red" align="center">

Also you have no DOCTYPE declared. You should at least add:

<!DOCTYPE html> 

Check empty string in Swift?

isEmpty will do as you think it will, if string == "", it'll return true. Some of the other answers point to a situation where you have an optional string.

PLEASE use Optional Chaining!!!!

If the string is not nil, isEmpty will be used, otherwise it will not.

Below, the optionalString will NOT be set because the string is nil

let optionalString: String? = nil
if optionalString?.isEmpty == true {
     optionalString = "Lorem ipsum dolor sit amet"

Obviously you wouldn't use the above code. The gains come from JSON parsing or other such situations where you either have a value or not. This guarantees code will be run if there is a value.

Jquery Setting Value of Input Field

Put your jQuery function in



It's surely solved.

Sending Multipart File as POST parameters with RestTemplate requests

I recently struggled with this issue for 3 days. How the client is sending the request might not be the cause, the server might not be configured to handle multipart requests. This is what I had to do to get it working:

pom.xml - Added commons-fileupload dependency (download and add the jar to your project if you are not using dependency management such as maven)


web.xml - Add multipart filter and mapping


app-context.xml - Add multipart resolver

<beans:bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <beans:property name="maxUploadSize">

Your Controller

@RequestMapping(value=Constants.REQUEST_MAPPING_ADD_IMAGE, method = RequestMethod.POST, produces = { "application/json"})
public @ResponseBody boolean saveStationImage(
        @RequestParam(value = Constants.MONGO_STATION_PROFILE_IMAGE_FILE) MultipartFile file,
        @RequestParam(value = Constants.MONGO_STATION_PROFILE_IMAGE_URI) String imageUri, 
        @RequestParam(value = Constants.MONGO_STATION_PROFILE_IMAGE_TYPE) String imageType, 
        @RequestParam(value = Constants.MONGO_FIELD_STATION_ID) String stationId) {
    // Do something with file
    // Return results

Your client

public static Boolean updateStationImage(StationImage stationImage) {
    if(stationImage == null) {
        Log.w(TAG + ":updateStationImage", "Station Image object is null, returning.");
        return null;

    Log.d(TAG, "Uploading: " + stationImage.getImageUri());
    try {
        RestTemplate restTemplate = new RestTemplate();
        FormHttpMessageConverter formConverter = new FormHttpMessageConverter();
        restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());

        restTemplate.setRequestFactory(new HttpComponentsClientHttpRequestFactory());

        HttpHeaders httpHeaders = new HttpHeaders();

        MultiValueMap<String, Object> parts = new LinkedMultiValueMap<String, Object>();

        parts.add(Constants.STATION_PROFILE_IMAGE_FILE, new FileSystemResource(stationImage.getImageFile()));
        parts.add(Constants.STATION_PROFILE_IMAGE_URI, stationImage.getImageUri());
        parts.add(Constants.STATION_PROFILE_IMAGE_TYPE, stationImage.getImageType());
        parts.add(Constants.FIELD_STATION_ID, stationImage.getStationId());

        return restTemplate.postForObject(Constants.REST_CLIENT_URL_ADD_IMAGE, parts, Boolean.class);
    } catch (Exception e) {
        StringWriter sw = new StringWriter();
        e.printStackTrace(new PrintWriter(sw));

        Log.e(TAG + ":addStationImage", sw.toString());

    return false;

That should do the trick. I added as much information as possible because I spent days, piecing together bits and pieces of the full issue, I hope this will help.

Node.js Hostname/IP doesn't match certificate's altnames

I had the same issue using the request module to proxy POST request from somewhere else and it was because I left the host property in the header (I was copying the header from the original request).

Keyword not supported: "data source" initializing Entity Framework Context

I fixed this by changing EntityClient back to SqlClient, even though I was using Entity Framework.

So my complete connection string was in the format:

<add name="DefaultConnection" connectionString="Data Source=localhost;Initial Catalog=xxx;Persist Security Info=True;User ID=xxx;Password=xxx" providerName="System.Data.SqlClient" />

Directory-tree listing in Python

#import modules
import os


def rec_tree_traverse(curr_dir, indent):
    "recurcive function to traverse the directory"
    #print "[traverse_tree]"

    try :
        dfList = [os.path.join(curr_dir, f_or_d) for f_or_d in os.listdir(curr_dir)]
        print "wrong path name/directory name"

    for file_or_dir in dfList:

        if os.path.isdir(file_or_dir):
            #print "dir  : ",
            print indent, file_or_dir,"\\"
            rec_tree_traverse(file_or_dir, indent*2)

        if os.path.isfile(file_or_dir):
            #print "file : ",
            print indent, file_or_dir

    #end if for loop
#end of traverse_tree()

def main():

    base_dir = _CURRENT_DIR

    rec_tree_traverse(base_dir," ")

    raw_input("enter any key to exit....")
#end of main()

if __name__ == '__main__':

Interesting 'takes exactly 1 argument (2 given)' Python error

Am I getting it because the act of calling it via e.extractAll("th") also passes in self as an argument?

Yes, that's precisely it. If you like, the first parameter is the object name, e that you are calling it with.

And if so, by removing the self in the call, would I be making it some kind of class method that can be called like Extractor.extractAll("th")?

Not quite. A classmethod needs the @classmethod decorator, and that accepts the class as the first paramater (usually referenced as cls). The only sort of method that is given no automatic parameter at all is known as a staticmethod, and that again needs a decorator (unsurprisingly, it's @staticmethod). A classmethod is used when it's an operation that needs to refer to the class itself: perhaps instantiating objects of the class; a staticmethod is used when the code belongs in the class logically, but requires no access to class or instance.

But yes, both staticmethods and classmethods can be called by referencing the classname as you describe: Extractor.extractAll("th").

Changing the current working directory in Java?

The other possible answer to this question may depend on the reason you are opening the file. Is this a property file or a file that has some configuration related to your application?

If this is the case you may consider trying to load the file through the classpath loader, this way you can load any file Java has access to.

How can I backup a Docker-container with its data-volumes?

I have created a tool to orchestrate and launch backup of data and mysql containers, simply called docker-backup. There is even a ready-to-use image on the docker hub.

It's mainly written in Bash as it is mainly orchestration. It uses duplicity for the actual backup engine. You can currently backup to FTP(S) and Amazon S3.

The configuration is quite simple: write a config file in YAML describing what to backup and where, and here you go!

For data containers, it automatically mount the volumes shared by your container to backup and process it. For mysql containers, it links them and execute a mysqldump bundled with your container and process the result.

I wrote it because I use Docker-Cloud which is not up-to-date with recent docker-engine releases and because I wanted to embrace the Docker way by not including any process of backup inside my application containers.

How to use in jQuery :not and hasClass() to get a specific element without a class

You can also use jQuery - is(selector) Method:

var lastOpenSite = $(this).siblings().is(':not(.closedTab)');

Laravel - Model Class not found

Make sure to be careful when editing your model file. For example, in your post model:

namespace App;

use Illuminate\Database\Eloquent\Model;

class Post extends Model {
    protected $table = 'posts';    

You need to pay close attention to the class Post extend Model line. The class Post defined here will be your namespace for your controller.

When to encode space to plus (+) or %20?

+ means a space only in application/x-www-form-urlencoded content, such as the query part of a URL:

In this URL, the parameter name is query name with a space and the value is query value with a space, but the folder name in the path is literally foo+bar, not foo bar.

%20 is a valid way to encode a space in either of these contexts. So if you need to URL-encode a string for inclusion in part of a URL, it is always safe to replace spaces with %20 and pluses with %2B. This is what eg. encodeURIComponent() does in JavaScript. Unfortunately it's not what urlencode does in PHP (rawurlencode is safer).

See Also HTML 4.01 Specification application/x-www-form-urlencoded

Finding absolute value of a number without using Math.abs()

You can use :

abs_num = (num < 0) ? -num : num;

AttributeError: 'str' object has no attribute 'strftime'

you should change cr_date(str) to datetime object then you 'll change the date to the specific format:

cr_date = '2013-10-31 18:23:29.000227'
cr_date = datetime.datetime.strptime(cr_date, '%Y-%m-%d %H:%M:%S.%f')
cr_date = cr_date.strftime("%m/%d/%Y")

In a Django form, how do I make a field readonly (or disabled) so that it cannot be edited?

You can elegantly add readonly in the widget:

class SurveyModaForm(forms.ModelForm):
    class Meta:
        model  = Survey
        fields = ['question_no']
        widgets = {

How to use UTF-8 in resource properties with ResourceBundle

Open the Settings / Preferences dialog (Ctrl + Alt + S), then click Editor and File Encodings.

Screenshot of window shown

Then, on the bottom, you will fing default encodings for properties files. Choose your encoding type.

Alternatively you can use unicode symbols instead of text in your resource bundle (for example "??" equals \u0456\u0432)

AngularJS $watch window resize inside directive

You can listen resize event and fire where some dimension change


(function() {
'use strict';

    .directive('resize', ['$window', function ($window) {
        return {
            link: link,
            restrict: 'A'

        function link(scope, element, attrs){
            scope.width = $window.innerWidth;
            function onResize(){
                // uncomment for only fire when $window.innerWidth change   
                // if (scope.width !== $window.innerWidth)
                    scope.width = $window.innerWidth;

            function cleanUp() {
                angular.element($window).off('resize', onResize);

            angular.element($window).on('resize', onResize);
            scope.$on('$destroy', cleanUp);

In html

<div class="row" resize> ,
    <div class="col-sm-2 col-xs-6" ng-repeat="v in tag.vod"> 
        <h4 ng-bind="::v.known_as"></h4>

Controller :

$scope.$watch('width', function(old, newv){
     console.log(old, newv);

How do I make a Docker container start automatically on system boot?

Yes, docker has restart policies such as docker run --restart=always that will handle this. This is also available in the compose.yml config file as restart: always.

How do I change the text of a span element using JavaScript?

(function ($) {
    $("#myspan").text("This is span");
<script src=""></script>
<span id="myspan"> hereismytext </span>

user text() to change span text.

XML Document to String

First you need to get rid of all newline characters in all your text nodes. Then you can use an identity transform to output your DOM tree. Look at the javadoc for TransformerFactory#newTransformer().

UICollectionView Self Sizing Cells with Auto Layout

  1. Add flowLayout on viewDidLoad()

    override func viewDidLoad() {
        if let flowLayout = infoCollection.collectionViewLayout as? UICollectionViewFlowLayout {
            flowLayout.estimatedItemSize = CGSize(width: 1, height:1)
  2. Also, set an UIView as mainContainer for your cell and add all required views inside it.

  3. Refer to this awesome, mind-blowing tutorial for further reference: UICollectionView with autosizing cell using autolayout in iOS 9 & 10

What is the difference between SQL, PL-SQL and T-SQL?


SQL is used to communicate with a database, it is the standard language for relational database management systems.

In detail Structured Query Language is a special-purpose programming language designed for managing data held in a relational database management system (RDBMS), or for stream processing in a relational data stream management system (RDSMS).

Originally based upon relational algebra and tuple relational calculus, SQL consists of a data definition language and a data manipulation language. The scope of SQL includes data insert, query, update and delete, schema creation and modification, and data access control. Although SQL is often described as, and to a great extent is, a declarative language (4GL), it also includes procedural elements.


PL/SQL is a combination of SQL along with the procedural features of programming languages. It was developed by Oracle Corporation

Specialities of PL/SQL

  • completely portable, high-performance transaction-processing language.
  • provides a built-in interpreted and OS independent programming environment.
  • directly be called from the command-line SQL*Plus interface.
  • Direct call can also be made from external programming language calls to database.
  • general syntax is based on that of ADA and Pascal programming language.
  • Apart from Oracle, it is available in TimesTen in-memory database and IBM DB2.


Short for Transaction-SQL, an extended form of SQL that adds declared variables, transaction control, error and exceptionhandling and row processing to SQL

The Structured Query Language or SQL is a programming language that focuses on managing relational databases. SQL has its own limitations which spurred the software giant Microsoft to build on top of SQL with their own extensions to enhance the functionality of SQL. Microsoft added code to SQL and called it Transact-SQL or T-SQL. Keep in mind that T-SQL is proprietary and is under the control of Microsoft while SQL, although developed by IBM, is already an open format.

T-SQL adds a number of features that are not available in SQL.

This includes procedural programming elements and a local variable to provide more flexible control of how the application flows. A number of functions were also added to T-SQL to make it more powerful; functions for mathematical operations, string operations, date and time processing, and the like. These additions make T-SQL comply with the Turing completeness test, a test that determines the universality of a computing language. SQL is not Turing complete and is very limited in the scope of what it can do.

Another significant difference between T-SQL and SQL is the changes done to the DELETE and UPDATE commands that are already available in SQL. With T-SQL, the DELETE and UPDATE commands both allow the inclusion of a FROM clause which allows the use of JOINs. This simplifies the filtering of records to easily pick out the entries that match a certain criteria unlike with SQL where it can be a bit more complicated.

Choosing between T-SQL and SQL is all up to the user. Still, using T-SQL is still better when you are dealing with Microsoft SQL Server installations. This is because T-SQL is also from Microsoft, and using the two together maximizes compatibility. SQL is preferred by people who have multiple backends.

References , Wikipedea , Tutorial Points

swift 3.0 Data to String?

According to the Apple doc below, device token can not be decoded. So, I think the best thing to do is just leave it be.

Security Architecture

A device token is an opaque NSData instance that contains a unique identifier assigned by Apple to a specific app on a specific device. Only APNs can decode and read the contents of a device token. Each app instance receives its unique device token when it registers with APNs, and must then forward the token to its provider, as described in Configuring Remote Notification Support. The provider must include the device token in each push notification request that targets the associated device; APNs uses the device token to ensure the notification is delivered only to the unique app-device combination for which it is intended.

git diff between cloned and original remote repository

Another reply to your questions (assuming you are on master and already did "git fetch origin" to make you repo aware about remote changes):

1) Commits on remote branch since when local branch was created:

git diff HEAD...origin/master

2) I assume by "working copy" you mean your local branch with some local commits that are not yet on remote. To see the differences of what you have on your local branch but that does not exist on remote branch run:

git diff origin/master...HEAD

3) See the answer by dbyrne.

How to Convert Int to Unsigned Byte and Back

Handling bytes and unsigned integers with BigInteger:

byte[] b = ...                    // your integer in big-endian
BigInteger ui = new BigInteger(b) // let BigInteger do the work
int i = ui.intValue()             // unsigned value assigned to i

JavaScript onclick redirect

Just do


The javascript: prefix is only required for link URLs.

One line if statement not working

One line if:

<statement> if <condition>

Your case:

"Yes" if @item.rigged

"No" if [email protected] # or: "No" unless @item.rigged

No plot window in matplotlib

--pylab no longer works for Jupyter, but fortunately we can add a tweak in the file to get both pylab as well as autoreload functionalities.

c.InteractiveShellApp.extensions = ['autoreload', 'pylab']
c.InteractiveShellApp.exec_lines = ['%autoreload 2', '%pylab']

C# equivalent of the IsNull() function in SQL Server

This is meant half as a joke, since the question is kinda silly.

public static bool IsNull (this System.Object o)
   return (o == null);

This is an extension method, however it extends System.Object, so every object you use now has an IsNull() method.

Then you can save tons of code by doing:

if (foo.IsNull())

instead of the super lame:

if (foo == null)

Switch case in C# - a constant value is expected

See C# switch statement limitations - why?

Basically Switches cannot have evaluated statements in the case statement. They must be statically evaluated.

javax.mail.AuthenticationFailedException: failed to connect, no password specified?

It might be worth verifying that the gmail account hasn't been locked out due to several unsuccessful login attempts, you may need to reset your password. I had the same problem as you, and this turned out to be the solution.

How can I get the current screen orientation?

I just want to propose another alternative that will concern some of you :


implies that we explicitly declare the layout to be injected.

In case we want to keep the automatic injection thanks to the layout-land and layout folders. All you have to do is add it to the onCreate:

    if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_LANDSCAPE) {

    } else if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT) {

Here, we display or not the actionbar depending on the orientation of the phone

How do you get the Git repository's name in some Git repository?

I think this is a better way to unambiguously identify a clone of a repository.

git config --get remote.origin.url and checking to make sure that the origin matches ssh://your/repo.

How do you delete a column by name in data.table?

You can also use set for this, which avoids the overhead of [.data.table in loops:

dt <- data.table( a=letters, b=LETTERS, c=seq(26), d=letters, e=letters )
set( dt, j=c(1L,3L,5L), value=NULL )
> dt[1:5]
   b d
1: A a
2: B b
3: C c
4: D d
5: E e

If you want to do it by column name, which(colnames(dt) %in% c("a","c","e")) should work for j.

ActionBarActivity cannot resolve a symbol

Follow the steps mentioned for using support ActionBar in Android Studio(0.4.2) :

Download the Android Support Repository from Android SDK Manager, SDK Manager icon will be available on Android Studio tool bar (or Tools -> Android -> SDK Manager).

enter image description here

After download you will find your Support repository here


Open your main module's build.gradle file and add following dependency for using action bar in lower API level

dependencies {
    compile ''

Sync your project with gradle using the tiny Gradle icon available in toolbar (or Tools -> Android -> Sync Project With Gradle Files).

There is some issue going on with Android Studio 0.4.2 so check this as well if you face any issue while importing classes in code.

Import Google Play Services library in Android Studio

If Required follow the steps as well :

  • Exit Android Studio
  • Delete all the .iml files and files inside .idea folder from your project
  • Relaunch Android Studio and wait till the project synced completely with gradle. If it shows an error in Event Log with import option click on Import Project.

This is bug in Android Studio 0.4.2 and fixed for Android Studio 0.4.3 release.

How to check whether a string is Base64 encoded or not


this regular expression helped me identify the base64 in my application in rails, I only had one problem, it is that it recognizes the string "errorDescripcion", I generate an error, to solve it just validate the length of a string.

Add onClick event to document.createElement("th")

var newTH = document.createElement('th');
newTH.addEventListener( 'click', function(){
  // delete the column here
} );

Best practice for REST token-based authentication with JAX-RS and Jersey

This answer is all about authorization and it is a complement of my previous answer about authentication

Why another answer? I attempted to expand my previous answer by adding details on how to support JSR-250 annotations. However the original answer became the way too long and exceeded the maximum length of 30,000 characters. So I moved the whole authorization details to this answer, keeping the other answer focused on performing authentication and issuing tokens.

Supporting role-based authorization with the @Secured annotation

Besides authentication flow shown in the other answer, role-based authorization can be supported in the REST endpoints.

Create an enumeration and define the roles according to your needs:

public enum Role {

Change the @Secured name binding annotation created before to support roles:

@Target({TYPE, METHOD})
public @interface Secured {
    Role[] value() default {};

And then annotate the resource classes and methods with @Secured to perform the authorization. The method annotations will override the class annotations:

public class ExampleResource {

    public Response myMethod(@PathParam("id") Long id) {
        // This method is not annotated with @Secured
        // But it's declared within a class annotated with @Secured({Role.ROLE_1})
        // So it only can be executed by the users who have the ROLE_1 role

    @Secured({Role.ROLE_1, Role.ROLE_2})
    public Response myOtherMethod(@PathParam("id") Long id) {
        // This method is annotated with @Secured({Role.ROLE_1, Role.ROLE_2})
        // The method annotation overrides the class annotation
        // So it only can be executed by the users who have the ROLE_1 or ROLE_2 roles

Create a filter with the AUTHORIZATION priority, which is executed after the AUTHENTICATION priority filter defined previously.

The ResourceInfo can be used to get the resource Method and resource Class that will handle the request and then extract the @Secured annotations from them:

public class AuthorizationFilter implements ContainerRequestFilter {

    private ResourceInfo resourceInfo;

    public void filter(ContainerRequestContext requestContext) throws IOException {

        // Get the resource class which matches with the requested URL
        // Extract the roles declared by it
        Class<?> resourceClass = resourceInfo.getResourceClass();
        List<Role> classRoles = extractRoles(resourceClass);

        // Get the resource method which matches with the requested URL
        // Extract the roles declared by it
        Method resourceMethod = resourceInfo.getResourceMethod();
        List<Role> methodRoles = extractRoles(resourceMethod);

        try {

            // Check if the user is allowed to execute the method
            // The method annotations override the class annotations
            if (methodRoles.isEmpty()) {
            } else {

        } catch (Exception e) {

    // Extract the roles from the annotated element
    private List<Role> extractRoles(AnnotatedElement annotatedElement) {
        if (annotatedElement == null) {
            return new ArrayList<Role>();
        } else {
            Secured secured = annotatedElement.getAnnotation(Secured.class);
            if (secured == null) {
                return new ArrayList<Role>();
            } else {
                Role[] allowedRoles = secured.value();
                return Arrays.asList(allowedRoles);

    private void checkPermissions(List<Role> allowedRoles) throws Exception {
        // Check if the user contains one of the allowed roles
        // Throw an Exception if the user has not permission to execute the method

If the user has no permission to execute the operation, the request is aborted with a 403 (Forbidden).

To know the user who is performing the request, see my previous answer. You can get it from the SecurityContext (which should be already set in the ContainerRequestContext) or inject it using CDI, depending on the approach you go for.

If a @Secured annotation has no roles declared, you can assume all authenticated users can access that endpoint, disregarding the roles the users have.

Supporting role-based authorization with JSR-250 annotations

Alternatively to defining the roles in the @Secured annotation as shown above, you could consider JSR-250 annotations such as @RolesAllowed, @PermitAll and @DenyAll.

JAX-RS doesn't support such annotations out-of-the-box, but it could be achieved with a filter. Here are a few considerations to keep in mind if you want to support all of them:

So an authorization filter that checks JSR-250 annotations could be like:

public class AuthorizationFilter implements ContainerRequestFilter {

    private ResourceInfo resourceInfo;

    public void filter(ContainerRequestContext requestContext) throws IOException {

        Method method = resourceInfo.getResourceMethod();

        // @DenyAll on the method takes precedence over @RolesAllowed and @PermitAll
        if (method.isAnnotationPresent(DenyAll.class)) {

        // @RolesAllowed on the method takes precedence over @PermitAll
        RolesAllowed rolesAllowed = method.getAnnotation(RolesAllowed.class);
        if (rolesAllowed != null) {
            performAuthorization(rolesAllowed.value(), requestContext);

        // @PermitAll on the method takes precedence over @RolesAllowed on the class
        if (method.isAnnotationPresent(PermitAll.class)) {
            // Do nothing

        // @DenyAll can't be attached to classes

        // @RolesAllowed on the class takes precedence over @PermitAll on the class
        rolesAllowed = 
        if (rolesAllowed != null) {
            performAuthorization(rolesAllowed.value(), requestContext);

        // @PermitAll on the class
        if (resourceInfo.getResourceClass().isAnnotationPresent(PermitAll.class)) {
            // Do nothing

        // Authentication is required for non-annotated methods
        if (!isAuthenticated(requestContext)) {

     * Perform authorization based on roles.
     * @param rolesAllowed
     * @param requestContext
    private void performAuthorization(String[] rolesAllowed, 
                                      ContainerRequestContext requestContext) {

        if (rolesAllowed.length > 0 && !isAuthenticated(requestContext)) {

        for (final String role : rolesAllowed) {
            if (requestContext.getSecurityContext().isUserInRole(role)) {


     * Check if the user is authenticated.
     * @param requestContext
     * @return
    private boolean isAuthenticated(final ContainerRequestContext requestContext) {
        // Return true if the user is authenticated or false otherwise
        // An implementation could be like:
        // return requestContext.getSecurityContext().getUserPrincipal() != null;

     * Refuse the request.
    private void refuseRequest() {
        throw new AccessDeniedException(
            "You don't have permissions to perform this action.");

Note: The above implementation is based on the Jersey RolesAllowedDynamicFeature. If you use Jersey, you don't need to write your own filter, just use the existing implementation.

What does the question mark in Java generics' type parameter mean?

The question mark is used to define wildcards. Checkout the Oracle documentation about them:

How do I write a RGB color value in JavaScript?

ES6 (template literal) helper functions:

function rgba(r, g, b, a=1){
    return `rgba(${r}, ${g}, ${b}, ${a})`
function rgb(r, g, b){
    return `rgb(${r}, ${g}, ${b})`

How do I test for an empty JavaScript object?

Try Destructuring

const a = {};
const { b } = a;
const emptryOrNot = (b) ? 'not Empty' : 'empty';

Extract subset of key-value pairs from Python dictionary object?

You can also use map (which is a very useful function to get to know anyway):

sd = dict(map(lambda k: (k, l.get(k, None)), l))


large_dictionary = {'a1':123, 'a2':45, 'a3':344}
list_of_keys = ['a1', 'a3']
small_dictionary = dict(map(lambda key: (key, large_dictionary.get(key, None)), list_of_keys))

PS: I borrowed the .get(key, None) from a previous answer :)

Static methods - How to call a method from another method?

class.method should work.

class SomeClass:
  def some_class_method(cls):

  def some_static_method():


pandas unique values multiple columns

pd.unique returns the unique values from an input array, or DataFrame column or index.

The input to this function needs to be one-dimensional, so multiple columns will need to be combined. The simplest way is to select the columns you want and then view the values in a flattened NumPy array. The whole operation looks like this:

>>> pd.unique(df[['Col1', 'Col2']].values.ravel('K'))
array(['Bob', 'Joe', 'Bill', 'Mary', 'Steve'], dtype=object)

Note that ravel() is an array method that returns a view (if possible) of a multidimensional array. The argument 'K' tells the method to flatten the array in the order the elements are stored in the memory (pandas typically stores underlying arrays in Fortran-contiguous order; columns before rows). This can be significantly faster than using the method's default 'C' order.

An alternative way is to select the columns and pass them to np.unique:

>>> np.unique(df[['Col1', 'Col2']].values)
array(['Bill', 'Bob', 'Joe', 'Mary', 'Steve'], dtype=object)

There is no need to use ravel() here as the method handles multidimensional arrays. Even so, this is likely to be slower than pd.unique as it uses a sort-based algorithm rather than a hashtable to identify unique values.

The difference in speed is significant for larger DataFrames (especially if there are only a handful of unique values):

>>> df1 = pd.concat([df]*100000, ignore_index=True) # DataFrame with 500000 rows
>>> %timeit np.unique(df1[['Col1', 'Col2']].values)
1 loop, best of 3: 1.12 s per loop

>>> %timeit pd.unique(df1[['Col1', 'Col2']].values.ravel('K'))
10 loops, best of 3: 38.9 ms per loop

>>> %timeit pd.unique(df1[['Col1', 'Col2']].values.ravel()) # ravel using C order
10 loops, best of 3: 49.9 ms per loop

How to git-svn clone the last n revisions from a Subversion repository?

... 7 years later, in the desert, a tumbleweed blows by ...

I wasn't satisfied with the accepted answer so I created some scripts to do this for you available on Github. These should help anyone who wants to use git svn clone but doesn't want to clone the entire repository and doesn't want to hunt for a specific revision to clone from in the middle of the history (maybe you're cloning a bunch of repos). Here we can just clone the last N revisions:

Use git svn clone to clone the last 50 revisions

# -u    The SVN URL to clone
# -l    The limit of revisions
# -o    The output directory

./ -u https://server/project/trunk -l 50 -o myproj --authors-file=svn-authors.txt

Find the previous N revision from an SVN repo

# -u    The SVN URL to clone
# -l    The limit of revisions

./ -u https://server/project/trunk -l 5     

MySQL/SQL: Group by date only on a Datetime column

Cast the datetime to a date, then GROUP BY using this syntax:

SELECT SUM(foo), DATE(mydate) FROM a_table GROUP BY DATE(a_table.mydate);

Or you can GROUP BY the alias as @orlandu63 suggested:

SELECT SUM(foo), DATE(mydate) DateOnly FROM a_table GROUP BY DateOnly;

Though I don't think it'll make any difference to performance, it is a little clearer.

What are -moz- and -webkit-?

These are the vendor-prefixed properties offered by the relevant rendering engines (-webkit for Chrome, Safari; -moz for Firefox, -o for Opera, -ms for Internet Explorer). Typically they're used to implement new, or proprietary CSS features, prior to final clarification/definition by the W3.

This allows properties to be set specific to each individual browser/rendering engine in order for inconsistencies between implementations to be safely accounted for. The prefixes will, over time, be removed (at least in theory) as the unprefixed, the final version, of the property is implemented in that browser.

To that end it's usually considered good practice to specify the vendor-prefixed version first and then the non-prefixed version, in order that the non-prefixed property will override the vendor-prefixed property-settings once it's implemented; for example:

.elementClass {
    -moz-border-radius: 2em;
    -ms-border-radius: 2em;
    -o-border-radius: 2em;
    -webkit-border-radius: 2em;
    border-radius: 2em;

Specifically, to address the CSS in your question, the lines you quote:

-webkit-column-count: 3;
-webkit-column-gap: 10px;
-webkit-column-fill: auto;
-moz-column-count: 3;
-moz-column-gap: 10px;
-moz-column-fill: auto;

Specify the column-count, column-gap and column-fill properties for Webkit browsers and Firefox.


Writing to a file in a for loop

The main problem was that you were opening/closing files repeatedly inside your loop.

Try this approach:

with open('new.txt') as text_file, open('xyz.txt', 'w') as myfile:  
    for line in text_file:
        var1, var2 = line.split(",");

We open both files at once and because we are using with they will be automatically closed when we are done (or an exception occurs). Previously your output file was repeatedly openend inside your loop.

We are also processing the file line-by-line, rather than reading all of it into memory at once (which can be a problem when you deal with really big files).

Note that write() doesn't append a newline ('\n') so you'll have to do that yourself if you need it (I replaced your writelines() with write() as you are writing a single item, not a list of items).

When opening a file for rread, the 'r' is optional since it's the default mode.

How to get all the values of input array element jquery

By Using map

var values = $("input[name='pname[]']")
              .map(function(){return $(this).val();}).get();

How create table only using <div> tag and Css

In building a custom set of layout tags, I found another answer to this problem. Provided here is the custom set of tags and their CSS classes.


       <layout-column> 1 a</layout-column>
       <layout-column>  </layout-column>
       <layout-column> 3 </layout-column>
       <layout-column> 4 </layout-column>

       <layout-column> a </layout-column>
       <layout-column> a 1</layout-column>
       <layout-column> a </layout-column>
       <layout-column> a </layout-column>

       <layout-column> 1 </layout-column>
       <layout-column>  </layout-column>
       <layout-column> 3 b</layout-column>
       <layout-column> 4 </layout-column>


    display : table;
    clear : both;
    table-layout : fixed;
    width : 100%;

    color : red;
    border: 1px blue solid;
    empty-cells : show;

layout-header, layout-footer, layout-row 
    display : table-row;
    clear : both;   
    empty-cells : show;
    width : 100%;

    display : table-column;
    float : left;
    width : 25%;
    min-width : 25%;
    empty-cells : show;
    box-sizing: border-box;
    /* border: 1px solid white; */
    padding : 1px 1px 1px 1px;

    background-color : lightblue;

{ background-color: #f5f5f5 }

The key to getting empty cells and cells in general to be the right size, is Box-Sizing and Padding. Border will do the same thing as well, but creates a line in the row. Padding doesn't. And, while I haven't tried it, I think Margin will act the same way as Padding, in forcing and empty cell to be rendered properly.

How to add include and lib paths to configure/make cycle?

This took a while to get right. I had this issue when cross-compiling in Ubuntu for an ARM target. I solved it with:

PATH=$PATH:/ccpath/bin CC=ccname-gcc AR=ccname-ar LD=ccname-ld CPPFLAGS="-nostdinc -I/ccrootfs/usr/include ..." LDFLAGS=-L/ccrootfs/usr/lib ./ --build=`config.guess` --host=armv5tejl-unknown-linux-gnueabihf

Notice CFLAGS is not used with, using it gave me the error: "configure: error: C compiler cannot create executables". In the build environment I was using an script was provided, if you don't have an script substitute ./ with ./configure in the command above. I ran config.guess on the target system to get the --host parameter.

After successfully running, compile with:

PATH=$PATH:/ccpath/bin CC=ccname-gcc AR=ccname-ar LD=ccname-ld CPPFLAGS="-nostdinc -I/ccrootfs/usr/include ..." LDFLAGS=-L/ccrootfs/usr/lib CFLAGS="-march=... -mcpu=... etc." make

The CFLAGS I chose to use were: "-march=armv5te -fno-tree-vectorize -mthumb-interwork -mcpu=arm926ej-s". It will take a while to get all of the include directories set up correctly: you might want some includes pointing to your cross-compiler and some pointing to your root file system includes, and there will likely be some conflicts.

I'm sure this is not the perfect answer. And I am still seeing some include directories pointing to / and not /ccrootfs in the Makefiles. Would love to know how to correct this. Hope this helps someone.

Loop through columns and add string lengths as new columns

With dplyr and stringr you can use mutate_all:

> df %>% mutate_all(funs(length = str_length(.)))

     col1     col2 col1_length col2_length
1     abc adf qqwe           3           8
2    abcd        d           4           1
3       a        e           1           1
4 abcdefg        f           7           1

How can I find out what version of git I'm running?

$ git --version
git version

git help and man git both hint at the available arguments you can pass to the command-line tool

SQL order string as number

If possible you should change the data type of the column to a number if you only store numbers anyway.

If you can't do that then cast your column value to an integer explicitly with

select col from yourtable
order by cast(col as unsigned)

or implicitly for instance with a mathematical operation which forces a conversion to number

select col from yourtable
order by col + 0

BTW MySQL converts strings from left to right. Examples:

string value  |  integer value after conversion
'1'           |  1
'ABC'         |  0   /* the string does not contain a number, so the result is 0 */
'123miles'    |  123 
'$123'        |  0   /* the left side of the string does not start with a number */

How to navigate to a section of a page

Use hypertext reference and the ID tag,

Target Text Title

Some paragraph text

Target Text

<h1><a href="#target">Target Text Title</a></h1>
<p id="target">Target Text</p>

How can I get key's value from dictionary in Swift?

Use subscripting to access the value for a dictionary key. This will return an Optional:

let apple: String? = companies["AAPL"]


if let apple = companies["AAPL"] {
    // ...

You can also enumerate over all of the keys and values:

var companies = ["AAPL" : "Apple Inc", "GOOG" : "Google Inc", "AMZN" : ", Inc", "FB" : "Facebook Inc"]

for (key, value) in companies {
    print("\(key) -> \(value)")

Or enumerate over all of the values:

for value in Array(companies.values) {

jQuery get text as number

Use the javascript parseInt method (

var number = parseInt($(this).find('.number').text(), 10);
var current = 600;
if (current > number){
     // do something

Don't forget to specify the radix value of 10 which tells parseInt that it's in base 10.

optional parameters in SQL Server stored proc?

2014 and above at least you can set a default and it will take that and NOT error when you do not pass that parameter. Partial Example: the 3rd parameter is added as optional. exec of the actual procedure with only the first two parameters worked fine

exec getlist 47,1,0

create procedure getlist
   @convId int,
   @SortOrder int,
   @contestantsOnly bit = 0

PHP using Gettext inside <<<EOF string

As far as I can see in the manual, it is not possible to call functions inside HEREDOC strings. A cumbersome way would be to prepare the words beforehand:


    $world = _("World");

    $str = <<<EOF
    echo $str;

a workaround idea that comes to mind is building a class with a magic getter method.

You would declare a class like this:

class Translator
 public function __get($name) {
  return _($name); // Does the gettext lookup

Initialize an object of the class at some point:

  $translate = new Translator();

You can then use the following syntax to do a gettext lookup inside a HEREDOC block:

    $str = <<<EOF
    echo $str;

$translate->World will automatically be translated to the gettext lookup thanks to the magic getter method.

To use this method for words with spaces or special characters (e.g. a gettext entry named Hello World!!!!!!, you will have to use the following notation:

 $translate->{"Hello World!!!!!!"}

This is all untested but should work.

Update: As @mario found out, it is possible to call functions from HEREDOC strings after all. I think using getters like this is a sleek solution, but using a direct function call may be easier. See the comments on how to do this.

How to crop an image using C#?

use bmp.SetResolution(image.HorizontalResolution, image .VerticalResolution);

this may be necessary to do even if you implement best answer here especially if your image is real great and resolutions are not exactly 96.0

My test example:

    static Bitmap LoadImage()
        return (Bitmap)Bitmap.FromFile( @"e:\Tests\d_bigImage.bmp" ); // here is large image 9222x9222 pixels and 95.96 dpi resolutions

    static void TestBigImagePartDrawing()
        using( var absentRectangleImage = LoadImage() )
            using( var currentTile = new Bitmap( 256, 256 ) )
                currentTile.SetResolution(absentRectangleImage.HorizontalResolution, absentRectangleImage.VerticalResolution);

                using( var currentTileGraphics = Graphics.FromImage( currentTile ) )
                    currentTileGraphics.Clear( Color.Black );
                    var absentRectangleArea = new Rectangle( 3, 8963, 256, 256 );
                    currentTileGraphics.DrawImage( absentRectangleImage, 0, 0, absentRectangleArea, GraphicsUnit.Pixel );


Array inside a JavaScript Object?

Kill the braces.

var defaults = {
 backgroundcolor: '#000',
 color: '#fff',
 weekdays: ['sun','mon','tue','wed','thu','fri','sat']

html5 localStorage error with Safari: "QUOTA_EXCEEDED_ERR: DOM Exception 22: An attempt was made to add something to storage that exceeded the quota."

I had the same problem using Ionic framework (Angular + Cordova). I know this not solve the problem, but it's the code for Angular Apps based on the answers above. You will have a ephemeral solution for localStorage on iOS version of Safari.

Here is the code:

angular.module('myApp.factories', [])
.factory('$fakeStorage', [
        function FakeStorage() {};
        FakeStorage.prototype.setItem = function (key, value) {
            this[key] = value;
        FakeStorage.prototype.getItem = function (key) {
            return typeof this[key] == 'undefined' ? null : this[key];
        FakeStorage.prototype.removeItem = function (key) {
            this[key] = undefined;
        FakeStorage.prototype.clear = function(){
            for (var key in this) {
                if( this.hasOwnProperty(key) )
        FakeStorage.prototype.key = function(index){
            return Object.keys(this)[index];
        return new FakeStorage();
.factory('$localstorage', [
    '$window', '$fakeStorage',
    function($window, $fakeStorage) {
        function isStorageSupported(storageName) 
            var testKey = 'test',
                storage = $window[storageName];
                storage.setItem(testKey, '1');
                return true;
            catch (error) 
                return false;
        var storage = isStorageSupported('localStorage') ? $window.localStorage : $fakeStorage;
        return {
            set: function(key, value) {
                storage.setItem(key, value);
            get: function(key, defaultValue) {
                return storage.getItem(key) || defaultValue;
            setObject: function(key, value) {
                storage.setItem(key, JSON.stringify(value));
            getObject: function(key) {
                return JSON.parse(storage.getItem(key) || '{}');
            remove: function(key){
            clear: function() {
            key: function(index){


Enjoy your coding!

Call jQuery Ajax Request Each X Minutes

No plugin required. You can use only jquery.

If you want to set something on a timer, you can use JavaScript's setTimeout or setInterval methods:

setTimeout ( expression, timeout );
setInterval ( expression, interval );

Git conflict markers

The line (or lines) between the lines beginning <<<<<<< and ====== here:

<<<<<<< HEAD:file.txt
Hello world

... is what you already had locally - you can tell because HEAD points to your current branch or commit. The line (or lines) between the lines beginning ======= and >>>>>>>:

>>>>>>> 77976da35a11db4580b80ae27e8d65caf5208086:file.txt

... is what was introduced by the other (pulled) commit, in this case 77976da35a11. That is the object name (or "hash", "SHA1sum", etc.) of the commit that was merged into HEAD. All objects in git, whether they're commits (version), blobs (files), trees (directories) or tags have such an object name, which identifies them uniquely based on their content.

How To Save Canvas As An Image With canvas.toDataURL()?

You cannot use the methods previously mentioned to download an image when running in Cordova. You will need to use the Cordova File Plugin. This will allow you to pick where to save it and leverage different persistence settings. Details here:

Alternatively, you can convert the image to base64 then store the string in localStorage but this will fill your quota pretty quickly if you have many images or high-res.

Visual Studio Code open tab in new window

If you are using the excellent

VSCode for Mac, 2020

simply tap Apple-Shift-N (as in "new window")

Drag whatever you want there.

Removing object from array in Swift 3

In Swift 3 and 4

var array = ["a", "b", "c", "d", "e", "f"]

for (index, element) in array.enumerated().reversed() {
    array.remove(at: index)

From Swift 4.2 you can use more advanced approach(faster and memory efficient)

array.removeAll(where: { $0 == "c" })

instead of

array = array.filter { !$0.hasPrefix("c") }

Read more here

Heap vs Binary Search Tree (BST)

Heap just guarantees that elements on higher levels are greater (for max-heap) or smaller (for min-heap) than elements on lower levels, whereas BST guarantees order (from "left" to "right"). If you want sorted elements, go with BST.

How can I get an int from stdio in C?

I'm not fully sure that this is what you're looking for, but if your question is how to read an integer using <stdio.h>, then the proper syntax is

int myInt;
scanf("%d", &myInt);

You'll need to do a lot of error-handling to ensure that this works correctly, of course, but this should be a good start. In particular, you'll need to handle the cases where

  1. The stdin file is closed or broken, so you get nothing at all.
  2. The user enters something invalid.

To check for this, you can capture the return code from scanf like this:

int result = scanf("%d", &myInt);

If stdin encounters an error while reading, result will be EOF, and you can check for errors like this:

int myInt;
int result = scanf("%d", &myInt);

if (result == EOF) {
    /* ... you're not going to get any input ... */

If, on the other hand, the user enters something invalid, like a garbage text string, then you need to read characters out of stdin until you consume all the offending input. You can do this as follows, using the fact that scanf returns 0 if nothing was read:

int myInt;
int result = scanf("%d", &myInt);

if (result == EOF) {
    /* ... you're not going to get any input ... */
if (result == 0) {
    while (fgetc(stdin) != '\n') // Read until a newline is found

Hope this helps!

EDIT: In response to the more detailed question, here's a more appropriate answer. :-)

The problem with this code is that when you write

printf("got the number: %d", scanf("%d", &x));

This is printing the return code from scanf, which is EOF on a stream error, 0 if nothing was read, and 1 otherwise. This means that, in particular, if you enter an integer, this will always print 1 because you're printing the status code from scanf, not the number you read.

To fix this, change this to

int x;
scanf("%d", &x);
/* ... error checking as above ... */
printf("got the number: %d", x);

Hope this helps!

Getting unix timestamp from Date()

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.TimeZone;

public class Timeconversion {
    private DateFormat dateFormat = new SimpleDateFormat("yyyyMMddHHmm", Locale.ENGLISH); //Specify your locale

    public long timeConversion(String time) {
        long unixTime = 0;
        dateFormat.setTimeZone(TimeZone.getTimeZone("GMT+5:30")); //Specify your timezone
        try {
            unixTime = dateFormat.parse(time).getTime();
            unixTime = unixTime / 1000;
        } catch (ParseException e) {
        return unixTime;

Call a "local" function within module.exports from another function in module.exports?

Starting with Node.js version 13 you can take advantage of ES6 Modules.

export function foo() {
    return 'foo';

export function bar() {
    return foo();

Following the Class approach:

class MyClass {

    foo() {
        return 'foo';

    bar() {

module.exports = new MyClass();

This will instantiate the class only once, due to Node's module caching:

How to fix div on scroll

You can find an example below. Basically you attach a function to window's scroll event and trace scrollTop property and if it's higher than desired threshold you apply position: fixed and some other css properties.

jQuery(function($) {_x000D_
  $(window).scroll(function fix_element() {_x000D_
      $(window).scrollTop() > 100_x000D_
        ? { 'position': 'fixed', 'top': '10px' }_x000D_
        : { 'position': 'relative', 'top': 'auto' }_x000D_
    return fix_element;_x000D_
body {_x000D_
  height: 2000px;_x000D_
  padding-top: 100px;_x000D_
code {_x000D_
  padding: 5px;_x000D_
  background: #efefef;_x000D_
#target {_x000D_
  color: #c00;_x000D_
  font: 15px arial;_x000D_
  padding: 10px;_x000D_
  margin: 10px;_x000D_
  border: 1px solid #c00;_x000D_
  width: 200px;_x000D_
<script src=""></script>_x000D_
<div id="target">This <code>div</code> is going to be fixed</div>

Why do I get an error instantiating an interface?

You can't instantiate interfaces or abstract classes.

That's because it wouldn't have any logic to it.

Interfaces provide a contract of the methods that should be in a class, without implementation. (So there's no actual logic in the interface).

Abstract classes provide basic logic of a class, but are not fully functional (not everything is implemented). So again, you won't be able to do anything with it.

How to get row count using ResultSet in Java?

your sql Statement creating code may be like

statement = connection.createStatement();

To solve " The requested operation is not supported on forward only result sets" exception change above code with

statement = connection.createStatement(

After above change you can use

int size = 0;
try {
    size = resultSet.getRow();
catch(Exception ex) {
    return 0;
return size;

to get row count

UnicodeEncodeError: 'ascii' codec can't encode character u'\xa0' in position 20: ordinal not in range(128)

Update for python 3.0 and later. Try the following in the python editor:

locale-gen en_US.UTF-8
export LANG=en_US.UTF-8 LANGUAGE=en_US.en

This sets the system`s default locale encoding to the UTF-8 format.

More can be read here at PEP 538 -- Coercing the legacy C locale to a UTF-8 based locale.

How to calculate difference in hours (decimal) between two dates in SQL Server?

Declare @date1 datetime
Declare @date2 datetime

Set @date1 = '11/20/2009 11:00:00 AM'
Set @date2 = '11/20/2009 12:00:00 PM'

Select Cast(DateDiff(hh, @date1, @date2) as decimal(3,2)) as HoursApart

Result = 1.00

jQuery, simple polling example

jQuery.Deferred() can simplify management of asynchronous sequencing and error handling.

polling_active = true // set false to interrupt polling

function initiate_polling()
    $.Deferred().resolve() // optional boilerplate providing the initial 'then()'
    .then( () => $.Deferred( d=>setTimeout(()=>d.resolve(),5000) ) ) // sleep
    .then( () => $.get('/my-api') ) // initiate AJAX
    .then( response =>
        if ( JSON.parse(response).my_result == my_target ) polling_active = false
        if ( ...unhappy... ) return $.Deferred().reject("unhappy") // abort
        if ( polling_active ) initiate_polling() // iterative recursion
    .fail( r => { polling_active=false, alert('failed: '+r) } ) // report errors

This is an elegant approach, but there are some gotchas...

  • If you don't want a then() to fall through immediately, the callback should return another thenable object (probably another Deferred), which the sleep and ajax lines both do.
  • The others are too embarrassing to admit. :)

mysql datetime comparison

I know its pretty old but I just encounter the problem and there is what I saw in the SQL doc :

[For best results when using BETWEEN with date or time values,] use CAST() to explicitly convert the values to the desired data type. Examples: If you compare a DATETIME to two DATE values, convert the DATE values to DATETIME values. If you use a string constant such as '2001-1-1' in a comparison to a DATE, cast the string to a DATE.

I assume it's better to use STR_TO_DATE since they took the time to make a function just for that and also the fact that i found this in the BETWEEN doc...

Getting "TypeError: failed to fetch" when the request hasn't actually failed

I know it's a relative old post but, I would like to share what worked for me: I've simply input "http://" before "localhost" in the url. Hope it helps somebody.

Importing PNG files into Numpy?

If you are loading images, you are likely going to be working with one or both of matplotlib and opencv to manipulate and view the images.

For this reason, I tend to use their image readers and append those to lists, from which I make a NumPy array.

import os
import matplotlib.pyplot as plt
import cv2
import numpy as np

# Get the file paths
im_files = os.listdir('path/to/files/')

# imagine we only want to load PNG files (or JPEG or whatever...)
EXTENSION = '.png'

# Load using matplotlib
images_plt = [plt.imread(f) for f in im_files if f.endswith(EXTENSION)]
# convert your lists into a numpy array of size (N, H, W, C)
images = np.array(images_plt)

# Load using opencv
images_cv = [cv2.imread(f) for f in im_files if f.endswith(EXTENSION)]
# convert your lists into a numpy array of size (N, C, H, W)
images = np.array(images_cv)

The only difference to be aware of is the following:

  • opencv loads channels first
  • matplotlib loads channels last.

So a single image that is 256*256 in size would produce matrices of size (3, 256, 256) with opencv and (256, 256, 3) using matplotlib.

C split a char array into different variables

In addition, you can use sscanf for some very simple scenarios, for example when you know exactly how many parts the string has and what it consists of. You can also parse the arguments on the fly. Do not use it for user inputs because the function will not report conversion errors.


char text[] = "1:22:300:4444:-5";
int i1, i2, i3, i4, i5;
sscanf(text, "%d:%d:%d:%d:%d", &i1, &i2, &i3, &i4, &i5);
printf("%d, %d, %d, %d, %d", i1, i2, i3, i4, i5);


1, 22, 300, 4444, -5

For anything more advanced, strtok() and strtok_r() are your best options, as mentioned in other answers.

How do I resolve "Please make sure that the file is accessible and that it is a valid assembly or COM component"?

'It' requires a dll file called cvextern.dll . 'It' can be either your own cs file or some other third party dll which you are using in your project.

To call native dlls to your own cs file, copy the dll into your project's root\lib directory and add it as an existing item. (Add -Existing item) and use Dllimport with correct location.

For third party , copy the native library to the folder where the third party library resides and add it as an existing item.

After building make sure that the required dlls are appearing in Build folder. In some cases it may not appear or get replaced in Build folder. Delete the Build folder manually and build again.

How do I escape a string inside JavaScript code inside an onClick handler?

Try avoid using string-literals in your HTML and use JavaScript to bind JavaScript events.

Also, avoid 'href=#' unless you really know what you're doing. It breaks so much usability for compulsive middleclickers (tab opener).

<a id="tehbutton" href="">Select</a>

My JavaScript library of choice just happens to be jQuery:

<script type="text/javascript">//<!-- <![CDATA[
        SelectSurveyItem('<%itemid%>', '<%itemname%>');
        return false;

If you happen to be rendering a list of links like that, you may want to do this:

<a id="link_1" href="foo">Bar</a>
<a id="link_2" href="foo2">Baz</a>

<script type="text/javascript">
        var l = [[1,'Bar'],[2,'Baz']];
           $("#link_" + v[0] ).click(function(){
                return false;

Cannot find java. Please use the --jdkhome switch

  1. Go to the netbeans installation directory
  2. Find configuration file [installation-directory]/etc/netbeans.conf
  3. towards the end find the line netbeans_jdkhome=...
  4. comment this line line using '#'
  5. now run netbeans. launcher will find jdk itself (from $JDK_HOME/$JAVA_HOME) environment variable


sudo vim /usr/local/netbeans-8.2/etc/netbeans.conf

TypeError: only length-1 arrays can be converted to Python scalars while trying to exponentially fit data

Here is another way to reproduce this error in Python2.7 with numpy:

import numpy as np
a = np.array([1,2,3])
b = np.array([4,5,6])
c = np.concatenate(a,b)   #note the lack of tuple format for a and b

The np.concatenate method produces an error:

TypeError: only length-1 arrays can be converted to Python scalars

If you read the documentation around numpy.concatenate, then you see it expects a tuple of numpy array objects. So surrounding the variables with parens fixed it:

import numpy as np
a = np.array([1,2,3])
b = np.array([4,5,6])
c = np.concatenate((a,b))  #surround a and b with parens, packaging them as a tuple

Then it prints:

[1 2 3 4 5 6]

What's going on here?

That error is a case of bubble-up implementation - it is caused by duck-typing philosophy of python. This is a cryptic low-level error python guts puke up when it receives some unexpected variable types, tries to run off and do something, gets part way through, the pukes, attempts remedial action, fails, then tells you that "you can't reformulate the subspace responders when the wind blows from the east on Tuesday".

In more sensible languages like C++ or Java, it would have told you: "you can't use a TypeA where TypeB was expected". But Python does it's best to soldier on, does something undefined, fails, and then hands you back an unhelpful error. The fact we have to be discussing this is one of the reasons I don't like Python, or its duck-typing philosophy.

Oracle Trigger ORA-04098: trigger is invalid and failed re-validation

in my case, this error is raised due to sequence was not created..


AngularJS access scope from outside js function

You can also try:

function change() {
    var scope = angular.element( document.getElementById('outer') ).scope();
        scope.msg = 'Superhero';

How can I overwrite file contents with new content in PHP?

$fname = "database.php";
$fhandle = fopen($fname,"r");
$content = fread($fhandle,filesize($fname));
$content = str_replace("", "localhost", $content);

$fhandle = fopen($fname,"w");

Execute PHP function with onclick

This is the easiest possible way. If form is posted via post, do php function. Note that if you want to perform function asynchronously (without the need to reload the page), then you'll need AJAX.

<form method="post">
    <button name="test">test</button>

      //do php stuff  

Abstract Class vs Interface in C++

Please don't put members into an interface; though it's correct in phrasing. Please don't "delete" an interface.

class IInterface() 
   Virtual ~IInterface(){}; 

Class ClassImpl : public IInterface 

Int main() 

  IInterface* pInterface = new ClassImpl(); 
  delete pInterface; // Wrong in OO Programming, correct in C++.

Select row on click react-table

I am not familiar with, react-table, so I do not know it has direct support for selecting and deselecting (it would be nice if it had).

If it does not, with the piece of code you already have you can install the onCLick handler. Now instead of trying to attach style directly to row, you can modify state, by for instance adding selected: true to row data. That would trigger rerender. Now you only have to override how are rows with selected === true rendered. Something along lines of:

// Any Tr element will be green if its (row.age > 20) 
  getTrProps={(state, rowInfo, column) => {
    return {
      style: {
        background: rowInfo.row.selected ? 'green' : 'red'

How to use DISTINCT and ORDER BY in same SELECT statement?

if object_id ('tempdb..#tempreport') is not null
drop table #tempreport
create table #tempreport (
Category  nvarchar(510),
CreationDate smallint )
insert into #tempreport 
select distinct Category from MonitoringJob (nolock) 
select * from #tempreport  ORDER BY CreationDate DESC

Nginx not picking up site in sites-enabled?

I had the same problem. It was because I had accidentally used a relative path with the symbolic link.

Are you sure you used full paths, e.g.:

ln -s /etc/nginx/sites-available/ /etc/nginx/sites-enabled/

How can I detect window size with jQuery?

You could also use plain Javascript window.innerWidth to compare width.

But use jQuery's .resize() fired automatically for you:

$( window ).resize(function() {
  // your code...

How might I convert a double to the nearest integer value?

For Unity, use Mathf.RoundToInt.

using UnityEngine;

public class ExampleScript : MonoBehaviour
    void Start()
        // Prints 10
        // Prints 10
        // Prints 11
        // Prints 10
        // Prints 12

        // Prints -10
        // Prints -10
        // Prints -11
        // Prints -10
        // Prints -12


public static int RoundToInt(float f) { return (int)Math.Round(f); }

How do I create a list of random numbers without duplicates?

If the list of N numbers from 1 to N is randomly generated, then yes, there is a possibility that some numbers may be repeated.

If you want a list of numbers from 1 to N in a random order, fill an array with integers from 1 to N, and then use a Fisher-Yates shuffle or Python's random.shuffle().

How do I handle the window close event in Tkinter?

You should use destroy() to close a tkinter window.

   from Tkinter import *
   root = Tk()
   Button(root, text="Quit", command=root.destroy).pack()


root.quit() The above line just Bypasses the root.mainloop() i.e root.mainloop() will still be running in background if quit() command is executed.

root.destroy() While destroy() command vanish out root.mainloop() i.e root.mainloop() stops.

So as you just want to quit the program so you should use root.destroy() as it will it stop the mainloop()`.

But if you want to run some infinite loop and you don't want to destroy your Tk window and want to execute some code after root.mainloop() line then you should use root.quit(). Ex:

from Tkinter import *
def quit():
    global root

root = Tk()
while True:
    Button(root, text="Quit", command=quit).pack()
    #do something

Print a list of all installed node.js modules

Why not grab them from dependencies in package.json?

Of course, this will only give you the ones you actually saved, but you should be doing that anyway.


In a Git repository, how to properly rename a directory?

Simply rename the folder. git is a "content-tracker", so the SHA1 hashes are the same and git knows, that you rename it. The only thing that changes is the tree-object.

rm <directory>
git add .
git commit

"The POM for ... is missing, no dependency information available" even though it exists in Maven Repository

Read carefully the warning message :

The POM for org.raml:jaxrs-code-generator:jar:2.0.0 is missing, no dependency information available

The problem is not the jar, but the pom.xml that is missing.
The pom.xml lists the required dependencies for this jar that Maven will pull during the build and overall the packaging of your application. So, you may really need it.

Note that this problem may of course occur for other Maven dependencies and the ideas to solve that is always the same.

The Mule website documents very well that in addition to some information related to.

How to solve ?

1) Quick workaround : looking for in the internet the pom.xml of the artifact

Googling the artifact id, the group id and its version gives generally interesting results : maven repository links to download it.
In the case of the org.raml:jaxrs-code-generator:jar:2.0.0 dependency, you can download the pom.xml from the Maven mule repository :

2) Clean workaround for a single Maven project : adding the repository declaration in your pom.

In your case, add the Maven mule repositories :

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="" xmlns:xsi=""
            <name>MuleSoft Repository</name>
            <name>MuleSoft Snapshot Repository</name>

3) Clean workaround for any Maven projects : add the repository declaration in your settings.xml

      <name>MuleSoft Repository</name>
      <name>MuleSoft Snapshot Repository</name>

Note that in some rare cases, the pom.xml declaring the dependencies is nowhere. So, you have to identify yourself whether the artifact requires dependencies.

Differences between TCP sockets and web sockets, one more time

When you send bytes from a buffer with a normal TCP socket, the send function returns the number of bytes of the buffer that were sent. If it is a non-blocking socket or a non-blocking send then the number of bytes sent may be less than the size of the buffer. If it is a blocking socket or blocking send, then the number returned will match the size of the buffer but the call may block. With WebSockets, the data that is passed to the send method is always either sent as a whole "message" or not at all. Also, browser WebSocket implementations do not block on the send call.

But there are more important differences on the receiving side of things. When the receiver does a recv (or read) on a TCP socket, there is no guarantee that the number of bytes returned corresponds to a single send (or write) on the sender side. It might be the same, it may be less (or zero) and it might even be more (in which case bytes from multiple send/writes are received). With WebSockets, the recipient of a message is event-driven (you generally register a message handler routine), and the data in the event is always the entire message that the other side sent.

Note that you can do message based communication using TCP sockets, but you need some extra layer/encapsulation that is adding framing/message boundary data to the messages so that the original messages can be re-assembled from the pieces. In fact, WebSockets is built on normal TCP sockets and uses frame headers that contains the size of each frame and indicate which frames are part of a message. The WebSocket API re-assembles the TCP chunks of data into frames which are assembled into messages before invoking the message event handler once per message.

Function to clear the console in R and RStudio

Another option for RStudio is rstudioapi::sendToConsole("\014"). This will work even if output is diverted.


cat("\014") # Console not cleared

rstudioapi::sendToConsole("\014") # Console cleared


How to convert string to Date in Angular2 \ Typescript?

You can use date filter to convert in date and display in specific format.

In .ts file (typescript):

let dateString = '1968-11-16T00:00:00' 
let newDate = new Date(dateString);


{{dateString |  date:'MM/dd/yyyy'}}

Below are some formats which you can implement :


public todayDate = new Date();


<option value=""></option>
<option value="MM/dd/yyyy">[{{todayDate | date:'MM/dd/yyyy'}}]</option>
<option value="EEEE, MMMM d, yyyy">[{{todayDate | date:'EEEE, MMMM d, yyyy'}}]</option>
<option value="EEEE, MMMM d, yyyy h:mm a">[{{todayDate | date:'EEEE, MMMM d, yyyy h:mm a'}}]</option>
<option value="EEEE, MMMM d, yyyy h:mm:ss a">[{{todayDate | date:'EEEE, MMMM d, yyyy h:mm:ss a'}}]</option>
<option value="MM/dd/yyyy h:mm a">[{{todayDate | date:'MM/dd/yyyy h:mm a'}}]</option>
<option value="MM/dd/yyyy h:mm:ss a">[{{todayDate | date:'MM/dd/yyyy h:mm:ss a'}}]</option>
<option value="MMMM d">[{{todayDate | date:'MMMM d'}}]</option>   
<option value="yyyy-MM-ddTHH:mm:ss">[{{todayDate | date:'yyyy-MM-ddTHH:mm:ss'}}]</option>
<option value="h:mm a">[{{todayDate | date:'h:mm a'}}]</option>
<option value="h:mm:ss a">[{{todayDate | date:'h:mm:ss a'}}]</option>      
<option value="EEEE, MMMM d, yyyy hh:mm:ss a">[{{todayDate | date:'EEEE, MMMM d, yyyy hh:mm:ss a'}}]</option>
<option value="MMMM yyyy">[{{todayDate | date:'MMMM yyyy'}}]</option> 

MySQL - Meaning of "PRIMARY KEY", "UNIQUE KEY" and "KEY" when used together while creating a table

A key is just a normal index. A way over simplification is to think of it like a card catalog at a library. It points MySQL in the right direction.

A unique key is also used for improved searching speed, but it has the constraint that there can be no duplicated items (there are no two x and y where x is not y and x == y).

The manual explains it as follows:

A UNIQUE index creates a constraint such that all values in the index must be distinct. An error occurs if you try to add a new row with a key value that matches an existing row. This constraint does not apply to NULL values except for the BDB storage engine. For other engines, a UNIQUE index permits multiple NULL values for columns that can contain NULL. If you specify a prefix value for a column in a UNIQUE index, the column values must be unique within the prefix.

A primary key is a 'special' unique key. It basically is a unique key, except that it's used to identify something.

The manual explains how indexes are used in general: here.

In MSSQL, the concepts are similar. There are indexes, unique constraints and primary keys.

Untested, but I believe the MSSQL equivalent is:

  uid varchar(255) NOT NULL CONSTRAINT uid_unique UNIQUE,
  name varchar(255) NOT NULL,
  tag int NOT NULL DEFAULT 0,
  description varchar(255),

CREATE INDEX idx_name ON tmp (name);
CREATE INDEX idx_tag ON tmp (tag);

Edit: the code above is tested to be correct; however, I suspect that there's a much better syntax for doing it. Been a while since I've used SQL server, and apparently I've forgotten quite a bit :).

LINQ - Full Outer Join

I've written this extensions class for an app perhaps 6 years ago, and have been using it ever since in many solutions without issues. Hope it helps.

edit: I noticed some might not know how to use an extension class.

To use this extension class, just reference its namespace in your class by adding the following line using joinext;

^ this should allow you to to see the intellisense of extension functions on any IEnumerable object collection you happen to use.

Hope this helps. Let me know if it's still not clear, and I'll hopefully write a sample example on how to use it.

Now here is the class:

namespace joinext
public static class JoinExtensions
        public static IEnumerable<TResult> FullOuterJoin<TOuter, TInner, TKey, TResult>(
            this IEnumerable<TOuter> outer,
            IEnumerable<TInner> inner,
            Func<TOuter, TKey> outerKeySelector,
            Func<TInner, TKey> innerKeySelector,
            Func<TOuter, TInner, TResult> resultSelector)
            where TInner : class
            where TOuter : class
            var innerLookup = inner.ToLookup(innerKeySelector);
            var outerLookup = outer.ToLookup(outerKeySelector);

            var innerJoinItems = inner
                .Where(innerItem => !outerLookup.Contains(innerKeySelector(innerItem)))
                .Select(innerItem => resultSelector(null, innerItem));

            return outer
                .SelectMany(outerItem =>
                    var innerItems = innerLookup[outerKeySelector(outerItem)];

                    return innerItems.Any() ? innerItems : new TInner[] { null };
                }, resultSelector)

        public static IEnumerable<TResult> LeftJoin<TOuter, TInner, TKey, TResult>(
            this IEnumerable<TOuter> outer,
            IEnumerable<TInner> inner,
            Func<TOuter, TKey> outerKeySelector,
            Func<TInner, TKey> innerKeySelector,
            Func<TOuter, TInner, TResult> resultSelector)
            return outer.GroupJoin(
                (o, i) =>
                    new { o = o, i = i.DefaultIfEmpty() })
                    .SelectMany(m => m.i.Select(inn =>
                        resultSelector(m.o, inn)


        public static IEnumerable<TResult> RightJoin<TOuter, TInner, TKey, TResult>(
            this IEnumerable<TOuter> outer,
            IEnumerable<TInner> inner,
            Func<TOuter, TKey> outerKeySelector,
            Func<TInner, TKey> innerKeySelector,
            Func<TOuter, TInner, TResult> resultSelector)
            return inner.GroupJoin(
                (i, o) =>
                    new { i = i, o = o.DefaultIfEmpty() })
                    .SelectMany(m => m.o.Select(outt =>
                        resultSelector(outt, m.i)



Specified cast is not valid?

Try this:

public void LoadData()
            SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=Stocks;Integrated Security=True;Pooling=False");
            SqlDataAdapter sda = new SqlDataAdapter("Select * From [Stocks].[dbo].[product]", con);
            DataTable dt = new DataTable();

        foreach (DataRow item in dt.Rows)
            int n = DataGridView1.Rows.Add();
            DataGridView1.Rows[n].Cells[0].Value = item["ProductCode"].ToString();
            DataGridView1.Rows[n].Cells[1].Value = item["Productname"].ToString();
            DataGridView1.Rows[n].Cells[2].Value = item["qty"].ToString();                
            if ((bool)item["productstatus"])
                DataGridView1.Rows[n].Cells[3].Value = "Active";
                DataGridView1.Rows[n].Cells[3].Value = "Deactive";

Check if textbox has empty value

var inp = $("#txt").val();
if(jQuery.trim(inp).length > 0)
   //do something

Removes white space before checking. If the user entered only spaces then this will still work.

SSIS package creating Hresult: 0x80004005 Description: "Login timeout expired" error

I finally found the problem. The error was not the good one.

Apparently, Ole DB source have a bug that might make it crash and throw that error. I replaced the OLE DB destination with a OLE DB Command with the insert statement in it and it fixed it.

The link the got me there:

Strange Bug, Hope it will help other people.

How to find a text inside SQL Server procedures / triggers?

This will work for you:

use [ANALYTICS]  ---> put your DB name here
SELECT sm.object_id, OBJECT_NAME(sm.object_id) AS object_name, o.type, o.type_desc, sm.definition
FROM sys.sql_modules AS sm
JOIN sys.objects AS o ON sm.object_id = o.object_id
where sm.definition like '%SEARCH_WORD_HERE%' collate SQL_Latin1_General_CP1_CI_AS
ORDER BY o.type;

How to display my location on Google Maps for Android API v2

Java code:

public class MapActivity extends FragmentActivity implements LocationListener  {

    GoogleMap googleMap;
    LatLng myPosition;

    protected void onCreate(Bundle savedInstanceState) {

        // Getting reference to the SupportMapFragment of activity_main.xml
        SupportMapFragment fm = (SupportMapFragment)

        // Getting GoogleMap object from the fragment
        googleMap = fm.getMap();

        // Enabling MyLocation Layer of Google Map

        // Getting LocationManager object from System Service LOCATION_SERVICE
        LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);

        // Creating a criteria object to retrieve provider
        Criteria criteria = new Criteria();

        // Getting the name of the best provider
        String provider = locationManager.getBestProvider(criteria, true);

        // Getting Current Location
        Location location = locationManager.getLastKnownLocation(provider);

        if (location != null) {
            // Getting latitude of the current location
            double latitude = location.getLatitude();

            // Getting longitude of the current location
            double longitude = location.getLongitude();

            // Creating a LatLng object for the current location
            LatLng latLng = new LatLng(latitude, longitude);

            myPosition = new LatLng(latitude, longitude);

            googleMap.addMarker(new MarkerOptions().position(myPosition).title("Start"));


<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android=""

You will get your current location in a blue circle.

Prevent HTML5 video from being downloaded (right-click saved)?

We could make that not so easy by hiding context menu, like this:

<video oncontextmenu="return false;"  controls>
  <source src="" >

Simple JavaScript Checkbox Validation

If the check box's ID "Delete" then for the "onclick" event of the submit button the javascript function can be as follows:

<input type="checkbox" name="Delete" value="Delete" id="Delete"></td>
<input type="button" value="Delete" name="delBtn" id="delBtn" onclick="deleteData()">

<script type="text/Javascript">
    function deleteData() {
            alert('Checkbox not checked');
            return false;

nginx: send all requests to a single html page

Your original rewrite should almost work. I'm not sure why it would be redirecting, but I think what you really want is just

rewrite ^ /base.html break;

You should be able to put that in a location or directly in the server.

org.hibernate.exception.SQLGrammarException: could not insert [com.sample.Person]

I solved the error by modifying the following property in hibernate.cfg.xml

  <property name="">validate</property>

Earlier, the table was getting deleted each time I ran the program and now it doesnt, as hibernate only validates the schema and does not affect changes to it.

Purpose of installing Twitter Bootstrap through npm?

If you NPM those modules you can serve them using static redirect.

First install the packages:

npm install jquery
npm install bootstrap

Then on the server.js:

var express = require('express');
var app = express();

// prepare server
app.use('/api', api); // redirect API calls
app.use('/', express.static(__dirname + '/www')); // redirect root
app.use('/js', express.static(__dirname + '/node_modules/bootstrap/dist/js')); // redirect bootstrap JS
app.use('/js', express.static(__dirname + '/node_modules/jquery/dist')); // redirect JS jQuery
app.use('/css', express.static(__dirname + '/node_modules/bootstrap/dist/css')); // redirect CSS bootstrap

Then, finally, at the .html:

<link rel="stylesheet" href="/css/bootstrap.min.css">
<script src="/js/jquery.min.js"></script>
<script src="/js/bootstrap.min.js"></script>

I would not serve pages directly from the folder where your server.js file is (which is usually the same as node_modules) as proposed by timetowonder, that way people can access your server.js file.

Of course you can simply download and copy & paste on your folder, but with NPM you can simply update when needed... easier, I think.

Reading a single char in Java

.... char ch; ...; . . It's the easy way to get character.

Open directory dialog

I know this is an old question, but a simple way to do this is use the FileDialog option provided by WPF and using System.IO.Path.GetDirectory(filename).

Normalization in DOM parsing with java - how does it work?

As an extension to @JBNizet's answer for more technical users here's what implementation of org.w3c.dom.Node interface in looks like, gives you the idea how it actually works.

public void normalize() {
    // No need to normalize if already normalized.
    if (isNormalized()) {
    if (needsSyncChildren()) {
    ChildNode kid;
    for (kid = firstChild; kid != null; kid = kid.nextSibling) {

It traverses all the nodes recursively and calls kid.normalize()
This mechanism is overridden in org.apache.xerces.dom.ElementImpl

public void normalize() {
     // No need to normalize if already normalized.
     if (isNormalized()) {
     if (needsSyncChildren()) {
     ChildNode kid, next;
     for (kid = firstChild; kid != null; kid = next) {
         next = kid.nextSibling;

         // If kid is a text node, we need to check for one of two
         // conditions:
         //   1) There is an adjacent text node
         //   2) There is no adjacent text node, but kid is
         //      an empty text node.
         if ( kid.getNodeType() == Node.TEXT_NODE )
             // If an adjacent text node, merge it with kid
             if ( next!=null && next.getNodeType() == Node.TEXT_NODE )
                 removeChild( next );
                 next = kid; // Don't advance; there might be another.
                 // If kid is empty, remove it
                 if ( kid.getNodeValue() == null || kid.getNodeValue().length() == 0 ) {
                     removeChild( kid );

         // Otherwise it might be an Element, which is handled recursively
         else if (kid.getNodeType() == Node.ELEMENT_NODE) {

     // We must also normalize all of the attributes
     if ( attributes!=null )
         for( int i=0; i<attributes.getLength(); ++i )
             Node attr = attributes.item(i);

    // changed() will have occurred when the removeChild() was done,
    // so does not have to be reissued.


Hope this saves you some time.

Converting xml to string using C#

As Chris suggests, you can do it like this:

public string GetXMLAsString(XmlDocument myxml)
    return myxml.OuterXml;

Or like this:

public string GetXMLAsString(XmlDocument myxml)

        StringWriter sw = new StringWriter();
        XmlTextWriter tx = new XmlTextWriter(sw);

        string str = sw.ToString();// 
        return str;

and if you really want to create a new XmlDocument then do this

XmlDocument newxmlDoc= myxml

clearInterval() not working

i think you should do:

var myInterval
on.onclick = function() {
    myInterval=setInterval(fontChange, 500);

off.onclick = function() {

PHP add elements to multidimensional array with array_push

As in the multi-dimensional array an entry is another array, specify the index of that value to array_push:

array_push($md_array['recipe_type'], $newdata);

jQuery autocomplete with callback ajax json

I hope this helps:

var token = document.getElementById('token').value;
var nombre = document.getElementById('txtNombre').value;    

$("#txtNombre").keyup(function () {
        type: "POST",
        url: host() + "Formulario/BuscarNombreAutocompletar/",
        data: JSON.stringify({ "nombre": nombre }),
        headers: {
            'Authorization': 'Bearer ' + token
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function (data) {
            var dataArray = [];
            if (controlCarga(data)) {

                $.each(data[1], function (i, item) {

                    clearButton: true,
                    source: dataArray,
                    selectFirst: true,
                    minLength: 2
        error: function (xhr, textStatus, errorThrown) {
            console.log('Error: ' + xhr.responseText);

Strip off URL parameter with PHP

This is to complement Marc B's answer with an example, while it may look quite long, it's a safe way to remove a parameter. In this example we remove page_number

$x = '';

$parsed = parse_url($x);
$query = $parsed['query'];

parse_str($query, $params);

$string = http_build_query($params);

Elasticsearch : Root mapping definition has unsupported parameters index : not_analyzed

You're almost here, you're just missing a few things:

PUT /test
  "mappings": {
    "type_name": {                <--- add the type name
      "properties": {             <--- enclose all field definitions in "properties"
        "field1": {
          "type": "integer"
        "field2": {
          "type": "integer"
        "field3": {
          "type": "string",
          "index": "not_analyzed"
        "field4,": {
          "type": "string",
          "analyzer": "autocomplete",
          "search_analyzer": "standard"
  "settings": {


If your index already exists, you can also modify your mappings like this:

PUT test/_mapping/type_name
    "properties": {             <--- enclose all field definitions in "properties"
        "field1": {
          "type": "integer"
        "field2": {
          "type": "integer"
        "field3": {
          "type": "string",
          "index": "not_analyzed"
        "field4,": {
          "type": "string",
          "analyzer": "autocomplete",
          "search_analyzer": "standard"


As of ES 7, mapping types have been removed. You can read more details here

Fit Image in ImageButton in Android

I'm using android:scaleType="fitCenter" with satisfaction.

Conversion from 12 hours time to 24 hours time in java

This is the extract of code that I have done.

    String s="08:10:45";
    String[] s1=s.split(":");
    int milipmHrs=0;
    char[] arr=s1[2].toCharArray();
    boolean isFound=s1[2].contains("PM");
        int pmHrs=Integer.parseInt(s1[0]);


Hex colors: Numeric representation for "transparent"?

Very simple: no color, no opacity:

rgba(0, 0, 0, 0);

MySQL high CPU usage

If this server is visible to the outside world, It's worth checking if it's having lots of requests to connect from the outside world (i.e. people trying to break into it)

Script @php artisan package:discover handling the post-autoload-dump event returned with error code 1

I have same issue

above this error

Script @php artisan package:discover handling the post-autoload-dump event returned with error code 1

I found one more message in my terminal like: "

"Cartalyst\Stripe\Laravel\StripeServiceProvider::class, not found in your ProviderRepository.php"

then i go config/app.php and find


comment it out then run

composer update

it will work fine **In your case maybe package name is different please check your terminal **