Programs & Examples On #Respond to

Given a class, see if instance has method (Ruby)

On my case working with ruby 2.5.3 the following sentences have worked perfectly :

value = "hello world"

value.methods.include? :upcase

It will return a boolean value true or false.

ActionController::UnknownFormat

Update the create action as below:

def create
  ...
  respond_to do |format|
    if @reservation.save
      format.html do
        redirect_to '/'
      end
      format.json { render json: @reservation.to_json }
    else
      format.html { render 'new'} ## Specify the format in which you are rendering "new" page
      format.json { render json: @reservation.errors } ## You might want to specify a json format as well
    end
  end
end

You are using respond_to method but anot specifying the format in which a new page is rendered. Hence, the error ActionController::UnknownFormat .

Multiple FROMs - what it means

The first answer is too complex, historic, and uninformative for my tastes.


It's actually rather simple. Docker provides for a functionality called multi-stage builds the basic idea here is to,

  • Free you from having to manually remove what you don't want, by forcing you to whitelist what you do want,
  • Free resources that would otherwise be taken up because of Docker's implementation.

Let's start with the first. Very often with something like Debian you'll see.

RUN apt-get update \ 
  && apt-get dist-upgrade \
  && apt-get install <whatever> \
  && apt-get clean

We can explain all of this in terms of the above. The above command is chained together so it represents a single change with no intermediate Images required. If it was written like this,

RUN apt-get update ;
RUN apt-get dist-upgrade;
RUN apt-get install <whatever>;
RUN apt-get clean;

It would result in 3 more temporary intermediate Images. Having it reduced to one image, there is one remaining problem: apt-get clean doesn't clean up artifacts used in the install. If a Debian maintainer includes in his install a script that modifies the system that modification will also be present in the final solution (see something like pepperflashplugin-nonfree for an example of that).

By using a multi-stage build you get all the benefits of a single changed action, but it will require you to manually whitelist and copy over files that were introduced in the temporary image using the COPY --from syntax documented here. Moreover, it's a great solution where there is no alternative (like an apt-get clean), and you would otherwise have lots of un-needed files in your final image.

See also

Configure Flask dev server to be visible across the network

If your cool app has it's configuration loaded from an external file, like in the following example, then don't forget to update the corresponding config file with HOST="0.0.0.0"

cool.app.run(
    host=cool.app.config.get("HOST", "localhost"),
    port=cool.app.config.get("PORT", 9000)
)            

no such file to load -- rubygems (LoadError)

This is the first answer when Googling 'require': cannot load such file -- ubygems (LoadError) after Google autocorrected "ubygems" to "rubygems". Turns out this was an intentional change between Ruby 2.4 and 2.5 (Bug #14322). Scripts that detect the user gems directory without taking into account the ruby version will most likely fail.

Ruby 2.4

ruby -rubygems -e 'puts Gem.user_dir'

Ruby 2.5

ruby -rrubygems -e 'puts Gem.user_dir'

user authentication libraries for node.js?

A different take on authentication is Passwordless, a token-based authentication module for express that circumvents the inherent problem of passwords [1]. It's fast to implement, doesn't require too many forms, and offers better security for the average user (full disclosure: I'm the author).

[1]: Passwords are Obsolete

libclntsh.so.11.1: cannot open shared object file.

I ran into this same problem last weekend when I needed to use cx_Oracle. After spending a lot of time trying to modify the LD_LIBRARY_PATH variable to include the $ORACLE_HOME/lib directoy, where libclntsh.so resides, I ended up solving the problem by creating symbolic links from all the Oracle xlibx.so libraries into /lib/xlibx.so. This certainly isn't the "cleanest" solution, but it has a good chance of working without causing too much trouble:

 cd $ORACLE_HOME/lib
 for f in `ls ./*.so*`; do;
   sudo ln -s $ORACLE_HOME/lib/$f /lib/$f 
 done

After I did that, cx_Oracle worked like a charm.

How do I get an apk file from an Android device?

One liner which works for all Android versions:

adb shell 'cat `pm path com.example.name | cut -d':' -f2`' > app.apk

How to do multiline shell script in Ansible

I prefer this syntax as it allows to set configuration parameters for the shell:

---
- name: an example
  shell:
    cmd: |
      docker build -t current_dir .
      echo "Hello World"
      date

    chdir: /home/vagrant/

Where is database .bak file saved from SQL Server Management Studio?

I dont think default backup location is stored within the SQL server itself. The settings are stored in Registry. Look for "BackupDirectory" key and you'll find the default backup.

The "msdb.dbo.backupset" table consists of list of backups taken, if no backup is taken for a database, it won't show you anything

How do I concatenate two arrays in C#?

More efficient (faster) to use Buffer.BlockCopy over Array.CopyTo,

int[] x = new int [] { 1, 2, 3};
int[] y = new int [] { 4, 5 };

int[] z = new int[x.Length + y.Length];
var byteIndex = x.Length * sizeof(int);
Buffer.BlockCopy(x, 0, z, 0, byteIndex);
Buffer.BlockCopy(y, 0, z, byteIndex, y.Length * sizeof(int));

I wrote a simple test program that "warms up the Jitter", compiled in release mode and ran it without a debugger attached, on my machine.

For 10,000,000 iterations of the example in the question

Concat took 3088ms

CopyTo took 1079ms

BlockCopy took 603ms

If I alter the test arrays to two sequences from 0 to 99 then I get results similar to this,

Concat took 45945ms

CopyTo took 2230ms

BlockCopy took 1689ms

From these results I can assert that the CopyTo and BlockCopy methods are significantly more efficient than Concat and furthermore, if performance is a goal, BlockCopy has value over CopyTo.

To caveat this answer, if performance doesn't matter, or there will be few iterations choose the method you find easiest. Buffer.BlockCopy does offer some utility for type conversion beyond the scope of this question.

How do I get DOUBLE_MAX?

You are looking for the float.h header.

Call to undefined function curl_init().?

The CURL extension ext/curl is not installed or enabled in your PHP installation. Check the manual for information on how to install or enable CURL on your system.

How do you determine the size of a file in C?

Here's a simple and clean function that returns the file size.

long get_file_size(char *path)
{
    FILE *fp;
    long size = -1;
    /* Open file for reading */
    fp = fopen(path, "r");
    fseek(fp, 0, SEEK_END);
    size = ftell(fp); 
    fp.close();
    return 
}

Submit form using AJAX and jQuery

First give your form an id attribute, then use code like this:

$(document).ready( function() {
  var form = $('#my_awesome_form');

  form.find('select:first').change( function() {
    $.ajax( {
      type: "POST",
      url: form.attr( 'action' ),
      data: form.serialize(),
      success: function( response ) {
        console.log( response );
      }
    } );
  } );

} );

So this code uses .serialize() to pull out the relevant data from the form. It also assumes the select you care about is the first one in the form.

For future reference, the jQuery docs are very, very good.

Does GPS require Internet?

As others have said, you do not need internet for GPS.

GPS is basically a satellite based positioning system that is designed to calculate geographic coordinates based on timing information received from multiple satellites in the GPS constellation. GPS has a relatively slow time to first fix (TTFF), and from a cold start (meaning without a last known position), it can take up to 15 minutes to download the data it needs from the satellites to calculate a position. A-GPS used by cellular networks shortens this time by using the cellular network to deliver the satellite data to the phone.

But regardless of whether it is an A-GPS or GPS location, all that is derived is Geographic Coordinates (latitude/longitude). It is impossible to obtain more from GPS only.

To be able to return anything other than coordinates (such as an address), you need some mechanism to do Reverse Geocoding. Typically this is done by querying a server or a web service (like using Google Maps or Bing Maps, but there are others). Some of the services will allow you to cache data locally, but it would still require an internet connection for periods of time to download the map information in the surrounding area.

While it requires a significant amount of effort, you can write your own tool to do the reverse geocoding, but you still need to be able to house the data somewhere as the amount of data required to do this is far more you can store on a phone, which means you still need an internet connection to do it. If you think of tools like Garmin GPS Navigation units, they do store the data locally, so it is possible, but you will need to optimize it for maximum storage and would probably need more than is generally available in a phone.

Bottom line:

The short answer to your question is, no you do not need an active internet connection to get coordinates, but unless you are building a specialized device or have unlimited storage, you will need an internet connection to turn those coordinates into anything else.

Java 8 - Difference between Optional.flatMap and Optional.map

What helped me was a look at the source code of the two functions.

Map - wraps the result in an Optional.

public<U> Optional<U> map(Function<? super T, ? extends U> mapper) {
    Objects.requireNonNull(mapper);
    if (!isPresent())
        return empty();
    else {
        return Optional.ofNullable(mapper.apply(value)); //<--- wraps in an optional
    }
}

flatMap - returns the 'raw' object

public<U> Optional<U> flatMap(Function<? super T, Optional<U>> mapper) {
    Objects.requireNonNull(mapper);
    if (!isPresent())
        return empty();
    else {
        return Objects.requireNonNull(mapper.apply(value)); //<---  returns 'raw' object
    }
}

Converting to upper and lower case in Java

WordUtils.capitalizeFully(str) from apache commons-lang has the exact semantics as required.

Why do Twitter Bootstrap tables always have 100% width?

Bootstrap 3:

Why fight it? Why not simply control your table width using the bootstrap grid?

<div class="row">
    <div class="col-sm-6">
        <table></table>
    </div>
</div>

This will create a table that is half (6 out of 12) of the width of the containing element.

I sometimes use inline styles as per the other answers, but it is discouraged.

Bootstrap 4:

Bootstrap 4 has some nice helper classes for width like w-25, w-50, w-75, w-100, and w-auto. This will make the table 50% width:

<table class="w-50"></table>

Here's the doc: https://getbootstrap.com/docs/4.0/utilities/sizing/

Start systemd service after specific service?

After= dependency is only effective when service including After= and service included by After= are both scheduled to start as part of your boot up.

Ex:

a.service
[Unit]
After=b.service

This way, if both a.service and b.service are enabled, then systemd will order b.service after a.service.

If I am not misunderstanding, what you are asking is how to start b.service when a.service starts even though b.service is not enabled.

The directive for this is Wants= or Requires= under [Unit].

website.service
[Unit]
Wants=mongodb.service
After=mongodb.service

The difference between Wants= and Requires= is that with Requires=, a failure to start b.service will cause the startup of a.service to fail, whereas with Wants=, a.service will start even if b.service fails. This is explained in detail on the man page of .unit.

Can I write into the console in a unit test? If yes, why doesn't the console window open?

As stated, unit tests are designed to run without interaction.

However, you can debug unit tests, just like any other code. The easiest way is to use the Debug button in the Test Results tab.

Being able to debug means being able to use breakpoints. Being able to use breakpoints, then, means being able to use Tracepoints, which I find extremely useful in every day debugging.

Essentially, Tracepoints allow you to write to the Output window (or, more accurately, to standard output). Optionally, you can continue to run, or you can stop like a regular breakpoint. This gives you the "functionality" you are asking for, without the need to rebuild your code, or fill it up with debug information.

Simply add a breakpoint, and then right-click on that breakpoint. Select the "When Hit..." option:

When hitting option

Which brings up the dialog:

When a breakpoint is hit

A few things to note:

  1. Notice that the breakpoint is now shown as a diamond, instead of a sphere, indicating a trace point
  2. You can output the value of a variable by enclosing it like {this}.
  3. Uncheck the "Continue Execution" checkbox to have the code break on this line, like any regular breakpoint
  4. You have the option of running a macro. Please be careful - you may cause harmful side effects.

See the documentation for more details.

How do I use Node.js Crypto to create a HMAC-SHA1 hash?

Documentation for crypto: http://nodejs.org/api/crypto.html

const crypto = require('crypto')

const text = 'I love cupcakes'
const key = 'abcdeg'

crypto.createHmac('sha1', key)
  .update(text)
  .digest('hex')

JPA and Hibernate - Criteria vs. JPQL or HQL

There is a difference in terms of performance between HQL and criteriaQuery, everytime you fire a query using criteriaQuery, it creates a new alias for the table name which does not reflect in the last queried cache for any DB. This leads to an overhead of compiling the generated SQL, taking more time to execute.

Regarding fetching strategies [http://www.hibernate.org/315.html]

  • Criteria respects the laziness settings in your mappings and guarantees that what you want loaded is loaded. This means one Criteria query might result in several SQL immediate SELECT statements to fetch the subgraph with all non-lazy mapped associations and collections. If you want to change the "how" and even the "what", use setFetchMode() to enable or disable outer join fetching for a particular collection or association. Criteria queries also completely respect the fetching strategy (join vs select vs subselect).
  • HQL respects the laziness settings in your mappings and guarantees that what you want loaded is loaded. This means one HQL query might result in several SQL immediate SELECT statements to fetch the subgraph with all non-lazy mapped associations and collections. If you want to change the "how" and even the "what", use LEFT JOIN FETCH to enable outer-join fetching for a particular collection or nullable many-to-one or one-to-one association, or JOIN FETCH to enable inner join fetching for a non-nullable many-to-one or one-to-one association. HQL queries do not respect any fetch="join" defined in the mapping document.

Redirect all output to file using Bash on Linux?

You can execute a subshell and redirect all output while still putting the process in the background:

( ./script.sh blah > ~/log/blah.log 2>&1 ) &
echo $! > ~/pids/blah.pid

How can I check whether a variable is defined in Node.js?

Determine if property is existing (but is not a falsy value):

if (typeof query !== 'undefined' && query !== null){
   doStuff();
}

Usually using

if (query){
   doStuff();
}

is sufficient. Please note that:

if (!query){
   doStuff();
}

doStuff() will execute even if query was an existing variable with falsy value (0, false, undefined or null)

Btw, there's a sexy coffeescript way of doing this:

if object?.property? then doStuff()

which compiles to:

if ((typeof object !== "undefined" && object !== null ? object.property : void 0) != null) 

{
  doStuff();
}

Only allow Numbers in input Tag without Javascript

Of course, you can't fully rely on the client-side (javascript) validation, but that's not a reason to avoid it completely. With or without it, you have to do the server-side validation anyway (since the client can disable javascript). And that's just what you're left with, due to your non-javascript solution constraint.

So, after a submit, if the field value doesn't pass the server-side validation, the client should end up on the very same page, with additional error message specifying the requested value format. You also should provide the value format information beforehands, e.g. as a tool-tip hint (title attribute).

There's most certainly no passive client-side validation mechanism existing in HTML 4 / XHTML.

On the other hand, in HTML 5 you have two options:

  • input of type number:

    <input type="number" min="xxx" max="yyy" title="Format: 3 digits" />
    

    – only validates the range – if user enters a non-number, an empty value is submitted
    – the field visual is enhanced with increment / decrement controls (browser dependent)

  • the pattern attribute:

    <input type="text" pattern="[0-9]{3}" title="Format: 3 digits" />
    <input type="text" pattern="\d{3}" title="Format: 3 digits" />
    

    – this gives you a full contorl over the format (anything you can specify by regular expression)
    – no visual difference / enhancement

But here you still rely on browser capabilities, so do a server-side validation in either case.

How to use a parameter in ExecStart command line?

Although systemd indeed does not provide way to pass command-line arguments for unit files, there are possibilities to write instances: http://0pointer.de/blog/projects/instances.html

For example: /lib/systemd/system/[email protected] looks something like this:

[Unit]
Description=Serial Getty on %I
BindTo=dev-%i.device
After=dev-%i.device systemd-user-sessions.service

[Service]
ExecStart=-/sbin/agetty -s %I 115200,38400,9600
Restart=always
RestartSec=0

So, you may start it like:

$ systemctl start [email protected]
$ systemctl start [email protected]

For systemd it will different instances:

$ systemctl status [email protected]
[email protected] - Getty on ttyUSB0
      Loaded: loaded (/lib/systemd/system/[email protected]; static)
      Active: active (running) since Mon, 26 Sep 2011 04:20:44 +0200; 2s ago
    Main PID: 5443 (agetty)
      CGroup: name=systemd:/system/[email protected]/ttyUSB0
          + 5443 /sbin/agetty -s ttyUSB0 115200,38400,9600

It also mean great possibility enable and disable it separately.

Off course it lack much power of command line parsing, but in common way it is used as some sort of config files selection. For example you may look at Fedora [email protected]: http://pkgs.fedoraproject.org/cgit/openvpn.git/tree/[email protected]

Is it possible in Java to check if objects fields are null and then add default value to all those attributes?

I tried this and it works without any issues to validate if the field is empty. I have answered your question partially as I haven't personally tried to add default values to attributes

if(field.getText()!= null && !field.getText().isEmpty())

Hope it helps

"CAUTION: provisional headers are shown" in Chrome debugger

HTTP/2 Pushed resources will produce Provisional headers are shown in the inspector for the same theory as @wvega posted in his answer above.

e.g: Since the server pushed the resource(s) to the client (before the client requested them), the browser has the resources cached and therefore the client never makes/needs a requests; So because...

...the real headers are updated when the server responds, but there is no response if the request was blocked.

Visual Studio: How to show Overloads in IntelliSense?

Ctrl+Shift+Space shows the Edit.ParameterInfo for the selected method, and by selected method I mean the caret must be within the method parentheses.

Here is the Visual Studio 2010 Keybinding Poster.

And for those still using 2008.

How to send authorization header with axios

Rather than adding it to every request, you can just add it as a default config like so.

axios.defaults.headers.common['Authorization'] = `Bearer ${access_token}` 

Copy or rsync command

Rsync is better since it will only copy only the updated parts of the updated file, instead of the whole file. It also uses compression and encryption if you want. Check out this tutorial.

Looking for a short & simple example of getters/setters in C#

In C#, Properties represent your Getters and Setters.

Here's an example:

public class PropertyExample
{
    private int myIntField = 0;

    public int MyInt
    {
        // This is your getter.
        // it uses the accessibility of the property (public)
        get
        {
            return myIntField;
        }
        // this is your setter
        // Note: you can specify different accessibility
        // for your getter and setter.
        protected set
        {
            // You can put logic into your getters and setters
            // since they actually map to functions behind the scenes
            DoSomeValidation(value)
            {
                // The input of the setter is always called "value"
                // and is of the same type as your property definition
                myIntField = value;
            }
        }
    }
}

You would access this property just like a field. For example:

PropertyExample example = new PropertyExample();
example.MyInt = 4; // sets myIntField to 4
Console.WriteLine( example.MyInt ); // prints 4

A few other things to note:

  1. You don't have to specifiy both a getter and a setter, you can omit either one.
  2. Properties are just "syntactic sugar" for your traditional getter and setter. The compiler will actually build get_ and set_ functions behind the scenes (in the compiled IL) and map all references to your property to those functions.

Android - Handle "Enter" in an EditText

Just as an addendum to Chad's response (which worked almost perfectly for me), I found that I needed to add a check on the KeyEvent action type to prevent my code executing twice (once on the key-up and once on the key-down event).

if (actionId == EditorInfo.IME_NULL && event.getAction() == KeyEvent.ACTION_DOWN)
{
    // your code here
}

See http://developer.android.com/reference/android/view/KeyEvent.html for info about repeating action events (holding the enter key) etc.

How do I pass along variables with XMLHTTPRequest

Following is correct way:

xmlhttp.open("GET","getuser.php?fname="+abc ,true);

FormsAuthentication.SignOut() does not log the user out

After lots of search finally this worked for me . I hope it helps.

public ActionResult LogOff()
{
    AuthenticationManager.SignOut();
    HttpContext.User = new GenericPrincipal(new GenericIdentity(string.Empty), null);
    return RedirectToAction("Index", "Home");
}

<li class="page-scroll">@Html.ActionLink("Log off", "LogOff", "Account")</li>

How To Get Selected Value From UIPickerView

You will need to ask the picker's delegate, in the same way your application does. Here is how I do it from within my UIPickerViewDelegate:

func selectedRowValue(picker : UIPickerView, ic : Int) -> String {

    //Row Index
    let ir  = picker.selectedRow(inComponent: ic);

    //Value
    let val = self.pickerView(picker,
                              titleForRow:  ir,
                              forComponent: ic);
    return val!;
}

browser.msie error after update to jQuery 1.9.1

Using this:

if (navigator.userAgent.match("MSIE")) {}

How to check if a String contains another String in a case insensitive manner in Java?

String x="abCd";
System.out.println(Pattern.compile("c",Pattern.CASE_INSENSITIVE).matcher(x).find());

How can I delete all of my Git stashes at once?

this command enables you to look all stashed changes.

git stash list

Here is the following command use it to clear all of your stashed Changes

git stash clear

Now if you want to delete one of the stashed changes from stash area

git stash drop stash@{index}   // here index will be shown after getting stash list.

Note : git stash list enables you to get index from stash area of git.

submit the form using ajax

You can catch form input values using FormData and send them by fetch

fetch(form.action,{method:'post', body: new FormData(form)});

_x000D_
_x000D_
function send(e,form) {_x000D_
  fetch(form.action,{method:'post', body: new FormData(form)});_x000D_
_x000D_
  console.log('We send post asynchronously (AJAX)');_x000D_
  e.preventDefault();_x000D_
}
_x000D_
<form method="POST" action="myapi/send" onsubmit="send(event,this)">_x000D_
    <input hidden name="crsfToken" value="a1e24s1">_x000D_
    <input name="email" value="[email protected]">_x000D_
    <input name="phone" value="123-456-789">_x000D_
    <input type="submit">    _x000D_
</form>_x000D_
_x000D_
Look on chrome console>network before 'submit'
_x000D_
_x000D_
_x000D_

Delete a row from a SQL Server table

You may change the "columnName" type from TEXT to VARCHAR(MAX). TEXT column can't be used with "=".
see this topic

Execute Shell Script after post build in Jenkins

If I'm reading your question right, you want to run a script in the post build actions part of the build.

I myself use PostBuildScript Plugin for running git clean -fxd after the build has archived artifacts and published test results. My Jenkins slaves have SSD disks, so I do not have the room keep generated files in the workspace.

Using lambda expressions for event handlers

Performance-wise it's the same as a named method. The big problem is when you do the following:

MyButton.Click -= (o, i) => 
{ 
    //snip 
} 

It will probably try to remove a different lambda, leaving the original one there. So the lesson is that it's fine unless you also want to be able to remove the handler.

json.dumps vs flask.jsonify

consider

data={'fld':'hello'}

now

jsonify(data)

will yield {'fld':'hello'} and

json.dumps(data)

gives

"<html><body><p>{'fld':'hello'}</p></body></html>"

How to sign in kubernetes dashboard?

If you don't want to grant admin permission to dashboard service account, you can create cluster admin service account.

$ kubectl create serviceaccount cluster-admin-dashboard-sa
$ kubectl create clusterrolebinding cluster-admin-dashboard-sa \
  --clusterrole=cluster-admin \
  --serviceaccount=default:cluster-admin-dashboard-sa

And then, you can use the token of just created cluster admin service account.

$ kubectl get secret | grep cluster-admin-dashboard-sa
cluster-admin-dashboard-sa-token-6xm8l   kubernetes.io/service-account-token   3         18m
$ kubectl describe secret cluster-admin-dashboard-sa-token-6xm8l

I quoted it from giantswarm guide - https://docs.giantswarm.io/guides/install-kubernetes-dashboard/

How to set viewport meta for iPhone that handles rotation properly?

<meta name="viewport" content="width=device-width, minimum-scale=1, maximum-scale=1">

suport all iphones, all ipads, all androids.

How can a Jenkins user authentication details be "passed" to a script which uses Jenkins API to create jobs?

Try this way: (for example delete the job)

curl --silent --show-error http://<username>:<api-token>@<jenkins-server>/job/<job-name>/doDelete

The api-token can be obtained from http://<jenkins-server>/user/<username>/configure.

Is Java a Compiled or an Interpreted programming language ?

enter image description here

Code written in Java is:

  • First compiled to bytecode by a program called javac as shown in the left section of the image above;
  • Then, as shown in the right section of the above image, another program called java starts the Java runtime environment and it may compile and/or interpret the bytecode by using the Java Interpreter/JIT Compiler.

When does java interpret the bytecode and when does it compile it? The application code is initially interpreted, but the JVM monitors which sequences of bytecode are frequently executed and translates them to machine code for direct execution on the hardware. For bytecode which is executed only a few times, this saves the compilation time and reduces the initial latency; for frequently executed bytecode, JIT compilation is used to run at high speed, after an initial phase of slow interpretation. Additionally, since a program spends most time executing a minority of its code, the reduced compilation time is significant. Finally, during the initial code interpretation, execution statistics can be collected before compilation, which helps to perform better optimization.

How do I POST an array of objects with $.ajax (jQuery or Zepto)

Be sure to stringify before sending. I leaned on the libraries too much and thought they would encode properly based on the contentType I was posting, but they do not seem to.

Works:

$.ajax({
    url: _saveAllDevicesUrl
,   type: 'POST'
,   contentType: 'application/json'
,   data: JSON.stringify(postData) //stringify is important
,   success: _madeSave.bind(this)
});

I prefer this method to using a plugin like $.toJSON, although that does accomplish the same thing.

Difference between save and saveAndFlush in Spring data jpa

On saveAndFlush, changes will be flushed to DB immediately in this command. With save, this is not necessarily true, and might stay just in memory, until flush or commit commands are issued.

But be aware, that even if you flush the changes in transaction and do not commit them, the changes still won't be visible to the outside transactions until the commit in this transaction.

In your case, you probably use some sort of transactions mechanism, which issues commit command for you if everything works out fine.

What is the difference between task and thread?

I usually use Task to interact with Winforms and simple background worker to make it not freezing the UI. here an example when I prefer using Task

private async void buttonDownload_Click(object sender, EventArgs e)
{
    buttonDownload.Enabled = false;
    await Task.Run(() => {
        using (var client = new WebClient())
        {
            client.DownloadFile("http://example.com/file.mpeg", "file.mpeg");
        }
    })
    buttonDownload.Enabled = true;
}

VS

private void buttonDownload_Click(object sender, EventArgs e)
{
    buttonDownload.Enabled = false;
    Thread t = new Thread(() =>
    {
        using (var client = new WebClient())
        {
            client.DownloadFile("http://example.com/file.mpeg", "file.mpeg");
        }
        this.Invoke((MethodInvoker)delegate()
        {
            buttonDownload.Enabled = true;
        });
    });
    t.IsBackground = true;
    t.Start();
}

the difference is you don't need to use MethodInvoker and shorter code.

Eslint: How to disable "unexpected console statement" in Node.js?

in my vue project i fixed this problem like this :

vim package.json
...
"rules": {
    "no-console": "off"
},
...

ps : package.json is a configfile in the vue project dir, finally the content shown like this:

{
  "name": "metadata-front",
  "version": "0.1.0",
  "private": true,
  "scripts": {
    "serve": "vue-cli-service serve",
    "build": "vue-cli-service build",
    "lint": "vue-cli-service lint"
  },
  "dependencies": {
    "axios": "^0.18.0",
    "vue": "^2.5.17",
    "vue-router": "^3.0.2"
  },
  "devDependencies": {
    "@vue/cli-plugin-babel": "^3.0.4",
    "@vue/cli-plugin-eslint": "^3.0.4",
    "@vue/cli-service": "^3.0.4",
    "babel-eslint": "^10.0.1",
    "eslint": "^5.8.0",
    "eslint-plugin-vue": "^5.0.0-0",
    "vue-template-compiler": "^2.5.17"
  },
  "eslintConfig": {
    "root": true,
    "env": {
      "node": true
    },
    "extends": [
      "plugin:vue/essential",
      "eslint:recommended"
    ],
    "rules": {
        "no-console": "off"
    },
    "parserOptions": {
      "parser": "babel-eslint"
    }
  },
  "postcss": {
    "plugins": {
      "autoprefixer": {}
    }
  },
  "browserslist": [
    "> 1%",
    "last 2 versions",
    "not ie <= 8"
  ]
}

Ping all addresses in network, windows

@ECHO OFF

IF "%SUBNET%"=="" SET SUBNET=10

:ARGUMENTS
ECHO SUBNET=%SUBNET%
ECHO ARGUMENT %1 
IF "%1"=="SUM" GOTO SUM
IF "%1"=="SLOW" GOTO SLOW
IF "%1"=="ARP" GOTO ARP
IF "%1"=="FAST" GOTO FAST

REM PRINT ARP TABLE BY DEFAULT
:DEFAULT
ARP -a
GOTO END

REM METHOD 1 ADDRESS AT A TIME
:SLOW
ECHO START SCAN
ECHO %0 > ipaddresses.txt
DATE /T >> ipaddresses.txt
TIME /T >> ipaddresses.txt
FOR /L %%i IN (1,1,254) DO ping -a -n 2 192.168.%SUBNET%.%%i | FIND /i "TTL="  >> ipaddresses.txt
GOTO END

REM METHOD 2 MULTITASKING ALL ADDRESS AT SAME TIME
:FAST
ECHO START FAST SCANNING 192.168.%SUBNET%.X
set /a n=0
:FASTLOOP
set /a n+=1
ECHO 192.168.%SUBNET%.%n%
START CMD.exe /c call ipaddress.bat 192.168.%SUBNET%.%n% 
IF %n% lss 254 GOTO FASTLOOP
GOTO END

:SUM
ECHO START SUM
ECHO %0 > ipaddresses.txt
DATE /T >> ipaddresses.txt
TIME /T >> ipaddresses.txt
FOR /L %%i IN (1,1,254) DO TYPE ip192.168.%SUBNET%.%%i.txt | FIND /i "TTL=" >> ipaddresses.txt
FOR /L %%i IN (1,1,254) DO DEL ip192.168.%SUBNET%.%%i.txt
type ipaddresses.txt
GOTO END

:ARP
ARP -a >> ipaddresses.txt
type ipaddresses.txt
GOTO END


:END
ECHO DONE WITH IP SCANNING
ECHO OPTION "%0 SLOW" FOR SCANNING 1 AT A TIME
ECHO OPTION "%0 SUM" FOR COMBINE ALL TO FILE
ECHO OPTION "%0 ARP" FOR ADD ARP - IP LIST
ECHO PARAMETER "SET SUBNET=X" FOR SUBNET
ECHO.

How do I convert dmesg timestamp to custom date format?

In recent versions of dmesg, you can just call dmesg -T.

No plot window in matplotlib

Try this:

import matplotlib
matplotlib.use('TkAgg') 

BEFORE import pylab

How to convert a Hibernate proxy to a real entity object

Thank you for the suggested solutions! Unfortunately, none of them worked for my case: receiving a list of CLOB objects from Oracle database through JPA - Hibernate, using a native query.

All of the proposed approaches gave me either a ClassCastException or just returned java Proxy object (which deeply inside contained the desired Clob).

So my solution is the following (based on several above approaches):

Query sqlQuery = manager.createNativeQuery(queryStr);
List resultList = sqlQuery.getResultList();
for ( Object resultProxy : resultList ) {
    String unproxiedClob = unproxyClob(resultProxy);
    if ( unproxiedClob != null ) {
       resultCollection.add(unproxiedClob);
    }
}

private String unproxyClob(Object proxy) {
    try {
        BeanInfo beanInfo = Introspector.getBeanInfo(proxy.getClass());
        for (PropertyDescriptor property : beanInfo.getPropertyDescriptors()) {
            Method readMethod = property.getReadMethod();
            if ( readMethod.getName().contains("getWrappedClob") ) {
                Object result = readMethod.invoke(proxy);
                return clobToString((Clob) result);
            }
        }
    }
    catch (InvocationTargetException | IntrospectionException | IllegalAccessException | SQLException | IOException e) {
        LOG.error("Unable to unproxy CLOB value.", e);
    }
    return null;
}

private String clobToString(Clob data) throws SQLException, IOException {
    StringBuilder sb = new StringBuilder();
    Reader reader = data.getCharacterStream();
    BufferedReader br = new BufferedReader(reader);

    String line;
    while( null != (line = br.readLine()) ) {
        sb.append(line);
    }
    br.close();

    return sb.toString();
}

Hope this will help somebody!

What is the { get; set; } syntax in C#?

Its basically a shorthand. You can write public string Name { get; set; } like in many examples, but you can also write it:

private string _name;

public string Name
{
    get { return _name; }
    set { _name = value ; } // value is a special keyword here
}

Why it is used? It can be used to filter access to a property, for example you don't want names to include numbers.

Let me give you an example:

private class Person {
    private int _age;  // Person._age = 25; will throw an error
    public int Age{
        get { return _age; }  // example: Console.WriteLine(Person.Age);
        set { 
            if ( value >= 0) {
                _age = value; }  // valid example: Person.Age = 25;
        }
    }
}

Officially its called Auto-Implemented Properties and its good habit to read the (programming guide). I would also recommend tutorial video C# Properties: Why use "get" and "set".

How to move the cursor word by word in the OS X Terminal

Out of the box you can use the quite bizarre Esc+F to move to the beginning of the next word and Esc+B to move to the beginning of the current word.

Explain __dict__ attribute

Basically it contains all the attributes which describe the object in question. It can be used to alter or read the attributes. Quoting from the documentation for __dict__

A dictionary or other mapping object used to store an object's (writable) attributes.

Remember, everything is an object in Python. When I say everything, I mean everything like functions, classes, objects etc (Ya you read it right, classes. Classes are also objects). For example:

def func():
    pass

func.temp = 1

print(func.__dict__)

class TempClass:
    a = 1
    def temp_function(self):
        pass

print(TempClass.__dict__)

will output

{'temp': 1}
{'__module__': '__main__', 
 'a': 1, 
 'temp_function': <function TempClass.temp_function at 0x10a3a2950>, 
 '__dict__': <attribute '__dict__' of 'TempClass' objects>, 
 '__weakref__': <attribute '__weakref__' of 'TempClass' objects>, 
 '__doc__': None}

What is path of JDK on Mac ?

Have a look and see if the the JDK is at:

Library/Java/JavaVirtualMachines/ Or /System/Library/Java/JavaVirtualMachines/

Check this earlier SO post: JDK on OSX 10.7 Lion

best OCR (Optical character recognition) example in android

Like you I also faced many problems implementing OCR in Android, but after much Googling I found the solution, and it surely is the best example of OCR.

Let me explain using step-by-step guidance.

First, download the source code from https://github.com/rmtheis/tess-two.

Import all three projects. After importing you will get an error. To solve the error you have to create a res folder in the tess-two project

enter image description here

First, just create res folder in tess-two by tess-two->RightClick->new Folder->Name it "res"

After doing this in all three project the error should be gone.

Now download the source code from https://github.com/rmtheis/android-ocr, here you will get best example.

Now you just need to import it into your workspace, but first you have to download android-ndk from this site:

http://developer.android.com/tools/sdk/ndk/index.html i have windows 7 - 32 bit PC so I have download http://dl.google.com/android/ndk/android-ndk-r9-windows-x86.zip this file

Now extract it suppose I have extract it into E:\Software\android-ndk-r9 so I will set this path on Environment Variable

Right Click on MyComputer->Property->Advance-System-Settings->Advance->Environment Variable-> find PATH on second below Box and set like path like below picture

enter image description here

done it

Now open cmd and go to on D:\Android Workspace\tess-two like below

enter image description here

If you have successfully set up environment variable of NDK then just type ndk-build just like above picture than enter you will not get any kind of error and all file will be compiled successfully:

Now download other source code also from https://github.com/rmtheis/tess-two , and extract and import it and give it name OCRTest, like in my PC which is in D:\Android Workspace\OCRTest

enter image description here

Import test-two in this and run OCRTest and run it; you will get the best example of OCR.

Can't connect to local MySQL server through socket '/var/mysql/mysql.sock' (38)

In my case the solution was that I had mariadb installed, which was aliased to mysql. So all service commands relating to mysql were not recognised... I just needed:

service mariadb start

And for good measure:

chkconfig mariadb on

Check if object exists in JavaScript

Two ways.

typeof for local variables

You can test for a local object using typeof:

if (typeof object !== "undefined") {}

window for global variables

You can test for a global object (one defined on the global scope) by inspecting the window object:

if (window.FormData) {}

How can I find the version of php that is running on a distinct domain name?

Possibly use something like firefox's tamperdata and look at the header returned (if they have publishing enabled).

How to change TIMEZONE for a java.util.Calendar/Date

  1. The class Date/Timestamp represents a specific instant in time, with millisecond precision, since January 1, 1970, 00:00:00 GMT. So this time difference (from epoch to current time) will be same in all computers across the world with irrespective of Timezone.

  2. Date/Timestamp doesn't know about the given time is on which timezone.

  3. If we want the time based on timezone we should go for the Calendar or SimpleDateFormat classes in java.

  4. If you try to print a Date/Timestamp object using toString(), it will convert and print the time with the default timezone of your machine.

  5. So we can say (Date/Timestamp).getTime() object will always have UTC (time in milliseconds)

  6. To conclude Date.getTime() will give UTC time, but toString() is on locale specific timezone, not UTC.

Now how will I create/change time on specified timezone?

The below code gives you a date (time in milliseconds) with specified timezones. The only problem here is you have to give date in string format.

   DateFormat dateFormat = new SimpleDateFormat("yyyyMMdd HH:mm:ss");
   dateFormatLocal.setTimeZone(timeZone);
   java.util.Date parsedDate = dateFormatLocal.parse(date);

Use dateFormat.format for taking input Date (which is always UTC), timezone and return date as String.

How to store UTC/GMT time in DB:

If you print the parsedDate object, the time will be in default timezone. But you can store the UTC time in DB like below.

        Calendar calGMT = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
        Timestamp tsSchedStartTime = new Timestamp (parsedDate.getTime());
        if (tsSchedStartTime != null) {
            stmt.setTimestamp(11, tsSchedStartTime, calGMT );
        } else {
            stmt.setNull(11, java.sql.Types.DATE);
        }

iPhone UIView Animation Best Practice

The difference seems to be the amount of control you need over the animation.

The CATransition approach gives you more control and therefore more things to set up, eg. the timing function. Being an object, you can store it for later, refactor to point all your animations at it to reduce duplicated code, etc.

The UIView class methods are convenience methods for common animations, but are more limited than CATransition. For example, there are only four possible transition types (flip left, flip right, curl up, curl down). If you wanted to do a fade in, you'd have to either dig down to CATransition's fade transition, or set up an explicit animation of your UIView's alpha.

Note that CATransition on Mac OS X will let you specify an arbitrary CoreImage filter to use as a transition, but as it stands now you can't do this on the iPhone, which lacks CoreImage.

React-router urls don't work when refreshing or writing manually

If you're using firebase all you have to do is make sure you've got a rewrites property in your firebase.json file in the root of your app (in the hosting section).

For example:

{ 
  "hosting": {
    "rewrites": [{
      "source":"**",
      "destination": "/index.html"
    }]    
  }
}

Hope this saves somebody else a hoard of frustration and wasted time.

Happy coding...

Further reading on the subject:

https://firebase.google.com/docs/hosting/full-config#rewrites

Firebase CLI: "Configure as a single-page app (rewrite all urls to /index.html)"

connecting MySQL server to NetBeans

check the context.xml file in Web Pages -> META-INF, the username="user" must be the same as the database user, in my case was root, that solved the connection error

Hope helps

How to rebuild docker container in docker-compose.yml?

Simply use :

docker-compose build [yml_service_name]

Replace [yml_service_name] with your service name in docker-compose.yml file. You can use docker-compose restart to make sure changes are effected. You can use --no-cache to ignore the cache.

Multiple connections to a server or shared resource by the same user, using more than one user name, are not allowed

It may be that the Windows Credential Manager is holding onto credentials for the network share.

Credential Manager - Windows Credentials

Load up Credential Manager (the easiest way is perhaps just to Search for that in the Start Menu), see if there are any Windows Credentials for your network share, and try deleting/updating them.

Setting Windows PATH for Postgres tools

In order to connect my git bash to the postgreSQL, I had to add at least 4 environment variables to the windows. Git, Node.js, System 32 and postgreSQL. This is what I set as the value for the Path variable: C:\Windows\System32;C:\Program Files\Git\cmd;C:\Program Files\nodejs;C:\Program Files\PostgreSQL\12\bin; and It works perfectly.

How do I select an element with its name attribute in jQuery?

You could always do $('input[name="somename"]')

java calling a method from another class

You have to initialise the object (create the object itself) in order to be able to call its methods otherwise you would get a NullPointerException.

WordList words = new WordList();

Calculating moving average

  • Rolling Means/Maximums/Medians in the zoo package (rollmean)
  • MovingAverages in TTR
  • ma in forecast

Example use of "continue" statement in Python?

Let's say we want to print all numbers which are not multiples of 3 and 5

for x in range(0, 101):
    if x % 3 ==0 or x % 5 == 0:
        continue
        #no more code is executed, we go to the next number 
    print x

How do I do a bulk insert in mySQL using node.js

This is a fast "raw-copy-paste" snipped to push a file column in mysql with node.js >= 11

250k row in few seconds

'use strict';

const mysql = require('promise-mysql');
const fs = require('fs');
const readline = require('readline');

async function run() {
  const connection = await mysql.createConnection({
    host: '1.2.3.4',
    port: 3306,
    user: 'my-user',
    password: 'my-psw',
    database: 'my-db',
  });

  const rl = readline.createInterface({ input: fs.createReadStream('myfile.txt') });

  let total = 0;
  let buff = [];
  for await (const line of rl) {
    buff.push([line]);
    total++;
    if (buff.length % 2000 === 0) {
      await connection.query('INSERT INTO Phone (Number) VALUES ?', [buff]);
      console.log(total);
      buff = [];
    }
  }

  if (buff.length > 0) {
    await connection.query('INSERT INTO Phone (Number) VALUES ?', [buff]);
    console.log(total);
  }

  console.log('end');
  connection.close();
}

run().catch(console.log);

How to convert int to NSString?

NSString *string = [NSString stringWithFormat:@"%d", theinteger];

Windows equivalent to UNIX pwd

In PowerShell pwd is an alias to Get-Location so you can simply run pwd in it like in bash

It can also be called from cmd like this powershell -Command pwd although cd or echo %cd% in cmd would work just fine

Aborting a stash pop in Git

I could reproduce clean git stash pop on "dirty" directory, with uncommitted changes, but not yet pop that generates a merge conflict.

If on merge conflict the stash you tried to apply didn't disappear, you can try to examine git show stash@{0} (optionally with --ours or --theirs) and compare with git statis and git diff HEAD. You should be able to see which changes came from applying a stash.

Spring application context external properties?

<context:property-placeholder location="file:/apps/tomcat/ath/ath_conf/pcr.application.properties" />

This works for me. Local development machine path is C:\apps\tomcat\ath\ath_conf and in server /apps/tomcat/ath/ath_conf

Both works for me

How do I escape spaces in path for scp copy in Linux?

I had huge difficulty getting this to work for a shell variable containing a filename with whitespace. For some reason using:

file="foo bar/baz"
scp [email protected]:"'$file'"

as in @Adrian's answer seems to fail.

Turns out that what works best is using a parameter expansion to prepend backslashes to the whitespace as follows:

file="foo bar/baz"
file=${file// /\\ }
scp [email protected]:"$file"

iOS: UIButton resize according to text length

sizeToFit doesn't work correctly. instead:

myButton.size = myButton.sizeThatFits(CGSize.zero)

you also can add contentInset to the button:

myButton.contentEdgeInsets = UIEdgeInsetsMake(8, 8, 4, 8)

Handle Button click inside a row in RecyclerView

this is how I handle multiple onClick events inside a recyclerView:

Edit : Updated to include callbacks (as mentioned in other comments). I have used a WeakReference in the ViewHolder to eliminate a potential memory leak.

Define interface :

public interface ClickListener {

    void onPositionClicked(int position);
    
    void onLongClicked(int position);
}

Then the Adapter :

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {
    
    private final ClickListener listener;
    private final List<MyItems> itemsList;

    public MyAdapter(List<MyItems> itemsList, ClickListener listener) {
        this.listener = listener;
        this.itemsList = itemsList;
    }

    @Override public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        return new MyViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.my_row_layout), parent, false), listener);
    }

    @Override public void onBindViewHolder(MyViewHolder holder, int position) {
        // bind layout and data etc..
    }

    @Override public int getItemCount() {
        return itemsList.size();
    }

    public static class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener, View.OnLongClickListener {

        private ImageView iconImageView;
        private TextView iconTextView;
        private WeakReference<ClickListener> listenerRef;

        public MyViewHolder(final View itemView, ClickListener listener) {
            super(itemView);

            listenerRef = new WeakReference<>(listener);
            iconImageView = (ImageView) itemView.findViewById(R.id.myRecyclerImageView);
            iconTextView = (TextView) itemView.findViewById(R.id.myRecyclerTextView);

            itemView.setOnClickListener(this);
            iconTextView.setOnClickListener(this);
            iconImageView.setOnLongClickListener(this);
        }

        // onClick Listener for view
        @Override
        public void onClick(View v) {

            if (v.getId() == iconTextView.getId()) {
                Toast.makeText(v.getContext(), "ITEM PRESSED = " + String.valueOf(getAdapterPosition()), Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(v.getContext(), "ROW PRESSED = " + String.valueOf(getAdapterPosition()), Toast.LENGTH_SHORT).show();
            }
            
            listenerRef.get().onPositionClicked(getAdapterPosition());
        }


        //onLongClickListener for view
        @Override
        public boolean onLongClick(View v) {

            final AlertDialog.Builder builder = new AlertDialog.Builder(v.getContext());
            builder.setTitle("Hello Dialog")
                    .setMessage("LONG CLICK DIALOG WINDOW FOR ICON " + String.valueOf(getAdapterPosition()))
                    .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {

                        }
                    });

            builder.create().show();
            listenerRef.get().onLongClicked(getAdapterPosition());
            return true;
        }
    }
}

Then in your activity/fragment - whatever you can implement : Clicklistener - or anonymous class if you wish like so :

MyAdapter adapter = new MyAdapter(myItems, new ClickListener() {
            @Override public void onPositionClicked(int position) {
                // callback performed on click
            }

            @Override public void onLongClicked(int position) {
                // callback performed on click
            }
        });

To get which item was clicked you match the view id i.e. v.getId() == whateverItem.getId()

Hope this approach helps!

'node' is not recognized as an internal or an external command, operable program or batch file while using phonegap/cordova

In Windows, you need to set node.js folder path into system variables or user variables.

1) open Control Panel -> System and Security -> System -> Advanced System Settings -> Environment Variables

2) in "User variables" or "System variables" find variable PATH and add node.js folder path as value. Usually it is C:\Program Files\nodejs;. If variable doesn't exists, create it.

3) Restart your IDE or computer.

It is useful add also "npm" and "Git" paths as variable, separated by semicolon.

Customizing Bootstrap CSS template

Since Pabluez's answer back in December, there is now a better way to customize Bootstrap.

Use: Bootswatch to generate your bootstrap.css

Bootswatch builds the normal Twitter Bootstrap from the latest version (whatever you install in the bootstrap directory), but also imports your customizations. This makes it easy to use the the latest version of Bootstrap, while maintaining custom CSS, without having to change anything about your HTML. You can simply sway boostrap.css files.

Decrementing for loops

You need to give the range a -1 step

 for i in range(10,0,-1):
    print i

CodeIgniter: "Unable to load the requested class"

In Windows, capitalization in paths doesn't matter. In Linux it does.

When you autoload, use "Foo" not "foo".

I believe that will do the trick.

I think it works when you take it out of autoloading because codeigniter is smart enough to figure out the capitalization in the path and classes are case independent in php.

Passing data between view controllers

If you want to pass data from one controller to other, try this code:

File FirstViewController.h

@property (nonatomic, retain) NSString *str;

SecondViewController.h

@property (nonatomic, retain) NSString *str1;

File FirstViewController.m

- (void)viewDidLoad
   {
     // Message for the second SecondViewController
     self.str = @"text message";

     [super viewDidLoad];
   }

-(IBAction)ButtonClicked
 {
   SecondViewController *secondViewController = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];
   secondViewController.str1 = str;
  [self.navigationController pushViewController:secondViewController animated:YES];
 }

Static variable inside of a function in C

You will get 6 7 printed as, as is easily tested, and here's the reason: When foo is first called, the static variable x is initialized to 5. Then it is incremented to 6 and printed.

Now for the next call to foo. The program skips the static variable initialization, and instead uses the value 6 which was assigned to x the last time around. The execution proceeds as normal, giving you the value 7.

How to clear PermGen space Error in tomcat

If your using eclipse with tomcat follow the below steps

  1. On server window Double click on tomcat, It will open the tomcat's Overview window .

  2. In the Overview window you will find Open launch configuration under General information and click on Open launch configuration.

  3. In the edit Configuration window look for Arguments and click on It.
  4. In the arguments tag look for VM arguments.
  5. simply paste this -Xms256m -Xmx512m -XX:PermSize=256m -XX:MaxPermSize=512m to the end of the arguments.

edit launch configuration properties

How can I check if a user is logged-in in php?

Almost all of the answers on this page rely on checking a session variable's existence to validate a user login. That is absolutely fine, but it is important to consider that the PHP session state is not unique to your application if there are multiple virtual hosts/sites on the same bare metal.

If you have two PHP applications on a webserver, both checking a user's login status with a boolean flag in a session variable called 'isLoggedIn', then a user could log into one of the applications and then automagically gain access to the second without credentials.

I suspect even the most dinosaur of commercial shared hosting wouldn't let virtual hosts share the same PHP environment in such a way that this could happen across multiple customers site's (anymore), but its something to consider in your own environments.

The very simple solution is to use a session variable that identifies the app rather than a boolean flag. e.g $SESSION["isLoggedInToExample.com"].

Source: I'm a penetration tester, with a lot of experience on how you shouldn't do stuff.

Image style height and width not taken in outlook mails

The px needs to be left off, for some odd reason.

Optimal number of threads per core

The ideal is 1 thread per core, as long as none of the threads will block.

One case where this may not be true: there are other threads running on the core, in which case more threads may give your program a bigger slice of the execution time.

How do I delete multiple rows in Entity Framework (without foreach)

In EF 6.2 this works perfectly, sending the delete directly to the database without first loading the entities:

context.Widgets.Where(predicate).Delete();

With a fixed predicate it's quite straightforward:

context.Widgets.Where(w => w.WidgetId == widgetId).Delete();

And if you need a dynamic predicate have a look at LINQKit (Nuget package available), something like this works fine in my case:

Expression<Func<Widget, bool>> predicate = PredicateBuilder.New<Widget>(x => x.UserID == userID);
if (somePropertyValue != null)
{
    predicate = predicate.And(w => w.SomeProperty == somePropertyValue);
}
context.Widgets.Where(predicate).Delete();

Linq order by, group by and order by each group?

Sure:

var query = grades.GroupBy(student => student.Name)
                  .Select(group => 
                        new { Name = group.Key,
                              Students = group.OrderByDescending(x => x.Grade) })
                  .OrderBy(group => group.Students.First().Grade);

Note that you can get away with just taking the first grade within each group after ordering, because you already know the first entry will be have the highest grade.

Then you could display them with:

foreach (var group in query)
{
    Console.WriteLine("Group: {0}", group.Name);
    foreach (var student in group.Students)
    {
        Console.WriteLine("  {0}", student.Grade);
    }
}

Update Android SDK Tool to 22.0.4(Latest Version) from 22.0.1

I faced the same issue, I tried the below solution and it worked for me In Android SDK Manager Window, click on Tools->Options-> under "Others", check "Force https://... sources to be fetched using http://..."

Converting a string to an integer on Android

Use regular expression is best way to doing this as already mentioned by ashish sahu

public int getInt(String s){
return Integer.parseInt(s.replaceAll("[\\D]", ""));
}

In Java how does one turn a String into a char or a char into a String?

char firstLetter = someString.charAt(0);
String oneLetter = String.valueOf(someChar);

You find the documentation by identifying the classes likely to be involved. Here, candidates are java.lang.String and java.lang.Character.

You should start by familiarizing yourself with:

  • Primitive wrappers in java.lang
  • Java Collection framework in java.util

It also helps to get introduced to the API more slowly through tutorials.

default select option as blank

You could use Javascript to achieve this. Try the following code:

HTML

<select id="myDropdown">      
    <option>Option 1</option>     
    <option>Option 2</option>     
    <option>Option 3</option>     
</select> 

JS

document.getElementById("myDropdown").selectedIndex = -1;

or JQuery

$("#myDropdown").prop("selectedIndex", -1);

Vertically aligning text next to a radio button

I think this is what you might be asking for

http://jsbin.com/ixowuw/2/

CSS

label{
  font-size:18px;
  vertical-align: middle;
}

input[type="radio"]{
  vertical-align: middle;
}

HTML

<span>
  <input type="radio" id="oddsPref" name="oddsPref" value="decimal" />
  <label>Decimal</label>
</span>

Setting up JUnit with IntelliJ IDEA

I needed to enable the JUnit plugin, after I linked my project with the jar files.

To enable the JUnit plugin, go to File->Settings, type "JUnit" in the search bar, and under "Plugins," check "JUnit.

vikingsteve's advice above will probably get the libraries linked right. Otherwise, open File->Project Structure, go to Libraries, hit the plus, and then browse to

C:\Program Files (x86)\JetBrains\IntelliJ IDEA Community Edition 14.1.1\lib\

and add these jar files:

hamcrest-core-1.3.jar
junit-4.11.jar 
junit.jar 

DateTime.Now.ToShortDateString(); replace month and day

this.TextBox3.Text = DateTime.Now.ToString("MM.dd.yyyy");

Check if an array contains duplicate values

This should work with only one loop:

function checkIfArrayIsUnique(arr) {
    var map = {}, i, size;

    for (i = 0, size = arr.length; i < size; i++){
        if (map[arr[i]]){
            return false;
        }

        map[arr[i]] = true;
    }

    return true;
}

How can I update the current line in a C# Windows Console App?

If you want update one line, but the information is too long to show on one line, it may need some new lines. I've encountered this problem, and below is one way to solve this.

public class DumpOutPutInforInSameLine
{

    //content show in how many lines
    int TotalLine = 0;

    //start cursor line
    int cursorTop = 0;

    // use to set  character number show in one line
    int OneLineCharNum = 75;

    public void DumpInformation(string content)
    {
        OutPutInSameLine(content);
        SetBackSpace();

    }
    static void backspace(int n)
    {
        for (var i = 0; i < n; ++i)
            Console.Write("\b \b");
    }

    public  void SetBackSpace()
    {

        if (TotalLine == 0)
        {
            backspace(OneLineCharNum);
        }
        else
        {
            TotalLine--;
            while (TotalLine >= 0)
            {
                backspace(OneLineCharNum);
                TotalLine--;
                if (TotalLine >= 0)
                {
                    Console.SetCursorPosition(OneLineCharNum, cursorTop + TotalLine);
                }
            }
        }

    }

    private void OutPutInSameLine(string content)
    {
        //Console.WriteLine(TotalNum);

        cursorTop = Console.CursorTop;

        TotalLine = content.Length / OneLineCharNum;

        if (content.Length % OneLineCharNum > 0)
        {
            TotalLine++;

        }

        if (TotalLine == 0)
        {
            Console.Write("{0}", content);

            return;

        }

        int i = 0;
        while (i < TotalLine)
        {
            int cNum = i * OneLineCharNum;
            if (i < TotalLine - 1)
            {
                Console.WriteLine("{0}", content.Substring(cNum, OneLineCharNum));
            }
            else
            {
                Console.Write("{0}", content.Substring(cNum, content.Length - cNum));
            }
            i++;

        }
    }

}
class Program
{
    static void Main(string[] args)
    {

        DumpOutPutInforInSameLine outPutInSameLine = new DumpOutPutInforInSameLine();

        outPutInSameLine.DumpInformation("");
        outPutInSameLine.DumpInformation("bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb");


        outPutInSameLine.DumpInformation("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");
        outPutInSameLine.DumpInformation("bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb");

        //need several lines
        outPutInSameLine.DumpInformation("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");
        outPutInSameLine.DumpInformation("bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb");

        outPutInSameLine.DumpInformation("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");
        outPutInSameLine.DumpInformation("bbbbbbbbbbbbbbbbbbbbbbbbbbb");

    }
}

How to get on scroll events?

Listen to window:scroll event for window/document level scrolling and element's scroll event for element level scrolling.

window:scroll

@HostListener('window:scroll', ['$event'])
onWindowScroll($event) {

}

or

<div (window:scroll)="onWindowScroll($event)">

scroll

@HostListener('scroll', ['$event'])
onElementScroll($event) {

}

or

<div (scroll)="onElementScroll($event)">

@HostListener('scroll', ['$event']) won't work if the host element itself is not scroll-able.

Examples

Is there a way to programmatically scroll a scroll view to a specific edit text?

The above answers will work fine if the ScrollView is the direct parent of the ChildView. If your ChildView is being wrapped in another ViewGroup in the ScrollView, it will cause unexpected behavior because the View.getTop() get the position relative to its parent. In such case, you need to implement this:

public static void scrollToInvalidInputView(ScrollView scrollView, View view) {
    int vTop = view.getTop();

    while (!(view.getParent() instanceof ScrollView)) {
        view = (View) view.getParent();
        vTop += view.getTop();
    }

    final int scrollPosition = vTop;

    new Handler().post(() -> scrollView.smoothScrollTo(0, scrollPosition));
}

How do I create a Python function with optional arguments?

Just use the *args parameter, which allows you to pass as many arguments as you want after your a,b,c. You would have to add some logic to map args->c,d,e,f but its a "way" of overloading.

def myfunc(a,b, *args, **kwargs):
   for ar in args:
      print ar
myfunc(a,b,c,d,e,f)

And it will print values of c,d,e,f


Similarly you could use the kwargs argument and then you could name your parameters.

def myfunc(a,b, *args, **kwargs):
      c = kwargs.get('c', None)
      d = kwargs.get('d', None)
      #etc
myfunc(a,b, c='nick', d='dog', ...)

And then kwargs would have a dictionary of all the parameters that are key valued after a,b

How to convert "0" and "1" to false and true

My solution (vb.net):

Private Function ConvertToBoolean(p1 As Object) As Boolean
    If p1 Is Nothing Then Return False
    If IsDBNull(p1) Then Return False
    If p1.ToString = "1" Then Return True
    If p1.ToString.ToLower = "true" Then Return True
    Return False
End Function

How can I declare a global variable in Angular 2 / Typescript?

Here is the simplest solution w/o Service nor Observer:

Put the global variables in a file an export them.

//
// ===== File globals.ts    
//
'use strict';

export const sep='/';
export const version: string="22.2.2";    

To use globals in another file use an import statement: import * as myGlobals from 'globals';

Example:

// 
// ===== File heroes.component.ts    
//
import {Component, OnInit} from 'angular2/core';
import {Router} from 'angular2/router';
import {HeroService} from './hero.service';
import {HeroDetailComponent} from './hero-detail.component';
import {Hero} from './hero';
import * as myGlobals from 'globals'; //<==== this one (**Updated**)

export class HeroesComponent implements OnInit {
    public heroes: Hero[];
    public selectedHero: Hero;
    // 
    //
    // Here we access the global var reference.
    //  
    public helloString: string="hello " + myGlobals.sep + " there";

         ...

        }
    }

Thanks @eric-martinez

Sort ArrayList of custom Objects by property

You can Sort using java 8

yourList.sort(Comparator.comparing(Classname::getName));

or

yourList.stream().forEach(a -> a.getBObjects().sort(Comparator.comparing(Classname::getValue)));

vuejs update parent data from child component

In the child

 <input
            type="number"
            class="form-control"
            id="phoneNumber"
            placeholder
            v-model="contact_number"
            v-on:input="(event) => this.$emit('phoneNumber', event.target.value)"
    />

data(){
    return {
      contact_number : this.contact_number_props
    }
  },
  props : ['contact_number_props']

In parent

<contact-component v-on:phoneNumber="eventPhoneNumber" :contact_number_props="contact_number"></contact-component>


 methods : {
     eventPhoneNumber (value) {
      this.contact_number = value
    }

How do you set the EditText keyboard to only consist of numbers on Android?

Place the below lines in your <EditText>:

android:digits="0123456789"
android:inputType="phone"

org.apache.catalina.LifecycleException: Failed to start component [StandardServer[8005]]A child container failed during start

This seems to be an issue with local Maven repository. (i.e. .m2 folder) may be due to some corrupt .jar file

For me, the following actions helped to overcome this issue.

  1. On my local file system, I've deleted the directory .m2 (Maven local repository)

  2. In Eclipse, updated the project (select Maven > Update Project)

  3. Ran the app again on Tomcat server.

html select scroll bar

One options will be to show the selected option above (or below) the select list like following:

HTML

<div id="selText"><span>&nbsp;</span></div><br/>
<select size="4" id="mySelect" style="width:65px;color:#f98ad3;">
    <option value="1" selected>option 1 The Long Option</option>
    <option value="2">option 2</option>
    <option value="3">option 3</option>
    <option value="4">option 4</option>
    <option value="5">option 5 Another Longer than the Long Option ;)</option>
    <option value="6">option 6</option>
</select>

JavaScript

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.min.js"   
  type="text/javascript"></script> 
<script type="text/javascript">
$(document).ready(function(){        
    $("select#mySelect").change(function(){
      //$("#selText").html($($(this).children("option:selected")[0]).text());
       var txt = $($(this).children("option:selected")[0]).text();
       $("<span>" + txt + "<br/></span>").appendTo($("#selText span:last"));
    });
});
</script>

PS:- Set height of div#selText otherwise it will keep shifting select list downward.

How to get file creation & modification date/times in Python?

There are two methods to get the mod time, os.path.getmtime() or os.stat(), but the ctime is not reliable cross-platform (see below).

os.path.getmtime()

getmtime(path)
Return the time of last modification of path. The return value is a number giving the number of seconds since the epoch (see the time module). Raise os.error if the file does not exist or is inaccessible. New in version 1.5.2. Changed in version 2.3: If os.stat_float_times() returns True, the result is a floating point number.

os.stat()

stat(path)
Perform a stat() system call on the given path. The return value is an object whose attributes correspond to the members of the stat structure, namely: st_mode (protection bits), st_ino (inode number), st_dev (device), st_nlink (number of hard links), st_uid (user ID of owner), st_gid (group ID of owner), st_size (size of file, in bytes), st_atime (time of most recent access), st_mtime (time of most recent content modification), st_ctime (platform dependent; time of most recent metadata change on Unix, or the time of creation on Windows):

>>> import os
>>> statinfo = os.stat('somefile.txt')
>>> statinfo
(33188, 422511L, 769L, 1, 1032, 100, 926L, 1105022698,1105022732, 1105022732)
>>> statinfo.st_size
926L
>>> 

In the above example you would use statinfo.st_mtime or statinfo.st_ctime to get the mtime and ctime, respectively.

How to get the file ID so I can perform a download of a file from Google Drive API on Android?

Click with the right mouse button on the file in your Google Drive. Choose the option to get a link which can be shared from the menu. You will see the file id now. Don't forget to undo the share.

Search for exact match of string in excel row using VBA Macro

Use worksheet.find (worksheet is your worksheet) and use the row-range for its range-object. You can get the rangeobject like: worksheet.rows(rowIndex) as example

Then give find the required parameters it should find it for you fine. If I recall correctly, find returns the first match per default. I have no Excel at hand, so you have to look up find for yourself, sorry

I would advise against using a for-loop it is more fragile and ages slower than find.

How to checkout a specific Subversion revision from the command line?

You should never use TortoiseProc.exe as a command-line Subversion client! TortoiseProc should be utilized only for automating TortoiseSVN's GUI. See the note in TortoiseSVN's Manual:

Remember that TortoiseSVN is a GUI client, and this automation guide shows you how to make the TortoiseSVN dialogs appear to collect user input. If you want to write a script which requires no input, you should use the official Subversion command line client instead.

Use the Subversion command-line svn.exe client. With the command-line client, you can

You may notice that with svn checkout and svn export you can enter REV number as --revision REV argument and as trailing @REV after URL. The first one is called operative revision, and the second one is called peg revision. Read SVNBook for more information about peg and operative revisions concept.

LEFT JOIN in LINQ to entities?

May be I come later to answer but right now I'm facing with this... if helps there are one more solution (the way i solved it).

    var query2 = (
    from users in Repo.T_Benutzer
    join mappings in Repo.T_Benutzer_Benutzergruppen on mappings.BEBG_BE equals users.BE_ID into tmpMapp
    join groups in Repo.T_Benutzergruppen on groups.ID equals mappings.BEBG_BG into tmpGroups
    from mappings in tmpMapp.DefaultIfEmpty()
    from groups in tmpGroups.DefaultIfEmpty()
    select new
    {
         UserId = users.BE_ID
        ,UserName = users.BE_User
        ,UserGroupId = mappings.BEBG_BG
        ,GroupName = groups.Name
    }

);

By the way, I tried using the Stefan Steiger code which also helps but it was slower as hell.

How to start automatic download of a file in Internet Explorer?

Back to the roots, i use this:

<meta http-equiv="refresh" content="0; url=YOURFILEURL"/>

Maybe not WC3 conform but works perfect on all browsers, no HTML5/JQUERY/Javascript.

Greetings Tom :)

PostgreSQL create table if not exists

Try this:

CREATE TABLE IF NOT EXISTS app_user (
  username varchar(45) NOT NULL,
  password varchar(450) NOT NULL,
  enabled integer NOT NULL DEFAULT '1',
  PRIMARY KEY (username)
)

Difference between Iterator and Listiterator?

the following is that the difference between iterator and listIterator

iterator :

boolean hasNext();
E next();
void remove();

listIterator:

boolean hasNext();
E next();
boolean hasPrevious();
E previous();
int nextIndex();
int previousIndex();
void remove();
void set(E e);
void add(E e);

How to change the docker image installation directory?

I was having docker version 19.03.14. Below link helped me.

Check this Link

in /etc/docker/daemon.json file I added below section:-

 {
    "data-root": "/hdd2/docker",
    "storage-driver": "overlay2"
 }

HTTP Request in Kotlin

GET and POST using OkHttp

private const val CONNECT_TIMEOUT = 15L
private const val READ_TIMEOUT = 15L
private const val WRITE_TIMEOUT = 15L

private fun performPostOperation(urlString: String, jsonString: String, token: String): String? {
    return try {
        val client = OkHttpClient.Builder()
            .connectTimeout(CONNECT_TIMEOUT, TimeUnit.SECONDS)
            .writeTimeout(WRITE_TIMEOUT, TimeUnit.SECONDS)
            .readTimeout(READ_TIMEOUT, TimeUnit.SECONDS)
            .build()

        val body = jsonString.toRequestBody("application/json; charset=utf-8".toMediaTypeOrNull())

        val request = Request.Builder()
            .url(URL(urlString))
            .header("Authorization", token)
            .post(body)
            .build()

        val response = client.newCall(request).execute()
        response.body?.string()
    }
    catch (e: IOException) {
        e.printStackTrace()
        null
    }
}

private fun performGetOperation(urlString: String, token: String): String? {
    return try {
        val client = OkHttpClient.Builder()
            .connectTimeout(CONNECT_TIMEOUT, TimeUnit.SECONDS)
            .writeTimeout(WRITE_TIMEOUT, TimeUnit.SECONDS)
            .readTimeout(READ_TIMEOUT, TimeUnit.SECONDS)
            .build()

        val request = Request.Builder()
            .url(URL(urlString))
            .header("Authorization", token)
            .get()
            .build()

        val response = client.newCall(request).execute()
        response.body?.string()
    }
    catch (e: IOException) {
        e.printStackTrace()
        null
    }
}

Object serialization and deserialization

@Throws(JsonProcessingException::class)
fun objectToJson(obj: Any): String {
    return ObjectMapper().writeValueAsString(obj)
}

@Throws(IOException::class)
fun jsonToAgentObject(json: String?): MyObject? {
    return if (json == null) { null } else {
        ObjectMapper().readValue<MyObject>(json, MyObject::class.java)
    }
}

Dependencies

Put the following lines in your gradle (app) file. Jackson is optional. You can use it for object serialization and deserialization.

implementation 'com.squareup.okhttp3:okhttp:4.3.1'
implementation 'com.fasterxml.jackson.core:jackson-core:2.9.8'
implementation 'com.fasterxml.jackson.core:jackson-annotations:2.9.8'
implementation 'com.fasterxml.jackson.core:jackson-databind:2.9.8'

Error: Main method not found in class Calculate, please define the main method as: public static void main(String[] args)

My suggestions :

  • Keep the program modular. Keep the Calculate class in a separate Calculate.java file and create a new class that calls the main method. This would make the code readable.
  • For setting the values in the number, use constructors. Do not use like the methods you have used above like :

    public void setNumber(double fnum, double snum){ this.fn = fnum; this.sn = snum; }

    Constructors exists to initialize the objects.This is their job and they are pretty good at it.

  • Getters for members of Calculate class seem in place. But setters are not. Getters and setters serves as one important block in the bridge of efficient programming with java. Put setters for fnum and snum as well

  • In the main class, create a Calculate object using the new operator and the constructor in place.

  • Call the getAnswer() method with the created Calculate object.

Rest of the code looks fine to me. Be modular. You could read your program in a much better way.

Here is my modular piece of code. Two files : Main.java & Calculate.java

Calculate.java

public class Calculate {


private double fn;
private double sn;
private char op;

    public double getFn() {
        return fn;
    }

    public void setFn(double fn) {
        this.fn = fn;
    }

    public double getSn() {
        return sn;
    }

    public void setSn(double sn) {
        this.sn = sn;
    }

    public char getOp() {
        return op;
    }

    public void setOp(char op) {
        this.op = op;
    }



    public Calculate(double fn, double sn, char op) {
        this.fn = fn;
        this.sn = sn;
        this.op = op;
    }


public void getAnswer(){
    double ans;
    switch (getOp()){
        case '+': 
            ans = add(getFn(), getSn());
            ansOutput(ans);
            break;
        case '-': 
            ans = sub (getFn(), getSn());
            ansOutput(ans);
            break;
        case '*': 
            ans = mul (getFn(), getSn());
            ansOutput(ans);
            break;
        case '/': 
            ans = div (getFn(), getSn());
            ansOutput(ans);
            break;
        default:
            System.out.println("--------------------------");
            System.out.println("Invalid choice of operator");
            System.out.println("--------------------------");
        }
    }
    public static double add(double x,double y){
        return x + y;
    }
    public static double sub(double x, double y){
        return x - y;
    }
    public static double mul(double x, double y){
        return x * y;
    }
    public static double div(double x, double y){
        return x / y;
    }

    public static void ansOutput(double x){
        System.out.println("----------- -------");
        System.out.printf("the answer is %.2f\n", x);
        System.out.println("-------------------");
    }
}

Main.java

public class Main {
    public static void main(String args[])
    {
        Calculate obj = new Calculate(1,2,'+');
        obj.getAnswer();
    }
}

LIMIT 10..20 in SQL Server

SELECT TOP 10 *
FROM TABLE
WHERE IDCOLUMN NOT IN (SELECT TOP 10 IDCOLUMN FROM TABLE)

Should give records 11-20. Probably not too efficient if incrementing to get further pages, and not sure how it might be affected by ordering. Might have to specify this in both WHERE statements.

Python Pandas: How to read only first n rows of CSV files in?

If you only want to read the first 999,999 (non-header) rows:

read_csv(..., nrows=999999)

If you only want to read rows 1,000,000 ... 1,999,999

read_csv(..., skiprows=1000000, nrows=999999)

nrows : int, default None Number of rows of file to read. Useful for reading pieces of large files*

skiprows : list-like or integer Row numbers to skip (0-indexed) or number of rows to skip (int) at the start of the file

and for large files, you'll probably also want to use chunksize:

chunksize : int, default None Return TextFileReader object for iteration

pandas.io.parsers.read_csv documentation

How set maximum date in datepicker dialog in android?

use this code directly in main method hope it will help you...

@RequiresApi(api = Build.VERSION_CODES.N)       
public DatePickerDialog datePickerDialog_db()
{

    DatePickerDialog pickerDialog = new DatePickerDialog(getApplicationContext(),your view, myCalendar.get(Calendar.YEAR), myCalendar.get(Calendar.MONTH),
    myCalendar.get(Calendar.DAY_OF_MONTH));

    pickerDialog.getDatePicker().setMaxDate(Calendar.getInstance().getTimeInMillis());

    pickerDialog.show();

    return null;       
}

Angular ngClass and click event for toggling class

If you want to toggle text with a toggle button.

HTMLfile which is using bootstrap:

<input class="btn" (click)="muteStream()"  type="button"
          [ngClass]="status ? 'btn-success' : 'btn-danger'" 
          [value]="status ? 'unmute' : 'mute'"/>

TS file:

muteStream() {
   this.status = !this.status;
}

How to style SVG with external CSS?

What works for me: style tag with @import rule

<defs>
    <style type="text/css">
        @import url("svg-common.css");
    </style>
</defs>

How to write to a CSV line by line?

General way:

##text=List of strings to be written to file
with open('csvfile.csv','wb') as file:
    for line in text:
        file.write(line)
        file.write('\n')

OR

Using CSV writer :

import csv
with open(<path to output_csv>, "wb") as csv_file:
        writer = csv.writer(csv_file, delimiter=',')
        for line in data:
            writer.writerow(line)

OR

Simplest way:

f = open('csvfile.csv','w')
f.write('hi there\n') #Give your csv text here.
## Python will convert \n to os.linesep
f.close()

How to iterate over a TreeMap?

Just to point out the generic way to iterate over any map:

 private <K, V> void iterateOverMap(Map<K, V> map) {
    for (Map.Entry<K, V> entry : map.entrySet()) {
        System.out.println("key ->" + entry.getKey() + ", value->" + entry.getValue());
    }
    }

How do I check if a property exists on a dynamic anonymous type in c#?

    public static void Test()
    {
        int LOOP_LENGTH = 100000000;
        {
            long first_memory = GC.GetTotalMemory(true);
            var stopWatch = Stopwatch.StartNew();

            Console.WriteLine("doesPropertyExist");

            dynamic testdo = new { A = 1, B = (string)null, C = "A" };
            for (int i = 0; i < LOOP_LENGTH; i++)
            {
                if (!TestDynamic.doesPropertyExist(testdo, "A"))
                {
                    Console.WriteLine("throw find");
                    break;
                }

                if (TestDynamic.doesPropertyExist(testdo, "ABC"))
                {
                    Console.WriteLine("throw not find");
                    break;
                }
            }
            stopWatch.Stop();
            var last_memory = GC.GetTotalMemory(true);
            Console.WriteLine($" Time:{stopWatch.Elapsed.TotalSeconds}s\t Memory:{last_memory - first_memory}");
        }

        {
            long first_memory = GC.GetTotalMemory(true);
            var stopWatch = Stopwatch.StartNew();

            Console.WriteLine("HasProperty");

            dynamic testdo = new { A = 1, B = (string)null, C = "A" };
            for (int i = 0; i < LOOP_LENGTH; i++)
            {
                if (!TestDynamic.HasProperty(testdo, "A"))
                {
                    Console.WriteLine("throw find");
                    break;
                }

                if (TestDynamic.HasProperty(testdo, "ABC"))
                {
                    Console.WriteLine("throw not find");
                    break;
                }
            }
            stopWatch.Stop();
            var last_memory = GC.GetTotalMemory(true);
            Console.WriteLine($" Time:{stopWatch.Elapsed.TotalSeconds}s\t Memory:{last_memory - first_memory}");
        }


        {
            long first_memory = GC.GetTotalMemory(true);
            var stopWatch = Stopwatch.StartNew();

            Console.WriteLine("IsPropertyExist");

            dynamic testdo = new { A = 1, B = (string)null, C = "A" };
            for (int i = 0; i < LOOP_LENGTH; i++)
            {
                if (!TestDynamic.IsPropertyExist(testdo, "A"))
                {
                    Console.WriteLine("throw find");
                    break;
                }

                if (TestDynamic.IsPropertyExist(testdo, "ABC"))
                {
                    Console.WriteLine("throw not find");
                    break;
                }
            }
            stopWatch.Stop();
            var last_memory = GC.GetTotalMemory(true);
            Console.WriteLine($" Time:{stopWatch.Elapsed.TotalSeconds}s\t Memory:{last_memory - first_memory}");
        }

        {
            long first_memory = GC.GetTotalMemory(true);
            var stopWatch = Stopwatch.StartNew();

            Console.WriteLine("IsPropertyExistBinderException");

            dynamic testdo = new { A = 1, B = (string)null, C = "A" };
            for (int i = 0; i < LOOP_LENGTH; i++)
            {
                if (!TestDynamic.IsPropertyExistBinderException(testdo, "A"))
                {
                    Console.WriteLine("throw find");
                    break;
                }

                if (TestDynamic.IsPropertyExistBinderException(testdo, "ABC"))
                {
                    Console.WriteLine("throw not find");
                    break;
                }
            }
            stopWatch.Stop();
            var last_memory = GC.GetTotalMemory(true);
            Console.WriteLine($" Time:{stopWatch.Elapsed.TotalSeconds}s\t Memory:{last_memory - first_memory}");
        }


        {
            long first_memory = GC.GetTotalMemory(true);
            var stopWatch = Stopwatch.StartNew();

            Console.WriteLine("PropertyExists");

            dynamic testdo = new { A = 1, B = (string)null, C = "A" };
            for (int i = 0; i < LOOP_LENGTH; i++)
            {
                if (!TestDynamic.PropertyExists(testdo, "A"))
                {
                    Console.WriteLine("throw find");
                    break;
                }

                if (TestDynamic.PropertyExists(testdo, "ABC"))
                {
                    Console.WriteLine("throw not find");
                    break;
                }
            }
            stopWatch.Stop();
            var last_memory = GC.GetTotalMemory(true);
            Console.WriteLine($" Time:{stopWatch.Elapsed.TotalSeconds}s\t Memory:{last_memory - first_memory}");
        }


        {
            long first_memory = GC.GetTotalMemory(true);
            var stopWatch = Stopwatch.StartNew();

            Console.WriteLine("PropertyExistsJToken");

            dynamic testdo = new { A = 1, B = (string)null, C = "A" };
            for (int i = 0; i < LOOP_LENGTH; i++)
            {
                if (!TestDynamic.PropertyExistsJToken(testdo, "A"))
                {
                    Console.WriteLine("throw find");
                    break;
                }

                if (TestDynamic.PropertyExistsJToken(testdo, "ABC"))
                {
                    Console.WriteLine("throw not find");
                    break;
                }
            }
            stopWatch.Stop();
            var last_memory = GC.GetTotalMemory(true);
            Console.WriteLine($" Time:{stopWatch.Elapsed.TotalSeconds}s\t Memory:{last_memory - first_memory}");
        }




    }

    public static bool IsPropertyExist(dynamic settings, string name)
    {
        if (settings is ExpandoObject)
            return ((IDictionary<string, object>)settings).ContainsKey(name);

        return settings.GetType().GetProperty(name) != null;
    }

    public static bool HasProperty(dynamic obj, string name)
    {
        Type objType = obj.GetType();

        if (objType == typeof(ExpandoObject))
        {
            return ((IDictionary<string, object>)obj).ContainsKey(name);
        }

        return objType.GetProperty(name) != null;
    }


    public static bool PropertyExists(dynamic obj, string name)
    {
        if (obj == null) return false;
        if (obj is IDictionary<string, object> dict)
        {
            return dict.ContainsKey(name);
        }
        return obj.GetType().GetProperty(name) != null;
    }

    // public static bool HasPropertyExist(dynamic settings, string name)
    // {
    //     if (settings is System.Dynamic.ExpandoObject)
    //         return ((IDictionary<string, object>)settings).ContainsKey(name);
    //     if (settings is DynamicJsonObject)
    //         try
    //         {
    //             return settings[name] != null;
    //         }
    //         catch (KeyNotFoundException)
    //         {
    //             return false;
    //         }
    //     return settings.GetType().GetProperty(name) != null;
    // }

    public static bool IsPropertyExistBinderException(dynamic dynamicObj, string property)
    {
        try
        {
            var value = dynamicObj[property].Value;
            return true;
        }
        catch (RuntimeBinderException)
        {

            return false;
        }

    }

    public static bool HasPropertyFoundException(dynamic obj, string name)
    {
        try
        {
            var value = obj[name];
            return true;
        }
        catch (KeyNotFoundException)
        {
            return false;
        }
    }


    public static bool doesPropertyExist(dynamic obj, string property)
    {
        return ((Type)obj.GetType()).GetProperties().Where(p => p.Name.Equals(property)).Any();
    }

    public static bool PropertyExistsJToken(dynamic obj, string name)
    {
        if (obj == null) return false;
        if (obj is ExpandoObject)
            return ((IDictionary<string, object>)obj).ContainsKey(name);
        if (obj is IDictionary<string, object> dict1)
            return dict1.ContainsKey(name);
        if (obj is IDictionary<string, JToken> dict2)
            return dict2.ContainsKey(name);
        return obj.GetType().GetProperty(name) != null;
    }

    // public static bool PropertyExistsJsonObject(dynamic settings, string name)
    // {
    //     if (settings is ExpandoObject)
    //         return ((IDictionary<string, object>)settings).ContainsKey(name);
    //     else if (settings is DynamicJsonObject)
    //         return ((DynamicJsonObject)settings).GetDynamicMemberNames().Contains(name);

    //     return settings.GetType().GetProperty(name) != null;
    // }
}

doesPropertyExist

Time:59.5907507s Memory:403680

HasProperty

Time:30.8231781s Memory:14968

IsPropertyExist

Time:39.6179575s Memory:97000

IsPropertyExistBinderException throw find

PropertyExists

Time:56.009761s Memory:13464

PropertyExistsJToken

Time:61.6146953s Memory:15952

How to assign more memory to docker container

Allocate maximum memory to your docker machine from (docker preference -> advance )

Screenshot of advance settings: Screenshot of advance settings.

This will set the maximum limit docker consume while running containers. Now run your image in new container with -m=4g flag for 4 gigs ram or more. e.g.

docker run -m=4g {imageID}

Remember to apply the ram limit increase changes. Restart the docker and double check that ram limit did increased. This can be one of the factor you not see the ram limit increase in docker containers.

T-SQL Subquery Max(Date) and Joins

Try this:

Select *,
    Price = (Select top 1 Price 
             From MyPrices 
             where PartID = mp.PartID 
             order by PriceDate desc
            )
from MyParts mp

ReactJS: setTimeout() not working?

Your code scope (this) will be your window object, not your react component, and that is why setTimeout(this.setState({position: 1}), 3000) will crash this way.

That comes from javascript not React, it is js closure


So, in order to bind your current react component scope, do this:

setTimeout(function(){this.setState({position: 1})}.bind(this), 3000);

Or if your browser supports es6 or your projs has support to compile es6 to es5, try arrow function as well, as arrow func is to fix 'this' issue:

setTimeout(()=>this.setState({position: 1}), 3000);

Angular 4 Pipe Filter

The transform method signature changed somewhere in an RC of Angular 2. Try something more like this:

export class FilterPipe implements PipeTransform {
    transform(items: any[], filterBy: string): any {
        return items.filter(item => item.id.indexOf(filterBy) !== -1);
    }
}

And if you want to handle nulls and make the filter case insensitive, you may want to do something more like the one I have here:

export class ProductFilterPipe implements PipeTransform {

    transform(value: IProduct[], filterBy: string): IProduct[] {
        filterBy = filterBy ? filterBy.toLocaleLowerCase() : null;
        return filterBy ? value.filter((product: IProduct) =>
            product.productName.toLocaleLowerCase().indexOf(filterBy) !== -1) : value;
    }
}

And NOTE: Sorting and filtering in pipes is a big issue with performance and they are NOT recommended. See the docs here for more info: https://angular.io/guide/pipes#appendix-no-filterpipe-or-orderbypipe

How-to turn off all SSL checks for postman for a specific site

enter image description here

This steps are used in spring boot with self signed ssl certificate implementation

if SSL turns off then HTTPS call will be worked as expected.

https://localhost:8443/test/hello

These are the steps we have to follow,

  1. Generate self signed ssl certificate
keytool -genkeypair -alias tomcat -keyalg RSA -keysize 2048 -storetype PKCS12 -keystore keystore.p12 -validity 3650

after key generation has done then copy that file in to the resource foder in your project

  1. add key store properties in applicaiton.properties
server.port: 8443
server.ssl.key-store:classpath:keystore.p12
server.ssl.key-store-password: test123
server.ssl.keyStoreType: PKCS12
server.ssl.keyAlias: tomcat
  1. change your postman ssl verification settings to turn OFF

now verify the url: https://localhost:8443/test/hello

Undefined symbols for architecture i386

At the risk of sounding obvious, always check the spelling of your forward class files. Sometimes XCode (at least XCode 4.3.2) will turn a declaration green that's actually camel cased incorrectly. Like in this example:

"_OBJC_CLASS_$_RadioKit", referenced from:
  objc-class-ref in RadioPlayerViewController.o

If RadioKit was a class file and you make it a property of another file, in the interface declaration, you might see that

Radiokit *rk;

has "Radiokit" in green when the actual decalaration should be:

RadioKit *rk;

This error will also throw this type of error. Another example (in my case), is when you have _iPhone and _iphone extensions on your class names for universal apps. Once I changed the appropriate file from _iphone to the correct _iPhone, the errors went away.

selenium - chromedriver executable needs to be in PATH

Another way is download and unzip chromedriver and put 'chromedriver.exe' in C:\Python27\Scripts and then you need not to provide the path of driver, just

driver= webdriver.Chrome()

will work

Initialize class fields in constructor or at declaration?

What if I told you, it depends?

I in general initialize everything and do it in a consistent way. Yes it's overly explicit but it's also a little easier to maintain.

If we are worried about performance, well then I initialize only what has to be done and place it in the areas it gives the most bang for the buck.

In a real time system, I question if I even need the variable or constant at all.

And in C++ I often do next to no initialization in either place and move it into an Init() function. Why? Well, in C++ if you're initializing something that can throw an exception during object construction you open yourself to memory leaks.

Meaning of *& and **& in C++

To understand those phrases let's look at the couple of things:

typedef double Foo;
void fooFunc(Foo &_bar){ ... }

So that's passing a double by reference.

typedef double* Foo;
void fooFunc(Foo &_bar){ ... }

now it's passing a pointer to a double by reference.

typedef double** Foo;
void fooFunc(Foo &_bar){ ... }

Finally, it's passing a pointer to a pointer to a double by reference. If you think in terms of typedefs like this you'll understand the proper ordering of the & and * plus what it means.

Center a popup window on screen?

My recommendation is to use top location 33% or 25% from remaining space,
and not 50% as other examples posted here,
mainly because of the window header,
which look better and more comfort to the user,

complete code:

    <script language="javascript" type="text/javascript">
        function OpenPopupCenter(pageURL, title, w, h) {
            var left = (screen.width - w) / 2;
            var top = (screen.height - h) / 4;  // for 25% - devide by 4  |  for 33% - devide by 3
            var targetWin = window.open(pageURL, title, 'toolbar=no, location=no, directories=no, status=no, menubar=no, scrollbars=no, resizable=no, copyhistory=no, width=' + w + ', height=' + h + ', top=' + top + ', left=' + left);
        } 
    </script>
</head>
<body>
    <button onclick="OpenPopupCenter('http://www.google.com', 'TEST!?', 800, 600);">click on me</button>
</body>
</html>



check out this line:
var top = (screen.height - h) / 4; // for 25% - devide by 4 | for 33% - devide by 3

Regarding Java switch statements - using return and omitting breaks in each case

If you're going to have a method that just runs the switch and then returns some value, then sure this way works. But if you want a switch with other stuff in a method then you can't use return or the rest of the code inside the method will not execute. Notice in the tutorial how it has a print after the code? Yours would not be able to do this.

Adding values to specific DataTable cells

If it were a completely new row that you wanted to only set one value, you would need to add the whole row and then set the individual value:

DataRow dr = dt.NewRow();
dr[3].Value = "Some Value";
dt.Rows.Add(dr);

Otherwise, you can find the existing row and set the cell value

DataRow dr = dt.Rows[theRowNumber];
dr[3] = "New Value";

Java and SQLite

When you compile and run the code, you should set the classpath options value. Just like the following:

javac -classpath .;sqlitejdbc-v056.jar Text.java

java -classpath .;sqlitejdbc-v056.jar Text

Please pay attention to "." and the sparate ";"(win, the linux is ":")

Java collections maintaining insertion order

  • The insertion order is inherently not maintained in hash tables - that's just how they work (read the linked-to article to understand the details). It's possible to add logic to maintain the insertion order (as in the LinkedHashMap), but that takes more code, and at runtime more memory and more time. The performance loss is usually not significant, but it can be.
  • For TreeSet/Map, the main reason to use them is the natural iteration order and other functionality added in the SortedSet/Map interface.

What is your most productive shortcut with Vim?

A third criteria for making editing faster is the number of keystrokes required. I would say this is more important than your other 2. In vim, almost all operations require fewer keystrokes than any other editor I'm familiar with.

You mention that you are having trouble with cut & paste, but it sounds like you need more experience with general motion commands in vim. yank 3 words: y3w yank from the cursor to the next semi-colon: yf; yank to the next occurrence of your most recent search: yn All of those are much faster than trying to navigate with a mouse while holding down a modifier key. Also, as seen in some of the examples in CMS's response, vim's motion commands are highly optimized for efficient navigation in C and C++ source code.

As to the question 'how do I use vim that makes me more productive?', I hope the answer is: "efficiently".

Function passed as template argument

Came here with the additional requirement, that also parameter/return types should vary. Following Ben Supnik this would be for some type T

typedef T(*binary_T_op)(T, T);

instead of

typedef int(*binary_int_op)(int, int);

The solution here is to put the function type definition and the function template into a surrounding struct template.

template <typename T> struct BinOp
{
    typedef T(*binary_T_op )(T, T); // signature for all valid template params
    template<binary_T_op op>
    T do_op(T a, T b)
    {
       return op(a,b);
    }
};


double mulDouble(double a, double b)
{
    return a * b;
}


BinOp<double> doubleBinOp;

double res = doubleBinOp.do_op<&mulDouble>(4, 5);

Alternatively BinOp could be a class with static method template do_op(...), then called as

double res = BinOp<double>::do_op<&mulDouble>(4, 5);

How can I solve equations in Python?

Python may be good, but it isn't God...

There are a few different ways to solve equations. SymPy has already been mentioned, if you're looking for analytic solutions.

If you're happy to just have a numerical solution, Numpy has a few routines that can help. If you're just interested in solutions to polynomials, numpy.roots will work. Specifically for the case you mentioned:

>>> import numpy
>>> numpy.roots([2,-6])
array([3.0])

For more complicated expressions, have a look at scipy.fsolve.

Either way, you can't escape using a library.

Convenient C++ struct initialisation

I know this question is old, but there is a way to solve this until C++20 finally brings this feature from C to C++. What you can do to solve this is use preprocessor macros with static_asserts to check your initialization is valid. (I know macros are generally bad, but here I don't see another way.) See example code below:

#define INVALID_STRUCT_ERROR "Instantiation of struct failed: Type, order or number of attributes is wrong."

#define CREATE_STRUCT_1(type, identifier, m_1, p_1) \
{ p_1 };\
static_assert(offsetof(type, m_1) == 0, INVALID_STRUCT_ERROR);\

#define CREATE_STRUCT_2(type, identifier, m_1, p_1, m_2, p_2) \
{ p_1, p_2 };\
static_assert(offsetof(type, m_1) == 0, INVALID_STRUCT_ERROR);\
static_assert(offsetof(type, m_2) >= sizeof(identifier.m_1), INVALID_STRUCT_ERROR);\

#define CREATE_STRUCT_3(type, identifier, m_1, p_1, m_2, p_2, m_3, p_3) \
{ p_1, p_2, p_3 };\
static_assert(offsetof(type, m_1) == 0, INVALID_STRUCT_ERROR);\
static_assert(offsetof(type, m_2) >= sizeof(identifier.m_1), INVALID_STRUCT_ERROR);\
static_assert(offsetof(type, m_3) >= (offsetof(type, m_2) + sizeof(identifier.m_2)), INVALID_STRUCT_ERROR);\

#define CREATE_STRUCT_4(type, identifier, m_1, p_1, m_2, p_2, m_3, p_3, m_4, p_4) \
{ p_1, p_2, p_3, p_4 };\
static_assert(offsetof(type, m_1) == 0, INVALID_STRUCT_ERROR);\
static_assert(offsetof(type, m_2) >= sizeof(identifier.m_1), INVALID_STRUCT_ERROR);\
static_assert(offsetof(type, m_3) >= (offsetof(type, m_2) + sizeof(identifier.m_2)), INVALID_STRUCT_ERROR);\
static_assert(offsetof(type, m_4) >= (offsetof(type, m_3) + sizeof(identifier.m_3)), INVALID_STRUCT_ERROR);\

// Create more macros for structs with more attributes...

Then when you have a struct with const attributes, you can do this:

struct MyStruct
{
    const int attr1;
    const float attr2;
    const double attr3;
};

const MyStruct test = CREATE_STRUCT_3(MyStruct, test, attr1, 1, attr2, 2.f, attr3, 3.);

It's a bit inconvenient, because you need macros for every possible number of attributes and you need to repeat the type and name of your instance in the macro call. Also you cannot use the macro in a return statement, because the asserts come after the initialization.

But it does solve your problem: When you change the struct, the call will fail at compile-time.

If you use C++17, you can even make these macros more strict by forcing the same types, e.g.:

#define CREATE_STRUCT_3(type, identifier, m_1, p_1, m_2, p_2, m_3, p_3) \
{ p_1, p_2, p_3 };\
static_assert(offsetof(type, m_1) == 0, INVALID_STRUCT_ERROR);\
static_assert(offsetof(type, m_2) >= sizeof(identifier.m_1), INVALID_STRUCT_ERROR);\
static_assert(offsetof(type, m_3) >= (offsetof(type, m_2) + sizeof(identifier.m_2)), INVALID_STRUCT_ERROR);\
static_assert(typeid(p_1) == typeid(identifier.m_1), INVALID_STRUCT_ERROR);\
static_assert(typeid(p_2) == typeid(identifier.m_2), INVALID_STRUCT_ERROR);\
static_assert(typeid(p_3) == typeid(identifier.m_3), INVALID_STRUCT_ERROR);\

Set textbox to readonly and background color to grey in jquery

Can add disable like below and can get data on submit. something like this .. DEMO

Html

<input type="hidden" name="email" value="email" />
<input type="text" id="dis" class="disable" value="email"   name="email" >

JS

 $("#dis").attr('disabled','disabled');

CSS

    .disable { opacity : .35; background-color:lightgray; border:1px solid gray;}

Why do people hate SQL cursors so much?

The "overhead" with cursors is merely part of the API. Cursors are how parts of the RDBMS work under the hood. Often CREATE TABLE and INSERT have SELECT statements, and the implementation is the obvious internal cursor implementation.

Using higher-level "set-based operators" bundles the cursor results into a single result set, meaning less API back-and-forth.

Cursors predate modern languages that provide first-class collections. Old C, COBOL, Fortran, etc., had to process rows one at a time because there was no notion of "collection" that could be used widely. Java, C#, Python, etc., have first-class list structures to contain result sets.

The Slow Issue

In some circles, the relational joins are a mystery, and folks will write nested cursors rather than a simple join. I've seen truly epic nested loop operations written out as lots and lots of cursors. Defeating an RDBMS optimization. And running really slowly.

Simple SQL rewrites to replace nested cursor loops with joins and a single, flat cursor loop can make programs run in 100th the time. [They thought I was the god of optimization. All I did was replace nested loops with joins. Still used cursors.]

This confusion often leads to an indictment of cursors. However, it isn't the cursor, it's the misuse of the cursor that's the problem.

The Size Issue

For really epic result sets (i.e., dumping a table to a file), cursors are essential. The set-based operations can't materialize really large result sets as a single collection in memory.

Alternatives

I try to use an ORM layer as much as possible. But that has two purposes. First, the cursors are managed by the ORM component. Second, the SQL is separated from the application into a configuration file. It's not that the cursors are bad. It's that coding all those opens, closes and fetches is not value-add programming.

ImportError: DLL load failed: %1 is not a valid Win32 application

You could try installing the 32 bit version of opencv

querySelectorAll with multiple conditions

Is it possible to make a search by querySelectorAll using multiple unrelated conditions?

Yes, because querySelectorAll accepts full CSS selectors, and CSS has the concept of selector groups, which lets you specify more than one unrelated selector. For instance:

var list = document.querySelectorAll("form, p, legend");

...will return a list containing any element that is a form or p or legend.

CSS also has the other concept: Restricting based on more criteria. You just combine multiple aspects of a selector. For instance:

var list = document.querySelectorAll("div.foo");

...will return a list of all div elements that also (and) have the class foo, ignoring other div elements.

You can, of course, combine them:

var list = document.querySelectorAll("div.foo, p.bar, div legend");

...which means "Include any div element that also has the foo class, any p element that also has the bar class, and any legend element that's also inside a div."

Scanf/Printf double variable C

When a float is passed to printf, it is automatically converted to a double. This is part of the default argument promotions, which apply to functions that have a variable parameter list (containing ...), largely for historical reasons. Therefore, the “natural” specifier for a float, %f, must work with a double argument. So the %f and %lf specifiers for printf are the same; they both take a double value.

When scanf is called, pointers are passed, not direct values. A pointer to float is not converted to a pointer to double (this could not work since the pointed-to object cannot change when you change the pointer type). So, for scanf, the argument for %f must be a pointer to float, and the argument for %lf must be a pointer to double.

How to get JSON data from the URL (REST API) to UI using jQuery or plain JavaScript?

You can use native JS so you don't have to rely on external libraries.

(I will use some ES2015 syntax, a.k.a ES6, modern javascript) What is ES2015?

fetch('/api/rest/abc')
    .then(response => response.json())
    .then(data => {
        // Do what you want with your data
    });

You can also capture errors if any:

fetch('/api/rest/abc')
    .then(response => response.json())
    .then(data => {
        // Do what you want with your data
    })
    .catch(err => {
        console.error('An error ocurred', err);
    });

By default it uses GET and you don't have to specify headers, but you can do all that if you want. For further reference: Fetch API reference

Printing 1 to 1000 without loop or conditionals

I don't suppose this is a "trick question" . . . "?:" isn't an conditional, it is an operator.

So use recursion and the ?: operator to detect the when to stop?

int recurse(i)
{
   printf("%d\n", i);
   int unused = i-1000?recurse(i+1):0;

}

recurse(1);

Or along a similar perverted line of thinking . . . the second clause in an "&" condition is only executed if the first value is true. So recurse something like this:

i-1000 & recurse(i+1);

Perhaps the interviewer considers that an expression instead of a conditional.

Add row to query result using select

is it possible to extend query results with literals like this?

Yes.

Select Name
From Customers
UNION ALL
Select 'Jason'
  • Use UNION to add Jason if it isn't already in the result set.
  • Use UNION ALL to add Jason whether or not he's already in the result set.

MIT vs GPL license

You are correct that the GPL is more restrictive than the MIT license.

You cannot include GPL code in a MIT licensed product. If you distribute a combined work that combines GPL and MIT code (except in some particular situations, e.g. 'mere aggregation'), that distribution must be compliant with the GPL.

You can include MIT licensed code in a GPL product. The whole combined work must be distributed in a way compliant with the GPL. If you have made changes to the MIT parts of the code, you would be required to publish the source for those changes if you distribute an application that contains GPL and MIT code.

If you are the copyright owner of the GPL code, you can of course choose to release that code under the MIT license instead - in that case it's your code and you can publish it under as many licenses as you want.

ssh: connect to host github.com port 22: Connection timed out

ISSUE: Step to produce issue: git clone [email protected]:sramachand71/test.git for the first time in the new laptop ERROR ssh: connect to host github.com port 22: Connection timed out fatal: Could not read from remote repository.

Please make sure you have the correct access rights and the repository exists. SOLUTION for the first time in the system to clone we need to give double quotes for the clone command. $ git clone "[email protected]:sramachand71/test.git" i face this issue in the system even after everything was correct but noticed at last that double quote is must for url "repository_url.git" for first time or new user in the system.

Can I have an IF block in DOS batch file?

Instead of this goto mess, try using the ampersand & or double ampersand && (conditional to errorlevel 0) as command separators.

I fixed a script snippet with this trick, to summarize, I have three batch files, one which calls the other two after having found which letters the external backup drives have been assigned. I leave the first file on the primary external drive so the calls to its backup routine worked fine, but the calls to the second one required an active drive change. The code below shows how I fixed it:

for %%b in (d e f g h i j k l m n o p q r s t u v w x y z) DO (
if exist "%%b:\Backup.cmd" %%b: & CALL "%%b:\Backup.cmd"
)

Float a div in top right corner without overlapping sibling header

If you can change the order of the elements, floating will work.

_x000D_
_x000D_
section {_x000D_
  position: relative;_x000D_
  width: 50%;_x000D_
  border: 1px solid;_x000D_
}_x000D_
h1 {_x000D_
  display: inline;_x000D_
}_x000D_
div {_x000D_
  float: right;_x000D_
}
_x000D_
<section>_x000D_
  <div>_x000D_
    <button>button</button>_x000D_
  </div>_x000D_
_x000D_
  <h1>some long long long long header, a whole line, 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6</h1>_x000D_
</section>
_x000D_
_x000D_
_x000D_

?By placing the div before the h1 and floating it to the right, you get the desired effect.

How to prevent Browser cache for php site

Here, if you want to control it through HTML: do like below Option 1:

<meta http-equiv="expires" content="Sun, 01 Jan 2014 00:00:00 GMT"/>
<meta http-equiv="pragma" content="no-cache" />

And if you want to control it through PHP: do it like below Option 2:

header('Expires: Sun, 01 Jan 2014 00:00:00 GMT');
header('Cache-Control: no-store, no-cache, must-revalidate');
header('Cache-Control: post-check=0, pre-check=0', FALSE);
header('Pragma: no-cache');

AND Option 2 IS ALWAYS BETTER in order to avoid proxy based caching issue.

IOS 7 Navigation Bar text and arrow color

Swift 5/iOS 13

To change color of title in controller:

UINavigationBar.appearance().titleTextAttributes = [NSAttributedString.Key.foregroundColor: UIColor.white]

What does if [ $? -eq 0 ] mean for shell scripts?

It is an extremely overused way to check for the success/failure of a command. Typically, the code snippet you give would be refactored as:

if grep -e ERROR ${LOG_DIR_PATH}/${LOG_NAME} > /dev/null; then
   ...
fi

(Although you can use 'grep -q' in some instances instead of redirecting to /dev/null, doing so is not portable. Many implementations of grep do not support the -q option, so your script may fail if you use it.)

Search for an item in a Lua list

Use the following representation instead:

local items = { apple=true, orange=true, pear=true, banana=true }
if items.apple then
    ...
end

php string to int

You can use the str_replace when you declare your variable $b like that :

$b = str_replace(" ", "", '88 8888');
echo (int)$b;

Or the most beautiful solution is to use intval :

$b = intval(str_replace(" ", "", '88 8888');
echo $b;

If your value '88 888' is from an other variable, just replace the '88 888' by the variable who contains your String.

Render partial from different folder (not shared)

The VirtualPathProviderViewEngine, on which the WebFormsViewEngine is based, is supposed to support the "~" and "/" characters at the front of the path so your examples above should work.

I noticed your examples use the path "~/Account/myPartial.ascx", but you mentioned that your user control is in the Views/Account folder. Have you tried

<%Html.RenderPartial("~/Views/Account/myPartial.ascx");%>

or is that just a typo in your question?

Factorial using Recursion in Java

Well variable "result" is a local variable. When fact() method is called from "main" method variable "result" is stored in different variable.

Also line : result = fact(n-1) * n; 

here logic is finding factorial using recursion. Recursion in java is a procedure in which a method calls itself.

Meanwhile you can refer this resource on factorial of a number using recursion.

How to download dependencies in gradle

Downloading java dependencies is possible, if you actually really need to download them into a folder.

Example:

apply plugin: 'java'

dependencies {
  runtime group: 'com.netflix.exhibitor', name: 'exhibitor-standalone', version: '1.5.2'
  runtime group: 'org.apache.zookeeper',  name: 'zookeeper', version: '3.4.6'
}

repositories { mavenCentral() }

task getDeps(type: Copy) {
  from sourceSets.main.runtimeClasspath
  into 'runtime/'
}

Download the dependencies (and their dependencies) into the folder runtime when you execute gradle getDeps.

Ubuntu says "bash: ./program Permission denied"

Sounds like you don't have the execute flag set on the file permissions, try:

chmod u+x program_name

Adding a rule in iptables in debian to open a new port

About your command line:

root@debian:/# sudo iptables -A INPUT -p tcp --dport 3306 --jump ACCEPT
root@debian:/# iptables-save
  • You are already authenticated as root so sudo is redundant there.

  • You are missing the -j or --jump just before the ACCEPT parameter (just tought that was a typo and you are inserting it correctly).

About yout question:

If you are inserting the iptables rule correctly as you pointed it in the question, maybe the issue is related to the hypervisor (virtual machine provider) you are using.

If you provide the hypervisor name (VirtualBox, VMWare?) I can further guide you on this but here are some suggestions you can try first:

check your vmachine network settings and:

  • if it is set to NAT, then you won't be able to connect from your base machine to the vmachine.

  • if it is set to Hosted, you have to configure first its network settings, it is usually to provide them an IP in the range 192.168.56.0/24, since is the default the hypervisors use for this.

  • if it is set to Bridge, same as Hosted but you can configure it whenever IP range makes sense for you configuration.

Hope this helps.

Adding script tag to React/JSX

I tried to edit the accepted answer by @Alex McMillan but it won't let me so heres a separate answer where your able to get the value of the library your loading in. A very important distinction that people asked for and I needed for my implementation with stripe.js.

useScript.js

import { useState, useEffect } from 'react'

export const useScript = (url, name) => {

  const [lib, setLib] = useState({})

  useEffect(() => {
    const script = document.createElement('script')

    script.src = url
    script.async = true
    script.onload = () => setLib({ [name]: window[name] })

    document.body.appendChild(script)

    return () => {
      document.body.removeChild(script)
    }
  }, [url])

  return lib

}

usage looks like

const PaymentCard = (props) => {
  const { Stripe } = useScript('https://js.stripe.com/v2/', 'Stripe')
}

NOTE: Saving the library inside an object because often times the library is a function and React will execute the function when storing in state to check for changes -- which will break libs (like Stripe) that expect to be called with specific args -- so we store that in an object to hide that from React and protect library functions from being called.

Default visibility for C# classes and members (fields, methods, etc.)?

All of the information you are looking for can be found here and here (thanks Reed Copsey):

From the first link:

Classes and structs that are declared directly within a namespace (in other words, that are not nested within other classes or structs) can be either public or internal. Internal is the default if no access modifier is specified.

...

The access level for class members and struct members, including nested classes and structs, is private by default.

...

interfaces default to internal access.

...

Delegates behave like classes and structs. By default, they have internal access when declared directly within a namespace, and private access when nested.


From the second link:

Top-level types, which are not nested in other types, can only have internal or public accessibility. The default accessibility for these types is internal.

And for nested types:

Members of    Default member accessibility
----------    ----------------------------
enum          public
class         private
interface     public
struct        private

C# - Create SQL Server table programmatically

First, check whether the table exists or not. Accordingly, create table if doesn't exist.

var commandStr= "If not exists (select name from sysobjects where name = 'Customer') CREATE TABLE Customer(First_Name char(50),Last_Name char(50),Address char(50),City char(50),Country char(25),Birth_Date datetime)";

using (SqlCommand command = new SqlCommand(commandStr, con))
command.ExecuteNonQuery();

How to remove duplicates from Python list and keep order?

A list can be sorted and deduplicated using built-in functions:

myList = sorted(set(myList))
  • set is a built-in function for Python >= 2.3
  • sorted is a built-in function for Python >= 2.4

Alternative to iFrames with HTML5

object is an easy alternative in HTML5:

_x000D_
_x000D_
<object data="https://github.com/AbrarJahin/Asp.NetCore_3.1-PostGRE_Role-Claim_Management/"
width="400"
height="300"
type="text/html">
    Alternative Content
</object>
_x000D_
_x000D_
_x000D_

You can also try embed:

_x000D_
_x000D_
<embed src="https://github.com/AbrarJahin/Asp.NetCore_3.1-PostGRE_Role-Claim_Management/"
width=200
height=200
onerror="alert('URL invalid !!');" />
_x000D_
_x000D_
_x000D_

Re-

As currently, StackOverflow has turned off support for showing external URL contents, run code snippet is not showing anything. But for your site, it will work perfactly.

Implement Stack using Two Queues

Here is my solution that works for O(1) in average case. There are two queues: in and out. See pseudocode bellow:

PUSH(X) = in.enqueue(X)

POP: X =
  if (out.isEmpty and !in.isEmpty)
    DUMP(in, out)
  return out.dequeue

DUMP(A, B) =
  if (!A.isEmpty)
    x = A.dequeue()
    DUMP(A, B)
    B.enqueue(x)

Device not detected in Eclipse when connected with USB cable

Do following steps to detect your device in eclipse : -

On Mobile Side:- For Connect USB sync, your Android device needs to have USB Debugging enabled.

To enable Android USB Debugging Mode do following steps :-

Android 2.x - 3.x devices:

Go to Settings > Application > Development > USB Debugging.

Android 4.x devices:

Go to Settings > Developer Options > USB Debugging.

For devices running Android 4.2.2 or later, you may need to unlock Developer Options before it is available within the Menu:

  1. Go to Android home screen.
  2. Pull down the notification bar.
  3. Tap "Settings"
  4. Tap "About Device"
  5. Tap on the "Build Number" button about 7 times.
  6. Developer Mode should now be unlocked and available in Settings > More > Developer Options or in Settings > Developer Options

On PC side

  1. Connect your device to the PC with USB cable.
  2. Download Google USB Driver
  3. Extract/Unzip “latest_usb_driver_windows.zip” file on your computer (using 7-zip free software, preferably)
  4. Open device manager on your PC
    • Windows 7 & 8 users ? search for Device Manager from Start (or Start screen) and click to open.
    • Windows XP users ? Google it
  5. You will see list of all devices attached to your computer in the device manager. Just find your device (it’ll most probably be in the Other devices list with a yellow exclamation mark by the name of ADB devices), then Right-click on it and select Update Driver Software.
  6. Select “Browse my computer for driver software” in the next window
  7. Now click the “Browse…” button and select the “usb_driver” folder that we extracted in Step 3 from “latest_usb_driver_windows.zip” file.
  8. Do NOT select the zip file, select the folder where the contents of the zip file are extracted. And keep the Include subfolders box checked
  9. During the installation (as a security check) Windows may ask your permission to install the drivers, click “Install”
  10. Once the installation is complete you’ll see a refreshed list of devices on the Device manager screen showing your phone’s driver installed successfully.

Now in eclipse do following steps to install your app in your device:-

  1. Go to Run > Run Configurations > Target tab.
  2. Check option "Always prompt to pick device". And then running the application from Eclipse,the prompt window finally showed your device.

How do I get an object's unqualified (short) class name?

I use this:

basename(str_replace('\\', '/', get_class($object)));

ASP.NET Core form POST results in a HTTP 415 Unsupported Media Type response

For forms, use the [FromForm] attribute instead of the [FromBody] attribute.

The below controller works with ASP.NET Core 1.1:

public class MyController : Controller
{
    [HttpPost]
    public async Task<IActionResult> Submit([FromForm] MyModel model)
    {
        //...
    }
}

Note: [FromXxx] is required if your controller is annotated with [ApiController]. For normal view controllers it can be omitted.

Making a drop down list using swift?

A 'drop down menu' is a web control / term. In iOS we don't have these. You might be better looking at UIPopoverController. Check out this tutorial for a bit of an insight to PopoverControllers

http://www.raywenderlich.com/29472/ipad-for-iphone-developers-101-in-ios-6-uipopovercontroller-tutorial

git pull while not in a git directory

Starting git 1.8.5 (Q4 2013), you will be able to "use a Git command, but without having to change directories".

Just like "make -C <directory>", "git -C <directory> ..." tells Git to go there before doing anything else.

See commit 44e1e4 by Nazri Ramliy:

It takes more keypresses to invoke Git command in a different directory without leaving the current directory:

  1. (cd ~/foo && git status)
    git --git-dir=~/foo/.git --work-tree=~/foo status
    GIT_DIR=~/foo/.git GIT_WORK_TREE=~/foo git status
  2. (cd ../..; git grep foo)
  3. for d in d1 d2 d3; do (cd $d && git svn rebase); done

The methods shown above are acceptable for scripting but are too cumbersome for quick command line invocations.

With this new option, the above can be done with fewer keystrokes:

  1. git -C ~/foo status
  2. git -C ../.. grep foo
  3. for d in d1 d2 d3; do git -C $d svn rebase; done

Since Git 2.3.4 (March 2015), and commit 6a536e2 by Karthik Nayak (KarthikNayak), git will treat "git -C '<path>'" as a no-op when <path> is empty.

'git -C ""' unhelpfully dies with error "Cannot change to ''", whereas the shell treats cd ""' as a no-op.
Taking the shell's behavior as a precedent, teach git to treat -C ""' as a no-op, as well.


4 years later, Git 2.23 (Q3 2019) documents that 'git -C ""' works and doesn't change directory

It's been behaving so since 6a536e2 (git: treat "git -C '<path>'" as a no-op when <path> is empty, 2015-03-06, Git v2.3.4).

That means the documentation now (finally) includes:

If '<path>' is present but empty, e.g. -C "", then the current working directory is left unchanged.


You can see git -C used with Git 2.26 (Q1 2020), as an example.

See commit b441717, commit 9291e63, commit 5236fce, commit 10812c2, commit 62d58cd, commit b87b02c, commit 9b92070, commit 3595d10, commit f511bc0, commit f6041ab, commit f46c243, commit 99c049b, commit 3738439, commit 7717242, commit b8afb90 (20 Dec 2019) by Denton Liu (Denton-L).
(Merged by Junio C Hamano -- gitster -- in commit 381e8e9, 05 Feb 2020)

t1507: inline full_name()

Signed-off-by: Denton Liu

Before, we were running test_must_fail full_name. However, test_must_fail should only be used on git commands.
Inline full_name() so that we can use test_must_fail on the git command directly.

When full_name() was introduced in 28fb84382b ("Introduce <branch>@{upstream} notation", 2009-09-10, Git v1.7.0-rc0 -- merge), the git -C option wasn't available yet (since it was introduced in 44e1e4d67d ("git: run in a directory given with -C option", 2013-09-09, Git v1.8.5-rc0 -- merge listed in batch #5)).
As a result, the helper function removed the need to manually cd each time. However, since git -C is available now, we can just use that instead and inline full_name().

How to use JavaScript variables in jQuery selectors?

var name = this.name;
$("input[name=" + name + "]").hide();

OR you can do something like this.

var id = this.id;
$('#' + id).hide();

OR you can give some effect also.

$("#" + this.id).slideUp();

If you want to remove the entire element permanently form the page.

$("#" + this.id).remove();

You can also use it in this also.

$("#" + this.id).slideUp('slow', function (){
    $("#" + this.id).remove();
});

Change header text of columns in a GridView

Better to find cells from gridview instead of static/fix index so it will not generate any problem whenever you will add/remove any columns on gridview.

ASPX:

<asp:GridView ID="GridView1" OnRowDataBound="GridView1_RowDataBound" >
    <Columns>
        <asp:BoundField HeaderText="Date" DataField="CreatedDate" />
    </Columns>
</asp:GridView>

CS:

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.Header)
    {
        for (int i = 0; i < e.Row.Cells.Count; i++)
        {
            if (string.Compare(e.Row.Cells[i].Text, "Date", true) == 0)
            {
                e.Row.Cells[i].Text = "Created Date";
            }
        }
    }
}

Regular expressions inside SQL Server

stored value in DB is: 5XXXXXX [where x can be any digit]

You don't mention data types - if numeric, you'll likely have to use CAST/CONVERT to change the data type to [n]varchar.

Use:

WHERE CHARINDEX(column, '5') = 1
  AND CHARINDEX(column, '.') = 0 --to stop decimals if needed
  AND ISNUMERIC(column) = 1

References:

i have also different cases like XXXX7XX for example, so it has to be generic.

Use:

WHERE PATINDEX('%7%', column) = 5
  AND CHARINDEX(column, '.') = 0 --to stop decimals if needed
  AND ISNUMERIC(column) = 1

References:

Regex Support

SQL Server 2000+ supports regex, but the catch is you have to create the UDF function in CLR before you have the ability. There are numerous articles providing example code if you google them. Once you have that in place, you can use:

  • 5\d{6} for your first example
  • \d{4}7\d{2} for your second example

For more info on regular expressions, I highly recommend this website.

Best way to Bulk Insert from a C# DataTable

This is going to be largely dependent on the RDBMS you're using, and whether a .NET option even exists for that RDBMS.

If you're using SQL Server, use the SqlBulkCopy class.

For other database vendors, try googling for them specifically. For example a search for ".NET Bulk insert into Oracle" turned up some interesting results, including this link back to Stack Overflow: Bulk Insert to Oracle using .NET.

How to submit form on change of dropdown list?

Simple JavaScript will do -

<form action="myservlet.do" method="POST">
    <select name="myselect" id="myselect" onchange="this.form.submit()">
        <option value="1">One</option>
        <option value="2">Two</option>
        <option value="3">Three</option>
        <option value="4">Four</option>
    </select>
</form>

Here is a link for a good javascript tutorial.

How to save all files from source code of a web site?

In Chrome, go to options (Customize and Control, the 3 dots/bars at top right) ---> More Tools ---> save page as

save page as  
filename     : any_name.html 
save as type : webpage complete.

Then you will get any_name.html and any_name folder.

C++ "Access violation reading location" Error

Vertex *f=(findvertex(from));
if(!f) {
    cerr << "vertex not found" << endl;
    exit(1) // or return;
}

Because findVertex can return NULL if it can't find the vertex.

Otherwise this f->adj; is trying to do

NULL->adj;

Which causes access violation.

Alter and Assign Object Without Side Effects

Objects are passed by reference.. To create a new object, I follow this approach..

//Template code for object creation.
function myElement(id, value) {
    this.id = id;
    this.value = value;
}
var myArray = [];

//instantiate myEle
var myEle = new myElement(0, 0);
//store myEle
myArray[0] = myEle;

//Now create a new object & store it
myEle = new myElement(0, 1);
myArray[1] = myEle;

How to map with index in Ruby?

Over the top obfuscation:

arr = ('a'..'g').to_a
indexes = arr.each_index.map(&2.method(:+))
arr.zip(indexes)

jQuery Scroll to Div

I ran into the same. Saw an example using this: https://github.com/flesler/jquery.scrollTo

I use it as follows:

$('#arrow_back').click(function () {
    $.scrollTo('#features_1', 1000, { easing: 'easeInOutExpo', offset: 0, 'axis': 'y' }); 
});

Clean solution. Works for me!

Aggregate multiple columns at once

We can use the formula method of aggregate. The variables on the 'rhs' of ~ are the grouping variables while the . represents all other variables in the 'df1' (from the example, we assume that we need the mean for all the columns except the grouping), specify the dataset and the function (mean).

aggregate(.~id1+id2, df1, mean)

Or we can use summarise_each from dplyr after grouping (group_by)

library(dplyr)
df1 %>%
    group_by(id1, id2) %>% 
    summarise_each(funs(mean))

Or using summarise with across (dplyr devel version - ‘0.8.99.9000’)

df1 %>% 
    group_by(id1, id2) %>%
    summarise(across(starts_with('val'), mean))

Or another option is data.table. We convert the 'data.frame' to 'data.table' (setDT(df1), grouped by 'id1' and 'id2', we loop through the subset of data.table (.SD) and get the mean.

library(data.table)
setDT(df1)[, lapply(.SD, mean), by = .(id1, id2)] 

data

df1 <- structure(list(id1 = c("a", "a", "a", "a", "b", "b", 
"b", "b"
), id2 = c("x", "x", "y", "y", "x", "y", "x", "y"), 
val1 = c(1L, 
2L, 3L, 4L, 1L, 4L, 3L, 2L), val2 = c(9L, 4L, 5L, 9L, 7L, 4L, 
9L, 8L)), .Names = c("id1", "id2", "val1", "val2"), 
class = "data.frame", row.names = c("1", 
"2", "3", "4", "5", "6", "7", "8"))

Callback when CSS3 transition finishes

The accepted answer currently fires twice for animations in Chrome. Presumably this is because it recognizes webkitAnimationEnd as well as animationEnd. The following will definitely only fires once:

/* From Modernizr */
function whichTransitionEvent(){

    var el = document.createElement('fakeelement');
    var transitions = {
        'animation':'animationend',
        'OAnimation':'oAnimationEnd',
        'MSAnimation':'MSAnimationEnd',
        'WebkitAnimation':'webkitAnimationEnd'
    };

    for(var t in transitions){
        if( transitions.hasOwnProperty(t) && el.style[t] !== undefined ){
            return transitions[t];
        }
    }
}

$("#elementToListenTo")
    .on(whichTransitionEvent(),
        function(e){
            console.log('Transition complete!  This is the callback!');
            $(this).off(e);
        });

sort files by date in PHP

$files = array_diff(scandir($dir,SCANDIR_SORT_DESCENDING), array('..', '.'));
print_r($files);

How to get a view table query (code) in SQL Server 2008 Management Studio

Additionally, if you have restricted access to the database (IE: Can't use "Script Function as > CREATE To"), there is another option to get this query.

Find your View > right click > "Design".

This will give you the query you are looking for.

Unable to add window -- token android.os.BinderProxy is not valid; is your activity running?

I solved it by putting this:

@Override
protected void onDestroy() {
    accessTokenTracker.stopTracking();
    super.onDestroy();
}