Posted (Updated ) in Javascript, PHP

Even though it hasn’t worked for quite some time now, my previous PHP WebSocket chat application has garnered quite a bit of attention and is still one of my most heavily trafficked posts. As a result I thought I’d provide you all with a working script as of Feb 15, 2012. Also, because I’m your typical lazy developer, I’ll be building on top of other peoples’ work – most notably PHPWebSocket.

You can download the final script here. According to the Wikipedia article on WebSockets, it should work in IE10+, Firefox 7+ and Chrome 14+. Personally I tested with Chrome 17.0.963.46 and Firefox 10.0.1.

I want to stress that this tutorial is designed to be extremely basic and as such does not give alot of functionality out of the box (but provides all the tools required to add more). It’s simply a working example of a PHP-based WebSocket server.

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Posted (Updated ) in Linux

Tonight I discovered I had an entire folder of dual audio MKV files with the wrong default language and wrong default subtitle track. I could have used mkvpropedit to manually change each file but that’s such a hassle. Instead, here’s a handy one-liner to do them all at once:

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find . -name "*.mkv" -exec mkvpropedit {} --edit track:a1 --set flag-default=0 --edit track:a2 --set flag-default=1 --edit track:s1 --set flag-default=0 --edit track:s2 --set flag-default=1 \;

 

Explanation

At first glance they may look a bit complicated, but let’s break it down a bit:

Find all .mkv files and execute an operation on them:

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find . -name "*.mkv" -exec ... \;

Do an mkvpropedit on the current matched file:

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mkvpropedit {}

Set the first audio track to not be default, the second audio track to be default, and do the same with the subtitle tracks:

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--edit track:a1 --set flag-default=0
--edit track:a2 --set flag-default=1
--edit track:s1 --set flag-default=0
--edit track:s2 --set flag-default=1

 

You’ll need mkvtoolnix installed for the mkvpropedit command. To determine what the various tracks contain, do a

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mkvinfo /path/to/file.mkv

or mkvinfo -g for you GUI users 🙂 This can be a bit tricky to read though so I tend to just open the file in VLC and look at the audio and video tracks that way.

As an added bonus, here’s the Windows equivalent of the above script:

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@echo off
FOR /f "tokens=*" %%G IN ('dir /a-d /b') DO (
	mkvpropedit.exe "%%G" --edit track:2 --set flag-default=0
	mkvpropedit.exe "%%G" --edit track:3 --set flag-default=0
	mkvpropedit.exe "%%G" --edit track:4 --set flag-default=1
	mkvpropedit.exe "%%G" --edit track:5 --set flag-default=0
	echo.
)
pause

I’ve been told the Windows version works but haven’t tested personally.

Happy viewing!

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Posted (Updated ) in PHP

Last night I was getting a strange error in LemonStand administration area when attempting to edit a product or category:

Fatal error: Maximum function nesting level of ‘100’ reached, aborting! in /path/to/phproad/modules/phpr/helpers/phpr_inflector.php on line 322

If you’re also experiencing this error, it’s caused by XDebug and can be solved by adding

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ini_set('xdebug.max_nesting_level', 200);

to your config/config.php file.

Thanks to Aleksey Bobkov and EHLOVader for their help in solving this issue. Here is the official LemonStand forum thread on the issue.

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Posted (Updated ) in Database, Linux, PHP

Tonight I had to move my WPMU install from my local development machine to the live server – this meant a change in installation path which is always a hassle with WordPress. Below I’ll detail my issues and the corresponding fixes in the hopes it will make life easier for others experiencing the same problems.

Redirection to wp-signup.php

First thing I noticed was that when loading the site on a live domain, I’d get instantly redirected to mydomain.com/wp-signup.php?new=mydomain.com. With a bit of Googling I came across this forum thread which recommended adding the following to my wp-config.php:

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define( 'NOBLOGREDIRECT', '' );
define( 'SUBDOMAIN_INSTALL', false );

Don’t do this! It will get the site closer to working order but it’s not going to help you in the long run – especially when you need the other domains working too. Instead here’s what you should be doing:

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#Dump your DB
mysqldump - u<username> -p<password> -h<host> <dbname> > test.sql
 
#Update folder path to that of the new servers
sed -i "s/path\/to\/install/new\/path\/to\/install/g" test.sql 
#If you installed into localhost/foo/bar/mysite, change that to your live servers domain
sed -i "s/url\/path\/to\/site/www\.domain\.com/g" test.sql

This is pretty standard behavior for moving WordPress sites, however if you load the above dump up on your live domain you’ll probably be greeted with the dreaded Error establishing a database connection.

Error establishing a database connection

Heading to www.domain.com/wp-admin will shed a little more light on the situation – you need to update your wp_blogs table for the main site. WPMU is currently using your development servers URL from this table and ignoring what’s in wp-config.php. To play things safe we’ll update any occurrances of our test servers domain in test.sql:

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#Update your live servers subdomain in wp_blogs to your live servers domain
sed -i  "s/yoursite\.localhost\.com/www\.yourdomain\.com/g" test.sql

This should do the trick. Load that bad boy into your live server and you should be good to go!

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Posted (Updated ) in Linux

For users not running Bumblebee or Ironhide, you’ve probably noticed alot of heat, low battery life and a roaring fan even when idle. This is almost entirely due to the nVidia graphics card. If you’re like me and don’t need that card at all, you have the option of disabling it entirely. To do so you’ll need to install acpi_call as a kernel module and use it to shut the GPU down.

Read on for a tutorial on how. I’ve also included some bonus Intel GPU tweaks!

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Posted in Database

MySQL’s built in FROM_UNIXTIME() function only handles positive numbers however we can still convert negative integers to dates using its handy DATE_ADD() function like so:

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SELECT DATE_ADD(FROM_UNIXTIME(0), INTERVAL -13391999 SECOND)

which gives:

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1969-07-30 10:00:01

Note that this also works with positive numbers, so if your database contains a mixture of both it’s still safe to use.

Credit to user fat_kid for his tutorial here.

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Posted in Database

Without any adieu what-so-ever, below is a MySQL implementation of PHP’s ucfirst function which capitalizes the first letter of each word in a string.

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DELIMITER $$
CREATE FUNCTION CAP_FIRST (INPUT VARCHAR(255))
 
RETURNS VARCHAR(255)
 
DETERMINISTIC
 
BEGIN
    DECLARE len INT;
    DECLARE i INT;
 
    SET len   = CHAR_LENGTH(INPUT);
    SET INPUT = LOWER(INPUT);
    SET i = 0;
 
    WHILE (i < len) DO
        IF (MID(INPUT,i,1) = ' ' OR i = 0) THEN
            IF (i < len) THEN
                SET INPUT = CONCAT(
                    LEFT(INPUT,i),
                    UPPER(MID(INPUT,i + 1,1)),
                    RIGHT(INPUT,len - i - 1)
                );
            END IF;
        END IF;
        SET i = i + 1;
    END WHILE;
 
    RETURN INPUT;
END$$
DELIMITER ;

Use it like so:

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SELECT CAP_FIRST('my string of words');

and you should get:

My String Of Words

All credit and many thanks for this function to Joezack.

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Posted (Updated ) in Javascript, PHP

JQuery Data Tables is an incredibly handy tool that can make a developers life alot easier – notably by handling search, pagination, filtering and sorting for you. The default functionality is very good, however you’ll often need a bit of customization. This post will detail how to add custom filters and position them to nicely theme with your table. The filters’ state will also be saved so they’ll still be there if you reload the page.

You can see the demo page for this post here. Select a filter and reload the page to see it in action.

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Posted in Linux, PHP

After upgrading to 11.10 recently, I occasionally noticed fuser firing up and using between 70% and astoundingly 9999% CPU. Googling the issue led me to this post with the solution.

As user grazer explains:

We have the same problem. This is the content of /etc/cron.d/php5 on 11.10:

09,39 *     * * *     root   [ -x /usr/lib/php5/maxlifetime ] &amp;&amp; [ -d /var/lib/php5 ] &amp;&amp; find /var/lib/php5/ -depth -mindepth 1 -maxdepth 1 -type f -cmin +$(/usr/lib/php5/maxlifetime) ! -execdir fuser -s {} 2&gt;/dev/null \; -delete

And this is the content on 11.04:

09,39 *     * * *     root   [ -x /usr/lib/php5/maxlifetime ] &amp;&amp; [ -d /var/lib/php5 ] &amp;&amp; find /var/lib/php5/ -depth -mindepth 1 -maxdepth 1 -type f -cmin +$(/usr/lib/php5/maxlifetime) -delete

Spot the difference?

The 11.10 version runs fuser for each PHP session file, thus using all the CPU when there are hundreds of sessions.

After commenting out the 11.10 line and replacing with the 11.04 equivalent, this problem was solved for me aswell. Thanks, grazer!

You can also check out the bug report to keep up to date on this issue. Hopefully a fix will be released quickly.

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Posted (Updated ) in PHP

I had a bit of an issue with this and the documentation wasn’t of much help so I thought I’d post about the process. I currently have CampaignMonitor and MailChimp modules in the LemonStand marketplace and wanted to allow customers to create subscription forms on their sites that AJAX submit.

Firstly, here is the documentation page on custom events. The docs show that you need two things:

  • A subscribeEvents() method in your module’s setup class containing an addEvent() call.
  • A method containing the code you want to execute, which will be triggered by your event.

I attempted to do the above with the following backend code:

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<?php
class MyModule_Module extends Core_ModuleBase
{
	public function subscribeEvents()
	{
		Backend::$events->addEvent('MyModule_Module:onSubmit', $this, 'on_submit');
	}
 
	public function onSubmit()
	{
		//...
	}
}

And frontend code:

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<form onsubmit="return $(this).sendRequest('MyModule_Module:onSubmit')" action="/" method="post">
	<input type='submit' name='submit' value='Submit' />
</form>

I submitted the form and was greeted with an error message:

An AJAX error occurred: AJAX handler not found.

After a little digging I came across the function excuted when you perform an AJAX query. Important lines are highlighted:

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public static function execAjaxHandler($name, $controller)
{
	$parts = explode(':', $name);
	if (count($parts) != 2)
		throw new Phpr_ApplicationException("Invalid event handler identifier: $name");
 
	$className = ucfirst($parts[0]).'_Actions';	if (!Phpr::$classLoader->load($className))
		throw new Phpr_ApplicationException("Actions scope class is not found: $className");
 
	$method = $parts[1];
	$isEventHandler = preg_match('/^on_/', $method);	if (!$isEventHandler)
		throw new Phpr_ApplicationException("Specified method is not AJAX event handler: $method");
 
	$obj = new $className();
	if (!method_exists($obj, $method))
		throw new Phpr_ApplicationException("AJAX handler not found: $name");
 
	$obj->copy_context_from($controller);
	try
	{
		$result = $obj->$method();
		$controller->copy_context_from($obj);
		return $result;
	}
	catch (Exception $ex)
	{
		$controller->copy_context_from($obj);
		throw $ex;
	}
}

There’s a couple of things to note here.

  • Your second and third arguments in addEvent() are ignored.
  • _Actions is concatenated onto the end of your class name
  • Your method name must start with on_

With the above in mind, it’s time for some rewriting:

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<?php
 
class MyModule_Module extends Core_ModuleBase
{
	public function subscribeEvents()
	{
		Backend::$events->addEvent('MyModule:on_submit', $this, 'on_submit');
	}
}
 
class MyModule_Actions extends Cms_ActionScope
{
	public function on_submit()
	{
		//...
	}
}

That worked like a charm. Good luck to all the module developers for LS out there – I’ve found LemonStand a number of quirks like this and we’ll just have to tackle them one at a time 🙂

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