Programs & Examples On #Dbal

Kubernetes service external ip pending

If it is your private k8s cluster, MetalLB would be a better fit. Below are the steps.

Step 1: Install MetalLB in your cluster

kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.9.3/manifests/namespace.yaml
kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.9.3/manifests/metallb.yaml
# On first install only
kubectl create secret generic -n metallb-system memberlist --from-literal=secretkey="$(openssl rand -base64 128)"

Step 2: Configure it by using a configmap

apiVersion: v1
kind: ConfigMap
metadata:
  namespace: metallb-system
  name: config
data:
  config: |
    address-pools:
    - name: default
      protocol: layer2
      addresses:
      - 172.42.42.100-172.42.42.105 #Update this with your Nodes IP range 

Step 3: Create your service to get an external IP (would be a private IP though).

FYR:

Before MetalLB installation: enter image description here

After MetalLB installation: enter image description here

enter image description here

Laravel: PDOException: could not find driver

You need to enable these extensions in the php.ini file

Before:

;extension=pdo_mysql
;extension=mysqli
;extension=pdo_sqlite
;extension=sqlite3

After:

extension=pdo_mysql
extension=mysqli
extension=pdo_sqlite
extension=sqlite3

It is advisable that you also activate the fileinfo extension, many packages require this.

What's the difference between ClusterIP, NodePort and LoadBalancer service types in Kubernetes?

Lets assume you created a Ubuntu VM on your local machine. It's IP address is 192.168.1.104.

You login into VM, and installed Kubernetes. Then you created a pod where nginx image running on it.

1- If you want to access this nginx pod inside your VM, you will create a ClusterIP bound to that pod for example:

$ kubectl expose deployment nginxapp --name=nginxclusterip --port=80 --target-port=8080

Then on your browser you can type ip address of nginxclusterip with port 80, like:

http://10.152.183.2:80

2- If you want to access this nginx pod from your host machine, you will need to expose your deployment with NodePort. For example:

$ kubectl expose deployment nginxapp --name=nginxnodeport --port=80 --target-port=8080 --type=NodePort

Now from your host machine you can access to nginx like:

http://192.168.1.104:31865/

In my dashboard they appear as:

enter image description here

Below is a diagram shows basic relationship.

enter image description here

getting error while updating Composer

The good solution for this error please run this command

composer install --ignore-platform-reqs

How can I resolve "Your requirements could not be resolved to an installable set of packages" error?

I encountered this problem in Laravel 5.8, what I did was to do composer require for each library and all where installed correctly.

Like so:

instead of adding it to the composer.json file or specifying a version:

composer require msurguy/honeypot: dev-master

I instead did without specifying any version:

composer require msurguy/honeypot

I hope it helps, thanks

How can I rename column in laravel using migration?

first thing you want to do is to create your migration file.

Type in your command line

php artisan make:migration rename_stk_column --table="YOUR TABLE" --create

After creating the file. Open the new created migration file in your app folder under database/migrations.

In your up method insert this:

Schema::table('stnk', function(Blueprint $table)
    {
        $table->renameColumn('id', 'id_stnk');
    });
}

and in your down method:

    Schema::table('stnk', function(Blueprint $table)
    {
        $table->renameColumn('id_stnk', 'id);
    });
}

then in your command line just type

php artisan migrate

Then wollah! you have just renamed id to id_stnk. BTW you can use

php artisan migrate:rollback

to undo the changes. Goodluck

Python "SyntaxError: Non-ASCII character '\xe2' in file"

For me the problem had caused due to "’" that symbol in the quotes. As i had copied the code from a pdf file it caused that error. I just replaced "’" by this "'".

The EntityManager is closed

// first need to reset current manager
$em->resetManager();
// and then get new
$em = $this->getContainer()->get("doctrine");
// or in this way, depending of your environment:
$em = $this->getDoctrine();

javax.persistence.NoResultException: No entity found for query

When using java 8, you may take advantage of stream API and simplify code to

return (YourEntityClass) entityManager.createQuery()
....
.getResultList()
.stream().findFirst();

That will give you java.util.Optional

If you prefer null instead, all you need is

 ...
.getResultList()
.stream().findFirst().orElse(null);

How to get the total number of rows of a GROUP BY query?

Keep in mind that a PDOStatement is Traversable. Given a query:

$query = $dbh->query('
    SELECT
        *
    FROM
        test
');

It can be iterated over:

$it = new IteratorIterator($query);
echo '<p>', iterator_count($it), ' items</p>';

// Have to run the query again unfortunately
$query->execute();
foreach ($query as $row) {
    echo '<p>', $row['title'], '</p>';
}

Or you can do something like this:

$it = new IteratorIterator($query);
$it->rewind();

if ($it->valid()) {
    do {
        $row = $it->current();
        echo '<p>', $row['title'], '</p>';
        $it->next();
    } while ($it->valid());
} else {
    echo '<p>No results</p>';
}

Detect if a NumPy array contains at least one non-numeric value?

If infinity is a possible value, I would use numpy.isfinite

numpy.isfinite(myarray).all()

If the above evaluates to True, then myarray contains no, numpy.nan, numpy.inf or -numpy.inf values.

numpy.nan will be OK with numpy.inf values, for example:

In [11]: import numpy as np

In [12]: b = np.array([[4, np.inf],[np.nan, -np.inf]])

In [13]: np.isnan(b)
Out[13]: 
array([[False, False],
       [ True, False]], dtype=bool)

In [14]: np.isfinite(b)
Out[14]: 
array([[ True, False],
       [False, False]], dtype=bool)

Preventing HTML and Script injections in Javascript

A one-liner:

var encodedMsg = $('<div />').text(message).html();

See it work:

https://jsfiddle.net/TimothyKanski/wnt8o12j/

How can I get the last day of the month in C#?

DateTime.DaysInMonth(DateTime.Now.Year, DateTime.Now.Month)

Is there a conditional ternary operator in VB.NET?

iif has always been available in VB, even in VB6.

Dim foo as String = iif(bar = buz, cat, dog)

It is not a true operator, as such, but a function in the Microsoft.VisualBasic namespace.

How to flush output of print function?

On Python 3, print can take an optional flush argument

print("Hello world!", flush=True)

On Python 2 you'll have to do

import sys
sys.stdout.flush()

after calling print. By default, print prints to sys.stdout (see the documentation for more about file objects).

How Do I Make Glyphicons Bigger? (Change Size?)

If you are using bootstrap and font-awesome then it is easy, no need to write a single line of new code, just add fa-Nx, as big you want, See the demo

<span class="glyphicon glyphicon-globe"></span>
<span class="glyphicon glyphicon-globe fa-lg"></span>
<span class="glyphicon glyphicon-globe fa-2x"></span>
<span class="glyphicon glyphicon-globe fa-3x"></span>
<span class="glyphicon glyphicon-globe fa-4x"></span>
<span class="glyphicon glyphicon-globe fa-5x"></span>

Comparing two .jar files

Extract each jar to it's own directory using the jar command with parameters xvf. i.e. jar xvf myjar.jar for each jar.

Then, use the UNIX command diff to compare the two directories. This will show the differences in the directories. You can use diff -r dir1 dir2 two recurse and show the differences in text files in each directory(.xml, .properties, etc).

This will also show if binary class files differ. To actually compare the class files you will have to decompile them as noted by others.

How to dump a dict to a json file?

import json
with open('result.json', 'w') as fp:
    json.dump(sample, fp)

This is an easier way to do it.

In the second line of code the file result.json gets created and opened as the variable fp.

In the third line your dict sample gets written into the result.json!

How do I protect javascript files?

Google Closure Compiler, YUI compressor, Minify, /Packer/... etc, are options for compressing/obfuscating your JS codes. But none of them can help you from hiding your code from the users.

Anyone with decent knowledge can easily decode/de-obfuscate your code using tools like JS Beautifier. You name it.

So the answer is, you can always make your code harder to read/decode, but for sure there is no way to hide.

How to return HTTP 500 from ASP.NET Core RC2 Web Api?

You could use Microsoft.AspNetCore.Mvc.ControllerBase.StatusCode and Microsoft.AspNetCore.Http.StatusCodes to form your response, if you don't wish to hardcode specific numbers.

return  StatusCode(StatusCodes.Status500InternalServerError);

UPDATE: Aug 2019

Perhaps not directly related to the original question but when trying to achieve the same result with Microsoft Azure Functions I found that I had to construct a new StatusCodeResult object found in the Microsoft.AspNetCore.Mvc.Core assembly. My code now looks like this;

return new StatusCodeResult(StatusCodes.Status500InternalServerError);

How to track untracked content?

I use the trick suggested by Peter Lada all the time, dubbed as "fake submodules":

http://debuggable.com/posts/git-fake-submodules:4b563ee4-f3cc-4061-967e-0e48cbdd56cb

It's very useful in several scenarios (p.e. I use it to keep all my Emacs config in a repository, including the current HEAD of all git repositories inside the elpa/el-get package directories, so I could easily roll back/forward to a known working version when some update breaks something).

nano error: Error opening terminal: xterm-256color

Mine was quite a unique case but this could help someone. On Android I tried to copy nano from my termux binary folder to /system/xbin. Placed all the library dependencies in /system/lib and got this error. The libncurses.so.6 file I copied from termux had it's TERMINFO file still pointed to /data/data/com.termux/files/usr/share/terminfo

View pointed path with command

strings path-to-libncurses.so | grep /terminfo

To fix either make the termux terminfo dir and subdirs readable and executable by the nano user or copy the terminfo folder somewhere else and use a hexeditor to modify the plain text path in the shared library file.

Link to zipped terminfo folder https://drive.google.com/file/d/1m1tfHgkGRehBGh1jPMK4EaTgQb9EyCG7/view?usp=drivesdk

Enable/disable buttons with Angular

Set a property for the current lesson: currentLesson. It will hold, obviously, the 'number' of the choosen lesson. On each button click, set the currentLesson value to 'number'/ order of the button, i.e. for the first button, it will be '1', for the second '2' and so on. Each button now can be disabled with [disabled] attribute, if it the currentLesson is not the same as it's order.

HTML

  <button  (click)="currentLesson = '1'"
         [disabled]="currentLesson !== '1'" class="primair">
           Start lesson</button>
  <button (click)="currentLesson = '2'"
         [disabled]="currentLesson !== '2'" class="primair">
           Start lesson</button>
 .....//so on

Typescript

currentLesson:string;

  classes = [
{
  name: 'string',
  level: 'string',
  code: 'number',
  currentLesson: '1'
}]

constructor(){
  this.currentLesson=this.classes[0].currentLesson
}

DEMO

Putting everything in a loop:

HTML

<div *ngFor="let class of classes; let i = index">
   <button [disabled]="currentLesson !== i + 1" class="primair">
           Start lesson {{i +  1}}</button>
</div>

Typescript

currentLesson:string;

classes = [
{
  name: 'Lesson1',
  level: 1,
  code: 1,
},{
  name: 'Lesson2',
  level: 1,
  code: 2,
},
{
  name: 'Lesson3',
  level: 2,
  code: 3,
}]

DEMO

Test a weekly cron job

I'm using Webmin because its a productivity gem for someone who finds command line administration a bit daunting and impenetrable.

There is a "Save and Run Now" button in the "System > Scheduled Cron Jobs > Edit Cron Job" web interface.

It displays the output of the command and is exactly what I needed.

What do I use for a max-heap implementation in Python?

Extending the int class and overriding __lt__ is one of the ways.

import queue
class MyInt(int):
    def __lt__(self, other):
        return self > other

def main():
    q = queue.PriorityQueue()
    q.put(MyInt(10))
    q.put(MyInt(5))
    q.put(MyInt(1))
    while not q.empty():
        print (q.get())


if __name__ == "__main__":
    main()

Custom CSS Scrollbar for Firefox

Here I have tried this CSS for all major browser & tested: Custom color are working fine on scrollbar.

Yes, there are limitations on several versions of different browsers.

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/* Only Chrome */
html::-webkit-scrollbar {width: 17px;}
html::-webkit-scrollbar-thumb {background-color: #0064a7; background-clip: padding-box; border: 1px solid #8ea5b5;}
html::-webkit-scrollbar-track {background-color: #8ea5b5; }
::-webkit-scrollbar-button {background-color: #8ea5b5;}
/* Only IE */
html {scrollbar-face-color: #0064a7; scrollbar-shadow-color: #8ea5b5; scrollbar-highlight-color: #8ea5b5;}
/* Only FireFox */
html {scrollbar-color: #0064a7 #8ea5b5;}
/* View Scrollbar */
html {overflow-y: scroll;overflow-x: hidden;}
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<!doctype html>
<html lang="en" class="no-js">
<head>
    <meta charset="utf-8">
    <meta http-equiv="x-ua-compatible" content="ie=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>
<body>
    <header>
        <div id="logo"><img src="/logo.png">HTML5&nbsp;Layout</div>
        <nav>  
            <ul>
                <li><a href="/">Home</a>
                <li><a href="https://html-css-js.com/">HTML</a>
                <li><a href="https://html-css-js.com/css/code/">CSS</a>
                <li><a href="https://htmlcheatsheet.com/js/">JS</a>
            </ul>
        </nav>
    </header>
    <section>
        <strong>Demonstration of a simple page layout using HTML5 tags: header, nav, section, main, article, aside, footer, address.</strong>
    </section>
    <section id="pageContent">
        <main role="main">
            <article>
                <h2>Stet facilis ius te</h2>
                <p>Lorem ipsum dolor sit amet, nonumes voluptatum mel ea, cu case ceteros cum. Novum commodo malorum vix ut. Dolores consequuntur in ius, sale electram dissentiunt quo te. Cu duo omnes invidunt, eos eu mucius fabellas. Stet facilis ius te, quando voluptatibus eos in. Ad vix mundi alterum, integre urbanitas intellegam vix in.</p>
            </article>
            <article>
                <h2>Illud mollis moderatius</h2>
                <p>Eum facete intellegat ei, ut mazim melius usu. Has elit simul primis ne, regione minimum id cum. Sea deleniti dissentiet ea. Illud mollis moderatius ut per, at qui ubique populo. Eum ad cibo legimus, vim ei quidam fastidii.</p>
            </article>
            <article>
                <h2>Ex ignota epicurei quo</h2>
                <p>Quo debet vivendo ex. Qui ut admodum senserit partiendo. Id adipiscing disputando eam, sea id magna pertinax concludaturque. Ex ignota epicurei quo, his ex doctus delenit fabellas, erat timeam cotidieque sit in. Vel eu soleat voluptatibus, cum cu exerci mediocritatem. Malis legere at per, has brute putant animal et, in consul utamur usu.</p>
            </article>
            <article>
                <h2>His at autem inani volutpat</h2>
                <p>Te has amet modo perfecto, te eum mucius conclusionemque, mel te erat deterruisset. Duo ceteros phaedrum id, ornatus postulant in sea. His at autem inani volutpat. Tollit possit in pri, platonem persecuti ad vix, vel nisl albucius gloriatur no.</p>
            </article>
        </main>
        <aside>
            <div>Sidebar 1</div>
            <div>Sidebar 2</div>
            <div>Sidebar 3</div>
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    </section>
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        <p>&copy; You can copy, edit and publish this template but please leave a link to our website | <a href="https://html5-templates.com/" target="_blank" rel="nofollow">HTML5 Templates</a></p>
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            Contact: <a href="mailto:[email protected]">Mail me</a>
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Iterating Through a Dictionary in Swift

Dictionaries in Swift (and other languages) are not ordered. When you iterate through the dictionary, there's no guarentee that the order will match the initialization order. In this example, Swift processes the "Square" key before the others. You can see this by adding a print statement to the loop. 25 is the 5th element of Square so largest would be set 5 times for the 5 elements in Square and then would stay at 25.

let interestingNumbers = [
    "Prime": [2, 3, 5, 7, 11, 13],
    "Fibonacci": [1, 1, 2, 3, 5, 8],
    "Square": [1, 4, 9, 16, 25]
]
var largest = 0
for (kind, numbers) in interestingNumbers {
    println("kind: \(kind)")
    for number in numbers {
        if number > largest {
            largest = number
        }
    }
}
largest

This prints:

kind: Square
kind: Prime
kind: Fibonacci

How to stop java process gracefully?

Thanks for you answers. Shutdown hooks seams like something that would work in my case. But I also bumped into the thing called Monitoring and Management beans:
http://java.sun.com/j2se/1.5.0/docs/guide/management/overview.html
That gives some nice possibilities, for remote monitoring, and manipulation of the java process. (Was introduced in Java 5)

Why is the <center> tag deprecated in HTML?

It's intended that markup, i.e. the HTML tags, represent meaning and structure, not appearance. It was badly mixed up in early versions of HTML but the standards people are trying to clean that up now.

One problem with letting tags control appearance is that your pages don't play well with devices for the handicapped, such as screen readers. It also leads to having lots and lots of tags in your text that don't help clarify the meaning, but rather clutter it with information of a different level.

So CSS was thought up to move formatting/display to a different language, which is separate from the text and can easily be kept that way. Among other things, this allows switching stylesheets to change the appearance of a Web page without touching the other markup. And to be able to do that for lots of pages in one swell foop.

The tools CSS gives you to do this are not always elegant, I'm on your side there. For instance, there is no way to do effective vertical centering. And horizontal centering, if it's not just text amenable to text-align, is not much better.

You have the choice of doing easy, effective and muddled or clean, elegant and cumbersome. I don't understand why Web developers put up with this mess, but I guess they're happy to have at least a chance to get their stuff done.

How to properly use the "choices" field option in Django

$ pip install django-better-choices

For those who are interested, I have created django-better-choices library, that provides a nice interface to work with Django choices for Python 3.7+. It supports custom parameters, lots of useful features and is very IDE friendly.

You can define your choices as a class:

from django_better_choices import Choices


class PAGE_STATUS(Choices):
    CREATED = 'Created'
    PENDING = Choices.Value('Pending', help_text='This set status to pending')
    ON_HOLD = Choices.Value('On Hold', value='custom_on_hold')

    VALID = Choices.Subset('CREATED', 'ON_HOLD')

    class INTERNAL_STATUS(Choices):
        REVIEW = 'On Review'

    @classmethod
    def get_help_text(cls):
        return tuple(
            value.help_text
            for value in cls.values()
            if hasattr(value, 'help_text')
        )

Then do the following operations and much much more:

print( PAGE_STATUS.CREATED )                # 'created'
print( PAGE_STATUS.ON_HOLD )                # 'custom_on_hold'
print( PAGE_STATUS.PENDING.display )        # 'Pending'
print( PAGE_STATUS.PENDING.help_text )      # 'This set status to pending'

'custom_on_hold' in PAGE_STATUS.VALID       # True
PAGE_STATUS.CREATED in PAGE_STATUS.VALID    # True

PAGE_STATUS.extract('CREATED', 'ON_HOLD')   # ~= PAGE_STATUS.VALID

for value, display in PAGE_STATUS:
    print( value, display )

PAGE_STATUS.get_help_text()
PAGE_STATUS.VALID.get_help_text()

And of course, it is fully supported by Django and Django Migrations:

class Page(models.Model):
    status = models.CharField(choices=PAGE_STATUS, default=PAGE_STATUS.CREATED)

Full documentation here: https://pypi.org/project/django-better-choices/

How to get a index value from foreach loop in jstl

use varStatus to get the index c:forEach varStatus properties

<c:forEach var="categoryName" items="${categoriesList}" varStatus="loop">
    <li><a onclick="getCategoryIndex(${loop.index})" href="#">${categoryName}</a></li>
</c:forEach>

What are the pros and cons of parquet format compared to other formats?

Tom's answer is quite detailed and exhaustive but you may also be interested in this simple study about Parquet vs Avro done at Allstate Insurance, summarized here:

"Overall, Parquet showed either similar or better results on every test [than Avro]. The query-performance differences on the larger datasets in Parquet’s favor are partly due to the compression results; when querying the wide dataset, Spark had to read 3.5x less data for Parquet than Avro. Avro did not perform well when processing the entire dataset, as suspected."

What are the options for (keyup) in Angular2?

Have hit the same problem today.

These are poorly documented, an open issue exist.

Some for keyup, like space:

<input (keyup.space)="doSomething()">
<input (keyup.spacebar)="doSomething()">  

Some for keydown
(may work for keyup too):

<input (keydown.enter)="...">
<input (keydown.a)="...">
<input (keydown.esc)="...">
<input (keydown.alt)="...">
<input (keydown.shift.esc)="...">
<input (keydown.shift.arrowdown)="...">
<input (keydown.f4)="...">

All above are from below links:

https://github.com/angular/angular/issues/18870
https://github.com/angular/angular/issues/8273
https://github.com/angular/angular/blob/master/packages/platform-browser/src/dom/events/key_events.ts
https://alligator.io/angular/binding-keyup-keydown-events/

Loading cross-domain endpoint with AJAX

You can use Ajax-cross-origin a jQuery plugin. With this plugin you use jQuery.ajax() cross domain. It uses Google services to achieve this:

The AJAX Cross Origin plugin use Google Apps Script as a proxy jSON getter where jSONP is not implemented. When you set the crossOrigin option to true, the plugin replace the original url with the Google Apps Script address and send it as encoded url parameter. The Google Apps Script use Google Servers resources to get the remote data, and return it back to the client as JSONP.

It is very simple to use:

    $.ajax({
        crossOrigin: true,
        url: url,
        success: function(data) {
            console.log(data);
        }
    });

You can read more here: http://www.ajax-cross-origin.com/

Why am I getting ImportError: No module named pip ' right after installing pip?

The ensurepip module was added in version 3.4 and then backported to 2.7.9.

So make sure your Python version is at least 2.7.9 if using Python 2, and at least 3.4 if using Python 3.

Which mime type should I use for mp3

Your best bet would be using the RFC defined mime-type audio/mpeg.

What's the purpose of SQL keyword "AS"?

There is no difference between both statements above. AS is just a more explicit way of mentioning the alias

How to join a slice of strings into a single string?

The title of your question is:

How to join a slice of strings into a single string?

but in fact, reg is not a slice, but a length-three array. [...]string is just syntactic sugar for (in this case) [3]string.

To get an actual slice, you should write:

reg := []string {"a","b","c"}

(Try it out: https://play.golang.org/p/vqU5VtDilJ.)

Incidentally, if you ever really do need to join an array of strings into a single string, you can get a slice from the array by adding [:], like so:

fmt.Println(strings.Join(reg[:], ","))

(Try it out: https://play.golang.org/p/zy8KyC8OTuJ.)

Get google map link with latitude/longitude

@vignesh the single quotes are only needed if you are using js variables

<iframe src = "https://maps.google.com/maps?q=10.305385,77.923029&hl=es;z=14&amp;output=embed"></iframe>

Could someone explain this for me - for (int i = 0; i < 8; i++)

The generic view of a loop is

for (initialization; condition; increment-decrement){}

The first part initializes the code. The second part is the condition that will continue to run the loop as long as it is true. The last part is what will be run after each iteration of the loop. The last part is typically used to increment or decrement a counter, but it doesn't have to.

How can I declare a Boolean parameter in SQL statement?

The same way you declare any other variable, just use the bit type:

DECLARE @MyVar bit
Set @MyVar = 1  /* True */
Set @MyVar = 0  /* False */

SELECT * FROM [MyTable] WHERE MyBitColumn = @MyVar

What is the difference between a definition and a declaration?

From the C99 standard, 6.7(5):

A declaration specifies the interpretation and attributes of a set of identifiers. A definition of an identifier is a declaration for that identifier that:

  • for an object, causes storage to be reserved for that object;
  • for a function, includes the function body;
  • for an enumeration constant or typedef name, is the (only) declaration of the identifier.

From the C++ standard, 3.1(2):

A declaration is a definition unless it declares a function without specifying the function's body, it contains the extern specifier or a linkage-specification and neither an initializer nor a function-body, it declares a static data member in a class declaration, it is a class name declaration, or it is a typedef declaration, a using-declaration, or a using-directive.

Then there are some examples.

So interestingly (or not, but I'm slightly surprised by it), typedef int myint; is a definition in C99, but only a declaration in C++.

How does Subquery in select statement work in oracle

It's simple-

SELECT empname,
       empid,
       (SELECT COUNT (profileid)
          FROM profile
         WHERE profile.empid = employee.empid)
           AS number_of_profiles
  FROM employee;

It is even simpler when you use a table join like this:

  SELECT e.empname, e.empid, COUNT (p.profileid) AS number_of_profiles
    FROM employee e LEFT JOIN profile p ON e.empid = p.empid
GROUP BY e.empname, e.empid;

Explanation for the subquery:

Essentially, a subquery in a select gets a scalar value and passes it to the main query. A subquery in select is not allowed to pass more than one row and more than one column, which is a restriction. Here, we are passing a count to the main query, which, as we know, would always be only a number- a scalar value. If a value is not found, the subquery returns null to the main query. Moreover, a subquery can access columns from the from clause of the main query, as shown in my query where employee.empid is passed from the outer query to the inner query.


Edit:

When you use a subquery in a select clause, Oracle essentially treats it as a left join (you can see this in the explain plan for your query), with the cardinality of the rows being just one on the right for every row in the left.


Explanation for the left join

A left join is very handy, especially when you want to replace the select subquery due to its restrictions. There are no restrictions here on the number of rows of the tables in either side of the LEFT JOIN keyword.

For more information read Oracle Docs on subqueries and left join or left outer join.

Get Unix timestamp with C++

As this is the first result on google and there's no C++20 answer yet, here's how to use std::chrono to do this:

#include <chrono>

//...

using namespace std::chrono;
int64_t timestamp = duration_cast<milliseconds>(system_clock::now().time_since_epoch()).count();

In versions of C++ before 20, system_clock's epoch being Unix epoch is a de-facto convention, but it's not standardized. If you're not on C++20, use at your own risk.

int object is not iterable?

Don't make it a int(), but make it a range() will solve this problem.

inp = range(input("Enter a number: "))

SSIS Excel Import Forcing Incorrect Column Type

This worked for me. Select the problematic column in Excel - highlight the whole column. Change the format to "Text". Save the Excel file.

In your SSIS package, go to the Data Flow pane for your import. Double click the Excel Source node. It should warn you that the types have changed and ask you if you want to remap them. Click Yes. Executing should now work and bring in all values.

Note: I'm using Excel 2013 and Visual Studio 2015, but I assume these instructions would work for earlier versions too.

How to create web service (server & Client) in Visual Studio 2012?

  1. Create a new empty Asp.NET Web Application.
  2. Solution Explorer right click on the project root.
  3. Choose the menu item Add-> Web Service

define a List like List<int,string>?

You could use an immutable struct

public struct Data
{
    public Data(int intValue, string strValue)
    {
        IntegerData = intValue;
        StringData = strValue;
    }

    public int IntegerData { get; private set; }
    public string StringData { get; private set; }
}

var list = new List<Data>();

Or a KeyValuePair<int, string>

using Data = System.Collections.Generic.KeyValuePair<int, string>
...
var list = new List<Data>();
list.Add(new Data(12345, "56789"));

How to download Google Play Services in an Android emulator?

This is how you make Android Google Maps API v2 work on your emulator.


Create a new emulator

  • for device choose "5.1'' WVGA (480 x 800: mdpi)"
  • for target choose "Android 4.1.2 - API level 16"
  • for "CPU/ABI" choose "ARM"
  • leave rest to defaults

these are the settings that are working for me. I don't know for different ones.


Start the emulator


install com.android.vending-1.apk and com.google.android.gms-1.apk via ADB install command


The longer answer is on my blog post about this issue https://medium.com/nemanja-kovacevic/how-to-make-android-google-maps-v2-work-in-android-emulator-e384f5423723

How to set character limit on the_content() and the_excerpt() in wordpress

Or even easier and without the need to create a filter: use PHP's mb_strimwidth to truncate a string to a certain width (length). Just make sure you use one of the get_ syntaxes. For example with the content:

<?php $content = get_the_content(); echo mb_strimwidth($content, 0, 400, '...');?>

This will cut the string at 400 characters and close it with .... Just add a "read more"-link to the end by pointing to the permalink with get_permalink().

<a href="<?php the_permalink() ?>">Read more </a>

Of course you could also build the read more in the first line. Than just replace '...' with '<a href="' . get_permalink() . '">[Read more]</a>'

How to create an Array with AngularJS's ng-model

How to create an array of inputs with ng-model

Use the ng-repeat directive:

<ol>
  <li ng-repeat="n in [] | range:count">
    <input name="telephone-{{$index}}"
           ng-model="telephones[$index].value" >
  </li>
</ol>

The DEMO

_x000D_
_x000D_
angular.module("app",[])_x000D_
.controller("ctrl",function($scope){_x000D_
  $scope.count = 3;_x000D_
  $scope.telephones = [];_x000D_
})_x000D_
.filter("range",function() {_x000D_
  return (x,n) => Array.from({length:n},(x,index)=>(index));_x000D_
})
_x000D_
<script src="//unpkg.com/angular/angular.js"></script>_x000D_
<body ng-app="app" ng-controller="ctrl">_x000D_
    <button>_x000D_
      Array length_x000D_
      <input type="number" ng-model="count" _x000D_
             ng-change="telephones.length=count">_x000D_
    </button>_x000D_
    <ol>_x000D_
      <li ng-repeat="n in [] | range:count">_x000D_
        <input name="telephone-{{$index}}"_x000D_
               ng-model="telephones[$index].value" >_x000D_
      </li>_x000D_
    </ol>  _x000D_
    {{telephones}}_x000D_
</body>
_x000D_
_x000D_
_x000D_

React-Router open Link in new tab

Starting with react_router 1.0, the props will be passed onto the anchor tag. You can directly use target="_blank". Discussed here: https://github.com/ReactTraining/react-router/issues/2188

Set value for particular cell in pandas DataFrame using index

Soo, your question to convert NaN at ['x',C] to value 10

the answer is..

df['x'].loc['C':]=10
df

alternative code is

df.loc['C', 'x']=10
df

Find Oracle JDBC driver in Maven repository

As of today (27, February 2020) Oracle announced that it has published all JDBC client libraries from version 11.2.0.4 (e.g. ojdbc6) to 19.3.0 (e.g. ojdbc10) on Maven Central under the group id com.oracle.database:

Example:

<dependency>
  <groupId>com.oracle.database.jdbc</groupId>
  <artifactId>ojdbc10</artifactId>
  <version>19.3.0.0</version>
</dependency>

Change primary key column in SQL Server

Assuming that your current primary key constraint is called pk_history, you can replace the following lines:

ALTER TABLE history ADD PRIMARY KEY (id)

ALTER TABLE history
DROP CONSTRAINT userId
DROP CONSTRAINT name

with these:

ALTER TABLE history DROP CONSTRAINT pk_history

ALTER TABLE history ADD CONSTRAINT pk_history PRIMARY KEY (id)

If you don't know what the name of the PK is, you can find it with the following query:

SELECT * 
  FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS 
 WHERE TABLE_NAME = 'history'

How do I exit a foreach loop in C#?

Use break.


Unrelated to your question, I see in your code the line:

Violated = !(name.firstname == null) ? false : true;

In this line, you take a boolean value (name.firstname == null). Then, you apply the ! operator to it. Then, if the value is true, you set Violated to false; otherwise to true. So basically, Violated is set to the same value as the original expression (name.firstname == null). Why not use that, as in:

Violated = (name.firstname == null);

User GETDATE() to put current date into SQL variable

You don't need the SELECT

DECLARE @LastChangeDate as date
SET @LastChangeDate = GetDate()

Resetting a form in Angular 2 after submit

form: NgForm;

form.reset()

This didn't work for me. It cleared the values but the controls raised an error.

But what worked for me was creating a hidden reset button and clicking the button when we want to clear the form.

<button class="d-none" type="reset" #btnReset>Reset</button>

And on the component, define the ViewChild and reference it in code.

@ViewChild('btnReset') btnReset: ElementRef<HTMLElement>;

Use this to reset the form.

this.btnReset.nativeElement.click();

Notice that the class d-none sets display: none; on the button.

Reorder HTML table rows using drag-and-drop

The jQuery UI sortable plugin provides drag-and-drop reordering. A save button can extract the IDs of each item to create a comma-delimited string of those IDs, added to a hidden textbox. The textbox is returned to the server using an async postback.

This fiddle example reorders table elements, but does not save them to a database.

The sortable plugin takes one line of code to turn any list into a sortable list. If you care to use them, it also provides CSS and images to provide a visual impact to sortable list (see the example that I linked to). Developers, however, must provide code to retrieve items in their new order. I embed unique IDs of each item in the list as an HTML attribute and then retrieve those IDs via jQuery.

For example:

// ----- code executed when the document loads
$(function() {
    wireReorderList();
});

function wireReorderList() {
    $("#reorderExampleItems").sortable();
    $("#reorderExampleItems").disableSelection();
}

function saveOrderClick() {
    // ----- Retrieve the li items inside our sortable list
    var items = $("#reorderExampleItems li");

    var linkIDs = [items.size()];
    var index = 0;

    // ----- Iterate through each li, extracting the ID embedded as an attribute
    items.each(
        function(intIndex) {
            linkIDs[index] = $(this).attr("ExampleItemID");
            index++;
        });

    $get("<%=txtExampleItemsOrder.ClientID %>").value = linkIDs.join(",");
}

Does Enter key trigger a click event?

What personally me fount usable for me is:

(mousedown)="callEvent()" (keyup.enter)="$event.preventDefault()

keyup.enter prevents the event from triggering on keyup, but it still occurs for keydown, that works for me.

Read text file into string. C++ ifstream

To read a whole line from a file into a string, use std::getline like so:

 std::ifstream file("my_file");
 std::string temp;
 std::getline(file, temp);

You can do this in a loop to until the end of the file like so:

 std::ifstream file("my_file");
 std::string temp;
 while(std::getline(file, temp)) {
      //Do with temp
 }

References

http://en.cppreference.com/w/cpp/string/basic_string/getline

http://en.cppreference.com/w/cpp/string/basic_string

blur vs focusout -- any real differences?

As stated in the JQuery documentation

The focusout event is sent to an element when it, or any element inside of it, loses focus. This is distinct from the blur event in that it supports detecting the loss of focus on descendant elements (in other words, it supports event bubbling).

Retrieving a random item from ArrayList

public static Item getRandomChestItem(List<Item> items) {
    return items.get(new Random().nextInt(items.size()));
}

How to add Button over image using CSS?

If I understood correctly, I would change the HTML to something like this:

<div id="shop">
    <div class="content">
        <img src="http://placehold.it/182x121"/> 
        <a href="#">Counter-Strike 1.6 Steam</a>
    </div>
</div>

Then I would be able to use position:absolute and position:relative to force the blue button down.

I have created a jsfiddle: http://jsfiddle.net/y9w99/

Start / Stop a Windows Service from a non-Administrator user account

I use the SubInACL utility for this. For example, if I wanted to give the user job on the computer VMX001 the ability to start and stop the World Wide Web Publishing Service (also know as w3svc), I would issue the following command as an Administrator:

subinacl.exe /service w3svc /grant=VMX001\job=PTO

The permissions you can grant are defined as follows (list taken from here):

F : Full Control
R : Generic Read
W : Generic Write
X : Generic eXecute
L : Read controL
Q : Query Service Configuration
S : Query Service Status
E : Enumerate Dependent Services
C : Service Change Configuration
T : Start Service
O : Stop Service
P : Pause/Continue Service
I : Interrogate Service 
U : Service User-Defined Control Commands

So, by specifying PTO, I am entitling the job user to Pause/Continue, Start, and Stop the w3svc service.

Catch browser's "zoom" event in JavaScript

There is a nifty plugin built from yonran that can do the detection. Here is his previously answered question on StackOverflow. It works for most of the browsers. Application is as simple as this:

window.onresize = function onresize() {
  var r = DetectZoom.ratios();
  zoomLevel.innerHTML =
    "Zoom level: " + r.zoom +
    (r.zoom !== r.devicePxPerCssPx
        ? "; device to CSS pixel ratio: " + r.devicePxPerCssPx
        : "");
}

Demo

ssh: check if a tunnel is alive

If you are using ssh in background, use this:

sudo lsof -i -n | egrep '\<ssh\>'

'ls' in CMD on Windows is not recognized

Use the command dir to list all the directories and files in a directory; ls is a unix command.

Bootstrap Align Image with text

I think this is helpful for you

<div class="container">
        <div class="page-header">
                <h1>About Me</h1>
            </div><!--END page-header-->
        <div class="row" id="features">
                <div class="col-sm-6 feature">
                        <img src="http://lorempixel.com/200/200" alt="Web Design" class="img-circle">
                </div><!--END feature-->

                <div class="col-sm-6 feature">
                        <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod
tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam,</p>
                </div><!--END feature-->
            </div><!--end features-->
    </div><!--end container-->

JOptionPane Yes or No window

Something along these lines ....

   //default icon, custom title
int n = JOptionPane.showConfirmDialog(null,"Would you like green eggs and ham?","An Inane Question",JOptionPane.YES_NO_OPTION);

String result = "?";
switch (n) {
case JOptionPane.YES_OPTION:
  result = "YES";
  break;
case JOptionPane.NO_OPTION:
  result = "NO";
  break;
default:
  ;
}
System.out.println("Replace? " + result);

you may also want to look at DialogDemo

How to set variable from a SQL query?

To ASSIGN variables using a SQL select the best practice is as shown below

->DECLARE co_id INT ;
->DECLARE sname VARCHAR(10) ;

->SELECT course_id INTO co_id FROM course_details ;
->SELECT student_name INTO sname FROM course_details;

IF you have to assign more than one variable in a single line you can use this same SELECT INTO

->DECLARE val1 int;
->DECLARE val2 int;

->SELECT student__id,student_name INTO val1,val2 FROM student_details;

--HAPPY CODING-- 

Winforms issue - Error creating window handle

The out of memory suggestion doesn't seem like a bad lead.

What is your program doing that it gets this error?

Is it creating a great many windows or controls? Does it create them programatically as opposed to at design time? If so, do you do this in a loop? Is that loop infinite? Are you consuming staggering boatloads of memory in some other way?

What happens when you watch the memory used by your application in task manager? Does it skyrocket to the moon? Or better yet, as suggested above use process monitor to dive into the details.

What is the difference between <p> and <div>?

The only difference between the two elements is semantics. Both elements, by default, have the CSS rule display: block (hence block-level) applied to them; nothing more (except somewhat extra margin in some instances). However, as aforementioned, they both different greatly in terms of semantics.

The <p> element, as its name somewhat implies, is for paragraphs. Thus, <p> should be used when you want to create blocks of paragraph text.

The <div> element, however, has little to no meaning semantically and therefore can be used as a generic block-level element — most commonly, people use it within layouts because it is meaningless semantically and can be used for generally anything you might require a block-level element for.

Link for more detail

How to use JavaScript to change div backgroundColor

If you are willing to insert non-semantic nodes into your document, you can do this in a CSS-only IE-compatible manner by wrapping your divs in fake A tags.

<style type="text/css">
  .content {
    background: #ccc;
  }

  .fakeLink { /* This is to make the link not look like one */
    cursor: default;
    text-decoration: none;
    color: #000;
  }

  a.fakeLink:hover .content {
    background: #000;
    color: #fff;
  }

</style>
<div id="catestory">

  <a href="#" onclick="return false();" class="fakeLink">
    <div class="content">
      <h2>some title here</h2>
      <p>some content here</p>
    </div>
  </a>

  <a href="#" onclick="return false();" class="fakeLink">
    <div class="content">
      <h2>some title here</h2>
      <p>some content here</p>
    </div>
  </a>

  <a href="#" onclick="return false();" class="fakeLink">
    <div class="content">
      <h2>some title here</h2>
      <p>some content here</p>
    </div>
  </a>

</div>

How to check if a function exists on a SQL database

I've found you can use a very non verbose and straightforward approach to checking for the existence various SQL Server objects this way:

IF OBJECTPROPERTY (object_id('schemaname.scalarfuncname'), 'IsScalarFunction') = 1
IF OBJECTPROPERTY (object_id('schemaname.tablefuncname'), 'IsTableFunction') = 1
IF OBJECTPROPERTY (object_id('schemaname.procname'), 'IsProcedure') = 1

This is based on the OBJECTPROPERTY function which is available in SQL 2005+. The MSDN article can be found here.

The OBJECTPROPERTY function uses the following signature:

OBJECTPROPERTY ( id , property ) 

You pass a literal value into the property parameter, designating the type of object you are looking for. There's a massive list of values you can supply.

How to capture Curl output to a file?

use --trace-asci output.txt can output the curl details to the output.txt

Undefined reference to sqrt (or other mathematical functions)

I suppose you have imported math.h with #include <math.h>

So the only other reason I can see is a missing linking information. You must link your code with the -lm option.

If you're simply trying to compile one file with gcc, just add -lm to your command line, otherwise, give some informations about your building process.

Running Google Maps v2 on the Android emulator

You need to try on an emulator with the Google API's version. Each platform has two versions, Android and Android+Google APIs. Ensure that when you create the AVD, you select the Google APIs version on target field.

And the page Ensure Devices Have the Google Play services APK can be also helpful.

How to compile C programming in Windows 7?

Get gcc for Windows . However, you will have to install MinGW as well.

You can use Visual Studio 2010 express edition as well. Link here

$.browser is undefined error

The .browser call has been removed in jquery 1.9 have a look at http://jquery.com/upgrade-guide/1.9/ for more details.

How to install mcrypt extension in xampp

Right from the PHP Docs: PHP 5.3 Windows binaries uses the static version of the MCrypt library, no DLL are needed.

http://php.net/manual/en/mcrypt.requirements.php

But if you really want to download it, just go to the mcrypt sourceforge page

http://sourceforge.net/projects/mcrypt/files/?source=navbar

Why compile Python code?

As already mentioned, you can get a performance increase from having your python code compiled into bytecode. This is usually handled by python itself, for imported scripts only.

Another reason you might want to compile your python code, could be to protect your intellectual property from being copied and/or modified.

You can read more about this in the Python documentation.

Random number in range [min - max] using PHP

rand(1,20)

Docs for PHP's rand function are here:

http://php.net/manual/en/function.rand.php

Use the srand() function to set the random number generator's seed value.

ASP.NET Setting width of DataBound column in GridView

<asp:GridView ID="GridView1" AutoGenerateEditButton="True" 
ondatabound="gv_DataBound" runat="server" DataSourceID="SqlDataSource1"
AutoGenerateColumns="False" width="600px">

<Columns>
                <asp:BoundField HeaderText="UserId" 
                DataField="UserId" 
                SortExpression="UserId" ItemStyle-Width="400px"></asp:BoundField>
   </Columns>
</asp:GridView>

What is the use of verbose in Keras while validating the model?

By default verbose = 1,

verbose = 1, which includes both progress bar and one line per epoch

verbose = 0, means silent

verbose = 2, one line per epoch i.e. epoch no./total no. of epochs

Simple line plots using seaborn

It's possible to get this done using seaborn.lineplot() but it involves some additional work of converting numpy arrays to pandas dataframe. Here's a complete example:

# imports
import seaborn as sns
import numpy as np
import pandas as pd

# inputs
In [41]: num = np.array([1, 2, 3, 4, 5])
In [42]: sqr = np.array([1, 4, 9, 16, 25])

# convert to pandas dataframe
In [43]: d = {'num': num, 'sqr': sqr}
In [44]: pdnumsqr = pd.DataFrame(d)

# plot using lineplot
In [45]: sns.set(style='darkgrid')
In [46]: sns.lineplot(x='num', y='sqr', data=pdnumsqr)
Out[46]: <matplotlib.axes._subplots.AxesSubplot at 0x7f583c05d0b8>

And we get the following plot:

square plot

Which JRE am I using?

The Java system property System.getProperty(...) to consult is "java.runtime.name". This will distinguish between "OpenJDK Runtime Environment" and "Java(TM) SE Runtime Environment". They both have the same vendor - "Oracle Corporation".

This property is also included in the output for java -version.

Inserting Data into Hive Table

Hive apparently supports INSERT...VALUES starting in Hive 0.14.

Please see the section 'Inserting into tables from SQL' at: https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DML

How do you easily horizontally center a <div> using CSS?

You should use position: relative and text-align: center on the parent element and then display: inline-block on the child element you want to center. This is a simple CSS design pattern that will work across all major browsers. Here is an example below or check out the CodePen Example.

_x000D_
_x000D_
p {_x000D_
  text-align: left;_x000D_
}_x000D_
.container {_x000D_
  position: relative;_x000D_
  display: block;_x000D_
  text-align: center;_x000D_
}_x000D_
/* Style your object */_x000D_
_x000D_
.object {_x000D_
  padding: 10px;_x000D_
  color: #ffffff;_x000D_
  background-color: #556270;_x000D_
}_x000D_
.centerthis {_x000D_
  display: inline-block;_x000D_
}
_x000D_
<div class="container">_x000D_
_x000D_
  <p>Aeroplanigera Mi Psychopathologia Subdistinctio Chirographum Intuor Sons Superbiloquentia Os Sors Sesquiseptimus Municipatio Archipresbyteratus O Conclusio Compedagogius An Maius Septentrionarius Plas Inproportionabilit Constantinopolis Particularisticus.</p>_x000D_
_x000D_
  <span class="object centerthis">Something Centered</span>_x000D_
_x000D_
  <p>Aeroplanigera Mi Psychopathologia Subdistinctio Chirographum Intuor Sons Superbiloquentia Os Sors Sesquiseptimus Municipatio Archipresbyteratus O Conclusio Compedagogius.</p>_x000D_
</div>
_x000D_
_x000D_
_x000D_

Regular Expressions- Match Anything

<?php
$str = "I bought _ sheep";
preg_match("/I bought (.*?) sheep", $str, $match);
print_r($match);
?>

http://sandbox.phpcode.eu/g/b2243.php

IF statement: how to leave cell blank if condition is false ("" does not work)

Here is what I do

=IF(OR(ISBLANK(AH38),AH38=""),"",IF(AI38=0,0,AH38/AI38))

Use the OR condition OR(ISBLANK(cell), cell="")

Converting string to numeric

As csgillespie said. stringsAsFactors is default on TRUE, which converts any text to a factor. So even after deleting the text, you still have a factor in your dataframe.

Now regarding the conversion, there's a more optimal way to do so. So I put it here as a reference :

> x <- factor(sample(4:8,10,replace=T))
> x
 [1] 6 4 8 6 7 6 8 5 8 4
Levels: 4 5 6 7 8
> as.numeric(levels(x))[x]
 [1] 6 4 8 6 7 6 8 5 8 4

To show it works.

The timings :

> x <- factor(sample(4:8,500000,replace=T))
> system.time(as.numeric(as.character(x)))
   user  system elapsed 
   0.11    0.00    0.11 
> system.time(as.numeric(levels(x))[x])
   user  system elapsed 
      0       0       0 

It's a big improvement, but not always a bottleneck. It gets important however if you have a big dataframe and a lot of columns to convert.

Username and password in https url

When you put the username and password in front of the host, this data is not sent that way to the server. It is instead transformed to a request header depending on the authentication schema used. Most of the time this is going to be Basic Auth which I describe below. A similar (but significantly less often used) authentication scheme is Digest Auth which nowadays provides comparable security features.

With Basic Auth, the HTTP request from the question will look something like this:

GET / HTTP/1.1
Host: example.com
Authorization: Basic Zm9vOnBhc3N3b3Jk

The hash like string you see there is created by the browser like this: base64_encode(username + ":" + password).

To outsiders of the HTTPS transfer, this information is hidden (as everything else on the HTTP level). You should take care of logging on the client and all intermediate servers though. The username will normally be shown in server logs, but the password won't. This is not guaranteed though. When you call that URL on the client with e.g. curl, the username and password will be clearly visible on the process list and might turn up in the bash history file.

When you send passwords in a GET request as e.g. http://example.com/login.php?username=me&password=secure the username and password will always turn up in server logs of your webserver, application server, caches, ... unless you specifically configure your servers to not log it. This only applies to servers being able to read the unencrypted http data, like your application server or any middleboxes such as loadbalancers, CDNs, proxies, etc. though.

Basic auth is standardized and implemented by browsers by showing this little username/password popup you might have seen already. When you put the username/password into an HTML form sent via GET or POST, you have to implement all the login/logout logic yourself (which might be an advantage and allows you to more control over the login/logout flow for the added "cost" of having to implement this securely again). But you should never transfer usernames and passwords by GET parameters. If you have to, use POST instead. The prevents the logging of this data by default.

When implementing an authentication mechanism with a user/password entry form and a subsequent cookie-based session as it is commonly used today, you have to make sure that the password is either transported with POST requests or one of the standardized authentication schemes above only.

Concluding I could say, that transfering data that way over HTTPS is likely safe, as long as you take care that the password does not turn up in unexpected places. But that advice applies to every transfer of any password in any way.

Round number to nearest integer

round(value,significantDigit) is the ordinary solution, however this does not operate as one would expect from a math perspective when round values ending in 5. If the 5 is in the digit just after the one you're rounded to, these values are only sometimes rounded up as expected (i.e. 8.005 rounding to two decimal digits gives 8.01). For certain values due to the quirks of floating point math, they are rounded down instead!

i.e.

>>> round(1.0005,3)
1.0
>>> round(2.0005,3)
2.001
>>> round(3.0005,3)
3.001
>>> round(4.0005,3)
4.0
>>> round(1.005,2)
1.0
>>> round(5.005,2)
5.0
>>> round(6.005,2)
6.0
>>> round(7.005,2)
7.0
>>> round(3.005,2)
3.0
>>> round(8.005,2)
8.01

Weird.

Assuming your intent is to do the traditional rounding for statistics in the sciences, this is a handy wrapper to get the round function working as expected needing to import extra stuff like Decimal.

>>> round(0.075,2)

0.07

>>> round(0.075+10**(-2*5),2)

0.08

Aha! So based on this we can make a function...

def roundTraditional(val,digits):
   return round(val+10**(-len(str(val))-1), digits)

Basically this adds a value guaranteed to be smaller than the least given digit of the string you're trying to use round on. By adding that small quantity it preserve's round's behavior in most cases, while now ensuring if the digit inferior to the one being rounded to is 5 it rounds up, and if it is 4 it rounds down.

The approach of using 10**(-len(val)-1) was deliberate, as it the largest small number you can add to force the shift, while also ensuring that the value you add never changes the rounding even if the decimal . is missing. I could use just 10**(-len(val)) with a condiditional if (val>1) to subtract 1 more... but it's simpler to just always subtract the 1 as that won't change much the applicable range of decimal numbers this workaround can properly handle. This approach will fail if your values reaches the limits of the type, this will fail, but for nearly the entire range of valid decimal values it should work.

You can also use the decimal library to accomplish this, but the wrapper I propose is simpler and may be preferred in some cases.


Edit: Thanks Blckknght for pointing out that the 5 fringe case occurs only for certain values. Also an earlier version of this answer wasn't explicit enough that the odd rounding behavior occurs only when the digit immediately inferior to the digit you're rounding to has a 5.

Saving and loading objects and using pickle

You can use anycache to do the job for you. Assuming you have a function myfunc which creates the instance:

from anycache import anycache

class Fruits:pass

@anycache(cachedir='/path/to/your/cache')    
def myfunc()
    banana = Fruits()
    banana.color = 'yellow'
    banana.value = 30
return banana

Anycache calls myfunc at the first time and pickles the result to a file in cachedir using an unique identifier (depending on the the function name and the arguments) as filename. On any consecutive run, the pickled object is loaded.

If the cachedir is preserved between python runs, the pickled object is taken from the previous python run.

The function arguments are also taken into account. A refactored implementation works likewise:

from anycache import anycache

class Fruits:pass

@anycache(cachedir='/path/to/your/cache')    
def myfunc(color, value)
    fruit = Fruits()
    fruit.color = color
    fruit.value = value
return fruit

Count number of cells with any value (string or number) in a column in Google Docs Spreadsheet

The SUBTOTAL function can be used if you want to get the count respecting any filters you use on the page.

=SUBTOTAL(103, A1:A200)

will help you get count of non-empty rows, respecting filters.

103 - is similar to COUNTA, but ignores empty rows and also respects filters.

Reference : SUBTOTAL function

browser.msie error after update to jQuery 1.9.1

The jQuery.browser options was deprecated earlier and removed in 1.9 release along with a lot of other deprecated items like .live.

For projects and external libraries which want to upgrade to 1.9 but still want to support these features jQuery have release a migration plugin for the time being.

If you need backward compatibility you can use migration plugin.

Shell equality operators (=, ==, -eq)

It's the other way around: = and == are for string comparisons, -eq is for numeric ones. -eq is in the same family as -lt, -le, -gt, -ge, and -ne, if that helps you remember which is which.

== is a bash-ism, by the way. It's better to use the POSIX =. In bash the two are equivalent, and in plain sh = is the only one guaranteed to work.

$ a=foo
$ [ "$a" = foo ]; echo "$?"       # POSIX sh
0
$ [ "$a" == foo ]; echo "$?"      # bash specific
0
$ [ "$a" -eq foo ]; echo "$?"     # wrong
-bash: [: foo: integer expression expected
2

(Side note: Quote those variable expansions! Do not leave out the double quotes above.)

If you're writing a #!/bin/bash script then I recommend using [[ instead. The doubled form has more features, more natural syntax, and fewer gotchas that will trip you up. Double quotes are no longer required around $a, for one:

$ [[ $a == foo ]]; echo "$?"      # bash specific
0

See also:

Abstract Class vs Interface in C++

I assume that with interface you mean a C++ class with only pure virtual methods (i.e. without any code), instead with abstract class you mean a C++ class with virtual methods that can be overridden, and some code, but at least one pure virtual method that makes the class not instantiable. e.g.:

class MyInterface
{
public:
  // Empty virtual destructor for proper cleanup
  virtual ~MyInterface() {}

  virtual void Method1() = 0;
  virtual void Method2() = 0;
};


class MyAbstractClass
{
public:
  virtual ~MyAbstractClass();

  virtual void Method1();
  virtual void Method2();
  void Method3();

  virtual void Method4() = 0; // make MyAbstractClass not instantiable
};

In Windows programming, interfaces are fundamental in COM. In fact, a COM component exports only interfaces (i.e. pointers to v-tables, i.e. pointers to set of function pointers). This helps defining an ABI (Application Binary Interface) that makes it possible to e.g. build a COM component in C++ and use it in Visual Basic, or build a COM component in C and use it in C++, or build a COM component with Visual C++ version X and use it with Visual C++ version Y. In other words, with interfaces you have high decoupling between client code and server code.

Moreover, when you want to build DLL's with a C++ object-oriented interface (instead of pure C DLL's), as described in this article, it's better to export interfaces (the "mature approach") instead of C++ classes (this is basically what COM does, but without the burden of COM infrastructure).

I'd use an interface if I want to define a set of rules using which a component can be programmed, without specifying a concrete particular behavior. Classes that implement this interface will provide some concrete behavior themselves.

Instead, I'd use an abstract class when I want to provide some default infrastructure code and behavior, and make it possible to client code to derive from this abstract class, overriding the pure virtual methods with some custom code, and complete this behavior with custom code. Think for example of an infrastructure for an OpenGL application. You can define an abstract class that initializes OpenGL, sets up the window environment, etc. and then you can derive from this class and implement custom code for e.g. the rendering process and handling user input:

// Abstract class for an OpenGL app.
// Creates rendering window, initializes OpenGL; 
// client code must derive from it 
// and implement rendering and user input.
class OpenGLApp
{
public:
  OpenGLApp();
  virtual ~OpenGLApp();
  ...

  // Run the app    
  void Run();


  // <---- This behavior must be implemented by the client ---->

  // Rendering
  virtual void Render() = 0;

  // Handle user input
  // (returns false to quit, true to continue looping)
  virtual bool HandleInput() = 0;

  // <--------------------------------------------------------->


private:
  //
  // Some infrastructure code
  //
  ... 
  void CreateRenderingWindow();
  void CreateOpenGLContext();
  void SwapBuffers();
};


class MyOpenGLDemo : public OpenGLApp
{
public:
  MyOpenGLDemo();
  virtual ~MyOpenGLDemo();

  // Rendering
  virtual void Render();  // implements rendering code

  // Handle user input
  virtual bool HandleInput(); // implements user input handling


  //  ... some other stuff
};

Maven: How to rename the war file for the project?

You need to configure the war plugin:

<project>
  ...
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-war-plugin</artifactId>
        <version>2.3</version>
        <configuration>
          <warName>bird.war</warName>
        </configuration>
      </plugin>
    </plugins>
  </build>
  ...
</project>

More info here

How to make python Requests work via socks proxy

In case someone has tried all of these older answers, and is still running into problems like:

requests.exceptions.ConnectionError: 
   SOCKSHTTPConnectionPool(host='myhost', port=80): 
   Max retries exceeded with url: /my/path 
   (Caused by NewConnectionError('<requests.packages.urllib3.contrib.socks.SOCKSConnection object at 0x106812bd0>: 
   Failed to establish a new connection: 
   [Errno 8] nodename nor servname provided, or not known',))

It may be because, by default, requests is configured to resolve DNS queries on the local side of the connection.

Try changing your proxy URL from socks5://proxyhost:1234 to socks5h://proxyhost:1234. Note the extra h (it stands for hostname resolution).

The PySocks package module default is to do remote resolution, and I'm not sure why requests made their integration this obscurely divergent, but here we are.

How to hide "Showing 1 of N Entries" with the dataTables.js library

try this for hide

$('#table_id').DataTable({
  "info": false
});

and try this for change label

$('#table_id').DataTable({
 "oLanguage": {
               "sInfo" : "Showing _START_ to _END_ of _TOTAL_ entries",// text you want show for info section
            },

});

How to overwrite styling in Twitter Bootstrap

If you want to overwrite any css in bootstrap use !important

Let's say here is the page header class in bootstrap which have 40px margin on top, my client don't like it and he want it to be 15 on top and 10 on bottom only

.page-header {
    border-bottom: 1px solid #EEEEEE;
    margin: 40px 0 20px;
    padding-bottom: 9px;
}

So I added on class in my site.css file with the same name like this

.page-header
{
    padding-bottom: 9px;
    margin: 15px 0 10px 0px !important;
}

Note the !important with my margin, which will overwrite the margin of bootstarp page-header class margin.

What does --net=host option in Docker command really do?

After the docker installation you have 3 networks by default:

docker network ls
NETWORK ID          NAME                DRIVER              SCOPE
f3be8b1ef7ce        bridge              bridge              local
fbff927877c1        host                host                local
023bb5940080        none                null                local

I'm trying to keep this simple. So if you start a container by default it will be created inside the bridge (docker0) network.

$ docker run -d jenkins
1498e581cdba        jenkins             "/bin/tini -- /usr..."   3 minutes ago       Up 3 minutes        8080/tcp, 50000/tcp   friendly_bell

In the dockerfile of jenkins the ports 8080 and 50000 are exposed. Those ports are opened for the container on its bridge network. So everything inside that bridge network can access the container on port 8080 and 50000. Everything in the bridge network is in the private range of "Subnet": "172.17.0.0/16", If you want to access them from the outside you have to map the ports with -p 8080:8080. This will map the port of your container to the port of your real server (the host network). So accessing your server on 8080 will route to your bridgenetwork on port 8080.

Now you also have your host network. Which does not containerize the containers networking. So if you start a container in the host network it will look like this (it's the first one):

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                 NAMES
1efd834949b2        jenkins             "/bin/tini -- /usr..."   6 minutes ago       Up 6 minutes                              eloquent_panini
1498e581cdba        jenkins             "/bin/tini -- /usr..."   10 minutes ago      Up 10 minutes       8080/tcp, 50000/tcp   friendly_bell

The difference is with the ports. Your container is now inside your host network. So if you open port 8080 on your host you will acces the container immediately.

$ sudo iptables -I INPUT 5 -p tcp -m tcp --dport 8080 -j ACCEPT

I've opened port 8080 in my firewall and when I'm now accesing my server on port 8080 I'm accessing my jenkins. I think this blog is also useful to understand it better.

Android: How to turn screen on and off programmatically?

If your app is a system app,you can use PowerManager.goToSleep() to turn screen off,you requires a special permission

before you use goToSleep(), you need use reflection just like:

public static void goToSleep(Context context) {
    PowerManager powerManager= (PowerManager)context.getSystemService(Context.POWER_SERVICE);
    try {
        powerManager.getClass().getMethod("goToSleep", new Class[]{long.class}).invoke(powerManager, SystemClock.uptimeMillis());
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    } catch (InvocationTargetException e) {
        e.printStackTrace();
    } catch (NoSuchMethodException e) {
        e.printStackTrace();
    }
}

Now,you can use goToSleep() to turn screen off.

This is what happens when the power key is pressed to turn off the screen.

google maps v3 marker info window on mouseover

Here's an example: http://duncan99.wordpress.com/2011/10/08/google-maps-api-infowindows/

marker.addListener('mouseover', function() {
    infowindow.open(map, this);
});

// assuming you also want to hide the infowindow when user mouses-out
marker.addListener('mouseout', function() {
    infowindow.close();
});

How to install the Raspberry Pi cross compiler on my Linux host machine?

For Windows host, I want to highly recommend this tutorial::

  • Download and install the toolchain
  • Sync sysroot with your RPi include/lib directories
  • Compile your code
  • Drag and drop the executable to your RPi using SmarTTY
  • Run it!

Nothing more, nothing less!

Prebuilt GNU Toolchains available for Raspberry, Beaglebone, Cubieboard, AVR (Atmel) and more

Convert Java string to Time, NOT Date

You might want to take a look at this example:

public static void main(String[] args) {

    String myTime = "10:30:54";
    SimpleDateFormat sdf = new SimpleDateFormat("hh:mm:ss");
    Date date = null;
    try {
        date = sdf.parse(myTime);
    } catch (ParseException e) {
        e.printStackTrace();
    }
    String formattedTime = sdf.format(date);

    System.out.println(formattedTime);

}

C# : changing listbox row color?

I find solution that instead of using ListBox I used ListView.It allows to change list items BackColor.

private void listView1_Refresh()
{
    for (int i = 0; i < listView1.Items.Count; i++)
    {
        listView1.Items[i].BackColor = Color.Red;
        for (int j = 0; j < existingStudents.Count; j++)
        {
            if (listView1.Items[i].ToString().Contains(existingStudents[j]))
            {
                listView1.Items[i].BackColor = Color.Green;
            }
        }
    }
}

How should strace be used?

Strace stands out as a tool for investigating production systems where you can't afford to run these programs under a debugger. In particular, we have used strace in the following two situations:

  • Program foo seems to be in deadlock and has become unresponsive. This could be a target for gdb; however, we haven't always had the source code or sometimes were dealing with scripted languages that weren't straight-forward to run under a debugger. In this case, you run strace on an already running program and you will get the list of system calls being made. This is particularly useful if you are investigating a client/server application or an application that interacts with a database
  • Investigating why a program is slow. In particular, we had just moved to a new distributed file system and the new throughput of the system was very slow. You can specify strace with the '-T' option which will tell you how much time was spent in each system call. This helped to determine why the file system was causing things to slow down.

For an example of analyzing using strace see my answer to this question.

Encoding Javascript Object to Json string

Unless the variable k is defined, that's probably what's causing your trouble. Something like this will do what you want:

var new_tweets = { };

new_tweets.k = { };

new_tweets.k.tweet_id = 98745521;
new_tweets.k.user_id = 54875;

new_tweets.k.data = { };

new_tweets.k.data.in_reply_to_screen_name = 'other_user';
new_tweets.k.data.text = 'tweet text';

// Will create the JSON string you're looking for.
var json = JSON.stringify(new_tweets);

You can also do it all at once:

var new_tweets = {
  k: {
    tweet_id: 98745521,
    user_id: 54875,
    data: {
      in_reply_to_screen_name: 'other_user',
      text: 'tweet_text'
    }
  }
}

Perform .join on value in array of objects

you can convert to array so get object name

_x000D_
_x000D_
var objs = [
      {name: "Joe", age: 22},
      {name: "Kevin", age: 24},
      {name: "Peter", age: 21}
    ];
document.body.innerHTML = Object.values(objs).map(function(obj){
   return obj.name;
});
_x000D_
_x000D_
_x000D_

Is there a way to detect if a browser window is not currently active?

Here is a solid, modern solution. (Short a sweet )

document.addEventListener("visibilitychange", () => {
  console.log( document.hasFocus() )
})

This will setup a listener to trigger when any visibility event is fired which could be a focus or blur.

Homebrew install specific version of formula?

Simple Workflow

Now that Homebrew/versions has been deprecated, Homebrew/core supports a few versions of formulae with a new naming format.

To install a specific version, e.g. postgresql 9.5 you simply run:

$ brew install [email protected]

To list the available versions run a search with @:

$ brew search postgresql@
==> Searching local taps...
[email protected] ?     [email protected]        [email protected]        [email protected]

iOS for VirtualBox

VirtualBox is a virtualizer, not an emulator. (The name kinda gives it away.) I.e. it can only virtualize a CPU that is actually there, not emulate one that isn't. In particular, VirtualBox can only virtualize x86 and AMD64 CPUs. iOS only runs on ARM CPUs.

mysql stored-procedure: out parameter

I just tried to call a function in terminal rather then MySQL Query Browser and it works. So, it looks like I'm doing something wrong in that program...

I don't know what since I called some procedures before successfully (but there where no out parameters)...

For this one I had entered

CALL my_sqrt(4,@out_value);
SELECT @out_value;

And it results with an error:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SELECT @out_value' at line 2

Strangely, if I write just:

CALL my_sqrt(4,@out_value); 

The result message is: "Query canceled"

I guess, for now I will use only terminal...

Android SDK Manager gives "Failed to fetch URL https://dl-ssl.google.com/android/repository/repository.xml" error when selecting repository

I had the same problem: the latest update failed to install because it couldn't rename the tools folder in android-sdk-windows. I'm using AVG antivirus and disabling it didn't help, but I don't think it had anything to do with the AV program anyway.

Fact is, running the Android SDK setup apparently uses items in the "android-sdk-windows\tools" directory. I'm on Win Vista x32 so maybe that causes some unique situation - I'm not sure.

Solution:

  • I made a copy of the tools folder itself (keeping it at the same directory tree level, thus "tools" and "tools-copy" were both in the "android-sdk-windows" folder).

  • I ran Android.bat from that copy

  • I ran the update without problems (it updated the original, not-being-used-at-the-moment tools folder, among whatever other items it needed to).

  • I closed the SDK, deleted the folder (I had to kill the adb.exe process first - not sure why that always persists but you can't delete the folder without doing that).

  • I restarted the SDK from the normal (now-updated) tools folder. Worked like a charm!

Note that simply killing adb.exe was NOT sufficient to get around the original issue... only by copying the tools folder and using the copy to run Android for the duration of the update process was enough to rectify the problem.

I hope this helps others... it's quite vexing to have to spend time resolving basic issues like this just to run an update.

How do I change the language of moment.js?

I am not sure what changed but importing the language file like this worked for me

import 'moment/src/locale/fr';
moment.locale('fr)

Notice the src in the import statement

How can I iterate over files in a given directory?

Python 3.4 and later offer pathlib in the standard library. You could do:

from pathlib import Path

asm_pths = [pth for pth in Path.cwd().iterdir()
            if pth.suffix == '.asm']

Or if you don't like list comprehensions:

asm_paths = []
for pth in Path.cwd().iterdir():
    if pth.suffix == '.asm':
        asm_pths.append(pth)

Path objects can easily be converted to strings.

Create a user with all privileges in Oracle

There are 2 differences:

2 methods creating a user and granting some privileges to him

create user userName identified by password;
grant connect to userName;

and

grant connect to userName identified by password;

do exactly the same. It creates a user and grants him the connect role.

different outcome

resource is a role in oracle, which gives you the right to create objects (tables, procedures, some more but no views!). ALL PRIVILEGES grants a lot more of system privileges.

To grant a user all privileges run you first snippet or

grant all privileges to userName identified by password;

How to check if an object is defined?

You check if it's null in C# like this:

if(MyObject != null) {
  //do something
}

If you want to check against default (tough to understand the question on the info given) check:

if(MyObject != default(MyObject)) {
 //do something
}

Python Set Comprehension

You can generate pairs like this:

{(x, x + 2) for x in r if x + 2 in r}

Then all that is left to do is to get a condition to make them prime, which you have already done in the first example.

A different way of doing it: (Although slower for large sets of primes)

{(x, y) for x in r for y in r if x + 2 == y}

Cancel a UIView animation?

Even if you cancel the animation in the ways above animation didStopSelector still runs. So if you have logic states in your application driven by animations you will have problems. For this reason with the ways described above I use the context variable of UIView animations. If you pass the current state of your program by the context param to the animation, when the animation stops your didStopSelector function may decide if it should do something or just return based on the current state and the state value passed as context.

Conda command is not recognized on Windows 10

You need to add the python.exe in C://.../Anaconda3 installation file as well as C://.../Anaconda3/Scripts to PATH.

First go to your installation directory, in my case it is installed in C://Users/user/Anaconda3 and shift+right click and press "Open command window here" or it might be "Open powershell here", if it is powershell, just write cmd and hit enter to run command window. Then run the following command setx PATH %cd%

Then go to C://Users/user/Anaconda3/Scripts and open the command window there as above, then run the same command "setx PATH %cd%"

xsd:boolean element type accept "true" but not "True". How can I make it accept it?

xs:boolean is predefined with regard to what kind of input it accepts. If you need something different, you have to define your own enumeration:

 <xs:simpleType name="my:boolean">
    <xs:restriction base="xs:string">
      <xs:enumeration value="True"/>
      <xs:enumeration value="False"/>
    </xs:restriction>
  </xs:simpleType>

Ignore mapping one property with Automapper

From Jimmy Bogard: CreateMap<Foo, Bar>().ForMember(x => x.Blarg, opt => opt.Ignore());

It's in one of the comments at his blog.

How to remove leading and trailing white spaces from a given html string?

I know this is a very old question but it still doesn't have an accepted answer. I see that you want the following removed: html tags that are "empty" and white spaces based on an html string.

I have come up with a solution based on your comment for the output you are looking for:

Trimming using JavaScript<br /><br /><br /><br />all leading and trailing white spaces 

_x000D_
_x000D_
var str = "<p>&nbsp;&nbsp;</p><div>&nbsp;</div>Trimming using JavaScript<br /><br /><br /><br />all leading and trailing white spaces<p>&nbsp;&nbsp;</p><div>&nbsp;</div>";_x000D_
console.log(str.trim().replace(/&nbsp;/g, '').replace(/<[^\/>][^>]*><\/[^>]+>/g, ""));
_x000D_
_x000D_
_x000D_

.trim() removes leading and trailing whitespace

.replace(/&nbsp;/g, '') removes &nbsp;

.replace(/<[^\/>][^>]*><\/[^>]+>/g, "")); removes empty tags

How to save a BufferedImage as a File

You can save a BufferedImage object using write method of the javax.imageio.ImageIO class. The signature of the method is like this:

public static boolean write(RenderedImage im, String formatName, File output) throws IOException

Here im is the RenderedImage to be written, formatName is the String containing the informal name of the format (e.g. png) and output is the file object to be written to. An example usage of the method for PNG file format is shown below:

ImageIO.write(image, "png", file);

Jquery Date picker Default Date

Are u using this datepicker http://jqueryui.com/demos/datepicker/ ? if yes there are options to set the default Date.If you didn't change anything , by default it will show the current date.

any way this will gives current date

$( ".selector" ).datepicker({ defaultDate: new Date() });

SVN Repository on Google Drive or DropBox

I would try fossil scm and the Chisel hosting service

simple, self contained and easily interchangeable with git should you desire in future

How do I find the install time and date of Windows?

We have enough answers here but I want to put my 5 cents.

I have Windows 10 installed on 10/30/2015 and Creators Update installed on 04/14/2017 on top of my previous installation. All of the methods described in the answers before mine gives me the date of the Creators Update installation.

Original Install Date

I've managed to find few files` date of creation which matches the real (clean) installation date of my Windows 10:

  • in C:\Windows

Few C:\Windows files

  • in C:\

Few C:\ files

How to get value in the session in jQuery

Sessions are stored on the server and are set from server side code, not client side code such as JavaScript.

What you want is a cookie, someone's given a brilliant explanation in this Stack Overflow question here: How do I set/unset cookie with jQuery?

You could potentially use sessions and set/retrieve them with jQuery and AJAX, but it's complete overkill if Cookies will do the trick.

html5 <input type="file" accept="image/*" capture="camera"> display as image rather than "choose file" button

You have to use Javascript Filereader for this. (Introduction into filereader-api: http://www.html5rocks.com/en/tutorials/file/dndfiles/)

Once the user have choose a image you can read the file-path of the chosen image and place it into your html.

Example:

<form id="form1" runat="server">
    <input type='file' id="imgInp" />
    <img id="blah" src="#" alt="your image" />
</form>

Javascript:

function readURL(input) {
    if (input.files && input.files[0]) {
        var reader = new FileReader();

        reader.onload = function (e) {
            $('#blah').attr('src', e.target.result);
        }

        reader.readAsDataURL(input.files[0]);
    }
}

$("#imgInp").change(function(){
    readURL(this);
});

Split comma separated column data into additional columns

If the number of fields in the CSV is constant then you could do something like this:

select a[1], a[2], a[3], a[4]
from (
    select regexp_split_to_array('a,b,c,d', ',')
) as dt(a)

For example:

=> select a[1], a[2], a[3], a[4] from (select regexp_split_to_array('a,b,c,d', ',')) as dt(a);
 a | a | a | a 
---+---+---+---
 a | b | c | d
(1 row)

If the number of fields in the CSV is not constant then you could get the maximum number of fields with something like this:

select max(array_length(regexp_split_to_array(csv, ','), 1))
from your_table

and then build the appropriate a[1], a[2], ..., a[M] column list for your query. So if the above gave you a max of 6, you'd use this:

select a[1], a[2], a[3], a[4], a[5], a[6]
from (
    select regexp_split_to_array(csv, ',')
    from your_table
) as dt(a)

You could combine those two queries into a function if you wanted.

For example, give this data (that's a NULL in the last row):

=> select * from csvs;
     csv     
-------------
 1,2,3
 1,2,3,4
 1,2,3,4,5,6

(4 rows)

=> select max(array_length(regexp_split_to_array(csv, ','), 1)) from csvs;
 max 
-----
   6
(1 row)

=> select a[1], a[2], a[3], a[4], a[5], a[6] from (select regexp_split_to_array(csv, ',') from csvs) as dt(a);
 a | a | a | a | a | a 
---+---+---+---+---+---
 1 | 2 | 3 |   |   | 
 1 | 2 | 3 | 4 |   | 
 1 | 2 | 3 | 4 | 5 | 6
   |   |   |   |   | 
(4 rows)

Since your delimiter is a simple fixed string, you could also use string_to_array instead of regexp_split_to_array:

select ...
from (
    select string_to_array(csv, ',')
    from csvs
) as dt(a);

Thanks to Michael for the reminder about this function.

You really should redesign your database schema to avoid the CSV column if at all possible. You should be using an array column or a separate table instead.

Cleanest Way to Invoke Cross-Thread Events

I made the following 'universal' cross thread call class for my own purpose, but I think it's worth to share it:

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;

namespace CrossThreadCalls
{
  public static class clsCrossThreadCalls
  {
    private delegate void SetAnyPropertyCallBack(Control c, string Property, object Value);
    public static void SetAnyProperty(Control c, string Property, object Value)
    {
      if (c.GetType().GetProperty(Property) != null)
      {
        //The given property exists
        if (c.InvokeRequired)
        {
          SetAnyPropertyCallBack d = new SetAnyPropertyCallBack(SetAnyProperty);
          c.BeginInvoke(d, c, Property, Value);
        }
        else
        {
          c.GetType().GetProperty(Property).SetValue(c, Value, null);
        }
      }
    }

    private delegate void SetTextPropertyCallBack(Control c, string Value);
    public static void SetTextProperty(Control c, string Value)
    {
      if (c.InvokeRequired)
      {
        SetTextPropertyCallBack d = new SetTextPropertyCallBack(SetTextProperty);
        c.BeginInvoke(d, c, Value);
      }
      else
      {
        c.Text = Value;
      }
    }
  }

And you can simply use SetAnyProperty() from another thread:

CrossThreadCalls.clsCrossThreadCalls.SetAnyProperty(lb_Speed, "Text", KvaserCanReader.GetSpeed.ToString());

In this example the above KvaserCanReader class runs its own thread and makes a call to set the text property of the lb_Speed label on the main form.

(SC) DeleteService FAILED 1072

In Windows 7, make sure Event Viewer closed before deleting.

Toggle Class in React

refs is not a DOM element. In order to find a DOM element, you need to use findDOMNode menthod first.

Do, this

var node = ReactDOM.findDOMNode(this.refs.btn);
node.classList.toggle('btn-menu-open');

alternatively, you can use like this (almost actual code)

this.state.styleCondition = false;


<a ref="btn" href="#" className={styleCondition ? "btn-menu show-on-small" : ""}><i></i></a>

you can then change styleCondition based on your state change conditions.

Change first commit of project with Git?

As mentioned by ecdpalma below, git 1.7.12+ (August 2012) has enhanced the option --root for git rebase:

"git rebase [-i] --root $tip" can now be used to rewrite all the history leading to "$tip" down to the root commit.

That new behavior was initially discussed here:

I personally think "git rebase -i --root" should be made to just work without requiring "--onto" and let you "edit" even the first one in the history.
It is understandable that nobody bothered, as people are a lot less often rewriting near the very beginning of the history than otherwise.

The patch followed.


(original answer, February 2010)

As mentioned in the Git FAQ (and this SO question), the idea is:

  1. Create new temporary branch
  2. Rewind it to the commit you want to change using git reset --hard
  3. Change that commit (it would be top of current HEAD, and you can modify the content of any file)
  4. Rebase branch on top of changed commit, using:

    git rebase --onto <tmp branch> <commit after changed> <branch>`
    

The trick is to be sure the information you want to remove is not reintroduced by a later commit somewhere else in your file. If you suspect that, then you have to use filter-branch --tree-filter to make sure the content of that file does not contain in any commit the sensible information.

In both cases, you end up rewriting the SHA1 of every commit, so be careful if you have already published the branch you are modifying the contents of. You probably shouldn’t do it unless your project isn’t yet public and other people haven’t based work off the commits you’re about to rewrite.

Switch role after connecting to database

--create a user that you want to use the database as:

create role neil;

--create the user for the web server to connect as:

create role webgui noinherit login password 's3cr3t';

--let webgui set role to neil:

grant neil to webgui; --this looks backwards but is correct.

webgui is now in the neil group, so webgui can call set role neil . However, webgui did not inherit neil's permissions.

Later, login as webgui:

psql -d some_database -U webgui
(enter s3cr3t as password)

set role neil;

webgui does not need superuser permission for this.

You want to set role at the beginning of a database session and reset it at the end of the session. In a web app, this corresponds to getting a connection from your database connection pool and releasing it, respectively. Here's an example using Tomcat's connection pool and Spring Security:

public class SetRoleJdbcInterceptor extends JdbcInterceptor {

    @Override
    public void reset(ConnectionPool connectionPool, PooledConnection pooledConnection) {

        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();

        if(authentication != null) {
            try {

                /* 
                  use OWASP's ESAPI to encode the username to avoid SQL Injection. Can't use parameters with SET ROLE. Need to write PG codec.

                  Or use a whitelist-map approach
                */
                String username = ESAPI.encoder().encodeForSQL(MY_CODEC, authentication.getName());

                Statement statement = pooledConnection.getConnection().createStatement();
                statement.execute("set role \"" + username + "\"");
                statement.close();
            } catch(SQLException exp){
                throw new RuntimeException(exp);
            }
        }
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

        if("close".equals(method.getName())){
            Statement statement = ((Connection)proxy).createStatement();
            statement.execute("reset role");
            statement.close();
        }

        return super.invoke(proxy, method, args);
    }
}

What is the meaning of "this" in Java?

Objects have methods and attributes(variables) which are derived from classes, in order to specify which methods and variables belong to a particular object the this reserved word is used. in the case of instance variables, it is important to understand the difference between implicit and explicit parameters. Take a look at the fillTank call for the audi object.

Car audi= new Car();

audi.fillTank(5); // 5 is the explicit parameter and the car object is the implicit parameter 

The value in the parenthesis is the implicit parameter and the object itself is the explicit parameter, methods that don't have explicit parameters, use implicit parameters, the fillTank method has both an explicit and an implicit parameter.

Lets take a closer look at the fillTank method in the Car class

public class Car()
{
   private double tank;

   public Car()
   {
      tank = 0;
   }

   public void fillTank(double gallons)
   {
      tank = tank + gallons;
   }

}

In this class we have an instance variable "tank". There could be many objects that use the tank instance variable, in order to specify that the instance variable "tank" is used for a particular object, in our case the "audi" object we constructed earlier, we use the this reserved keyword. for instance variables the use of 'this' in a method indicates that the instance variable, in our case "tank", is instance variable of the implicit parameter.

The java compiler automatically adds the this reserved word so you don't have to add it, it's a matter of preference. You can not use this without a dot(.) because those are the rules of java ( the syntax).

In summary.

  • Objects are defined by classes and have methods and variables
  • The use of this on an instance variable in a method indicates that, the instance variable belongs to the implicit parameter, or that it is an instance variable of the implicit parameter.
  • The implicit parameter is the object the method is called from in this case "audi".
  • The java compiler automatically adds the this reserved word, adding it is a matter of preference
  • this cannot be used without a dot(.) this is syntactically invalid
  • this can also be used to distinguish between local variables and global variables that have the same name
  • the this reserve word also applies to methods, to indicate a method belongs to a particular object.

How to use absolute path in twig functions

You probably want to use the assets_base_urls configuration.

framework:
    templating:
        assets_base_urls:
            http:   [http://www.website.com]
            ssl:   [https://www.website.com]

http://symfony.com/doc/current/reference/configuration/framework.html#assets


Note that the configuration is different since Symfony 2.7:

framework:
    # ...
    assets:
        base_urls:
            - 'http://cdn.example.com/'

Why is it OK to return a 'vector' from a function?

I do not agree and do not recommend to return a vector:

vector <double> vectorial(vector <double> a, vector <double> b)
{
    vector <double> c{ a[1] * b[2] - b[1] * a[2], -a[0] * b[2] + b[0] * a[2], a[0] * b[1] - b[0] * a[1] };
    return c;
}

This is much faster:

void vectorial(vector <double> a, vector <double> b, vector <double> &c)
{
    c[0] = a[1] * b[2] - b[1] * a[2]; c[1] = -a[0] * b[2] + b[0] * a[2]; c[2] = a[0] * b[1] - b[0] * a[1];
}

I tested on Visual Studio 2017 with the following results in release mode:

8.01 MOPs by reference
5.09 MOPs returning vector

In debug mode, things are much worse:

0.053 MOPS by reference
0.034 MOPs by return vector

Check if a string within a list contains a specific string with Linq

Thast should be easy enough

if( myList.Any( s => s.Contains(stringToCheck))){
  //do your stuff here
}

how to Call super constructor in Lombok

This is not possible in Lombok. Although it would be a really nice feature, it requires resolution to find the constructors of the super class. The super class is only known by name the moment Lombok gets invoked. Using the import statements and the classpath to find the actual class is not trivial. And during compilation you cannot just use reflection to get a list of constructors.

It is not entirely impossible but the results using resolution in val and @ExtensionMethod have taught us that is it hard and error-prone.

Disclosure: I am a Lombok developer.

Can Python test the membership of multiple values in a list?

[x for x in ['a','b'] if x in ['b', 'a', 'foo', 'bar']]

The reason I think this is better than the chosen answer is that you really don't need to call the 'all()' function. Empty list evaluates to False in IF statements, non-empty list evaluates to True.

if [x for x in ['a','b'] if x in ['b', 'a', 'foo', 'bar']]:
    ...Do something...

Example:

>>> [x for x in ['a','b'] if x in ['b', 'a', 'foo', 'bar']]
['a', 'b']
>>> [x for x in ['G','F'] if x in ['b', 'a', 'foo', 'bar']]
[]

How to send push notification to web browser?

May I redefine you question as below

Can we have our own back-end to send push notification to Chrome, Firefox, Opera & Safari?

Yes. By today (2017/05), you can use same client and server side implementation to handle Chrome, Firefox and Opera (no Safari). Because they have implemented web push notifications in a same way. That is Push API protocol by W3C. But Safari have their own old architecture. So we have to maintain Safari separately.

Refer browser-push repo for guide lines to implement web push notification for your web-app with your own back-end. It explains with examples how you can add web push notification support for your web application without any third party services.

IE 8: background-size fix

As pointed by @RSK IE8 doesn't support background-size. To figure out a way to deal with this, I used some IE specific hacks as showed here:

//IE8.0 Hack!
@media \0screen {
    .brand {
        background-image: url("./images/logo1.png");
        margin-top: 8px;
    }

    .navbar .brand {
        margin-left: -2px;
        padding-bottom: 2px;
    }
}

//IE7.0 Hack!
*+html .brand {
    background-image: url("./images/logo1.png");
    margin-top: 8px;
}

*+html .navbar .brand {
    margin-left: -2px;
    padding-bottom: 2px;
}

Using this I was able to change my logo image to a ugly resided picture. But the final result is fine. I suggest u try something like this.

String to char array Java

A string to char array is as simple as

String str = "someString"; 
char[] charArray = str.toCharArray();

Can you explain a little more on what you are trying to do?

* Update *

if I am understanding your new comment, you can use a byte array and example is provided.

byte[] bytes = ByteBuffer.allocate(4).putInt(1695609641).array();

for (byte b : bytes) {
   System.out.format("0x%x ", b);
}

With the following output

0x65 0x10 0xf3 0x29

Javascript sleep/delay/wait function

You can use this -

function sleep(milliseconds) {
    var start = new Date().getTime();
    for (var i = 0; i < 1e7; i++) {
        if ((new Date().getTime() - start) > milliseconds){
            break;
        }
    }
}

Find character position and update file name

The string is a .NET string so you can use .NET methods. In your case:

$index = "The string".IndexOf(" ")

will return 3, which is the first occurrence of space in the string. For more information see: http://msdn.microsoft.com/en-us/library/system.string.aspx

For your need try something like:

$s.SubString($s.IndexOf("_") + 1, $s.LastIndexOf(".") - $s.IndexOf("_") - 1)

Or you could use regexps:

if ($s -Match '(_)(.*)(\.)[^.]*$') {  $matches[2] }

(has to be adjusted depending on exactly what you need).

Change navbar text color Bootstrap

Try this

.nav.navbar-nav.navbar-right li a span{
    color: blue;
}

If it doesn't work try this

.nav.navbar-nav.navbar-right li a {
    color: blue;
}

How to render an array of objects in React?

You can do it in two ways:

First:

render() {
    const data =[{"name":"test1"},{"name":"test2"}];
    const listItems = data.map((d) => <li key={d.name}>{d.name}</li>);

    return (
      <div>
      {listItems }
      </div>
    );
  }

Second: Directly write the map function in the return

render() {
    const data =[{"name":"test1"},{"name":"test2"}];
    return (
      <div>
      {data.map(function(d, idx){
         return (<li key={idx}>{d.name}</li>)
       })}
      </div>
    );
  }

How to upload images into MySQL database using PHP code

Firstly, you should check if your image column is BLOB type!

I don't know anything about your SQL table, but if I'll try to make my own as an example.

We got fields id (int), image (blob) and image_name (varchar(64)).

So the code should look like this (assume ID is always '1' and let's use this mysql_query):

$image = addslashes(file_get_contents($_FILES['image']['tmp_name'])); //SQL Injection defence!
$image_name = addslashes($_FILES['image']['name']);
$sql = "INSERT INTO `product_images` (`id`, `image`, `image_name`) VALUES ('1', '{$image}', '{$image_name}')";
if (!mysql_query($sql)) { // Error handling
    echo "Something went wrong! :("; 
}

You are doing it wrong in many ways. Don't use mysql functions - they are deprecated! Use PDO or MySQLi. You should also think about storing files locations on disk. Using MySQL for storing images is thought to be Bad Idea™. Handling SQL table with big data like images can be problematic.

Also your HTML form is out of standards. It should look like this:

<form action="insert_product.php" method="POST" enctype="multipart/form-data">
    <label>File: </label><input type="file" name="image" />
    <input type="submit" />
</form>

Sidenote:

When dealing with files and storing them as a BLOB, the data must be escaped using mysql_real_escape_string(), otherwise it will result in a syntax error.

vbscript output to console

You mean:

Wscript.Echo "Like this?"

If you run that under wscript.exe (the default handler for the .vbs extension, so what you'll get if you double-click the script) you'll get a "MessageBox" dialog with your text in it. If you run that under cscript.exe you'll get output in your console window.

Exception thrown inside catch block - will it be caught again?

No, since the new throw is not in the try block directly.

Running java with JAVA_OPTS env variable has no effect

You can setup _JAVA_OPTIONS instead of JAVA_OPTS. This should work without $_JAVA_OPTIONS.

Setting SMTP details for php mail () function

Try from your dedicated server to telnet to smtp.gmail.com on port 465. It might be blocked by your internet provider

Reading JSON from a file?

The problem is using with statement:

with open('strings.json') as json_data:
    d = json.load(json_data)
    pprint(d)

The file is going to be implicitly closed already. There is no need to call json_data.close() again.

Export data from Chrome developer tool

You can use fiddler web debugger to import the HAR and then it is very easy from their on... Ctrl+A (select all) then Ctrl+c (copy summary) then paste in excel and have fun

In Python, how do I index a list with another list?

You could also use the __getitem__ method combined with map like the following:

L = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']
Idx = [0, 3, 7]
res = list(map(L.__getitem__, Idx))
print(res)
# ['a', 'd', 'h']

How to use performSelector:withObject:afterDelay: with primitive types in Cocoa?

Perhaps NSValue, just make sure your pointers are still valid after the delay (ie. no objects allocated on stack).

Programmatically get height of navigation bar

Handy Swift 4 extension, in case it's helpful to someone else. Works even if the current view controller does not display a navigation bar.

import UIKit

extension UINavigationController {
  static public func navBarHeight() -> CGFloat {
    let nVc = UINavigationController(rootViewController: UIViewController(nibName: nil, bundle: nil))
    let navBarHeight = nVc.navigationBar.frame.size.height
    return navBarHeight
  }
}

Usage:

UINavigationController.navBarHeight()

Databound drop down list - initial value

hi friend in this case you can use the

AppendDataBound="true"

and after this use the list item. for e.g.:

<asp:DropDownList ID="DropDownList1" runat="server" AppendDataBoundItems="true">
    <asp:ListItem Text="--Select One--" Value="" />   
</asp:DropDownList>

but the problem in this is after second time select data are append with old data.

Double.TryParse or Convert.ToDouble - which is faster and safer?

The .NET Framework design guidelines recommend using the Try methods. Avoiding exceptions is usually a good idea.

Convert.ToDouble(object) will do ((IConvertible) object).ToDouble(null);

Which will call Convert.ToDouble(string, null)

So it's faster to call the string version.

However, the string version just does this:

if (value == null)
{
    return 0.0;
}
return double.Parse(value, NumberStyles.Float | NumberStyles.AllowThousands, provider);

So it's faster to do the double.Parse directly.

Convert a list to a data frame

Extending on @Marek's answer: if you want to avoid strings to be turned into factors and efficiency is not a concern try

do.call(rbind, lapply(your_list, data.frame, stringsAsFactors=FALSE))

Regex match digits, comma and semicolon?

You almost have it, you just left out 0 and forgot the quantifier.

word.matches("^[0-9,;]+$")

Select all 'tr' except the first one

Since tr:not(:first-child) is not supported by IE 6, 7, 8. You can use the help of jQuery. You may find it here

Easiest way to convert int to string in C++

If you have Boost installed (which you should):

#include <boost/lexical_cast.hpp>

int num = 4;
std::string str = boost::lexical_cast<std::string>(num);

Insert line break in wrapped cell via code

Yes. The VBA equivalent of AltEnter is to use a linebreak character:

ActiveCell.Value = "I am a " & Chr(10) & "test"

Note that this automatically sets WrapText to True.

Proof:

Sub test()
Dim c As Range
Set c = ActiveCell
c.WrapText = False
MsgBox "Activcell WrapText is " & c.WrapText
c.Value = "I am a " & Chr(10) & "test"
MsgBox "Activcell WrapText is " & c.WrapText
End Sub

How can I represent 'Authorization: Bearer <token>' in a Swagger Spec (swagger.json)

By using the requestInterceptor, it worked for me:

const ui = SwaggerUIBundle({
  ...
  requestInterceptor: (req) => {
    req.headers.Authorization = "Bearer " + req.headers.Authorization;
    return req;
  },
  ...
});

check if jquery has been loaded, then load it if false

Try this :

<script>
  window.jQuery || document.write('<script src="js/jquery.min.js"><\/script>')
</script>

This checks if jQuery is available or not, if not it will add one dynamically from path specified.

Ref: Simulate an "include_once" for jQuery

OR

include_once equivalent for js. Ref: https://raw.github.com/kvz/phpjs/master/functions/language/include_once.js

function include_once (filename) {
  // http://kevin.vanzonneveld.net
  // +   original by: Legaev Andrey
  // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  // +   improved by: Michael White (http://getsprink.com)
  // +      input by: Brett Zamir (http://brett-zamir.me)
  // +   bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  // +   bugfixed by: Brett Zamir (http://brett-zamir.me)
  // -    depends on: include
  // %        note 1: Uses global: php_js to keep track of included files (though private static variable in namespaced version)
  // *     example 1: include_once('http://www.phpjs.org/js/phpjs/_supporters/pj_test_supportfile_2.js');
  // *     returns 1: true
  var cur_file = {};
  cur_file[this.window.location.href] = 1;

  // BEGIN STATIC
  try { // We can't try to access on window, since it might not exist in some environments, and if we use "this.window"
    //    we risk adding another copy if different window objects are associated with the namespaced object
    php_js_shared; // Will be private static variable in namespaced version or global in non-namespaced
    //   version since we wish to share this across all instances
  } catch (e) {
    php_js_shared = {};
  }
  // END STATIC
  if (!php_js_shared.includes) {
    php_js_shared.includes = cur_file;
  }
  if (!php_js_shared.includes[filename]) {
    if (this.include(filename)) {
      return true;
    }
  } else {
    return true;
  }
  return false;
}

How to manage a redirect request after a jQuery Ajax call

Additionally you will probably want to redirect user to the given in headers URL. So finally it will looks like this:

$.ajax({
    //.... other definition
    complete:function(xmlHttp){
        if(xmlHttp.status.toString()[0]=='3'){
        top.location.href = xmlHttp.getResponseHeader('Location');
    }
});

UPD: Opps. Have the same task, but it not works. Doing this stuff. I'll show you solution when I'll find it.

force Maven to copy dependencies into target/lib

supposing

  • you don't want to alter the pom.xml
  • you don't want test scoped (e.g. junit.jar) or provided dependencies (e.g. wlfullclient.jar)

here ist what worked for me:

mvn install dependency:copy-dependencies -DincludeScope=runtime -DoutputDirectory=target/lib

How do I add a bullet symbol in TextView?

This is how i ended up doing it.

 <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal">

            <View
                android:layout_width="20dp"
                android:layout_height="20dp"
                android:background="@drawable/circle"
                android:drawableStart="@drawable/ic_bullet_point" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_marginLeft="10dp"
                android:text="Your text"
                android:textColor="#000000"
                android:textSize="14sp" />
        </LinearLayout>

and the code for drawbale/circle.xml is

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
  android:innerRadius="0dp"
  android:shape="ring"
  android:thickness="5dp"
  android:useLevel="false">

 <solid android:color="@color/black1" />

</shape>

How do I change the color of radio buttons?

A quick fix would be to overlay the radio button input style using :after, however it's probably a better practice to create your own custom toolkit.

_x000D_
_x000D_
    input[type='radio']:after {_x000D_
        width: 15px;_x000D_
        height: 15px;_x000D_
        border-radius: 15px;_x000D_
        top: -2px;_x000D_
        left: -1px;_x000D_
        position: relative;_x000D_
        background-color: #d1d3d1;_x000D_
        content: '';_x000D_
        display: inline-block;_x000D_
        visibility: visible;_x000D_
        border: 2px solid white;_x000D_
    }_x000D_
_x000D_
    input[type='radio']:checked:after {_x000D_
        width: 15px;_x000D_
        height: 15px;_x000D_
        border-radius: 15px;_x000D_
        top: -2px;_x000D_
        left: -1px;_x000D_
        position: relative;_x000D_
        background-color: #ffa500;_x000D_
        content: '';_x000D_
        display: inline-block;_x000D_
        visibility: visible;_x000D_
        border: 2px solid white;_x000D_
    }
_x000D_
<input type='radio' name="gender"/>_x000D_
<input type='radio' name="gender"/>
_x000D_
_x000D_
_x000D_

Get list of all tables in Oracle?

Try the below data dictionary views.

tabs
dba_tables
all_tables
user_tables

Apache default VirtualHost

If you are using Debian style virtual host configuration (sites-available/sites-enabled), one way to set a Default VirtualHost is to include the specific configuration file first in httpd.conf or apache.conf (or what ever is your main configuration file).

# To set default VirtualHost, include it before anything else.
IncludeOptional sites-enabled/my.site.com.conf

# Load config files in the "/etc/httpd/conf.d" directory, if any.
IncludeOptional conf.d/*.conf

# Load virtual host config files from "/etc/httpd/sites-enabled/".
IncludeOptional sites-enabled/*.conf

Comparison of C++ unit test frameworks

I've just pushed my own framework, CATCH, out there. It's still under development but I believe it already surpasses most other frameworks. Different people have different criteria but I've tried to cover most ground without too many trade-offs. Take a look at my linked blog entry for a taster. My top five features are:

  • Header only
  • Auto registration of function and method based tests
  • Decomposes standard C++ expressions into LHS and RHS (so you don't need a whole family of assert macros).
  • Support for nested sections within a function based fixture
  • Name tests using natural language - function/ method names are generated

It also has Objective-C bindings. The project is hosted on Github

How to make blinking/flashing text with CSS 3

@-webkit-keyframes blinker {  
  0% { opacity: 1.0; }
  50% { opacity: 0.0; }
  100% { opacity: 1.0; }
}

_x000D_
_x000D_
@-webkit-keyframes blinker {  _x000D_
  0% { opacity: 1.0; }_x000D_
  50% { opacity: 0.0; }_x000D_
  100% { opacity: 1.0; }_x000D_
}_x000D_
_x000D_
.blink {_x000D_
  width: 10px;_x000D_
  height: 10px;_x000D_
  border-radius: 10px;_x000D_
  animation: blinker 2s linear infinite;_x000D_
  background-color: red;_x000D_
  margin-right: 5px;_x000D_
}_x000D_
_x000D_
.content {_x000D_
  display: flex;_x000D_
  flex-direction: row;_x000D_
  align-items: center;_x000D_
}
_x000D_
<div class="content">_x000D_
  <i class="blink"></i>_x000D_
  LIVE_x000D_
</div>
_x000D_
_x000D_
_x000D_

What are the best use cases for Akka framework

We are using akka with its camel plugin to distribute our analysis and trending processing for twimpact.com. We have to process between 50 and 1000 messages per second. In addition to multi-node processing with camel it is also used to distribute work on a single processor to multiple workers for maximum performance. Works quite well, but requires some understanding of how to handle congestions.

MongoDB not equal to

If there is a null in an array and you want to avoid it:

db.test.find({"contain" : {$ne :[] }}).pretty()

print highest value in dict with key

You could use use max and min with dict.get:

maximum = max(mydict, key=mydict.get)  # Just use 'min' instead of 'max' for minimum.
print(maximum, mydict[maximum])
# D 87

Failed to load resource 404 (Not Found) - file location error?

Looks like the path you gave doesn't have any bootstrap files in them.

href="~/lib/bootstrap/dist/css/bootstrap.min.css"

Make sure the files exist over there , else point the files to the correct path, which should be in your case

href="~/node_modules/bootstrap/dist/css/bootstrap.min.css"

How to tell 'PowerShell' Copy-Item to unconditionally copy files

From the documentation (help copy-item -full):

-force <SwitchParameter>
    Allows cmdlet to override restrictions such as renaming existing files as long as security is not compromised.

    Required?                    false
    Position?                    named
    Default value                False
    Accept pipeline input?       false
    Accept wildcard characters?  false

IF-THEN-ELSE statements in postgresql

In general, an alternative to case when ... is coalesce(nullif(x,bad_value),y) (that cannot be used in OP's case). For example,

select coalesce(nullif(y,''),x), coalesce(nullif(x,''),y), *
from (     (select 'abc' as x, '' as y)
 union all (select 'def' as x, 'ghi' as y)
 union all (select '' as x, 'jkl' as y)
 union all (select null as x, 'mno' as y)
 union all (select 'pqr' as x, null as y)
) q

gives:

 coalesce | coalesce |  x  |  y  
----------+----------+-----+-----
 abc      | abc      | abc | 
 ghi      | def      | def | ghi
 jkl      | jkl      |     | jkl
 mno      | mno      |     | mno
 pqr      | pqr      | pqr | 
(5 rows)

How to deal with certificates using Selenium?

Whenever I run into this issue with newer browsers, I just use AppRobotic Personal edition to click specific screen coordinates, or tab through the buttons and click.

Basically it's just using its macro functionality, but won't work on headless setups though.

NumPy array initialization (fill with identical values)

I believe fill is the fastest way to do this.

a = np.empty(10)
a.fill(7)

You should also always avoid iterating like you are doing in your example. A simple a[:] = v will accomplish what your iteration does using numpy broadcasting.

Why can't I use Docker CMD multiple times to run multiple services?

Even though CMD is written down in the Dockerfile, it really is runtime information. Just like EXPOSE, but contrary to e.g. RUN and ADD. By this, I mean that you can override it later, in an extending Dockerfile, or simple in your run command, which is what you are experiencing. At all times, there can be only one CMD.

If you want to run multiple services, I indeed would use supervisor. You can make a supervisor configuration file for each service, ADD these in a directory, and run the supervisor with supervisord -c /etc/supervisor to point to a supervisor configuration file which loads all your services and looks like

[supervisord]
nodaemon=true

[include]
files = /etc/supervisor/conf.d/*.conf

If you would like more details, I wrote a blog on this subject here: http://blog.trifork.com/2014/03/11/using-supervisor-with-docker-to-manage-processes-supporting-image-inheritance/

Attempted to read or write protected memory

In my case I had trouble with the "Environment variables" while adding reference to my COM DLL.

When I added the reference to my project, I was looking for P:\Core path, whereas I had added the c:\core path in past into path environment varaible.

So my code was attempting wrong path first. I removed that and un-registered the DLL reference and re-registered my DLL reference using (regsvr32). Hope this helps.

Create a simple Login page using eclipse and mysql

You Can simply Use One Jsp Page To accomplish the task.

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@page import="java.sql.*"%>
<!DOCTYPE html>
<html>
   <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>JSP Page</title>
</head>
<body>
    <%
        String username=request.getParameter("user_name");
        String password=request.getParameter("password");
        String role=request.getParameter("role");
        try
        {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/t_fleet","root","root");
            Statement st=con.createStatement();
            String query="select * from tbl_login where user_name='"+username+"' and password='"+password+"' and role='"+role+"'";
            ResultSet rs=st.executeQuery(query);
            while(rs.next())
            {
                session.setAttribute( "user_name",rs.getString(2));
                session.setMaxInactiveInterval(3000);
                response.sendRedirect("homepage.jsp");
            }
            %>



        <%}
        catch(Exception e)
        {
            out.println(e);
        }
    %>

</body>

I have use username, password and role to get into the system. One more thing to implement is you can do page permission checking through jsp and javascript function.

Update only specific fields in a models.Model

To update a subset of fields, you can use update_fields:

survey.save(update_fields=["active"]) 

The update_fields argument was added in Django 1.5. In earlier versions, you could use the update() method instead:

Survey.objects.filter(pk=survey.pk).update(active=True)

Sql query to insert datetime in SQL Server

You will want to use the YYYYMMDD for unambiguous date determination in SQL Server.

insert into table1(approvaldate)values('20120618 10:34:09 AM');

If you are married to the dd-mm-yy hh:mm:ss xm format, you will need to use CONVERT with the specific style.

insert into table1 (approvaldate)
       values (convert(datetime,'18-06-12 10:34:09 PM',5));

5 here is the style for Italian dates. Well, not just Italians, but that's the culture it's attributed to in Books Online.

Best C# API to create PDF

Update:

I'm not sure when or if the license changed for the iText# library, but it is licensed under AGPL which means it must be licensed if included with a closed-source product. The question does not (currently) require free or open-source libraries. One should always investigate the license type of any library used in a project.


I have used iText# with success in .NET C# 3.5; it is a port of the open source Java library for PDF generation and it's free.

There is a NuGet package available for iTextSharp version 5 and the official developer documentation, as well as C# examples, can be found at itextpdf.com

Windows Batch: How to add Host-Entries?

I am adding this answer in case someone else would like to store the host entry set in a txt file formatted like the normal host file. This looks for a TAB delimiter. This is based off of the answers from @Rashy and @that0n3guy. The differences can be noticed around the FOR command.

@echo off
TITLE Modifying your HOSTS file
ECHO.

:: BatchGotAdmin
:-------------------------------------
REM  --> Check for permissions
>nul 2>&1 "%SYSTEMROOT%\system32\cacls.exe" "%SYSTEMROOT%\system32\config\system"

REM --> If error flag set, we do not have admin.
if '%errorlevel%' NEQ '0' (
    echo Requesting administrative privileges...
    goto UACPrompt
) else ( goto gotAdmin )

:UACPrompt
    echo Set UAC = CreateObject^("Shell.Application"^) > "%temp%\getadmin.vbs"
    set params = %*:"="
    echo UAC.ShellExecute "cmd.exe", "/c %~s0 %params%", "", "runas", 1 >> "%temp%\getadmin.vbs"

    "%temp%\getadmin.vbs"
    del "%temp%\getadmin.vbs"
    exit /B

:gotAdmin
    pushd "%CD%"
    CD /D "%~dp0"
:--------------------------------------

:LOOP
SET Choice=
SET /P Choice="Do you want to modify HOSTS file ? (Y/N)"

IF NOT '%Choice%'=='' SET Choice=%Choice:~0,1%

ECHO.
IF /I '%Choice%'=='Y' GOTO ACCEPTED
IF /I '%Choice%'=='N' GOTO REJECTED
ECHO Please type Y (for Yes) or N (for No) to proceed!
ECHO.
GOTO Loop


:REJECTED
ECHO Your HOSTS file was left unchanged.
ECHO Finished.
GOTO END


:ACCEPTED
setlocal enabledelayedexpansion
::Create your list of host domains
for /F "tokens=1,2 delims=  " %%A in (%WINDIR%\System32\drivers\etc\storedhosts.txt) do (
    SET _host=%%B
    SET _ip=%%A
    SET NEWLINE=^& echo.
    ECHO Adding !_ip!       !_host!
    REM REM ::strip out this specific line and store in tmp file
    type %WINDIR%\System32\drivers\etc\hosts | findstr /v !_host! > tmp.txt
    REM REM ::re-add the line to it
    ECHO %NEWLINE%^!_ip!        !_host! >> tmp.txt
    REM ::overwrite host file
    copy /b/v/y tmp.txt %WINDIR%\System32\drivers\etc\hosts
    del tmp.txt 
)

ipconfig /flushdns
ECHO.
ECHO.
ECHO Finished, you may close this window now.
GOTO END

:END
ECHO.
PAUSE
EXIT

Example "storedhosts.txt" (tab delimited)

127.0.0.1   mysite.com
168.1.64.2  yoursite.com
192.1.0.1   internalsite.com

How can you get the Manifest Version number from the App's (Layout) XML variables?

IF you are using Gradle you can use the build.gradle file to programmatically add value to the xml resources at compile time.

Example Code extracted from: https://medium.com/@manas/manage-your-android-app-s-versioncode-versionname-with-gradle-7f9c5dcf09bf

buildTypes {
    debug {
        versionNameSuffix ".debug"
        resValue "string", "app_version", "${defaultConfig.versionName}${versionNameSuffix}"
    }
    release {
        resValue "string", "app_version", "${defaultConfig.versionName}"
    }
}

now use @string/app_version as needed in XML

It will add .debug to the version name as describe in the linked article when in debug mode.

How do I escape double quotes in attributes in an XML String in T-SQL?

Cannot comment anymore but voted it up and wanted to let folks know that &quot; works very well for the xml config files when forming regex expressions for RegexTransformer in Solr like so: regex=".*img src=&quot;(.*)&quot;.*" using the escaped version instead of double-quotes.

Forward host port to docker container

A simple but relatively insecure way would be to use the --net=host option to docker run.

This option makes it so that the container uses the networking stack of the host. Then you can connect to services running on the host simply by using "localhost" as the hostname.

This is easier to configure because you won't have to configure the service to accept connections from the IP address of your docker container, and you won't have to tell the docker container a specific IP address or host name to connect to, just a port.

For example, you can test it out by running the following command, which assumes your image is called my_image, your image includes the telnet utility, and the service you want to connect to is on port 25:

docker run --rm -i -t --net=host my_image telnet localhost 25

If you consider doing it this way, please see the caution about security on this page:

https://docs.docker.com/articles/networking/

It says:

--net=host -- Tells Docker to skip placing the container inside of a separate network stack. In essence, this choice tells Docker to not containerize the container's networking! While container processes will still be confined to their own filesystem and process list and resource limits, a quick ip addr command will show you that, network-wise, they live “outside” in the main Docker host and have full access to its network interfaces. Note that this does not let the container reconfigure the host network stack — that would require --privileged=true — but it does let container processes open low-numbered ports like any other root process. It also allows the container to access local network services like D-bus. This can lead to processes in the container being able to do unexpected things like restart your computer. You should use this option with caution.

formGroup expects a FormGroup instance

There are a few issues in your code

  • <div [formGroup]="form"> outside of a <form> tag
  • <form [formGroup]="form"> but the name of the property containing the FormGroup is loginForm therefore it should be <form [formGroup]="loginForm">
  • [formControlName]="dob" which passes the value of the property dob which doesn't exist. What you need is to pass the string dob like [formControlName]="'dob'" or simpler formControlName="dob"

Plunker example

Difference between CR LF, LF and CR line break types?

Jeff Atwood has a recent blog post about this: The Great Newline Schism

Here is the essence from Wikipedia:

The sequence CR+LF was in common use on many early computer systems that had adopted teletype machines, typically an ASR33, as a console device, because this sequence was required to position those printers at the start of a new line. On these systems, text was often routinely composed to be compatible with these printers, since the concept of device drivers hiding such hardware details from the application was not yet well developed; applications had to talk directly to the teletype machine and follow its conventions. The separation of the two functions concealed the fact that the print head could not return from the far right to the beginning of the next line in one-character time. That is why the sequence was always sent with the CR first. In fact, it was often necessary to send extra characters (extraneous CRs or NULs, which are ignored) to give the print head time to move to the left margin. Even after teletypes were replaced by computer terminals with higher baud rates, many operating systems still supported automatic sending of these fill characters, for compatibility with cheaper terminals that required multiple character times to scroll the display.

How do you upload a file to a document library in sharepoint?

You can upload documents to SharePoint libraries using the Object Model or SharePoint Webservices.

Upload using Object Model:

String fileToUpload = @"C:\YourFile.txt";
String sharePointSite = "http://yoursite.com/sites/Research/";
String documentLibraryName = "Shared Documents";

using (SPSite oSite = new SPSite(sharePointSite))
{
    using (SPWeb oWeb = oSite.OpenWeb())
    {
        if (!System.IO.File.Exists(fileToUpload))
            throw new FileNotFoundException("File not found.", fileToUpload);                    

        SPFolder myLibrary = oWeb.Folders[documentLibraryName];

        // Prepare to upload
        Boolean replaceExistingFiles = true;
        String fileName = System.IO.Path.GetFileName(fileToUpload);
        FileStream fileStream = File.OpenRead(fileToUpload);

        // Upload document
        SPFile spfile = myLibrary.Files.Add(fileName, fileStream, replaceExistingFiles);

        // Commit 
        myLibrary.Update();
    }
}

How do I update Homebrew?

  • cd /usr/local
  • git status
  • Discard all the changes (unless you actually want to try to commit to Homebrew - you probably don't)
  • git status til it's clean
  • brew update

Auto start node.js server on boot

Here is another solution I wrote in C# to auto startup native node server or pm2 server on Windows.

Laravel Eloquent compare date from datetime field

You can use this

whereDate('date', '=', $date)

If you give whereDate then compare only date from datetime field.

What's the meaning of exception code "EXC_I386_GPFLT"?

You can often get information from the header files. For example:

$ cd /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk
$ find usr -name \*.h -exec fgrep -l EXC_I386_GPFLT {} \;
usr/include/mach/i386/exception.h
^C
$ more usr/include/mach/i386/exception.h
....
#define EXC_I386_GPFLT          13      /* general protection fault     */

OK, so it's a general protection fault (as its name suggests anyway). Googling "i386 general protection fault" yields many hits, but this looks interesting:

Memory protection is also implemented using the segment descriptors. First, the processor checks whether a value loaded in a segment register references a valid descriptor. Then it checks that every linear address calculated actually lies within the segment. Also, the type of access (read, write, or execute) is checked against the information in the segment descriptor. Whenever one of these checks fails, exception (interrupt) 13 (hex 0D) is raised. This exception is called a General Protection Fault (GPF).

That 13 matches what we saw in the header files, so it looks like the same thing. However from the application programmer's point-of-view, it just means we're referencing memory we shouldn't be, and it's doesn't really matter how it's implemented on the hardware.

How to use concerns in Rails 4

I have been reading about using model concerns to skin-nize fat models as well as DRY up your model codes. Here is an explanation with examples:

1) DRYing up model codes

Consider a Article model, a Event model and a Comment model. An article or an event has many comments. A comment belongs to either Article or Event.

Traditionally, the models may look like this:

Comment Model:

class Comment < ActiveRecord::Base
  belongs_to :commentable, polymorphic: true
end

Article Model:

class Article < ActiveRecord::Base
  has_many :comments, as: :commentable 

  def find_first_comment
    comments.first(created_at DESC)
  end

  def self.least_commented
   #return the article with least number of comments
  end
end

Event Model

class Event < ActiveRecord::Base
  has_many :comments, as: :commentable 

  def find_first_comment
    comments.first(created_at DESC)
  end

  def self.least_commented
   #returns the event with least number of comments
  end
end

As we can notice, there is a significant piece of code common to both Event and Article. Using concerns we can extract this common code in a separate module Commentable.

For this create a commentable.rb file in app/models/concerns.

module Commentable
  extend ActiveSupport::Concern

  included do
    has_many :comments, as: :commentable
  end

  # for the given article/event returns the first comment
  def find_first_comment
    comments.first(created_at DESC)
  end

  module ClassMethods
    def least_commented
      #returns the article/event which has the least number of comments
    end
  end
end

And now your models look like this :

Comment Model:

class Comment < ActiveRecord::Base
  belongs_to :commentable, polymorphic: true
end

Article Model:

class Article < ActiveRecord::Base
  include Commentable
end

Event Model:

class Event < ActiveRecord::Base
  include Commentable
end

2) Skin-nizing Fat Models.

Consider a Event model. A event has many attenders and comments.

Typically, the event model might look like this

class Event < ActiveRecord::Base   
  has_many :comments
  has_many :attenders


  def find_first_comment
    # for the given article/event returns the first comment
  end

  def find_comments_with_word(word)
    # for the given event returns an array of comments which contain the given word
  end 

  def self.least_commented
    # finds the event which has the least number of comments
  end

  def self.most_attended
    # returns the event with most number of attendes
  end

  def has_attendee(attendee_id)
    # returns true if the event has the mentioned attendee
  end
end

Models with many associations and otherwise have tendency to accumulate more and more code and become unmanageable. Concerns provide a way to skin-nize fat modules making them more modularized and easy to understand.

The above model can be refactored using concerns as below: Create a attendable.rb and commentable.rb file in app/models/concerns/event folder

attendable.rb

module Attendable
  extend ActiveSupport::Concern

  included do 
    has_many :attenders
  end

  def has_attender(attender_id)
    # returns true if the event has the mentioned attendee
  end

  module ClassMethods
    def most_attended
      # returns the event with most number of attendes
    end
  end
end

commentable.rb

module Commentable
  extend ActiveSupport::Concern

  included do 
    has_many :comments
  end

  def find_first_comment
    # for the given article/event returns the first comment
  end

  def find_comments_with_word(word)
    # for the given event returns an array of comments which contain the given word
  end

  module ClassMethods
    def least_commented
      # finds the event which has the least number of comments
    end
  end
end

And now using Concerns, your Event model reduces to

class Event < ActiveRecord::Base
  include Commentable
  include Attendable
end

* While using concerns its advisable to go for 'domain' based grouping rather than 'technical' grouping. Domain Based grouping is like 'Commentable', 'Photoable', 'Attendable'. Technical grouping will mean 'ValidationMethods', 'FinderMethods' etc

Oracle SQL Where clause to find date records older than 30 days

Use:

SELECT *
  FROM YOUR_TABLE
 WHERE creation_date <= TRUNC(SYSDATE) - 30

SYSDATE returns the date & time; TRUNC resets the date to being as of midnight so you can omit it if you want the creation_date that is 30 days previous including the current time.

Depending on your needs, you could also look at using ADD_MONTHS:

SELECT *
  FROM YOUR_TABLE
 WHERE creation_date <= ADD_MONTHS(TRUNC(SYSDATE), -1)

How do I fix the indentation of selected lines in Visual Studio

To fix the indentation and formatting in all files of your solution:

  1. Install the Format All Files extension => close VS, execute the .vsix file and reopen VS;
  2. Menu Tools > Options... > Text Editor > All Languages > Tabs:
    1. Click on Smart (for resolving conflicts);
    2. Type the Tab Size and Indent Size you want (e.g. 2);
    3. Click on Insert Spaces if you want to replace tabs by spaces;
  3. In the Solution Explorer (Ctrl+Alt+L) right click in any file and choose from the menu Format All Files (near the bottom).

This will recursively open and save all files in your solution, setting the indentation you defined above.

You might want to check other programming languages tabs (Options...) for Code Style > Formatting as well.