Programs & Examples On #Remote server

remote-server is a machine used for data processing which is accessed via a network

Remove a file from a Git repository without deleting it from the local filesystem

You can also remove files from the repository based on your .gitignore without deleting them from the local file system :

git rm --cached `git ls-files -i -X .gitignore`

Or, alternatively, on Windows Powershell:

git rm --cached $(git ls-files -i -X .gitignore)

Connect to external server by using phpMyAdmin

To set up an external DB and still use your local DB, you need to edit the config.inc.php file:

On Ubuntu: sudo gedit /etc/phpmyadmin/config.inc.php

The file is roughly set up like this:

if (!empty($dbname)) {

    //Your local db setup

     $i++;
}

What you need to do is duplicate the "your local db setup" by copying and pasting it outside of the IF statement I've shown in the code below, and change the host to you external IP. Mine for example is:

$cfg['Servers'][$i]['host'] = '10.10.1.90:23306';

You can leave the defaults (unless you know you need to change them)

Save and refresh your PHPMYADMIN login page and a new dropdown should appear. You should be good to go.


EDIT: if you want to give the server a name to select at login page, rather than having just the IP address to select, add this to the server setup:

$cfg['Servers'][$i]['verbose'] = 'Name to show when selecting your server'; 

It's good if you have multiple server configs.

How to execute a shell script on a remote server using Ansible?

you can use script module

Example

- name: Transfer and execute a script.
  hosts: all
  tasks:

     - name: Copy and Execute the script 
       script: /home/user/userScript.sh

Connecting to remote MySQL server using PHP

I just solved this kind of a problem. What I've learned is:

  1. you'll have to edit the my.cnf and set the bind-address = your.mysql.server.address under [mysqld]
  2. comment out skip-networking field
  3. restart mysqld
  4. check if it's running

    mysql -u root -h your.mysql.server.address –p 
    
  5. create a user (usr or anything) with % as domain and grant her access to the database in question.

    mysql> CREATE USER 'usr'@'%' IDENTIFIED BY 'some_pass';
    mysql> GRANT ALL PRIVILEGES ON testDb.* TO 'monty'@'%' WITH GRANT OPTION;
    
  6. open firewall for port 3306 (you can use iptables. make sure to open port for eithe reveryone, or if you're in tight securety, then only allow the client address)

  7. restart firewall/iptables

you should be able to now connect mysql server form your client server php script.

How to open remote files in sublime text 3

On server

Install rsub:

wget -O /usr/local/bin/rsub \https://raw.github.com/aurora/rmate/master/rmate
chmod a+x /usr/local/bin/rsub

On local

  1. Install rsub Sublime3 package:

On Sublime Text 3, open Package Manager (Ctrl-Shift-P on Linux/Win, Cmd-Shift-P on Mac, Install Package), and search for rsub and install it

  1. Open command line and connect to remote server:

ssh -R 52698:localhost:52698 server_user@server_address

  1. after connect to server run this command on server:

rsub path_to_file/file.txt

  1. File opening auto in Sublime 3

As of today (2018/09/05) you should use : https://github.com/randy3k/RemoteSubl because you can find it in packagecontrol.io while "rsub" is not present.

How do I push a local Git branch to master branch in the remote?

$ git push origin develop:master

or, more generally

$ git push <remote> <local branch name>:<remote branch to push into>

How to connect to a remote Windows machine to execute commands using python?

Many answers already, but one more option

PyPSExec https://pypi.org/project/pypsexec/

It's a python clone of the famous psexec. Works without any installation on the remote windows machine.

Laravel Migration Error: Syntax error or access violation: 1071 Specified key was too long; max key length is 767 bytes

I'm just adding this answer here as it's the quickest solution for me. Just set the default database engine to 'InnoDB' on

/config/database.php

'mysql' => [
    ...,
    ...,
    'engine' => 'InnoDB',
 ]

then run php artisan config:cache to clear and refresh the configuration cache

EDIT: Answers found here might explain what's behind the scenes of this one

What is jQuery Unobtrusive Validation?

jQuery Validation Unobtrusive Native is a collection of ASP.Net MVC HTML helper extensions. These make use of jQuery Validation's native support for validation driven by HTML 5 data attributes. Microsoft shipped jquery.validate.unobtrusive.js back with MVC 3. It provided a way to apply data model validations to the client side using a combination of jQuery Validation and HTML 5 data attributes (that's the "unobtrusive" part).

Failed: Error in connection establishment: net::ERR_CONNECTION_REFUSED

In my case the answer is pretty simple. Please check carefully the hardcoded url port: it is 8080. For some reason the value has changed to: for example 3030.

Just refresh the port in your ajax url string to the appropriate one.

conn = new WebSocket('ws://localhost:3030'); //should solve the issue

Error sending json in POST to web API service

  1. You have to must add header property Content-Type:application/json
  2. When you define any POST request method input parameter that should be annotated as [FromBody], e.g.:

    [HttpPost]
    public HttpResponseMessage Post([FromBody]ActivityResult ar)
    {
      return new HttpResponseMessage(HttpStatusCode.OK);
    }
    
  3. Any JSON input data must be raw data.

Android how to convert int to String?

You called an incorrect method of String class, try:

int tmpInt = 10;
String tmpStr10 = String.valueOf(tmpInt);

You can also do:

int tmpInt = 10;
String tmpStr10 = Integer.toString(tmpInt);

Primitive type 'short' - casting in Java

What language are you using?

Many C based languages have a rule that any mathematical expression is performed in size int or larger. Because of this, once you add two shorts the result is of type int. This causes the need for a cast.

What precisely does 'Run as administrator' do?

The Run as *Anything command saves you from logging out and logging in as the user for which you use the runas command for.

The reason programs ask for this elevated privilege started with Black Comb and the Panther folder. There is 0 access to the Kernel in windows unless through the Admin prompt and then it is only a virtual relation with the O/S kernel.

Hoorah!

Display DateTime value in dd/mm/yyyy format in Asp.NET MVC

After few hours of searching, I just solved this issue with a few lines of code

Your model

      [Required(ErrorMessage = "Enter the issued date.")]
      [DataType(DataType.Date)]
      public DateTime IssueDate { get; set; }

Razor Page

     @Html.TextBoxFor(model => model.IssueDate)
     @Html.ValidationMessageFor(model => model.IssueDate)

Jquery DatePicker

<script type="text/javascript">
    $(document).ready(function () {
        $('#IssueDate').datepicker({
            dateFormat: "dd/mm/yy",
            showStatus: true,
            showWeeks: true,
            currentText: 'Now',
            autoSize: true,
            gotoCurrent: true,
            showAnim: 'blind',
            highlightWeek: true
        });
    });
</script>

Webconfig File

    <system.web>
        <globalization uiCulture="en" culture="en-GB"/>
    </system.web>

Now your text-box will accept "dd/MM/yyyy" format.

Copying formula to the next row when inserting a new row

Private Sub Worksheet_Change(ByVal Target As Range)

'data starts on row 3 which has the formulas
'the sheet is protected - input cells not locked - formula cells locked
'this routine is triggered on change of any cell on the worksheet so first check if
' it's a cell that we're interested in - and the row doesn't already have formulas
If Target.Column = 3 And Target.Row > 3 _
And Range("M" & Target.Row).Formula = "" Then

    On Error GoTo ERROR_OCCURRED

    'unprotect the sheet - otherwise can't copy and paste
    ActiveSheet.Unprotect
    'disable events - this prevents this routine from triggering again when
    'copy and paste below changes the cell values
    Application.EnableEvents = False

    'copy col D (with validation list) from row above to new row (not locked)
    Range("D" & Target.Row - 1).Copy
    Range("D" & Target.Row).PasteSpecial

    'copy col M to P (with formulas) from row above to new row
    Range("M" & Target.Row - 1 & ":P" & Target.Row - 1).Copy
    Range("M" & Target.Row).PasteSpecial

'make sure if an error occurs (or not) events are re-enabled and sheet re-protected

ERROR_OCCURRED:

    If Err.Number <> 0 Then
        MsgBox "An error occurred. Formulas may not have been copied." & vbCrLf & vbCrLf & _
            Err.Number & " - " & Err.Description
    End If

    're-enable events
    Application.EnableEvents = True
    're-protect the sheet
    ActiveSheet.Protect

    'put focus back on the next cell after routine was triggered
    Range("D" & Target.Row).Select

End If

End Sub

XPath: select text node

your xpath should work . i have tested your xpath and mine in both MarkLogic and Zorba Xquery/ Xpath implementation.

Both should work.

/node/child::text()[1] - should return Text1
/node/child::text()[2] - should return text2


/node/text()[1] - should return Text1
/node/text()[2] - should return text2

What is this spring.jpa.open-in-view=true property in Spring Boot?

The OSIV Anti-Pattern

Instead of letting the business layer decide how it’s best to fetch all the associations that are needed by the View layer, OSIV (Open Session in View) forces the Persistence Context to stay open so that the View layer can trigger the Proxy initialization, as illustrated by the following diagram.

enter image description here

  • The OpenSessionInViewFilter calls the openSession method of the underlying SessionFactory and obtains a new Session.
  • The Session is bound to the TransactionSynchronizationManager.
  • The OpenSessionInViewFilter calls the doFilter of the javax.servlet.FilterChain object reference and the request is further processed
  • The DispatcherServlet is called, and it routes the HTTP request to the underlying PostController.
  • The PostController calls the PostService to get a list of Post entities.
  • The PostService opens a new transaction, and the HibernateTransactionManager reuses the same Session that was opened by the OpenSessionInViewFilter.
  • The PostDAO fetches the list of Post entities without initializing any lazy association.
  • The PostService commits the underlying transaction, but the Session is not closed because it was opened externally.
  • The DispatcherServlet starts rendering the UI, which, in turn, navigates the lazy associations and triggers their initialization.
  • The OpenSessionInViewFilter can close the Session, and the underlying database connection is released as well.

At first glance, this might not look like a terrible thing to do, but, once you view it from a database perspective, a series of flaws start to become more obvious.

The service layer opens and closes a database transaction, but afterward, there is no explicit transaction going on. For this reason, every additional statement issued from the UI rendering phase is executed in auto-commit mode. Auto-commit puts pressure on the database server because each transaction issues a commit at end, which can trigger a transaction log flush to disk. One optimization would be to mark the Connection as read-only which would allow the database server to avoid writing to the transaction log.

There is no separation of concerns anymore because statements are generated both by the service layer and by the UI rendering process. Writing integration tests that assert the number of statements being generated requires going through all layers (web, service, DAO) while having the application deployed on a web container. Even when using an in-memory database (e.g. HSQLDB) and a lightweight webserver (e.g. Jetty), these integration tests are going to be slower to execute than if layers were separated and the back-end integration tests used the database, while the front-end integration tests were mocking the service layer altogether.

The UI layer is limited to navigating associations which can, in turn, trigger N+1 query problems. Although Hibernate offers @BatchSize for fetching associations in batches, and FetchMode.SUBSELECT to cope with this scenario, the annotations are affecting the default fetch plan, so they get applied to every business use case. For this reason, a data access layer query is much more suitable because it can be tailored to the current use case data fetch requirements.

Last but not least, the database connection is held throughout the UI rendering phase which increases connection lease time and limits the overall transaction throughput due to congestion on the database connection pool. The more the connection is held, the more other concurrent requests are going to wait to get a connection from the pool.

Spring Boot and OSIV

Unfortunately, OSIV (Open Session in View) is enabled by default in Spring Boot, and OSIV is really a bad idea from a performance and scalability perspective.

So, make sure that in the application.properties configuration file, you have the following entry:

spring.jpa.open-in-view=false

This will disable OSIV so that you can handle the LazyInitializationException the right way.

Starting with version 2.0, Spring Boot issues a warning when OSIV is enabled by default, so you can discover this problem long before it affects a production system.

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

Try replacing your meta tag with this below:

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

Or in addition to what you have, you should add http://* to both style-src and script-src as seen above added after 'self'.

If your server is including the Content-Security-Policy header, the header will override the meta.

How do I link a JavaScript file to a HTML file?

You can add script tags in your HTML document, ideally inside the which points to your javascript files. Order of the script tags are important. Load the jQuery before your script files if you want to use jQuery from your script.

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script type="text/javascript" src="relative/path/to/your/javascript.js"></script>

Then in your javascript file you can refer to jQuery either using $ sign or jQuery. Example:

jQuery.each(arr, function(i) { console.log(i); }); 

How can I print out all possible letter combinations a given phone number can represent?

This problem is similar to this leetcode problem. Here is the answer I submitted for this problem to leetcode (check github and video for explanation).

So the very first thing we need is some way to hold the mappings of a digit and we can use a map for this:

private Map<Integer, String> getDigitMap() {
        return Stream.of(
                new AbstractMap.SimpleEntry<>(2, "abc"),
                new AbstractMap.SimpleEntry<>(3, "def"),
                new AbstractMap.SimpleEntry<>(4, "ghi"),
                new AbstractMap.SimpleEntry<>(5, "jkl"),
                new AbstractMap.SimpleEntry<>(6, "mno"),
                new AbstractMap.SimpleEntry<>(7, "pqrs"),
                new AbstractMap.SimpleEntry<>(8, "tuv"),
                new AbstractMap.SimpleEntry<>(9, "wxyz"))
               .collect(Collectors.toMap(AbstractMap.SimpleEntry::getKey, 
                                AbstractMap.SimpleEntry::getValue));
}

The above method is preparing the map and next method I would use is to provide the mapping for provided digit:

private String getDigitMappings(String strDigit, Map<Integer,String> digitMap) {
        int digit = Integer.valueOf(strDigit);
        return digitMap.containsKey(digit) ? digitMap.get(digit) : "";
}

This problem can be solved using backtracking and a backtracking solution generally has a structure where the method signature will contain: result container, temp results, original source with index etc. So the method structure would be of the form:

private void compute(List<String> result, StringBuilder temp, String digits, int start, Map<Integer, String> digitMap) {
       // Condition to populate temp value to result
       // explore other arrangements based on the next input digit
       // Loop around the mappings of a digit and then to explore invoke the same method recursively
       // Also need to remove the digit which was in temp at last so as to get proper value in temp for next cycle in loop
}

And now the method body can be filled as (result will be kept in a list, temp in string builder etc.)

private void compute(List<String> result, StringBuilder temp, String digits, int start, Map<Integer, String> digitMap) {
        if(start >= digits.length()) { // condition
            result.add(temp.toString());
            return;
        }

        String letters = getDigitMappings(digits.substring(start, start + 1), digitMap); // mappings of a digit to loop around
        for (int i = 0; i < letters.length(); i++) {
            temp.append(letters.charAt(i));
            compute(result, temp, digits, start+1, digitMap); //explore for remaining digits
            temp.deleteCharAt(temp.length() - 1); // remove last in temp
        }
}

And finally the method can be invoked as:

public List<String> letterCombinations(String digits) {
        List<String> result = new ArrayList<>();
        if(digits == null || digits.length() == 0) return result;
        compute(result, new StringBuilder(), digits, 0, getDigitMap());
        return result;
}

Now the max mapped chars for a digit can be 4 (e.g. 9 has wxyz) and backtracking involves exhaustive search to explore all possible arrangements (state space tree) so for a digit of size n we are going to have 4x4x4....n times i.e. complexity would be O(4^n).

Difference between & and && in Java?

&& == logical AND

& = bitwise AND

Ruby max integer

as @Jörg W Mittag pointed out: in jruby, fix num size is always 8 bytes long. This code snippet shows the truth:

fmax = ->{
  if RUBY_PLATFORM == 'java'
    2**63 - 1
  else
    2**(0.size * 8 - 2) - 1
  end
}.call

p fmax.class     # Fixnum

fmax = fmax + 1  

p fmax.class     #Bignum

Combine two columns and add into one new column

Generally, I agree with @kgrittn's advice. Go for it.

But to address your basic question about concat(): The new function concat() is useful if you need to deal with null values - and null has neither been ruled out in your question nor in the one you refer to.

If you can rule out null values, the good old (SQL standard) concatenation operator || is still the best choice, and @luis' answer is just fine:

SELECT col_a || col_b;

If either of your columns can be null, the result would be null in that case. You could defend with COALESCE:

SELECT COALESCE(col_a, '') || COALESCE(col_b, '');

But that get tedious quickly with more arguments. That's where concat() comes in, which never returns null, not even if all arguments are null. Per documentation:

NULL arguments are ignored.

SELECT concat(col_a, col_b);

The remaining corner case for both alternatives is where all input columns are null in which case we still get an empty string '', but one might want null instead (at least I would). One possible way:

SELECT CASE
          WHEN col_a IS NULL THEN col_b
          WHEN col_b IS NULL THEN col_a
          ELSE col_a || col_b
       END;

This gets more complex with more columns quickly. Again, use concat() but add a check for the special condition:

SELECT CASE WHEN (col_a, col_b) IS NULL THEN NULL
            ELSE concat(col_a, col_b) END;

How does this work?
(col_a, col_b) is shorthand notation for a row type expression ROW (col_a, col_b). And a row type is only null if all columns are null. Detailed explanation:

Also, use concat_ws() to add separators between elements (ws for "with separator").


An expression like the one in Kevin's answer:

SELECT $1.zipcode || ' - ' || $1.city || ', ' || $1.state;

is tedious to prepare for null values in PostgreSQL 8.3 (without concat()). One way (of many):

SELECT COALESCE(
         CASE
            WHEN $1.zipcode IS NULL THEN $1.city
            WHEN $1.city    IS NULL THEN $1.zipcode
            ELSE $1.zipcode || ' - ' || $1.city
         END, '')
       || COALESCE(', ' || $1.state, '');

Function volatility is only STABLE

concat() and concat_ws() are STABLE functions, not IMMUTABLE because they can invoke datatype output functions (like timestamptz_out) that depend on locale settings.
Explanation by Tom Lane.

This prohibits their direct use in index expressions. If you know that the result is actually immutable in your case, you can work around this with an IMMUTABLE function wrapper. Example here:

SignalR - Sending a message to a specific user using (IUserIdProvider) *NEW 2.0.0*

SignalR provides ConnectionId for each connection. To find which connection belongs to whom (the user), we need to create a mapping between the connection and the user. This depends on how you identify a user in your application.

In SignalR 2.0, this is done by using the inbuilt IPrincipal.Identity.Name, which is the logged in user identifier as set during the ASP.NET authentication.

However, you may need to map the connection with the user using a different identifier instead of using the Identity.Name. For this purpose this new provider can be used with your custom implementation for mapping user with the connection.

Example of Mapping SignalR Users to Connections using IUserIdProvider

Lets assume our application uses a userId to identify each user. Now, we need to send message to a specific user. We have userId and message, but SignalR must also know the mapping between our userId and the connection.

To achieve this, first we need to create a new class which implements IUserIdProvider:

public class CustomUserIdProvider : IUserIdProvider
{
     public string GetUserId(IRequest request)
    {
        // your logic to fetch a user identifier goes here.

        // for example:

        var userId = MyCustomUserClass.FindUserId(request.User.Identity.Name);
        return userId.ToString();
    }
}

The second step is to tell SignalR to use our CustomUserIdProvider instead of the default implementation. This can be done in the Startup.cs while initializing the hub configuration:

public class Startup
{
    public void Configuration(IAppBuilder app)
    {
        var idProvider = new CustomUserIdProvider();

        GlobalHost.DependencyResolver.Register(typeof(IUserIdProvider), () => idProvider);          

        // Any connection or hub wire up and configuration should go here
        app.MapSignalR();
    }
}

Now, you can send message to a specific user using his userId as mentioned in the documentation, like:

public class MyHub : Hub
{
   public void Send(string userId, string message)
   {
      Clients.User(userId).send(message);
   }
}

Hope this helps.

CSS rounded corners in IE8

Rounded corners in IE8

Internet Explorer 8 (and earlier versions) doesn't support rounded corners, however there are few other solutions you may consider:

  • Use Rounded Corners Images instead (this generator is a good resource)

  • Use a jQuery Corner plugin from here

  • Use a very good script called CSS3 PIE from here (Pro's & Con's here)

  • Checkout CSS Juice from here

  • Another good script is IE-CSS3 from here

Even though CSS PIE is the most popular solution, I'm suggesting you to review all other solutions and choose what works best for your needs.

Hope it was useful. Good Luck!

Copy Paste in Bash on Ubuntu on Windows

you might have bash but it is still a windows window manager. Highlite some text in the bash terminal window. Right click on the title bar, select "Edit", select "Copy", Now Right Click again on the Title bar, select "Edit" , Select "Paste", Done. You should be able to Highlite text, hit "Enter" then Control V but this seems to be broken

How to convert milliseconds into human readable form?

Well, since nobody else has stepped up, I'll write the easy code to do this:

x = ms / 1000
seconds = x % 60
x /= 60
minutes = x % 60
x /= 60
hours = x % 24
x /= 24
days = x

I'm just glad you stopped at days and didn't ask for months. :)

Note that in the above, it is assumed that / represents truncating integer division. If you use this code in a language where / represents floating point division, you will need to manually truncate the results of the division as needed.

case-insensitive matching in xpath?

XPath 2 has a lower-case (and upper-case) string function. That's not quite the same as case-insensitive, but hopefully it will be close enough:

//CD[lower-case(@title)='empire burlesque']

If you are using XPath 1, there is a hack using translate.

Select query to remove non-numeric characters

This worked for me:

  1. I removed the single quotes.

  2. I then used a replace "," with ".".

Surely this will help someone:

" & txtFinalscore.Text.Replace(",", ".") & "

How to add text at the end of each line in Vim?

I have <M-DOWN>(alt down arrow) mapped to <DOWN>. so that I can repeat the last command on a series of lines very quickly. with this mapping I can:

A,<ESC>

And then hold alt while pressing down repeatedly to append the comma to the end of each line.
This works well for me because it allows very good control over what lines do and do not get the change.
(I also have the other arrows mapped similarly to allow for easy repeating of .)

Here's the mapping line to paste into your vimrc:

map <M-DOWN> <DOWN>.

What is the purpose of the return statement?

Just to add to @Nathan Hughes's excellent answer:

The return statement can be used as a kind of control flow. By putting one (or more) return statements in the middle of a function, we can say: "stop executing this function. We've either got what we wanted or something's gone wrong!"

Here's an example:

>>> def make_3_characters_long(some_string):
...     if len(some_string) == 3:
...         return False
...     if str(some_string) != some_string:
...         return "Not a string!"
...     if len(some_string) < 3:
...         return ''.join(some_string,'x')[:,3]
...     return some_string[:,3]
... 
>>> threechars = make_3_characters_long('xyz')    
>>> if threechars:
...     print threechars
... else:
...     print "threechars is already 3 characters long!"
... 
threechars is already 3 characters long!

See the Code Style section of the Python Guide for more advice on this way of using return.

VarBinary vs Image SQL Server Data Type to Store Binary Data?

Since image is deprecated, you should use varbinary.

per Microsoft (thanks for the link @Christopher)

ntext , text, and image data types will be removed in a future version of Microsoft SQL Server. Avoid using these data types in new development work, and plan to modify applications that currently use them. Use nvarchar(max), varchar(max), and varbinary(max) instead.

Fixed and variable-length data types for storing large non-Unicode and Unicode character and binary data. Unicode data uses the UNICODE UCS-2 character set.

.includes() not working in Internet Explorer

It works for me:

function stringIncludes(a, b) {
      return a.indexOf(b) !== -1;
}

How to check if a specific key is present in a hash or not?

While Hash#has_key? gets the job done, as Matz notes here, it has been deprecated in favour of Hash#key?.

hash.key?(some_key)

Java: Rotating Images

public static BufferedImage rotateCw( BufferedImage img )
{
    int         width  = img.getWidth();
    int         height = img.getHeight();
    BufferedImage   newImage = new BufferedImage( height, width, img.getType() );

    for( int i=0 ; i < width ; i++ )
        for( int j=0 ; j < height ; j++ )
            newImage.setRGB( height-1-j, i, img.getRGB(i,j) );

    return newImage;
}

from https://coderanch.com/t/485958/java/Rotating-buffered-image

python pandas: apply a function with arguments to a series

Steps:

  1. Create a dataframe
  2. Create a function
  3. Use the named arguments of the function in the apply statement.

Example

x=pd.DataFrame([1,2,3,4])  

def add(i1, i2):  
    return i1+i2

x.apply(add,i2=9)

The outcome of this example is that each number in the dataframe will be added to the number 9.

    0
0  10
1  11
2  12
3  13

Explanation:

The "add" function has two parameters: i1, i2. The first parameter is going to be the value in data frame and the second is whatever we pass to the "apply" function. In this case, we are passing "9" to the apply function using the keyword argument "i2".

What are the differences between stateless and stateful systems, and how do they impact parallelism?

A stateless system can be seen as a box [black? ;)] where at any point in time the value of the output(s) depends only on the value of the input(s) [after a certain processing time]

A stateful system instead can be seen as a box where at any point in time the value of the output(s) depends on the value of the input(s) and of an internal state, so basicaly a stateful system is like a state machine with "memory" as the same set of input(s) value can generate different output(s) depending on the previous input(s) received by the system.

From the parallel programming point of view, a stateless system, if properly implemented, can be executed by multiple threads/tasks at the same time without any concurrency issue [as an example think of a reentrant function] A stateful system will requires that multiple threads of execution access and update the internal state of the system in an exclusive way, hence there will be a need for a serialization [synchronization] point.

Using current time in UTC as default value in PostgreSQL

These are 2 equivalent solutions:

(in the following code, you should substitute 'UTC' for zone and now() for timestamp)

  1. timestamp AT TIME ZONE zone - SQL-standard-conforming
  2. timezone(zone, timestamp) - arguably more readable

The function timezone(zone, timestamp) is equivalent to the SQL-conforming construct timestamp AT TIME ZONE zone.


Explanation:

  • zone can be specified either as a text string (e.g., 'UTC') or as an interval (e.g., INTERVAL '-08:00') - here is a list of all available time zones
  • timestamp can be any value of type timestamp
  • now() returns a value of type timestamp (just what we need) with your database's default time zone attached (e.g. 2018-11-11T12:07:22.3+05:00).
  • timezone('UTC', now()) turns our current time (of type timestamp with time zone) into the timezonless equivalent in UTC.
    E.g., SELECT timestamp with time zone '2020-03-16 15:00:00-05' AT TIME ZONE 'UTC' will return 2020-03-16T20:00:00Z.

Docs: timezone()

Spring Bean Scopes

According to the documentation of Spring-Cloud-Config there is one extra scope next to the existing five. It is @RefreshScope.

This is the short description of RefreshScope:

When there is a configuration change, a Spring @Bean that is marked as @RefreshScope gets special treatment. This feature addresses the problem of stateful beans that only get their configuration injected when they are initialized. For instance, if a DataSource has open connections when the database URL is changed via the Environment, you probably want the holders of those connections to be able to complete what they are doing. Then, the next time something borrows a connection from the pool, it gets one with the new URL.

Sometimes, it might even be mandatory to apply the @RefreshScope annotation on some beans which can be only initialized once. If a bean is "immutable", you will have to either annotate the bean with @RefreshScope or specify the classname under the property key spring.cloud.refresh.extra-refreshable.

Refresh scope beans are lazy proxies that initialize when they are used (that is, when a method is called), and the scope acts as a cache of initialized values. To force a bean to re-initialize on the next method call, you must invalidate its cache entry.

The RefreshScope is a bean in the context and has a public refreshAll() method to refresh all beans in the scope by clearing the target cache. The /refresh endpoint exposes this functionality (over HTTP or JMX). To refresh an individual bean by name, there is also a refresh(String) method.

How to run an external program, e.g. notepad, using hyperlink?

The reasonable way how to launch apps from HTML is through url schemes. So you can launch email via mailto: links and irc through irc: links. Individual apps can implement these schemes, but I'm not sure WinMerge does this.

Bug? #1146 - Table 'xxx.xxxxx' doesn't exist

I encountered the same problem today. I was trying to create a table users, and was prompted that ERROR 1146 (42S02): Table users doesn't exist, which did not make any sense, because I was just trying to create the table!!

I then tried to drop the table by typing DROP TABLE users, knowing it would fail because it did not exist, and I got an error, saying Unknown table users. After getting this error, I tried to create the table again, and magically, it successfully created the table!

My intuition is that I probably created this table before and it was not completely cleared somehow. By explicitly saying DROP TABLE I managed to reset the internal state somehow? But that is just my guess.

In short, try DROP whatever table you are creating, and CREATE it again.

How do I convert a Python program to a runnable .exe Windows program?

If it is a simple py script refer here

Else for GUI :

$ pip3 install cx_Freeze

1) Create a setup.py file and put in the same directory as of the .py file you want to convert.

2)Copy paste the following lines in the setup.py and do change the "filename.py" into the filename you specified.

from cx_Freeze import setup, Executable
setup(
    name="GUI PROGRAM",
    version="0.1",
    description="MyEXE",
    executables=[Executable("filename.py", base="Win32GUI")],
    )

3) Run the setup.py "$python setup.py build"

4)A new directory will be there there called "build". Inside it you will get your .exe file to be ready to launced directly. (Make sure you copy paste the images files and other external files into the build directory)

How do I get the time of day in javascript/Node.js?

Check out the moment.js library. It works with browsers as well as with Node.JS. Allows you to write

moment().hour();

or

moment().hours();

without prior writing of any functions.

Global and local variables in R

<- does assignment in the current environment.

When you're inside a function R creates a new environment for you. By default it includes everything from the environment in which it was created so you can use those variables as well but anything new you create will not get written to the global environment.

In most cases <<- will assign to variables already in the global environment or create a variable in the global environment even if you're inside a function. However, it isn't quite as straightforward as that. What it does is checks the parent environment for a variable with the name of interest. If it doesn't find it in your parent environment it goes to the parent of the parent environment (at the time the function was created) and looks there. It continues upward to the global environment and if it isn't found in the global environment it will assign the variable in the global environment.

This might illustrate what is going on.

bar <- "global"
foo <- function(){
    bar <- "in foo"
    baz <- function(){
        bar <- "in baz - before <<-"
        bar <<- "in baz - after <<-"
        print(bar)
    }
    print(bar)
    baz()
    print(bar)
}
> bar
[1] "global"
> foo()
[1] "in foo"
[1] "in baz - before <<-"
[1] "in baz - after <<-"
> bar
[1] "global"

The first time we print bar we haven't called foo yet so it should still be global - this makes sense. The second time we print it's inside of foo before calling baz so the value "in foo" makes sense. The following is where we see what <<- is actually doing. The next value printed is "in baz - before <<-" even though the print statement comes after the <<-. This is because <<- doesn't look in the current environment (unless you're in the global environment in which case <<- acts like <-). So inside of baz the value of bar stays as "in baz - before <<-". Once we call baz the copy of bar inside of foo gets changed to "in baz" but as we can see the global bar is unchanged. This is because the copy of bar that is defined inside of foo is in the parent environment when we created baz so this is the first copy of bar that <<- sees and thus the copy it assigns to. So <<- isn't just directly assigning to the global environment.

<<- is tricky and I wouldn't recommend using it if you can avoid it. If you really want to assign to the global environment you can use the assign function and tell it explicitly that you want to assign globally.

Now I change the <<- to an assign statement and we can see what effect that has:

bar <- "global"
foo <- function(){
    bar <- "in foo"   
    baz <- function(){
        assign("bar", "in baz", envir = .GlobalEnv)
    }
    print(bar)
    baz()
    print(bar)
}
bar
#[1] "global"
foo()
#[1] "in foo"
#[1] "in foo"
bar
#[1] "in baz"

So both times we print bar inside of foo the value is "in foo" even after calling baz. This is because assign never even considered the copy of bar inside of foo because we told it exactly where to look. However, this time the value of bar in the global environment was changed because we explicitly assigned there.

Now you also asked about creating local variables and you can do that fairly easily as well without creating a function... We just need to use the local function.

bar <- "global"
# local will create a new environment for us to play in
local({
    bar <- "local"
    print(bar)
})
#[1] "local"
bar
#[1] "global"

Change default icon

Your application icon shows in the taskbar. The icon on the topleft (window) is the form-icon. Go to your form and fill the property "icon" with the same icon; problem solved. You don't need to put the icon in the outputfolder (that's just for setups).

Extract code country from phone number [libphonenumber]

If the string containing the phone number will always start this way (+33 or another country code) you should use regex to parse and get the country code and then use the library to get the country associated to the number.

Setting Column width in Apache POI

Please be carefull with the usage of autoSizeColumn(). It can be used without problems on small files but please take care that the method is called only once (at the end) for each column and not called inside a loop which would make no sense.

Please avoid using autoSizeColumn() on large Excel files. The method generates a performance problem.

We used it on a 110k rows/11 columns file. The method took ~6m to autosize all columns.

For more details have a look at: How to speed up autosizing columns in apache POI?

What would be the Unicode character for big bullet in the middle of the character?

You can use a span with 50% border radius.

_x000D_
_x000D_
 .mydot{_x000D_
     background: rgb(66, 183, 42);_x000D_
     border-radius: 50%;_x000D_
     display: inline-block;_x000D_
     height: 20px;_x000D_
     margin-left: 4px;_x000D_
     margin-right: 4px;_x000D_
     width: 20px;_x000D_
}    
_x000D_
<span class="mydot"></span>
_x000D_
_x000D_
_x000D_

How to increase scrollback buffer size in tmux?

This builds on ntc2 and Chris Johnsen's answer. I am using this whenever I want to create a new session with a custom history-limit. I wanted a way to create sessions with limited scrollback without permanently changing my history-limit for future sessions.

tmux set-option -g history-limit 100 \; new-session -s mysessionname \; set-option -g history-limit 2000

This works whether or not there are existing sessions. After setting history-limit for the new session it resets it back to the default which for me is 2000.

I created an executable bash script that makes this a little more useful. The 1st parameter passed to the script sets the history-limit for the new session and the 2nd parameter sets its session name:

#!/bin/bash
tmux set-option -g history-limit "${1}" \; new-session -s "${2}" \; set-option -g history-limit 2000

Append a single character to a string or char array in java?

You'll want to use the static method Character.toString(char c) to convert the character into a string first. Then you can use the normal string concatenation functions.

CSV with comma or semicolon?

In Windows it is dependent on the "Regional and Language Options" customize screen where you find a List separator. This is the char Windows applications expect to be the CSV separator.

Of course this only has effect in Windows applications, for example Excel will not automatically split data into columns if the file is not using the above mentioned separator. All applications that use Windows regional settings will have this behavior.

If you are writing a program for Windows that will require importing the CSV in other applications and you know that the list separator set for your target machines is ,, then go for it, otherwise I prefer ; since it causes less problems with decimal points, digit grouping and does not appear in much text.

Closing pyplot windows

plt.close() will close current instance.

plt.close(2) will close figure 2

plt.close(plot1) will close figure with instance plot1

plt.close('all') will close all fiures

Found here.

Remember that plt.show() is a blocking function, so in the example code you used above, plt.close() isn't being executed until the window is closed, which makes it redundant.

You can use plt.ion() at the beginning of your code to make it non-blocking, although this has other implications.

EXAMPLE

After our discussion in the comments, I've put together a bit of an example just to demonstrate how the plot functionality can be used.

Below I create a plot:

fig = plt.figure(figsize=plt.figaspect(0.75))
ax = fig.add_subplot(1, 1, 1)
....
par_plot, = plot(x_data,y_data, lw=2, color='red')

In this case, ax above is a handle to a pair of axes. Whenever I want to do something to these axes, I can change my current set of axes to this particular set by calling axes(ax).

par_plot is a handle to the line2D instance. This is called an artist. If I want to change a property of the line, like change the ydata, I can do so by referring to this handle.

I can also create a slider widget by doing the following:

axsliderA = axes([0.12, 0.85, 0.16, 0.075])
sA = Slider(axsliderA, 'A', -1, 1.0, valinit=0.5)
sA.on_changed(update)

The first line creates a new axes for the slider (called axsliderA), the second line creates a slider instance sA which is placed in the axes, and the third line specifies a function to call when the slider value changes (update).

My update function could look something like this:

def update(val):
    A = sA.val
    B = sB.val
    C = sC.val
    y_data = A*x_data*x_data + B*x_data + C
    par_plot.set_ydata(y_data)
    draw()

The par_plot.set_ydata(y_data) changes the ydata property of the Line2D object with the handle par_plot.

The draw() function updates the current set of axes.

Putting it all together:

from pylab import *
import matplotlib.pyplot as plt
import numpy

def update(val):
    A = sA.val
    B = sB.val
    C = sC.val
    y_data = A*x_data*x_data + B*x_data + C
    par_plot.set_ydata(y_data)
    draw()


x_data = numpy.arange(-100,100,0.1);

fig = plt.figure(figsize=plt.figaspect(0.75))
ax = fig.add_subplot(1, 1, 1)
subplots_adjust(top=0.8)

ax.set_xlim(-100, 100);
ax.set_ylim(-100, 100);
ax.set_xlabel('X')
ax.set_ylabel('Y')

axsliderA = axes([0.12, 0.85, 0.16, 0.075])
sA = Slider(axsliderA, 'A', -1, 1.0, valinit=0.5)
sA.on_changed(update)

axsliderB = axes([0.43, 0.85, 0.16, 0.075])
sB = Slider(axsliderB, 'B', -30, 30.0, valinit=2)
sB.on_changed(update)

axsliderC = axes([0.74, 0.85, 0.16, 0.075])
sC = Slider(axsliderC, 'C', -30, 30.0, valinit=1)
sC.on_changed(update)

axes(ax)
A = 1;
B = 2;
C = 1;
y_data = A*x_data*x_data + B*x_data + C;

par_plot, = plot(x_data,y_data, lw=2, color='red')

show()

A note about the above: When I run the application, the code runs sequentially right through (it stores the update function in memory, I think), until it hits show(), which is blocking. When you make a change to one of the sliders, it runs the update function from memory (I think?).

This is the reason why show() is implemented in the way it is, so that you can change values in the background by using functions to process the data.

Download and install an ipa from self hosted url on iOS

Create a Virtual Machine with Windows running on it and download the file to a shared folder. :-D

Using Java to find substring of a bigger string using Regular Expression

This is a working example :

RegexpExample.java

package org.regexp.replace;

import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class RegexpExample
{
    public static void main(String[] args)
    {
        String string = "var1[value1], var2[value2], var3[value3]";
        Pattern pattern = Pattern.compile("(\\[)(.*?)(\\])");
        Matcher matcher = pattern.matcher(string);

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

        while(matcher.find())
        {
            listMatches.add(matcher.group(2));
        }

        for(String s : listMatches)
        {
            System.out.println(s);
        }
    }
}

It displays :

value1
value2
value3

How to terminate a process in vbscript

The Win32_Process class provides access to both 32-bit and 64-bit processes when the script is run from a 64-bit command shell.

If this is not an option for you, you can try using the taskkill command:

Dim oShell : Set oShell = CreateObject("WScript.Shell")

' Launch notepad '
oShell.Run "notepad"
WScript.Sleep 3000

' Kill notepad '
oShell.Run "taskkill /im notepad.exe", , True

How do I deploy Node.js applications as a single executable file?

There are a number of steps you have to go through to create an installer and it varies for each Operating System. For Example:

How do you create optional arguments in php?

Some notes that I also found useful:

  • Keep your default values on the right side.

    function whatever($var1, $var2, $var3="constant", $var4="another")
    
  • The default value of the argument must be a constant expression. It can't be a variable or a function call.

Excel VBA to Export Selected Sheets to PDF

Once you have Selected a group of sheets, you can use Selection

Consider:

Sub luxation()
    ThisWorkbook.Sheets(Array("Sheet1", "Sheet2", "Sheet3")).Select
    Selection.ExportAsFixedFormat _
        Type:=xlTypePDF, _
        Filename:="C:\TestFolder\temp.pdf", _
        Quality:=xlQualityStandard, _
        IncludeDocProperties:=True, _
        IgnorePrintAreas:=False, _
        OpenAfterPublish:=True
End Sub

EDIT#1:

Further testing has reveled that this technique depends on the group of cells selected on each worksheet. To get a comprehensive output, use something like:

Sub Macro1()

   Sheets("Sheet1").Activate
   ActiveSheet.UsedRange.Select
   Sheets("Sheet2").Activate
   ActiveSheet.UsedRange.Select
   Sheets("Sheet3").Activate
   ActiveSheet.UsedRange.Select

   ThisWorkbook.Sheets(Array("Sheet1", "Sheet2", "Sheet3")).Select
   Selection.ExportAsFixedFormat Type:=xlTypePDF, Filename:= _
      "C:\Users\James\Desktop\pdfmaker.pdf", Quality:=xlQualityStandard, _
      IncludeDocProperties:=True, IgnorePrintAreas:=False, OpenAfterPublish:= _
      True
End Sub

Rename Oracle Table or View

Past 10g the current answer no longer works for renaming views. The only method that still works is dropping and recreating the view. The best way I can think of to do this would be:

SELECT TEXT FROM ALL_VIEWS WHERE owner='some_schema' and VIEW_NAME='some_view';

Add this in front of the SQL returned

Create or replace view some_schema.new_view_name as ...

Drop the old view

Drop view some_schema.some_view;

How do I filter ForeignKey choices in a Django ModelForm?

This is simple, and works with Django 1.4:

class ClientAdminForm(forms.ModelForm):
    def __init__(self, *args, **kwargs):
        super(ClientAdminForm, self).__init__(*args, **kwargs)
        # access object through self.instance...
        self.fields['base_rate'].queryset = Rate.objects.filter(company=self.instance.company)

class ClientAdmin(admin.ModelAdmin):
    form = ClientAdminForm
    ....

You don't need to specify this in a form class, but can do it directly in the ModelAdmin, as Django already includes this built-in method on the ModelAdmin (from the docs):

ModelAdmin.formfield_for_foreignkey(self, db_field, request, **kwargs)¶
'''The formfield_for_foreignkey method on a ModelAdmin allows you to 
   override the default formfield for a foreign keys field. For example, 
   to return a subset of objects for this foreign key field based on the
   user:'''

class MyModelAdmin(admin.ModelAdmin):
    def formfield_for_foreignkey(self, db_field, request, **kwargs):
        if db_field.name == "car":
            kwargs["queryset"] = Car.objects.filter(owner=request.user)
        return super(MyModelAdmin, self).formfield_for_foreignkey(db_field, request, **kwargs)

An even niftier way to do this (for example in creating a front-end admin interface that users can access) is to subclass the ModelAdmin and then alter the methods below. The net result is a user interface that ONLY shows them content that is related to them, while allowing you (a super-user) to see everything.

I've overridden four methods, the first two make it impossible for a user to delete anything, and it also removes the delete buttons from the admin site.

The third override filters any query that contains a reference to (in the example 'user' or 'porcupine' (just as an illustration).

The last override filters any foreignkey field in the model to filter the choices available the same as the basic queryset.

In this way, you can present an easy to manage front-facing admin site that allows users to mess with their own objects, and you don't have to remember to type in the specific ModelAdmin filters we talked about above.

class FrontEndAdmin(models.ModelAdmin):
    def __init__(self, model, admin_site):
        self.model = model
        self.opts = model._meta
        self.admin_site = admin_site
        super(FrontEndAdmin, self).__init__(model, admin_site)

remove 'delete' buttons:

    def get_actions(self, request):
        actions = super(FrontEndAdmin, self).get_actions(request)
        if 'delete_selected' in actions:
            del actions['delete_selected']
        return actions

prevents delete permission

    def has_delete_permission(self, request, obj=None):
        return False

filters objects that can be viewed on the admin site:

    def get_queryset(self, request):
        if request.user.is_superuser:
            try:
                qs = self.model.objects.all()
            except AttributeError:
                qs = self.model._default_manager.get_queryset()
            return qs

        else:
            try:
                qs = self.model.objects.all()
            except AttributeError:
                qs = self.model._default_manager.get_queryset()

            if hasattr(self.model, ‘user’):
                return qs.filter(user=request.user)
            if hasattr(self.model, ‘porcupine’):
                return qs.filter(porcupine=request.user.porcupine)
            else:
                return qs

filters choices for all foreignkey fields on the admin site:

    def formfield_for_foreignkey(self, db_field, request, **kwargs):
        if request.employee.is_superuser:
            return super(FrontEndAdmin, self).formfield_for_foreignkey(db_field, request, **kwargs)

        else:
            if hasattr(db_field.rel.to, 'user'):
                kwargs["queryset"] = db_field.rel.to.objects.filter(user=request.user)
            if hasattr(db_field.rel.to, 'porcupine'):
                kwargs["queryset"] = db_field.rel.to.objects.filter(porcupine=request.user.porcupine)
            return super(ModelAdminFront, self).formfield_for_foreignkey(db_field, request, **kwargs)

Does Visual Studio Code have box select/multi-line edit?

Press Ctrl+Alt+Down or Ctrl+Alt+Up to insert cursors below or above.

CSS media queries: max-width OR max-height

There are two ways for writing a proper media queries in css. If you are writing media queries for larger device first, then the correct way of writing will be:

@media only screen 
and (min-width : 415px){
    /* Styles */
}

@media only screen 
and (min-width : 769px){
    /* Styles */
}

@media only screen 
and (min-width : 992px){
    /* Styles */
}

But if you are writing media queries for smaller device first, then it would be something like:

@media only screen 
and (max-width : 991px){
    /* Styles */
}

@media only screen 
and (max-width : 768px){
    /* Styles */
}

@media only screen 
and (max-width : 414px){
    /* Styles */
}

Render Content Dynamically from an array map function in React Native

Don't forget to return the mapped array , like:

lapsList() {

    return this.state.laps.map((data) => {
      return (
        <View><Text>{data.time}</Text></View>
      )
    })

}

Reference for the map() method: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map

Do C# Timers elapse on a separate thread?

If the elapsed event takes longer then the interval, it will create another thread to raise the elapsed event. But there is a workaround for this

static void timer_Elapsed(object sender, ElapsedEventArgs e)    
{     
   try
   {
      timer.Stop(); 
      Thread.Sleep(2000);        
      Debug.WriteLine(Thread.CurrentThread.ManagedThreadId);    
   }
   finally
   {
     timer.Start();
   }
}

Not connecting to SQL Server over VPN

Make sure SQL Server is enabled for TCP/IP (someone may have disabled it)?

This will also help you to check/verify the port number the SQL instance is using (in case someone changed it from the default of port 1433).

Obviously port 1433 (or whatever port SQL is listening on) needs to be unblocked by any firewalls between your machine and the box SQL is running on.

To check SQL's network configuration (requires SQL Server Client Tools installed): Start -> Programs -> SQL Server 200x -> Configuration Tools -> SQL Server Configuration Manager

Connect to the machine you need then expand the Tree Item (LHS) "SQL Server Network Configuration", then pick instance. You should have four options - Shared Memory, Named Pipes, TCP/IP and VIA. You can check that TCP/IP is enabled in the RHS window.

If you double click TCP/IP and hit the "Advanced" tab, you can also view the Port number.

Other thoughts.. Are you using SQL Authentication or Windows (Domain) authentication?

  • If SQL Authentication (which I assume you are using given you said username and password), are you sure the SQL instance you're connecting to has mixed mode authentication enabled? If not, you have to connect as Administrator and change the default security settings to allow SQL authentication.

  • If Windows Authentication, could your network be using Kerberos potentially? One would think the VPN credentials would be used for the handshake. I'd check your account has appropriate login rights.

Creating a JSON Array in node js

Build up a JavaScript data structure with the required information, then turn it into the json string at the end.

Based on what I think you're doing, try something like this:

var result = [];
for (var name in goals) {
  if (goals.hasOwnProperty(name)) {
    result.push({name: name, goals: goals[name]});
  }
}

res.contentType('application/json');
res.send(JSON.stringify(result));

or something along those lines.

Where can I find the Tomcat 7 installation folder on Linux AMI in Elastic Beanstalk?

As of October 3, 2012, a new "Elastic Beanstalk for Java with Apache Tomcat 7" Linux x64 AMI deployed with the Sample Application has the install here:

/etc/tomcat7/

The /etc/tomcat7/tomcat7.conf file has the following settings:

# Where your java installation lives
JAVA_HOME="/usr/lib/jvm/jre"

# Where your tomcat installation lives
CATALINA_BASE="/usr/share/tomcat7"
CATALINA_HOME="/usr/share/tomcat7"
JASPER_HOME="/usr/share/tomcat7"
CATALINA_TMPDIR="/var/cache/tomcat7/temp"

How to view user privileges using windows cmd?

I'd start with:

secedit /export /areas USER_RIGHTS /cfg OUTFILE.CFG

Then examine the line for the relevant privilege. However, the problem now is that the accounts are listed as SIDs, not usernames.

MongoDB vs Firebase

Firebase provides some good features like real time change reflection , easy integration of authentication mechanism , and lots of other built-in features for rapid web development. Firebase, really makes Web development so simple that never exists. Firebase database is a fork of MongoDB.

What's the advantage of using Firebase over MongoDB?

You can take advantage of all built-in features of Firebase over MongoDB.

How to setup virtual environment for Python in VS Code?

I had the same problem and the solution was pretty easy:

"If you create a new conda environment while VS Code is running, use the Reload Window command to refresh the environment list shown with Python: Select Interpreter; otherwise you may not see the environment there. It might take a short time to appear; if you don't see it at first, wait 15 seconds then try using the command again."

That's written on Vscode site

Note: to Reload Window: ctrl+shift+p in Vscode, then write reload window

Node.js: Difference between req.query[] and req.params

I want to mention one important note regarding req.query , because currently I am working on pagination functionality based on req.query and I have one interesting example to demonstrate to you...

Example:

// Fetching patients from the database
exports.getPatients = (req, res, next) => {

const pageSize = +req.query.pageSize;
const currentPage = +req.query.currentPage;

const patientQuery = Patient.find();
let fetchedPatients;

// If pageSize and currentPage are not undefined (if they are both set and contain valid values)
if(pageSize && currentPage) {
    /**
     * Construct two different queries 
     * - Fetch all patients 
     * - Adjusted one to only fetch a selected slice of patients for a given page
     */
    patientQuery
        /**
         * This means I will not retrieve all patients I find, but I will skip the first "n" patients
         * For example, if I am on page 2, then I want to skip all patients that were displayed on page 1,
         * 
         * Another example: if I am displaying 7 patients per page , I want to skip 7 items because I am on page 2,
         * so I want to skip (7 * (2 - 1)) => 7 items
         */
        .skip(pageSize * (currentPage - 1))

        /**
         * Narrow dont the amound documents I retreive for the current page
         * Limits the amount of returned documents
         * 
         * For example: If I got 7 items per page, then I want to limit the query to only
         * return 7 items. 
         */
        .limit(pageSize);
}
patientQuery.then(documents => {
    res.status(200).json({
        message: 'Patients fetched successfully',
        patients: documents
    });
  });
};

You will noticed + sign in front of req.query.pageSize and req.query.currentPage

Why? If you delete + in this case, you will get an error, and that error will be thrown because we will use invalid type (with error message 'limit' field must be numeric).

Important: By default if you extracting something from these query parameters, it will always be a string, because it's coming the URL and it's treated as a text.

If we need to work with numbers, and convert query statements from text to number, we can simply add a plus sign in front of statement.

How to get number of video views with YouTube API?

You can use the new YouTube Data API v3

if you retrieve the video, the statistics part contains the viewCount:

from the doc:

https://developers.google.com/youtube/v3/docs/videos#resource

statistics.viewCount / The number of times the video has been viewed.

You can retrieve this info in the client side, or in the server side using some of the client libraries:

https://developers.google.com/youtube/v3/libraries

And you can test the API call from the doc:

https://developers.google.com/youtube/v3/docs/videos/list

Sample:

Request:

GET https://www.googleapis.com/youtube/v3/videos?part=statistics&id=Q5mHPo2yDG8&key={YOUR_API_KEY}

Authorization:  Bearer ya29.AHES6ZSCT9BmIXJmjHlRlKMmVCU22UQzBPRuxzD7Zg_09hsG
X-JavaScript-User-Agent:  Google APIs Explorer

Response:

200 OK

- Show headers -

{
 "kind": "youtube#videoListResponse",
 "etag": "\"g-RLCMLrfPIk8n3AxYYPPliWWoo/dZ8K81pnD1mOCFyHQkjZNynHpYo\"",
 "pageInfo": {
  "totalResults": 1,
  "resultsPerPage": 1
 },
 "items": [
  {

   "id": "Q5mHPo2yDG8",
   "kind": "youtube#video",
   "etag": "\"g-RLCMLrfPIk8n3AxYYPPliWWoo/4NA7C24hM5mprqQ3sBwI5Lo9vZE\"",
   "statistics": {
    "viewCount": "36575966",
    "likeCount": "127569",
    "dislikeCount": "5715",
    "favoriteCount": "0",
    "commentCount": "20317"
   }
  }
 ]
}

What does the "+" (plus sign) CSS selector mean?

It selects the next paragraph and indents the beginning of the paragraph from the left just as you might in Microsoft Word.

Python 3 ImportError: No module named 'ConfigParser'

I got further with Valeres answer:

pip install configparser sudo cp /usr/lib/python3.6/configparser.py /usr/lib/python3.6/ConfigParser.py Then try to install the MYSQL-python again. That Worked for me

I would suggest to link the file instead of copy it. It is save to update. I linked the file to /usr/lib/python3/ directory.

How to use View.OnTouchListener instead of onClick

Presumably, if one wants to use an OnTouchListener rather than an OnClickListener, then the extra functionality of the OnTouchListener is needed. This is a supplemental answer to show more detail of how an OnTouchListener can be used.

Define the listener

Put this somewhere in your activity or fragment.

private View.OnTouchListener handleTouch = new View.OnTouchListener() {

    @Override
    public boolean onTouch(View v, MotionEvent event) {

        int x = (int) event.getX();
        int y = (int) event.getY();

        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                Log.i("TAG", "touched down");
                break;
            case MotionEvent.ACTION_MOVE:
                Log.i("TAG", "moving: (" + x + ", " + y + ")");
                break;
            case MotionEvent.ACTION_UP:
                Log.i("TAG", "touched up");
                break;
        }

        return true;
    }
};

Set the listener

Set the listener in onCreate (for an Activity) or onCreateView (for a Fragment).

myView.setOnTouchListener(handleTouch);

Notes

  • getX and getY give you the coordinates relative to the view (that is, the top left corner of the view). They will be negative when moving above or to the left of your view. Use getRawX and getRawY if you want the absolute screen coordinates.
  • You can use the x and y values to determine things like swipe direction.

How to select option in drop down protractorjs e2e tests

Select option by Index:

var selectDropdownElement= element(by.id('select-dropdown'));
selectDropdownElement.all(by.tagName('option'))
      .then(function (options) {
          options[0].click();
      });

WAMP Server ERROR "Forbidden You don't have permission to access /phpmyadmin/ on this server."

Change the file content of c:\wamp\alias\phpmyadmin.conf to the following.

<Directory "c:/wamp/apps/phpmyadmin3.4.5/">
    Options Indexes FollowSymLinks MultiViews
    AllowOverride all
        Order Deny,Allow
        Allow from all
</Directory>

Here my WAMP installation is in the c:\wamp folder. Change it according to your installation.

Previously, it was like this:

<Directory "c:/wamp/apps/phpmyadmin3.4.5/">
    Options Indexes FollowSymLinks MultiViews
    AllowOverride all
        Order Deny,Allow
    Deny from all
    Allow from 127.0.0.1
</Directory>

Restart your Apache server after making these changes.

Delete everything in a MongoDB database

For Meteor developers.

  1. Open a second terminal window while running your app in localhost:3000.

  2. In your project's folder run, meteor mongo.

    coolName = new Mongo.Collection('yourCollectionName');

  3. Then simply enter db.yourCollectionName.drop();

  4. You'll automatically see the changes in your local server.

For everybody else.

db.yourCollectionName.drop();

Select unique values with 'select' function in 'dplyr' library

In dplyr 0.3 this can be easily achieved using the distinct() method.

Here is an example:

distinct_df = df %>% distinct(field1)

You can get a vector of the distinct values with:

distinct_vector = distinct_df$field1

You can also select a subset of columns at the same time as you perform the distinct() call, which can be cleaner to look at if you examine the data frame using head/tail/glimpse.:

distinct_df = df %>% distinct(field1) %>% select(field1) distinct_vector = distinct_df$field1

How to detect if URL has changed after hash in JavaScript

In modern browsers (IE8+, FF3.6+, Chrome), you can just listen to the hashchange event on window.

In some old browsers, you need a timer that continually checks location.hash. If you're using jQuery, there is a plugin that does exactly that.

How to set a session variable when clicking a <a> link

In HTML:

<a href="index.php?link=home" name="home">home</a>

Then in PHP:

if(isset($_GET['link'])){$_SESSION['link'] = $_GET['link'];}

PHP returning JSON to JQUERY AJAX CALL

You can return json in PHP this way:

header('Content-Type: application/json');
echo json_encode(array('foo' => 'bar'));
exit;

How to prevent going back to the previous activity?

My suggestion would be to finish the activity that you don't want the users to go back to. For instance, in your sign in activity, right after you call startActivity, call finish(). When the users hit the back button, they will not be able to go to the sign in activity because it has been killed off the stack.

Youtube API Limitations

A little bit late, but you can request a higher quote here: https://support.google.com/youtube/contact/yt_api_form

What are all the common ways to read a file in Ruby?

File.open("my/file/path", "r") do |f|
  f.each_line do |line|
    puts line
  end
end
# File is closed automatically at end of block

It is also possible to explicitly close file after as above (pass a block to open closes it for you):

f = File.open("my/file/path", "r")
f.each_line do |line|
  puts line
end
f.close

100% width in React Native Flexbox

Simply add alignSelf: "stretch" to your item's stylesheet.

line1: {
    backgroundColor: '#FDD7E4',
    alignSelf: 'stretch',
    textAlign: 'center',
},

How to query SOLR for empty fields?

One caveat! If you want to compose this via OR or AND you cannot use it in this form:

-myfield:*

but you must use

(*:* NOT myfield:*)

This form is perfectly composable. Apparently SOLR will expand the first form to the second, but only when it is a top node. Hope this saves you some time!

python paramiko ssh

There is extensive paramiko API documentation you can find at: http://docs.paramiko.org/en/stable/index.html

I use the following method to execute commands on a password protected client:

import paramiko

nbytes = 4096
hostname = 'hostname'
port = 22
username = 'username' 
password = 'password'
command = 'ls'

client = paramiko.Transport((hostname, port))
client.connect(username=username, password=password)

stdout_data = []
stderr_data = []
session = client.open_channel(kind='session')
session.exec_command(command)
while True:
    if session.recv_ready():
        stdout_data.append(session.recv(nbytes))
    if session.recv_stderr_ready():
        stderr_data.append(session.recv_stderr(nbytes))
    if session.exit_status_ready():
        break

print 'exit status: ', session.recv_exit_status()
print ''.join(stdout_data)
print ''.join(stderr_data)

session.close()
client.close()

How do I execute .js files locally in my browser?

Around 1:51 in the video, notice how she puts a <script> tag in there? The way it works is like this:

Create an html file (that's just a text file with a .html ending) somewhere on your computer. In the same folder that you put index.html, put a javascript file (that's just a textfile with a .js ending - let's call it game.js). Then, in your index.html file, put some html that includes the script tag with game.js, like Mary did in the video. index.html should look something like this:

<html>
    <head>
        <script src="game.js"></script>
    </head>
</html>

Now, double click on that file in finder, and it should open it up in your browser. To open up the console to see the output of your javascript code, hit Command-alt-j (those three buttons at the same time).

Good luck on your journey, hope it's as fun for you as it has been for me so far :)

Visual Studio : short cut Key : Duplicate Line

http://www.jetbrains.com/resharper/

My story: started working in a new company, never used Visual Studio before. One of the first things - how to duplicate line. After setting up macro ReSharper told me: would you like to substitute my shortcut which was: "duplicate text" :)

Difference between ref and out parameters in .NET

Why does C# have both 'ref' and 'out'?

The caller of a method which takes an out parameter is not required to assign to the variable passed as the out parameter prior to the call; however, the callee is required to assign to the out parameter before returning.

In contrast ref parameters are considered initially assigned by the caller. As such, the callee is not required to assign to the ref parameter before use. Ref parameters are passed both into and out of a method.

So, out means out, while ref is for in and out.

These correspond closely to the [out] and [in,out] parameters of COM interfaces, the advantages of out parameters being that callers need not pass a pre-allocated object in cases where it is not needed by the method being called - this avoids both the cost of allocation, and any cost that might be associated with marshaling (more likely with COM, but not uncommon in .NET).

How do I convert NSInteger to NSString datatype?

Easy way to do:

NSInteger value = x;
NSString *string = [@(value) stringValue];

Here the @(value) converts the given NSInteger to an NSNumber object for which you can call the required function, stringValue.

Java abstract interface

Every interface is implicitly abstract.
This modifier is obsolete and should not be used in new programs.

[The Java Language Specification - 9.1.1.1 abstract Interfaces]

Also note that interface member methods are implicitly public abstract.
[The Java Language Specification - 9.2 Interface Members]

Why are those modifiers implicit? There is no other modifier (not even the 'no modifier'-modifier) that would be useful here, so you don't explicitly have to type it.

What is the difference between children and childNodes in JavaScript?

Element.children returns only element children, while Node.childNodes returns all node children. Note that elements are nodes, so both are available on elements.

I believe childNodes is more reliable. For example, MDC (linked above) notes that IE only got children right in IE 9. childNodes provides less room for error by browser implementors.

array of string with unknown size

I suppose that the array size if a computed value.

int size = ComputeArraySize();

// Then

String[] array = new String[size]; 

Node Version Manager (NVM) on Windows

An alternative to nvm-windows, which is mentioned in other answers would be Nodist.

I've had some issues with nvm-windows and admin privileges, which Nodist doesn't seem to have.

If Else in LINQ

I assume from db that this is LINQ-to-SQL / Entity Framework / similar (not LINQ-to-Objects);

Generally, you do better with the conditional syntax ( a ? b : c) - however, I don't know if it will work with your different queries like that (after all, how would your write the TSQL?).

For a trivial example of the type of thing you can do:

select new {p.PriceID, Type = p.Price > 0 ? "debit" : "credit" };

You can do much richer things, but I really doubt you can pick the table in the conditional. You're welcome to try, of course...

No mapping found for HTTP request with URI Spring MVC

With the web.xml configured they way you have in the question, in particular:

<servlet-mapping>
    <servlet-name>dispatcherServlet</servlet-name>
    <url-pattern>/*</url-pattern>
</servlet-mapping>

ALL requests being made to your web app will be directed to the DispatcherServlet. This includes requests like /tasklist/, /tasklist/some-thing.html, /tasklist/WEB-INF/views/index.jsp.

Because of this, when your controller returns a view that points to a .jsp, instead of allowing your server container to service the request, the DispatcherServlet jumps in and starts looking for a controller that can service this request, it doesn't find any and hence the 404.

The simplest way to solve is to have your servlet url mapping as follows:

<servlet-mapping>
    <servlet-name>dispatcherServlet</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>

Notice the missing *. This tells the container that any request that does not have a path info in it (urls without a .xxx at the end), should be sent to the DispatcherServlet. With this configuration, when a xxx.jsp request is received, the DispatcherServlet is not consulted, and your servlet container's default servlet will service the request and present the jsp as expected.

Hope this helps, I realize your earlier comments state that the problem has been resolved, but the solution CAN NOT be just adding method=RequestMethod.GET to the RequestMethod.

How do I Geocode 20 addresses without receiving an OVER_QUERY_LIMIT response?

No, there is not really any other way : if you have many locations and want to display them on a map, the best solution is to :

  • fetch the latitude+longitude, using the geocoder, when a location is created
  • store those in your database, alongside the address
  • and use those stored latitude+longitude when you want to display the map.

This is, of course, considering that you have a lot less creation/modification of locations than you have consultations of locations.


Yes, it means you'll have to do a bit more work when saving the locations -- but it also means :

  • You'll be able to search by geographical coordinates
    • i.e. "I want a list of points that are near where I'm now"
  • Displaying the map will be a lot faster
    • Even with more than 20 locations on it
  • Oh, and, also (last but not least) : this will work ;-)
    • You will less likely hit the limit of X geocoder calls in N seconds.
    • And you will less likely hit the limit of Y geocoder calls per day.

Match groups in Python

You could create a helper function:

def re_match_group(pattern, str, out_groups):
    del out_groups[:]
    result = re.match(pattern, str)
    if result:
        out_groups[:len(result.groups())] = result.groups()
    return result

And then use it like this:

groups = []
if re_match_group("I love (\w+)", statement, groups):
    print "He loves", groups[0]
elif re_match_group("Ich liebe (\w+)", statement, groups):
    print "Er liebt", groups[0]
elif re_match_group("Je t'aime (\w+)", statement, groups):
    print "Il aime", groups[0]

It's a little clunky, but it gets the job done.

Python display text with font & color?

I wrote a wrapper, that will cache text surfaces, only re-render when dirty. googlecode/ninmonkey/nin.text/demo/

What does the M stand for in C# Decimal literal notation?

Well, i guess M represent the mantissa. Decimal can be used to save money, but it doesn't mean, decimal only used for money.

$_SERVER['HTTP_REFERER'] missing

function redirectHome($theMsg, $url = null, $seconds = 3) {
    if ($url === null) {
        $url  = 'index.php';
        $link = 'Homepage';
    } else {
        if (isset($_SERVER['HTTP_REFERER']) && $_SERVER['HTTP_REFERER'] !== '') {
            $url = $_SERVER['HTTP_REFERER'];
            $link = 'Previous Page';
        } else {
            $url = 'index.php';
            $link = 'Homepage';
        }
    }
    echo $theMsg;
    echo "<div class='alert alert-info'>You Will Be Redirected to $link After $seconds Seconds.</div>";
    header("refresh:$seconds;url=$url");
    exit();
}

How do I discard unstaged changes in Git?

If all the staged files were actually committed, then the branch can simply be reset e.g. from your GUI with about three mouse clicks: Branch, Reset, Yes!

So what I often do in practice to revert unwanted local changes is to commit all the good stuff, and then reset the branch.

If the good stuff is committed in a single commit, then you can use "amend last commit" to bring it back to being staged or unstaged if you'd ultimately like to commit it a little differently.

This might not be the technical solution you are looking for to your problem, but I find it a very practical solution. It allows you to discard unstaged changes selectively, resetting the changes you don't like and keeping the ones you do.

So in summary, I simply do commit, branch reset, and amend last commit.

How to convert the time from AM/PM to 24 hour format in PHP?

$Hour1 = "09:00 am";
$Hour =  date("H:i", strtotime($Hour1));  

SharePoint : How can I programmatically add items to a custom list instance

I had a similar problem and was able to solve it by following the below approach (similar to other answers but needed credentials too),

1- add Microsoft.SharePointOnline.CSOM by tools->NuGet Package Manager->Manage NuGet Packages for solution->Browse-> select and install

2- Add "using Microsoft.SharePoint.Client; "

then the below code

        string siteUrl = "https://yourcompany.sharepoint.com/sites/Yoursite";
        SecureString passWord = new SecureString();

        var password = "Your password here";
        var securePassword = new SecureString();
        foreach (char c in password)
        {
            securePassword.AppendChar(c);
        }
        ClientContext clientContext = new ClientContext(siteUrl);
        clientContext.Credentials = new SharePointOnlineCredentials("[email protected]", securePassword);/*passWord*/
        List oList = clientContext.Web.Lists.GetByTitle("The name of your list here");
        ListItemCreationInformation itemCreateInfo = new ListItemCreationInformation();
        ListItem oListItem = oList.AddItem(itemCreateInfo);
        oListItem["PK"] = "1";
        oListItem["Precinct"] = "Mangere";
        oListItem["Title"] = "Innovation";
        oListItem["Project_x005F_x0020_Name"] = "test from C#";
        oListItem["Project_x005F_x0020_ID"] = "ID_123_from C#";
        oListItem["Project_x005F_x0020_start_x005F_x0020_date"] = "2020-05-01 01:01:01";
        oListItem.Update();

        clientContext.ExecuteQuery();

Remember that your fields may be different with what you see, for example in my list I see "Project Name", while the actual value is "Project_x005F_x0020_ID". How to get these values (i.e. internal filed values)?

A few approaches:

1- Use MS flow and see them

2- https://mstechtalk.com/check-column-internal-name-sharepoint-list/ or https://sharepoint.stackexchange.com/questions/787/finding-the-internal-name-and-display-name-for-a-list-column

3- Use a C# reader and read your sharepoint list

The rest of operations (update/delete): https://docs.microsoft.com/en-us/previous-versions/office/developer/sharepoint-2010/ee539976(v%3Doffice.14)

Getting a 'source: not found' error when using source in a bash script

In Ubuntu if you execute the script with sh scriptname.sh you get this problem.

Try executing the script with ./scriptname.sh instead.

Why is this jQuery click function not working?

Be sure there is nothing on your button (such a div or a trasparent img) that keeps from clicking the button. It sounds stupid, but sometimes we think that jQuery is not working and all that stuffs and the problem is on the positioning of DOM elements.

Using member variable in lambda capture list inside a member function

An alternate method that limits the scope of the lambda rather than giving it access to the whole this is to pass in a local reference to the member variable, e.g.

auto& localGrid = grid;
int i;
for_each(groups.cbegin(),groups.cend(),[localGrid,&i](pair<int,set<int>> group){
            i++;
            cout<<i<<endl;
   });

What is the difference between Builder Design pattern and Factory Design pattern?

IMHO

Builder is some kind of more complex Factory.

But in Builder you can instantiate objects with using another factories, that are required to build final and valid object.

So, talking about "Creational Patterns" evolution by complexity you can think about it in this way:

Dependency Injection Container -> Service Locator -> Builder -> Factory

Concatenating bits in VHDL

The concatenation operator '&' is allowed on the right side of the signal assignment operator '<=', only

How to get client's IP address using JavaScript?

I have my own api back end with laravel, so I usually just the following:

$(document).ready( function() {

    $.getJSON( "http://api.whoisdoma.com/v1/ip/visitor?api_key=key",
        function(data){
          alert( data.ip);
        }
    );

});

For extra security, I provide an api key which is required to get results.

Creating stored procedure and SQLite?

Yet, it is possible to fake it using a dedicated table, named for your fake-sp, with an AFTER INSERT trigger. The dedicated table rows contain the parameters for your fake sp, and if it needs to return results you can have a second (poss. temp) table (with name related to the fake-sp) to contain those results. It would require two queries: first to INSERT data into the fake-sp-trigger-table, and the second to SELECT from the fake-sp-results-table, which could be empty, or have a message-field if something went wrong.

How to search images from private 1.0 registry in docker?

Now from docker client you can simply search your private registry directly without using the HTTP APIs or any extra tools:

e.g. searching for centos image:

docker search localhost:5000/centos

Looking to understand the iOS UIViewController lifecycle

Haider's answer is correct for pre-iOS 6. However, as of iOS 6 viewDidUnload and viewWillUnload are never called. The docs state: "Views are no longer purged under low-memory conditions and so this method is never called."

jQuery Multiple ID selectors

That should work, you may need a space after the commas.

Also, the function you call afterwards must support an array of objects, and not just a singleton object.

How can I loop through a List<T> and grab each item?

This is how I would write using more functional way. Here is the code:

new List<Money>()
{
     new Money() { Amount = 10, Type = "US"},
     new Money() { Amount = 20, Type = "US"}
}
.ForEach(money =>
{
    Console.WriteLine($"amount is {money.Amount}, and type is {money.Type}");
});

How to replace � in a string

Use the unicode escape sequence. First you'll have to find the codepoint for the character you seek to replace (let's just say it is ABCD in hex):

str = str.replaceAll("\uABCD", "");

How do I turn off Unicode in a VC++ project?

you can go to project properties --> configuration properties --> General -->Project default and there change the "Character set" from "Unicode" to "Not set".

How do you determine the ideal buffer size when using FileInputStream?

Yes, it's probably dependent on various things - but I doubt it will make very much difference. I tend to opt for 16K or 32K as a good balance between memory usage and performance.

Note that you should have a try/finally block in the code to make sure the stream is closed even if an exception is thrown.

The following untracked working tree files would be overwritten by merge, but I don't care

The only commands that worked for me were:

git fetch --all
git reset --hard origin/{{your branch name}}

Disable hover effects on mobile browsers

I take it from your question that your hover effect changes the content of your page. In that case, my advice is to:

  • Add hover effects on touchstart and mouseenter.
  • Remove hover effects on mouseleave, touchmove and click.

Alternatively, you can edit your page that there is no content change.

Background

In order to simulate a mouse, browsers such as Webkit mobile fire the following events if a user touches and releases a finger on touch screen (like iPad) (source: Touch And Mouse on html5rocks.com):

  1. touchstart
  2. touchmove
  3. touchend
  4. 300ms delay, where the browser makes sure this is a single tap, not a double tap
  5. mouseover
  6. mouseenter
    • Note: If a mouseover, mouseenter or mousemove event changes the page content, the following events are never fired.
  7. mousemove
  8. mousedown
  9. mouseup
  10. click

It does not seem possible to simply tell the webbrowser to skip the mouse events.

What's worse, if a mouseover event changes the page content, the click event is never fired, as explained on Safari Web Content Guide - Handling Events, in particular figure 6.4 in One-Finger Events. What exactly a "content change" is, will depend on browser and version. I've found that for iOS 7.0, a change in background color is not (or no longer?) a content change.

Solution Explained

To recap:

  • Add hover effects on touchstart and mouseenter.
  • Remove hover effects on mouseleave, touchmove and click.

Note that there is no action on touchend!

This clearly works for mouse events: mouseenter and mouseleave (slightly improved versions of mouseover and mouseout) are fired, and add and remove the hover.

If the user actually clicks a link, the hover effect is also removed. This ensure that it is removed if the user presses the back button in the web browser.

This also works for touch events: on touchstart the hover effect is added. It is '''not''' removed on touchend. It is added again on mouseenter, and since this causes no content changes (it was already added), the click event is also fired, and the link is followed without the need for the user to click again!

The 300ms delay that a browser has between a touchstart event and click is actually put in good use because the hover effect will be shown during this short time.

If the user decides to cancel the click, a move of the finger will do so just as normal. Normally, this is a problem since no mouseleave event is fired, and the hover effect remains in place. Thankfully, this can easily be fixed by removing the hover effect on touchmove.

That's it!

Note that it is possible to remove the 300ms delay, for example using the FastClick library, but this is out of scope for this question.

Alternative Solutions

I've found the following problems with the following alternatives:

  • browser detection: Extremely prone to errors. Assumes that a device has either mouse or touch, while a combination of both will become more and more common when touch displays prolifirate.
  • CSS media detection: The only CSS-only solution I'm aware of. Still prone to errors, and still assumes that a device has either mouse or touch, while both are possible.
  • Emulate the click event in touchend: This will incorrectly follow the link, even if the user only wanted to scroll or zoom, without the intention of actually clicking the link.
  • Use a variable to suppress mouse events: This set a variable in touchend that is used as a if-condition in subsequent mouse events to prevents state changes at that point in time. The variable is reset in the click event. See Walter Roman's answer on this page. This is a decent solution if you really don't want a hover effect on touch interfaces. Unfortunately, this does not work if a touchend is fired for another reason and no click event is fired (e.g. the user scrolled or zoomed), and is subsequently trying to following the link with a mouse (i.e on a device with both mouse and touch interface).

Further Reading

How to get a context in a recycler view adapter

First globally declare

Context mContext;

pass context with the constructor, by modifying it.

public FeedAdapter(List<Post> myDataset, Context context) {
    mDataset = myDataset;
    this.mContext = context;
}

then use the mContext whereever you need it

How to add a classname/id to React-Bootstrap Component?

1st way is to use props

<Row id = "someRandomID">

Wherein, in the Definition, you may just go

const Row = props  => {
 div id = {props.id}
}

The same could be done with class, replacing id with className in the above example.


You might as well use react-html-id, that is an npm package. This is an npm package that allows you to use unique html IDs for components without any dependencies on other libraries.

Ref: react-html-id


Peace.

Prevent line-break of span element

Put this in your CSS:

white-space:nowrap;

Get more information here: http://www.w3.org/wiki/CSS/Properties/white-space

white-space

The white-space property declares how white space inside the element is handled.

Values

normal This value directs user agents to collapse sequences of white space, and break lines as necessary to fill line boxes.

pre This value prevents user agents from collapsing sequences of white space. Lines are only broken at newlines in the source, or at occurrences of "\A" in generated content.

nowrap This value collapses white space as for 'normal', but suppresses line breaks within text.

pre-wrap This value prevents user agents from collapsing sequences of white space. Lines are broken at newlines in the source, at occurrences of "\A" in generated content, and as necessary to fill line boxes.

pre-line This value directs user agents to collapse sequences of white space. Lines are broken at newlines in the source, at occurrences of "\A" in generated content, and as necessary to fill line boxes.

inherit Takes the same specified value as the property for the element's parent.

The response content cannot be parsed because the Internet Explorer engine is not available, or

You can disable need to run Internet Explorer's first launch configuration by running this PowerShell script, it will adjust corresponding registry property:

Set-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Internet Explorer\Main" -Name "DisableFirstRunCustomize" -Value 2

After this, WebClient will work without problems

Can an html element have multiple ids?

I don´t think you can have two Id´s but it should be possible. Using the same id twice is a different case... like two people using the same passport. However one person could have multiple passports... Came looking for this since I have a situation where a single employee can have several functions. Say "sysadm" and "team coordinator" having the id="sysadm teamcoordinator" would let me reference them from other pages so that employees.html#sysadm and employees.html#teamcoordinator would lead to the same place... One day somebody else might take over the team coordinator function while the sysadm remains the sysadm... then I only have to change the ids on the employees.html page ... but like I said - it doesn´t work :(

how to hide the content of the div in css

sounds silly but font-size:0; might just work. It did for me. And you can easily override this with the child element you need to show.

Compiling a java program into an executable

The thing you can do is create a .bat that will execute the .jar file created, checking if there is a JRE present.

From Mitch useful link (source)

java -classpath myprogram.jar de.vogella.eclipse.ide.first.MyFirstClass

This can be used into your batch...

Switch firefox to use a different DNS than what is in the windows.host file

Since http proxy protocol is similar to raw http protocol, you can redirect desired traffic to your development server by telling firefox it's a proxy server.

two limitations:

A. this won't let you use https connections.

B. some frameworks (e,g: wordpress) don't like this method and redirect the request the wrong way

just copy the following code into a .pac file (enter your site domain and IP address, of course), and switch development/production just by changing proxy configuration.

function FindProxyForURL(url, host) {
    var prox4site = {
        "mysite.com":"PROXY 10.0.1.100:80",
        "www.mysite.com":"PROXY 10.0.1.100:80"
    }

    return prox4site[host] || "DIRECT";
}

Which comes first in a 2D array, rows or columns?

Instinctively one thinks geometrically: horizontal (X) axis and then vertical (Y) axis. This is not, however, the case with a 2D array, rows come first and then columns.

Consider the following analogy: in geometry one walks to the ladder (X axis) and climbs it (Y axis). Conversely, in Java one descends the ladder (rows) and walks away (columns).

Where is HttpContent.ReadAsAsync?

It looks like it is an extension method (in System.Net.Http.Formatting):

HttpContentExtensions Class

Update:

PM> install-package Microsoft.AspNet.WebApi.Client

According to the System.Net.Http.Formatting NuGet package page, the System.Net.Http.Formatting package is now legacy and can instead be found in the Microsoft.AspNet.WebApi.Client package available on NuGet here.

Twitter bootstrap scrollable modal

None of this will work as expected.. The correct way is to change position: fixed to position: absolute for .modal class

SQL RANK() over PARTITION on joined tables

SELECT a.C_ID,a.QRY_ID,a.RES_ID,b.SCORE,ROW_NUMBER() OVER (ORDER BY SCORE DESC) AS [RANK]
FROM CONTACTS a JOIN RSLTS b ON a.QRY_ID=b.QRY_ID AND a.RES_ID=b.RES_ID
ORDER BY a.C_ID

How different is Objective-C from C++?

As others have said, Objective-C is much more dynamic in terms of how it thinks of objects vs. C++'s fairly static realm.

Objective-C, being in the Smalltalk lineage of object-oriented languages, has a concept of objects that is very similar to that of Java, Python, and other "standard", non-C++ object-oriented languages. Lots of dynamic dispatch, no operator overloading, send messages around.

C++ is its own weird animal; it mostly skipped the Smalltalk portion of the family tree. In some ways, it has a good module system with support for inheritance that happens to be able to be used for object-oriented programming. Things are much more static (overridable methods are not the default, for example).

How to deal with "java.lang.OutOfMemoryError: Java heap space" error?

I would like to add recommendations from oracle trouble shooting article.

Exception in thread thread_name: java.lang.OutOfMemoryError: Java heap space

The detail message Java heap space indicates object could not be allocated in the Java heap. This error does not necessarily imply a memory leak

Possible causes:

  1. Simple configuration issue, where the specified heap size is insufficient for the application.

  2. Application is unintentionally holding references to objects, and this prevents the objects from being garbage collected.

  3. Excessive use of finalizers.

One other potential source of this error arises with applications that make excessive use of finalizers. If a class has a finalize method, then objects of that type do not have their space reclaimed at garbage collection time

After garbage collection, the objects are queued for finalization, which occurs at a later time. finalizers are executed by a daemon thread that services the finalization queue. If the finalizer thread cannot keep up with the finalization queue, then the Java heap could fill up and this type of OutOfMemoryError exception would be thrown.

One scenario that can cause this situation is when an application creates high-priority threads that cause the finalization queue to increase at a rate that is faster than the rate at which the finalizer thread is servicing that queue.

In Ruby, how do I skip a loop in a .each loop, similar to 'continue'

next - it's like return, but for blocks! (So you can use this in any proc/lambda too.)

That means you can also say next n to "return" n from the block. For instance:

puts [1, 2, 3].map do |e|
  next 42 if e == 2
  e
end.inject(&:+)

This will yield 46.

Note that return always returns from the closest def, and never a block; if there's no surrounding def, returning is an error.

Using return from within a block intentionally can be confusing. For instance:

def my_fun
  [1, 2, 3].map do |e|
    return "Hello." if e == 2
    e
  end
end

my_fun will result in "Hello.", not [1, "Hello.", 2], because the return keyword pertains to the outer def, not the inner block.

Python Turtle, draw text with on screen with larger font

You can also use "bold" and "italic" instead of "normal" here. "Verdana" can be used for fontname..

But another question is this: How do you set the color of the text You write?

Answer: You use the turtle.color() method or turtle.fillcolor(), like this:

turtle.fillcolor("blue")

or just:

turtle.color("orange")

These calls must come before the turtle.write() command..

How to construct a std::string from a std::vector<char>?

std::string s(v.begin(), v.end());

Where v is pretty much anything iterable. (Specifically begin() and end() must return InputIterators.)

java.lang.ClassNotFoundException: javax.servlet.jsp.jstl.core.Config

Probably the jstl libraries are missing from your classpath/not accessible by tomcat.

You need to add at least the following jar files in your WEB-INF/lib directory:

  • jsf-impl.jar
  • jsf-api.jar
  • jstl.jar

How to recover closed output window in netbeans?

I was having the same problem. Currently I am using the version 8.1, First of all go to the window tab, that is just before the tab help. Click on window and there click reset "Reset Window", after that in the bottom right click on the tab where your project runs, right click and select show output.

X-Frame-Options on apache

This worked for me on all browsers:

  1. Created one page with all my javascript
  2. Created a 2nd page on the same server and embedded the first page using the object tag.
  3. On my third party site I used the Object tag to embed the 2nd page.
  4. Created a .htaccess file on the original server in the public_html folder and put Header unset X-Frame-Options in it.

Connecting to SQL Server using windows authentication

I was facing the same issue and the reason was single backslah. I used double backslash in my "Data source" and it worked

connetionString = "Data Source=localhost\\SQLEXPRESS;Database=databasename;Integrated Security=SSPI";

How to redirect output of an already running process

I collected some information on the internet and prepared the script that requires no external tool: See my response here. Hope it's helpful.

Remove the last three characters from a string

myString.Substring(myString.Length - 3, 3)

Here are examples on substring.>>

http://www.dotnetperls.com/substring

Refer those.

Why doesn't Dijkstra's algorithm work for negative weight edges?

Consider the graph shown below with the source as Vertex A. First try running Dijkstra’s algorithm yourself on it.

enter image description here

When I refer to Dijkstra’s algorithm in my explanation I will be talking about the Dijkstra's Algorithm as implemented below,

Dijkstra’s algorithm

So starting out the values (the distance from the source to the vertex) initially assigned to each vertex are,

initialization

We first extract the vertex in Q = [A,B,C] which has smallest value, i.e. A, after which Q = [B, C]. Note A has a directed edge to B and C, also both of them are in Q, therefore we update both of those values,

first iteration

Now we extract C as (2<5), now Q = [B]. Note that C is connected to nothing, so line16 loop doesn't run.

second iteration

Finally we extract B, after which Q is Phi. Note B has a directed edge to C but C isn't present in Q therefore we again don't enter the for loop in line16,

3rd?

So we end up with the distances as

no change guys

Note how this is wrong as the shortest distance from A to C is 5 + -10 = -5, when you go a to b to c.

So for this graph Dijkstra's Algorithm wrongly computes the distance from A to C.

This happens because Dijkstra's Algorithm does not try to find a shorter path to vertices which are already extracted from Q.

What the line16 loop is doing is taking the vertex u and saying "hey looks like we can go to v from source via u, is that (alt or alternative) distance any better than the current dist[v] we got? If so lets update dist[v]"

Note that in line16 they check all neighbors v (i.e. a directed edge exists from u to v), of u which are still in Q. In line14 they remove visited notes from Q. So if x is a visited neighbour of u, the path source to u to x is not even considered as a possible shorter way from source to v.

In our example above, C was a visited neighbour of B, thus the path A to B to C was not considered, leaving the current shortest path A to C unchanged.

This is actually useful if the edge weights are all positive numbers, because then we wouldn't waste our time considering paths that can't be shorter.

So I say that when running this algorithm if x is extracted from Q before y, then its not possible to find a path - not possible which is shorter. Let me explain this with an example,

As y has just been extracted and x had been extracted before itself, then dist[y] > dist[x] because otherwise y would have been extracted before x. (line 13 min distance first)

And as we already assumed that the edge weights are positive, i.e. length(x,y)>0. So the alternative distance (alt) via y is always sure to be greater, i.e. dist[y] + length(x,y)> dist[x]. So the value of dist[x] would not have been updated even if y was considered as a path to x, thus we conclude that it makes sense to only consider neighbors of y which are still in Q (note comment in line16)

But this thing hinges on our assumption of positive edge length, if length(u,v)<0 then depending on how negative that edge is we might replace the dist[x] after the comparison in line18.

So any dist[x] calculation we make will be incorrect if x is removed before all vertices v - such that x is a neighbour of v with negative edge connecting them - is removed.

Because each of those v vertices is the second last vertex on a potential "better" path from source to x, which is discarded by Dijkstra’s algorithm.

So in the example I gave above, the mistake was because C was removed before B was removed. While that C was a neighbour of B with a negative edge!

Just to clarify, B and C are A's neighbours. B has a single neighbour C and C has no neighbours. length(a,b) is the edge length between the vertices a and b.

Get all unique values in a JavaScript array (remove duplicates)

For a array of strings:

function removeDuplicatesFromArray(arr) {
  const unique = {};
  arr.forEach((word) => {
    unique[word] = 1; // it doesn't really matter what goes here
  });
  return Object.keys(unique);
}

How to rename with prefix/suffix?

In my case I have a group of files which needs to be renamed before I can work with them. Each file has its own role in group and has its own pattern.

As result I have a list of rename commands like this:

f=`ls *canctn[0-9]*`   ;  mv $f  CNLC.$f
f=`ls *acustb[0-9]*`   ;  mv $f  CATB.$f
f=`ls *accusgtb[0-9]*` ;  mv $f  CATB.$f
f=`ls *acus[0-9]*`     ;  mv $f  CAUS.$f

Try this also :

f=MyFileName; mv $f {pref1,pref2}$f{suf1,suf2}

This will produce all combinations with prefixes and suffixes:

pref1.MyFileName.suf1
...
pref2.MyFileName.suf2

Another way to solve same problem is to create mapping array and add corespondent prefix for each file type as shown below:

#!/bin/bash
unset masks
typeset -A masks
masks[ip[0-9]]=ip
masks[iaf_usg[0-9]]=ip_usg
masks[ipusg[0-9]]=ip_usg
...
for fileMask in ${!masks[*]}; 
do  
registryEntry="${masks[$fileMask]}";
fileName=*${fileMask}*
[ -e ${fileName} ] &&  mv ${fileName} ${registryEntry}.${fileName}  
done

Open a workbook using FileDialog and manipulate it in Excel VBA

Thankyou Frank.i got the idea. Here is the working code.

Option Explicit
Private Sub CommandButton1_Click()

  Dim directory As String, fileName As String, sheet As Worksheet, total As Integer
  Dim fd As Office.FileDialog

  Set fd = Application.FileDialog(msoFileDialogFilePicker)

  With fd
    .AllowMultiSelect = False
    .Title = "Please select the file."
    .Filters.Clear
    .Filters.Add "Excel 2003", "*.xls?"

    If .Show = True Then
      fileName = Dir(.SelectedItems(1))

    End If
  End With

  Application.ScreenUpdating = False
  Application.DisplayAlerts = False

  Workbooks.Open (fileName)

  For Each sheet In Workbooks(fileName).Worksheets
    total = Workbooks("import-sheets.xlsm").Worksheets.Count
    Workbooks(fileName).Worksheets(sheet.Name).Copy _
        after:=Workbooks("import-sheets.xlsm").Worksheets(total)
  Next sheet

  Workbooks(fileName).Close

  Application.ScreenUpdating = True
  Application.DisplayAlerts = True

End Sub

Is it possible to remove inline styles with jQuery?

The Lazy way (which will cause future designers to curse your name and murder you in your sleep):

#myelement 
{
    display: none !important;
}

Disclaimer: I do not advocate this approach, but it certainly is the lazy way.

Changing default shell in Linux

You should have a 'skeleton' somewhere in /etc, probably /etc/skeleton, or check the default settings, probably /etc/default or something. Those are scripts that define standard environment variables getting set during a login.

If it is just for your own account: check the (hidden) file ~/.profile and ~/.login. Or generate them, if they don't exist. These are also evaluated by the login process.

How can I join multiple SQL tables using the IDs?

Simple INNER JOIN VIEW code....

CREATE VIEW room_view
AS SELECT a.*,b.*
FROM j4_booking a INNER JOIN j4_scheduling b
on a.room_id = b.room_id;

Truncating Text in PHP?

$text="abc1234567890";

// truncate to 4 chars

echo substr(str_pad($text,4),0,4);

This avoids the problem of truncating a 4 char string to 10 chars .. (i.e. source is smaller than the required)

SQL Server: use CASE with LIKE

You can also do like this

select *
from table
where columnName like '%' + case when @varColumn is null then '' else @varColumn end  +  ' %'

JDBC connection failed, error: TCP/IP connection to host failed

important:
after any changes or new settings you must restart SQLSERVER service. run services.msc on Windows

What is a Memory Heap?

Presumably you mean heap from a memory allocation point of view, not from a data structure point of view (the term has multiple meanings).

A very simple explanation is that the heap is the portion of memory where dynamically allocated memory resides (i.e. memory allocated via malloc). Memory allocated from the heap will remain allocated until one of the following occurs:

  1. The memory is free'd
  2. The program terminates

If all references to allocated memory are lost (e.g. you don't store a pointer to it anymore), you have what is called a memory leak. This is where the memory has still been allocated, but you have no easy way of accessing it anymore. Leaked memory cannot be reclaimed for future memory allocations, but when the program ends the memory will be free'd up by the operating system.

Contrast this with stack memory which is where local variables (those defined within a method) live. Memory allocated on the stack generally only lives until the function returns (there are some exceptions to this, e.g. static local variables).

You can find more information about the heap in this article.

Difference between DataFrame, Dataset, and RDD in Spark

Spark RDD (resilient distributed dataset) :

RDD is the core data abstraction API and is available since very first release of Spark (Spark 1.0). It is a lower-level API for manipulating distributed collection of data. The RDD APIs exposes some extremely useful methods which can be used to get very tight control over underlying physical data structure. It is an immutable (read only) collection of partitioned data distributed on different machines. RDD enables in-memory computation on large clusters to speed up big data processing in a fault tolerant manner. To enable fault tolerance, RDD uses DAG (Directed Acyclic Graph) which consists of a set of vertices and edges. The vertices and edges in DAG represent the RDD and the operation to be applied on that RDD respectively. The transformations defined on RDD are lazy and executes only when an action is called

Spark DataFrame :

Spark 1.3 introduced two new data abstraction APIs – DataFrame and DataSet. The DataFrame APIs organizes the data into named columns like a table in relational database. It enables programmers to define schema on a distributed collection of data. Each row in a DataFrame is of object type row. Like an SQL table, each column must have same number of rows in a DataFrame. In short, DataFrame is lazily evaluated plan which specifies the operations needs to be performed on the distributed collection of the data. DataFrame is also an immutable collection.

Spark DataSet :

As an extension to the DataFrame APIs, Spark 1.3 also introduced DataSet APIs which provides strictly typed and object-oriented programming interface in Spark. It is immutable, type-safe collection of distributed data. Like DataFrame, DataSet APIs also uses Catalyst engine in order to enable execution optimization. DataSet is an extension to the DataFrame APIs.

Other Differences -

enter image description here

Oracle - What TNS Names file am I using?

Oracle provides a utility called tnsping:

R:\>tnsping someconnection

TNS Ping Utility for 32-bit Windows: Version 9.0.1.3.1 - Production on 27-AUG-20
08 10:38:07

Copyright (c) 1997 Oracle Corporation.  All rights reserved.

Used parameter files:
C:\Oracle92\network\ADMIN\sqlnet.ora
C:\Oracle92\network\ADMIN\tnsnames.ora

TNS-03505: Failed to resolve name

R:\>


R:\>tnsping entpr01

TNS Ping Utility for 32-bit Windows: Version 9.0.1.3.1 - Production on 27-AUG-20
08 10:39:22

Copyright (c) 1997 Oracle Corporation.  All rights reserved.

Used parameter files:
C:\Oracle92\network\ADMIN\sqlnet.ora
C:\Oracle92\network\ADMIN\tnsnames.ora

Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (COMMUNITY = **)
 (PROTOCOL = TCP) (Host = ****) (Port = 1521))) (CONNECT_DATA = (SID = ENTPR0
1)))
OK (40 msec)

R:\>

This should show what file you're using. The utility sits in the Oracle bin directory.

Can we rely on String.isEmpty for checking null condition on a String in Java?

I think the even shorter answer that you'll like is: StringUtils.isBlank(acct);

From the documentation: http://commons.apache.org/proper/commons-lang/javadocs/api-2.6/org/apache/commons/lang/StringUtils.html#isBlank%28java.lang.String%29

isBlank
public static boolean isBlank(String str)
Checks if a String is whitespace, empty ("") or null.

 StringUtils.isBlank(null)      = true
 StringUtils.isBlank("")        = true
 StringUtils.isBlank(" ")       = true
 StringUtils.isBlank("bob")     = false
 StringUtils.isBlank("  bob  ") = false
 
Parameters:
str - the String to check, may be null
Returns:
true if the String is null, empty or whitespace

Get the current displaying UIViewController on the screen in AppDelegate.m

Regarding NSNotificationCenter Post above (sorry can't find out where to post a comment under it...)

In case some were getting the -[NSConcreteNotification allKeys] error of sorts. Change this:

-(void)didReceiveRemoteNotification:(NSDictionary *)userInfo

to this:

-(void)didReceiveRemoteNotification:(NSNotification*)notif {
NSDictionary *dict = notif.userInfo;
}

How do I run a command on an already existing Docker container?

Some of the answers here are misleading because they concern containers that are running, not stopped.

Sven Dowideit explained on the Docker forum that containers are bound to their process (and Docker can't change the process of a stopped container, seemingly due at least to its internal structure: https://github.com/docker/docker/issues/1437). So, basically the only option is to commit the container to an image and run it with a different command.

See https://forums.docker.com/t/run-command-in-stopped-container/343
(I believe the "ENTRYPOINT with arguments" approach wouldn't work either, since you still wouldn't be able to change the arguments to a stopped container.)

assign multiple variables to the same value in Javascript

Nothing stops you from doing the above, but hold up!

There are some gotchas. Assignment in Javascript is from right to left so when you write:

var moveUp = moveDown = moveLeft = moveRight = mouseDown = touchDown = false;

it effectively translates to:

var moveUp = (moveDown = (moveLeft = (moveRight = (mouseDown = (touchDown = false)))));

which effectively translates to:

var moveUp = (window.moveDown = (window.moveLeft = (window.moveRight = (window.mouseDown = (window.touchDown = false)))));

Inadvertently, you just created 5 global variables--something I'm pretty sure you didn't want to do.

Note: My above example assumes you are running your code in the browser, hence window. If you were to be in a different environment these variables would attach to whatever the global context happens to be for that environment (i.e., in Node.js, it would attach to global which is the global context for that environment).

Now you could first declare all your variables and then assign them to the same value and you could avoid the problem.

var moveUp, moveDown, moveLeft, moveRight, mouseDown, touchDown;
moveUp = moveDown = moveLeft = moveRight = mouseDown = touchDown = false;

Long story short, both ways would work just fine, but the first way could potentially introduce some pernicious bugs in your code. Don't commit the sin of littering the global namespace with local variables if not absolutely necessary.


Sidenote: As pointed out in the comments (and this is not just in the case of this question), if the copied value in question was not a primitive value but instead an object, you better know about copy by value vs copy by reference. Whenever assigning objects, the reference to the object is copied instead of the actual object. All variables will still point to the same object so any change in one variable will be reflected in the other variables and will cause you a major headache if your intention was to copy the object values and not the reference.

React-Native Button style not work

As the answer by @plaul mentions TouchableOpacity, here is an example of how you can use that;

  <TouchableOpacity
    style={someStyles}
    onPress={doSomething}
  >
    <Text>Press Here</Text>
  </TouchableOpacity>

Android - Get value from HashMap

Note: If you know Key, use this code

String value=meMap.get(key);

What does $1 [QSA,L] mean in my .htaccess file?

This will capture requests for files like version, release, and README.md, etc. which should be treated either as endpoints, if defined (as in the case of /release), or as "not found."

HTML.HiddenFor value set

You can do this way

@Html.HiddenFor(model=>model.title, new {ng_init = string.Format("model.title='{0}'", Model.title) })

WhatsApp API (java/python)

Yowsup provide best solution with example.you can download api from https://github.com/tgalal/yowsup let me know if you have any issue.

How can I brew link a specific version?

brew switch libfoo mycopy

You can use brew switch to switch between versions of the same package, if it's installed as versioned subdirectories under Cellar/<packagename>/

This will list versions installed ( for example I had Cellar/sdl2/2.0.3, I've compiled into Cellar/sdl2/2.0.4)

brew info sdl2

Then to switch between them

brew switch sdl2 2.0.4
brew info 

Info now shows * next to the 2.0.4

To install under Cellar/<packagename>/<version> from source you can do for example

cd ~/somewhere/src/foo-2.0.4
./configure --prefix $(brew --Cellar)/foo/2.0.4
make

check where it gets installed with

make install -n

if all looks correct

make install

Then from cd $(brew --Cellar) do the switch between version.

I'm using brew version 0.9.5

How to make a HTML list appear horizontally instead of vertically using CSS only?

quite simple:

ul.yourlist li { float:left; }

or

ul.yourlist li { display:inline; }

How can a LEFT OUTER JOIN return more records than exist in the left table?

if multiple (x) rows in Dim_Member are associated with a single row in Susp_Visits, there will be x rows in the resul set.

Vertical divider CSS

<div class="headerdivider"></div>

and

.headerdivider {
    border-left: 1px solid #38546d;
    background: #16222c;
    width: 1px;
    height: 80px;
    position: absolute;
    right: 250px;
    top: 10px;
}

How to change the text color of first select option

If the first item is to be used as a placeholder (empty value) and your select is required then you can use the :invalid pseudo-class to target it.

_x000D_
_x000D_
select {_x000D_
  -webkit-appearance: menulist-button;_x000D_
  color: black;_x000D_
}_x000D_
_x000D_
select:invalid {_x000D_
  color: green;_x000D_
}
_x000D_
<select required>_x000D_
  <option value="">Item1</option>_x000D_
  <option value="Item2">Item2</option>_x000D_
  <option value="Item3">Item3</option>_x000D_
</select>
_x000D_
_x000D_
_x000D_

What is the difference between a port and a socket?

In a broad sense, Socket - is just that, a socket, just like your electrical, cable or telephone socket. A point where "requisite stuff" (power, signal, information) can go out and come in from. It hides a lot of detailed stuff, which is not required for the use of the "requisite stuff". In software parlance, it provides a generic way of defining a mechanism of communication between two entities (those entities could be anything - two applications, two physically separate devices, User & Kernel space within an OS, etc)

A Port is an endpoint discriminator. It differentiates one endpoint from another. At networking level, it differentiates one application from another, so that the networking stack can pass on information to the appropriate application.

How to install Hibernate Tools in Eclipse?

uncompress the zip HibernateTools-3.2.4.Beta1-R20081031133 later in eclipse --> menu Help -> Update Sofwate -> add site -> local add, and select de folder uncompress an install automatic

Detect rotation of Android phone in the browser with JavaScript

two-bit-fool's excellent answer provides all the background, but let me attempt a concise, pragmatic summary of how to handle orientation changes across iOS and Android:

  • If you only care about window dimensions (the typical scenario) - and not about the specific orientation:
    • Handle the resize event only.
    • In your handler, act on window.innerWidth and window.InnerHeight only.
    • Do NOT use window.orientation - it won't be current on iOS.
  • If you DO care about the specific orientation:
    • Handle only the resize event on Android, and only the orientationchange event on iOS.
    • In your handler, act on window.orientation (and window.innerWidth and window.InnerHeight)

These approaches offer slight benefits over remembering the previous orientation and comparing:

  • the dimensions-only approach also works while developing on desktop browsers that can otherwise simulate mobile devices, e.g., Chrome 23. (window.orientation is not available on desktop browsers).
  • no need for a global/anonymous-file-level-function-wrapper-level variable.

How do I merge a git tag onto a branch

Just complementing the answer.

Merging the last tag on a branch:

git checkout my-branch
git merge $(git describe --tags $(git rev-list --tags --max-count=1))

Inspired by https://gist.github.com/rponte/fdc0724dd984088606b0

MySQL SELECT only not null values

You should use IS NOT NULL. (The comparison operators = and <> both give UNKNOWN with NULL on either side of the expression.)

SELECT * 
FROM table 
WHERE YourColumn IS NOT NULL;

Just for completeness I'll mention that in MySQL you can also negate the null safe equality operator but this is not standard SQL.

SELECT *
FROM table 
WHERE NOT (YourColumn <=> NULL);

Edited to reflect comments. It sounds like your table may not be in first normal form in which case changing the structure may make your task easier. A couple of other ways of doing it though...

SELECT val1 AS val
FROM  your_table
WHERE val1 IS NOT NULL
UNION ALL
SELECT val2 
FROM  your_table
WHERE val2 IS NOT NULL
/*And so on for all your columns*/

The disadvantage of the above is that it scans the table multiple times once for each column. That may possibly be avoided by the below but I haven't tested this in MySQL.

SELECT CASE idx
         WHEN 1 THEN val1
         WHEN 2 THEN val2
       END AS val
FROM   your_table
        /*CROSS JOIN*/
       JOIN (SELECT 1 AS idx
                   UNION ALL
                   SELECT 2) t
HAVING val IS NOT NULL  /*Can reference alias in Having in MySQL*/

Undefined Reference to

Another way to get this error is by accidentally writing the definition of something in an anonymous namespace:

foo.h:

namespace foo {
    void bar();
}

foo.cc:

namespace foo {
    namespace {  // wrong
        void bar() { cout << "hello"; };
    }
}

other.cc file:

#include "foo.h"

void baz() {
    foo::bar();
}

Android Material: Status bar color won't change

As others have also mentioned, this can be readily solved by adding the following to the onCreate() of the Activity:

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
        getWindow().clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
        getWindow().setStatusBarColor(ContextCompat.getColor(this, R.color.primary_dark));
    }

However, the important point I want to add here is that in some cases, even the above does not change the status bar color. For example, when using MikePenz library for Navigation Drawer, it implicityly overrides the status bar color, so that you need to manually add the following for it to work:

.withStatusBarColorRes(R.color.status_bar_color)

Get Android .apk file VersionName or VersionCode WITHOUT installing apk

aapt dump badging test.apk | grep "VersionName" | sed -e "s/.*versionName='//" -e "s/' .*//"

This answers the question by returning only the version number as a result. However......

The goal as previously stated should be to find out if the apk on the server is newer than the one installed BEFORE attempting to download or install it. The easiest way to do this is include the version number in the filename of the apk hosted on the server eg myapp_1.01.apk

You will need to establish the name and version number of the apps already installed (if it is installed) in order to make the comparison. You will need a rooted device or a means of installing the aapt binary and busybox if they are not already included in the rom.

This script will get the list of apps from your server and compare with any installed apps. The result is a list flagged for upgrade/installation.

#/system/bin/sh
SERVER_LIST=$(wget -qO- "http://demo.server.com/apk/" | grep 'href' | grep '\.apk' | sed 's/.*href="//' | \
              sed 's/".*//' | grep -v '\/' | sed -E "s/%/\\\\x/g" | sed -e "s/x20/ /g" -e "s/\\\\//g")
LOCAL_LIST=$(for APP in $(pm list packages -f | sed -e 's/package://' -e 's/=.*//' | sort -u); do \
              INFO=$(echo -n $(aapt dump badging $APP | grep -e 'package: name=' -e 'application: label=')) 2>/dev/null; \
              PACKAGE=$(echo $INFO | sed "s/.*package: name='//" | sed "s/'.*$//"); \
              LABEL=$(echo $INFO | sed "s/.*application: label='//" | sed "s/'.*$//"); if [ -z "$LABEL" ]; then LABEL="$PACKAGE"; fi; \
              VERSION=$(echo $INFO | sed -e "s/.*versionName='//" -e "s/' .*//"); \
              NAME=$LABEL"_"$VERSION".apk"; echo "$NAME"; \
              done;)
OFS=$IFS; IFS=$'\t\n'
for REMOTE in $SERVER_LIST; do
    INSTALLED=0
    REMOTE_NAME=$(echo $REMOTE | sed 's/_.*//'); REMOTE_VER=$(echo $REMOTE | sed 's/^[^_]*_//g' | sed 's/[^0-9]*//g')
    for LOCAL in $LOCAL_LIST; do
        LOCAL_NAME=$(echo $LOCAL | sed 's/_.*//'); LOCAL_VER=$(echo $LOCAL | sed 's/^[^_]*_//g' | sed 's/[^0-9]*//g')
        if [ "$REMOTE_NAME" == "$LOCAL_NAME" ]; then INSTALLED=1; fi
        if [ "$REMOTE_NAME" == "$LOCAL_NAME" ] && [ ! "$REMOTE_VER" == "$LOCAL_VER" ]; then echo remote=$REMOTE ver=$REMOTE_VER local=$LOCAL ver=$LOCAL_VER; fi
    done
    if [ "$INSTALLED" == "0" ]; then echo "$REMOTE"; fi
done
IFS=$OFS

As somebody asked how to do it without using aapt. It is also possible to extract apk info with apktool and a bit of scripting. This way is slower and not simple in android but will work on windows/mac or linux as long as you have working apktool setup.

#!/bin/sh
APK=/path/to/your.apk
TMPDIR=/tmp/apktool
rm -f -R $TMPDIR
apktool d -q -f -s --force-manifest -o $TMPDIR $APK
APK=$(basename $APK)
VERSION=$(cat $TMPDIR/apktool.yml | grep "versionName" | sed -e "s/versionName: //")
LABEL=$(cat $TMPDIR/res/values/strings.xml | grep 'string name="title"' | sed -e 's/.*">//' -e 's/<.*//')
rm -f -R $TMPDIR
echo ${LABEL}_$(echo $V).apk

Also consider a drop folder on your server. Upload apks to it and a cron task renames and moves them to your update folder.

#!/bin/sh
# Drop Folder script for renaming APKs
# Read apk file from SRC folder and move it to TGT folder while changing filename to APKLABEL_APKVERSION.apk
# If an existing version of the APK exists in the target folder then script will remove it
# Define METHOD as "aapt" or "apktool" depending upon what is available on server 

# Variables
METHOD="aapt"
SRC="/home/user/public_html/dropfolders/apk"
TGT="/home/user/public_html/apk"
if [ -d "$SRC" ];then mkdir -p $SRC
if [ -d "$TGT" ]then mkdir -p $TGT

# Functions
get_apk_filename () {
    if [ "$1" = "" ]; then return 1; fi
    local A="$1"
    case $METHOD in
        "apktool")
            local D=/tmp/apktool
            rm -f -R $D
            apktool d -q -f -s --force-manifest -o $D $A
            local A=$(basename $A)
            local V=$(cat $D/apktool.yml | grep "versionName" | sed -e "s/versionName: //")
            local T=$(cat $D/res/values/strings.xml | grep 'string name="title"' | sed -e 's/.*">//' -e 's/<.*//')
            rm -f -R $D<commands>
            ;;
        "aapt")
            local A=$(aapt dump badging $A | grep -e "application-label:" -e "VersionName")
            local V=$(echo $A | sed -e "s/.*versionName='//" -e "s/' .*//")
            local T=$(echo $A | sed -e "s/.*application-label:'//" -e "s/'.*//")
            ;;
        esac
    echo ${T}_$(echo $V).apk
}

# Begin script
for APK in $(ls "$SRC"/*.apk); do
    APKNAME=$(get_apk_filename "$APK")
    rm -f $TGT/$(echo APKNAME | sed "s/_.*//")_*.apk
    mv "$APK" "$TGT"/$APKNAME
done

I am getting Failed to load resource: net::ERR_BLOCKED_BY_CLIENT with Google chrome

If you are running multiple extensions that perform ad or script blocking you will need to

individually update each one to your whitelist

Taking from this source, here are some of the extensions that may cause the case and how to deal with them.

Adblock Plus

  • Click the Adblock Plus icon.
  • Click “Enabled on this site” to disable ad blocking for the current site.
  • In Firefox Click “disable on wired.com” to disable ad blocking.
  • Reload the page you were viewing.
  • If problem still persist, cek if the character string "-300x600" is in the file name, that particular text pattern matches an expression list pattern in the AdBlock Plus.

Firefox Tracking Protection

  • In Firefox “Tracking Protection” may activate our adblock notice. It can be temporarily disabled for a browsing session by clicking the “shield” icon in the url bar if visible and following the instructions.

  • For further details on Tracking Protection please review Mozilla’s support.

Adblock

  • Click the Ad Block icon.
  • Click “Don’t run on pages on this domain”.
  • Reload the page you were viewing.

Ghostery

  • Click the Ghostery icon.
  • In Ghostery versions < 6.0 Click “Whitelist site”.
  • In Ghostery version 7.0 click “trust site”
  • In Versions < 6.0 You will see the message “Site is whitelisted”. Click “reload the page to see your changes.”
  • Reload the page you were viewing.

uBlock / uBlock Origin

  • Click the uBlock / uBlock Origin icon.

  • Click the “power” button in the menu that appears to whitelist the current web site.

  • Click the reload icon to reload the page you were viewing.

Disconnect

  • Click the Disconnect icon.
  • Click “Whitelist site”.

Kaspersky Ant-Banner
Please review How to configure Anti-Banner in Kaspersky Total Security for information on how to whitelist with Kaspersky Total Security.

Remove specific characters from a string in Javascript

if it is not the first two chars and you wanna remove F0 from the whole string then you gotta use this regex

_x000D_
_x000D_
   let string = 'F0123F0456F0';_x000D_
   let result = string.replace(/F0/ig, '');_x000D_
   console.log(result);
_x000D_
_x000D_
_x000D_

Postgresql -bash: psql: command not found

export PATH=/usr/pgsql-9.2/bin:$PATH

The program executable psql is in the directory /usr/pgsql-9.2/bin, and that directory is not included in the path by default, so we have to tell our shell (terminal) program where to find psql. When most packages are installed, they are added to an existing path, such as /usr/local/bin, but not this program.

So we have to add the program's path to the shell PATH variable if we do not want to have to type the complete path to the program every time we execute it.

This line should typically be added to theshell startup script, which for the bash shell will be in the file ~/.bashrc.

How to convert DateTime? to DateTime

You need to call the Value property of the nullable DateTime. This will return a DateTime.

Assuming that UpdatedDate is DateTime?, then this should work:

DateTime UpdatedTime = (DateTime)_objHotelPackageOrder.UpdatedDate == null ? DateTime.Now : _objHotelPackageOrder.UpdatedDate.Value;

To make the code a bit easier to read, you could use the HasValue property instead of the null check:

DateTime UpdatedTime = _objHotelPackageOrder.UpdatedDate.HasValue
                          ? _objHotelPackageOrder.UpdatedDate.Value
                          : DateTime.Now;

This can be then made even more concise:

DateTime UpdatedTime = _objHotelPackageOrder.UpdatedDate ?? DateTime.Now;

Error running android: Gradle project sync failed. Please fix your project and try again

I got this problem on Android studio, there in either sync or build square were this link like blue text about this issue, press that button and it download something that fix this problem

retrieve links from web page using python and BeautifulSoup

To find all the links, we will in this example use the urllib2 module together with the re.module *One of the most powerful function in the re module is "re.findall()". While re.search() is used to find the first match for a pattern, re.findall() finds all the matches and returns them as a list of strings, with each string representing one match*

import urllib2

import re
#connect to a URL
website = urllib2.urlopen(url)

#read html code
html = website.read()

#use re.findall to get all the links
links = re.findall('"((http|ftp)s?://.*?)"', html)

print links

react-router - pass props to handler component

Using ES6 you can just make component wrappers inline:

<Route path="/" component={() => <App myProp={someValue}/>} >

If you need to pass children:

<Route path="/" component={(props) => <App myProp={someValue}>{props.children}</App>} >

C#: Dynamic runtime cast

Try a generic:

public static T CastTo<T>(this dynamic obj, bool safeCast) where T:class
{
   try
   {
      return (T)obj;
   }
   catch
   {
      if(safeCast) return null;
      else throw;
   }
}

This is in extension method format, so its usage would be as if it were a member of dynamic objects:

dynamic myDynamic = new Something();
var typedObject = myDynamic.CastTo<Something>(false);

EDIT: Grr, didn't see that. Yes, you could reflectively close the generic, and it wouldn't be hard to hide in a non-generic extension method:

public static dynamic DynamicCastTo(this dynamic obj, Type castTo, bool safeCast)
{
   MethodInfo castMethod = this.GetType().GetMethod("CastTo").MakeGenericMethod(castTo);
   return castMethod.Invoke(null, new object[] { obj, safeCast });
}

I'm just not sure what you'd get out of this. Basically you're taking a dynamic, forcing a cast to a reflected type, then stuffing it back in a dynamic. Maybe you're right, I shouldn't ask. But, this'll probably do what you want. Basically when you go into dynamic-land, you lose the need to perform most casting operations as you can discover what an object is and does through reflective methods or trial and error, so there aren't many elegant ways to do this.

How to select a drop-down menu value with Selenium using Python?

firstly you need to import the Select class and then you need to create the instance of Select class. After creating the instance of Select class, you can perform select methods on that instance to select the options from dropdown list. Here is the code

from selenium.webdriver.support.select import Select

select_fr = Select(driver.find_element_by_id("fruits01"))
select_fr.select_by_index(0)

How to give a pattern for new line in grep?

Thanks to @jarno I know about the -z option and I found out that when using GNU grep with the -P option, matching against \n is possible. :)

Example:

grep -zoP 'foo\n\K.*'<<<$'foo\nbar'

Prints bar

Comparison of C++ unit test frameworks

API Sanity Checker — test framework for C/C++ libraries:

An automatic generator of basic unit tests for a shared C/C++ library. It is able to generate reasonable (in most, but unfortunately not all, cases) input data for parameters and compose simple ("sanity" or "shallow"-quality) test cases for every function in the API through the analysis of declarations in header files.

The quality of generated tests allows to check absence of critical errors in simple use cases. The tool is able to build and execute generated tests and detect crashes (segfaults), aborts, all kinds of emitted signals, non-zero program return code and program hanging.

Unique features in comparison with CppUnit, Boost and Google Test:

  • Automatic generation of test data and input arguments (even for complex data types)
  • Modern and highly reusable specialized types instead of fixtures and templates

Get first and last date of current month with JavaScript or jQuery

Very simple, no library required:

var date = new Date();
var firstDay = new Date(date.getFullYear(), date.getMonth(), 1);
var lastDay = new Date(date.getFullYear(), date.getMonth() + 1, 0);

or you might prefer:

var date = new Date(), y = date.getFullYear(), m = date.getMonth();
var firstDay = new Date(y, m, 1);
var lastDay = new Date(y, m + 1, 0);

EDIT

Some browsers will treat two digit years as being in the 20th century, so that:

new Date(14, 0, 1);

gives 1 January, 1914. To avoid that, create a Date then set its values using setFullYear:

var date = new Date();
date.setFullYear(14, 0, 1); // 1 January, 14

wkhtmltopdf: cannot connect to X server

for 14.04.1-Ubuntu https://wkhtmltopdf.org/downloads.html

wget https://downloads.wkhtmltopdf.org/0.12/0.12.4/wkhtmltox-0.12.4_linux-generic-amd64.tar.xz -O mktemp.tar.xz
tar xf mktemp.tar.xz
sudo cp wkhtmltox/bin/wkhtmltopdf /usr/bin/wkhtmltopdf
sudo chmod +x /usr/bin/wkhtmltopdf
rm mktemp.tar.xz
rm wkhtmltox -rf
apt-get update
apt-get install -y libxrender1 libxtst6 libxi6
wkhtmltopdf http://www.google.com test.pdf

How to store command results in a shell variable?

The syntax to store the command output into a variable is var=$(command).

So you can directly do:

result=$(ls -l | grep -c "rahul.*patle")

And the variable $result will contain the number of matches.

Open firewall port on CentOS 7

Firewalld is a bit non-intuitive for the iptables veteran. For those who prefer an iptables-driven firewall with iptables-like syntax in an easy configurable tree, try replacing firewalld with fwtree: https://www.linuxglobal.com/fwtree-flexible-linux-tree-based-firewall/ and then do the following:

 echo '-p tcp --dport 80 -m conntrack --cstate NEW -j ACCEPT' > /etc/fwtree.d/filter/INPUT/80-allow.rule
 systemctl reload fwtree 

How to view the assembly behind the code using Visual C++?

There are several approaches:

  1. You can normally see assembly code while debugging C++ in visual studio (and eclipse too). For this in Visual Studio put a breakpoint on code in question and when debugger hits it rigth click and find "Go To Assembly" ( or press CTRL+ALT+D )

  2. Second approach is to generate assembly listings while compiling. For this go to project settings -> C/C++ -> Output Files -> ASM List Location and fill in file name. Also select "Assembly Output" to "Assembly With Source Code".

  3. Compile the program and use any third-party debugger. You can use OllyDbg or WinDbg for this. Also you can use IDA (interactive disassembler). But this is hardcore way of doing it.

Setting a backgroundImage With React Inline Styles

Sometimes your SVG will be inlined by React so you need quotes around it:

     backgroundImage: `url("${Background}")`

otherwise it's invalid CSS and the browser dev tools will not show that you've set background-image at all.

Intellij idea cannot resolve anything in maven

  1. Close IntelliJ
  2. Open the same project
  3. When the project loads, at the lower right you can see a pop up saying non-managed pom.xml file found, if you click on it a new pop up will come, saying add as maven project, click on it, and done.

AngularJS - Trigger when radio button is selected

For dynamic values!

<div class="col-md-4" ng-repeat="(k, v) in tiposAcesso">
    <label class="control-label">
        <input type="radio" name="tipoAcesso" ng-model="userLogin.tipoAcesso" value="{{k}}" ng-change="changeTipoAcesso(k)" />              
        <span ng-bind="v"></span>
    </label>
</div>

in controller

$scope.changeTipoAcesso = function(value) {
    console.log(value);
};