Tiffany B. Brown » PHP

setInterval in PHP

tiffany — Tue, 25 Oct 2011 09:00:09 +0000

JavaScript has a native method for executing a function periodically: setInterval. But in PHP, it’s a little bit harder. PHP lacks a setInterval equivalent. The closest we can get are the sleep(), usleep(), and time_nanosleep() functions. These functions delay script execution by a certain period of time (either seconds, microseconds, or a combination or seconds and nanoseconds).

PHP does, however, have a means of executing code as long as a condition is true: the while loop. What we can do, then is combine a while loop with one of the sleep functions — in this case usleep() — to create a setInterval equivalent. Check out the code below.

function setInterval($func = null, $interval = 0, $times = 0){
  if( ($func == null) || (!function_exists($func)) ){
    throw new Exception('We need a valid function.');
  }

  /*
  usleep delays execution by the given number of microseconds.
  JavaScript setInterval uses milliseconds. microsecond = one
  millionth of a second. millisecond = 1/1000 of a second.
  Multiplying $interval by 1000 to mimic JS.
  */

  $seconds = $interval * 1000;

  /*
  If $times > 0, we will execute the number of times specified.
  Otherwise, we will execute until the client aborts the script.
  */

  if($times > 0){

    $i = 0;

    while($i < $times){
        call_user_func($func);
        $i++;
        usleep( $seconds );
    }
  } else {

    while(true){
        call_user_func($func); // Call the function you've defined.
        usleep( $seconds );
    }
  }
}

function doit(){
  print 'done!
';
}

To invoke, do something similar to the following.

setInterval('doit', 5000); // Invoke every five seconds, until user aborts script.

setInterval('doit', 1000, 100); // Invoke every second, up to 100 times.

Here’s the catch: no data will be sent to the browser until the script has completely executed.

Quick PHP Tip: Uploading multiple files in HTML5

tiffany — Tue, 29 Mar 2011 08:00:51 +0000

One of the neat things about HTML5 is that it allows for multiple file uploads in one file upload field. Of course, you have to have a browser that supports such a feature. Currently Opera 11.10 does. So do Firefox 4, the latest version of Chrome, and Safari 5.0.4. (Internet Explorer 9 does not.)

Now what’s less clear is how to send data from multiple files to a server-side PHP script. Turns out, it’s quite easy. Treat it in the same way you’d treat any other array of options (radio buttons, for example) and include square ([]) brackets in the field name. See the code below for an example:




	
	HTML5 Multiple File Upload

In processor.php, all we’re going to do is print the $_FILES array so you can see what’s happening.

Copy and paste this code and save it to your own server to see everything in action.

CodeIgniter’s “Disallowed Key Characters” error revisited

tiffany — Wed, 21 Jul 2010 16:19:53 +0000

Two years ago, I posted about CodeIgniter‘s “Disallowed Key Characters” error message, and one possible cause.

Recently, I stumbled across another cause: disallowed characters in a POST array. In my case, I had single-quotes as part of the variable name. My fingers mixed up PHP array syntax and HTML form syntax.

kalodont points out this can also happen when using accented characters, such as ó or ñ as keys in your array.

Quick tips for working with Amazon S3 and PHP

tiffany — Mon, 12 Apr 2010 20:46:55 +0000

Try Donovan Schonknecht’s Amazon S3 PHP Class because it supports large uploads and doesn’t require PEAR.
Set your Content-Disposition request header to ‘inline’ if you want files to display in your browser rather than forcing a download
Use S3::inputFile() when copying data from a source file — when uploading, for example. You don’t need to use it when creating files on the fly.

PHP in Arabic: An interview with Khaled Al-Shamaa

tiffany — Wed, 18 Nov 2009 16:24:22 +0000

PHP Classes interviews Khaled Al-Shamaa about his AR-PHP project, a series of PHP classes designed to handle Arabic-language web applications. Because Arabic uses a non-Latin character set, it presents a new set of challenges.

PC: Developing Web applications in Arabic requires special care. What are the most important concerns and what components do you provide to address those concerns?

KA: Besides the search issue presented above, some of Arab countries use Hijri calendar instead of Gregorian calendar. So I developed classes to convert dates between those two calendars, as well as an Arabic version from date and strtotime PHP functions. … Another issue that is handled in this project is related to rendering Arabic text correctly in some libraries like GD, PDF, SWF and even VRML.

This interested me simply because it raises awarness of cultural, linguistic, and character set challenges that monolingual developers, or Western character set developers don’t often think about. [Via PHP Developer]

[PHP quickie] Select a certain number of words from a string

tiffany — Thu, 26 Mar 2009 13:38:28 +0000

An alternative to subst() that selects entire words rather than a specified number of characters. I used this on a recent project where I needed to create a meta tag description from text and HTML stored in a database.

Uses PHP’s native str_word_count() function.

function select_number_of_words($input,$number_of_words){
	$output = '';
	$input = strip_tags($input);
	$input = str_word_count($input,1);  // second parameter returns the string as an array.
	for($i=0; $i< $number_of_words; $i++){
		$output .=$input[$i].' ';
	}
	return trim($output); // cut off the last space.
}

PHP: Sorting arrays randomly with array_randsort()

tiffany — Wed, 11 Mar 2009 16:18:31 +0000

Or, you know, just use the shuffle() function. Kim points out the drawbacks of shuffle in the comments below.

A custom PHP function. This function will return an array that’s been resorted in a random order. Supports both numerically-indexed and associative arrays. Uses PHP’s native array_rand() function.

function array_randsort($array,$preserve_keys=false){
	/*-------------------------------------/
	Preserving the keys works best with associative arrays.
	If you choose to preserve keys on a numerically-indexed or
    mixed-indexed array, use a foreach loop rather than a for loop
    to preserve the sorted order.
	/-------------------------------------*/

	if(!is_array($array)):
		exit('Supplied argument is not a valid array.');
	else:
		$i = NULL;

		// how long is the array?
		$array_length = count($array); 

		// Sorts the array keys in a random order.
		$randomize_array_keys = array_rand($array,$array_length);

		// if we are preserving the keys ...
		if($preserve_keys===true) {
			// reorganize the original array in a new array
			foreach($randomize_array_keys as $k=>$v){
				$randsort[$randomize_array_keys[$k]] = $array[$randomize_array_keys[$k]];
			}
		} else {
			// reorganize the original array in a new array
			for($i=0; $i < $array_length; $i++){
				$randsort[$i] = $array[$randomize_array_keys[$i]];
			}
		}
		return $randsort;
	endif;
}

Collecting e-commerce conversion data with Zen Cart and Google Analytics

tiffany — Thu, 19 Feb 2009 09:00:44 +0000

Google Analytics allows you to collect pretty robust data about how users move through your e-commerce site. Here’s how to make it work with Zen Cart, an open source shopping cart.

For this tutorial, you will need:

A Zen Cart-based shopping cart
A Google Analytics account and the tracking code for both conversions and page views.
Experience with PHP and MySQL programming

Also check out Google’s support article How do I track e-commerce transactions? and become BFFs with the Zen Cart wiki.

Creating a custom functions file

Create a file to house your custom functions. Name it whatever you’d like (with a PHP extension, of course). Put it in your includes/functions/extra_functions/ directory.

A word of caution: I created these functions with my own SQL, outside of the Zen Cart framework. There may be a better way to do it.

In the file you created above, add the following code:

# get the product ID out of session key
function custom_get_prodId($productkey){
	$pid = explode(':',$productkey);
	return $pid[0];
}

#get the product data
function custom_get_product($prodID,$return='all'){
	global $db;
	reset($data);
	$q = sprintf("SELECT
			pd.products_name,
			pd.products_description,
			cd.categories_name, p.products_price
			FROM categories_description AS cd, products AS p, products_description AS pd
	 		WHERE  p.products_id = 183
   				AND p.master_categories_id = cd.categories_id
   				AND p.products_id = pd.products_id",$prodID);
	$res = $db->Execute($q);
	return $res->fields;
}
# get the current user's data
function custom_get_userinfo($custID){
	global $db;
	reset($data);
	$q = sprintf("SELECT
			ab.entry_street_address,
			ab.entry_postcode,
			ab.entry_city,
			ab.entry_state,
			c.countries_name,
			c.countries_iso_code_2
			FROM address_book AS ab, countries AS c
			WHERE customers_id=%d
			   AND ab.entry_country_id = c.countries_id
				  ",(int)$custID);
	$res = $db->Execute($q);
	return $res->fields;
}

Adjust the names of the tables if you have added a custom table prefix during your Zen Cart configuration. We’ll use these functions to get us the user data and product data we need.

Edit the checkout success and global footer files

Add the conversion tracking code — provided by Google Analytics — to the checkout success page template. It’s located in your templates directory, includes/templates/YOUR_TEMPLATE_DIR/templates/tpl_checkout_success_default.php.

Also add the regular Google Analytics tracking code to your footer file (found in includes/templates/YOUR_TEMPLATE_DIR/common/tpl_footer.php).

Below your Google Analytics code, but also in your footer file, add the code below.

Providing this code with the following disclaimers:

It may not work for you.
I’m not responsible if it does.
I can’t offer personalized support.

In short: you’re on your own.

Simple pagination for arrays with PHP 5

tiffany — Mon, 15 Dec 2008 04:16:58 +0000

While working on a recent project, I had to build a feature that displayed a list of files available in a directory. A simple way is just to use scandir() and a foreach loop to spit out a pretty list.

There’s a small problem though: long lists aren’t all that user friendly. I decided instead to paginate the results. Here’s one way to do it using PHP 5:

Step 1: Read the directory

/*
 * scandir is only available in PHP 5 or higher.
 * It returns an array of ALL available files in the
 * specified directory
*/

$allfiles = scandir('/directory/to/scan/');

Now we don’t want to display every file. Some files are system files. Some files may not be the right format. Here, we’re going to eliminate any file name that starts with a period.

# intialize a new array of files that we want to show
$goodfiles = array();

# add a file to the $goodfiles array if its name doesn't begin with a period
foreach($allfiles as $f){
	if(strpos($f,'.')!==0){
		array_push($goodfiles,$f);
	}
}

Step 2: Split it! Split it good!

Now we get to the heart of things: determining how many pages there will be and how many items we’ll show per page. It’s remarkably simple thanks to PHP’s array_chunk() function. The array_chunk function takes two parameters: the array that you want to split, and the number of units that should be in each set.

$pages = array_chunk($goodfiles, 5);

This produces a multidimensional array which, if we print_r it, looks a bit like this (let’s assume we have 13 files in the directory).

Array
(
    [0] => Array
        (
            [0] => About_RFSB06WEB.flv
            [1] => Kids_Excited.flv
            [2] => Kids_Start_Run.flv
            [3] => Kids_start.jpg
            [4] => Kids_start_sm.jpg
        )

    [1] => Array
        (
            [0] => image01.jpg
            [1] => image02.jpg
            [2] => image03.jpg
            [3] => image04.jpg
            [4] => image05.jpg
        )

    [2] => Array
        (
            [0] => image06.jpg
            [1] => image07.jpg
            [2] => image08.jpg
        )
)

Each parent array is a page. Each child array is the content for that page. Now we just have to specify which page we want to view. In this example, we’re going to pass the desired page to the script as part of a query string — showfiles.php?showpage=1.

Step 3: Linking up

So now that our array is all split and chunked, we can build our page links. As I explained earlier, using array_chunk() creates our ‘pages.’ To build our pagination navigation, then, we just need to create as many links as there are pages. Let’s do this with a for loop.

Remember that we're doing a page count, so we want to start at one (not zero). Now it's just a matter of grabbing the variable's value to specify which array to show. We're grabbing that value from the query string in the URL.

$pgkey = (int)$_GET['showpage']; // forces $_GET['showpage'] to be an integer
$pages[$pgkey];

If you want to highlight which page the user is on, add if / else logic to check whether the value of $i is the same as the value of $_GET['showpage'] and apply a style or CSS class name.

Step 4: Showing the files

The final step is to show the files on each page. Simply use a foreach loop.

foreach($pages[$pgkey] as $file){ echo $file.'
'; }

This is a technique that you could conceivably use to display any array data across pages.

Atlanta, GA: php|works and PyWorks

tiffany — Fri, 18 Jul 2008 15:49:48 +0000

Marco Tabini & Associates, publishers of PHP Architect and Python Magazine are bringing their php|works conference back to Atlanta this fall, November 12th through 14th, 2008.

This year, though, the conference has an added bonus: PyWorks, a conference devoted to Python. Registering for one conference allows you to attend both.

Both conferences have an open call for papers, which ends July 25, 2008. Registration costs $599 (discounts are available).

RSS: Tech Events

Debugging tip: “Disallowed Key Character” error in CodeIgniter

tiffany — Tue, 06 May 2008 21:24:17 +0000

After 6 hours of massive anxiety, stress, near tears, one pound on my desk, and some hair pulling, I tracked down the source of a nagging Disallowed Key Character error that I received while using CodeIgniter: an extra line break.

The line feed (LF) and carriage return (CR) characters (and their hex code equivalents (%0D and %0A) are forbidden in CodeIgniter’s framework. The hard part is tracking down exactly where that extra line break character lives.

In my case, there was an extra line of blank, barren, not-all-that-obvious white space at the very, very end of one of my controller files, just after the closing ?>.

Turn text files into pull down menus

tiffany — Wed, 27 Feb 2008 02:16:43 +0000

UPDATE: This could also be done with the foreach() construct, but here — on my set-up at least — the for loop is a teensy bit faster.

I developed this PHP function for a project I’m working on. I’m posting it here in case I need it again, or in case you find it handy.

#Input text files must contain one item per line
function print_menu($txtfile_or_files){
	$args = func_get_args();
	$num_args = func_num_args();
	$input = array();

	for($i = 0; $i < $num_args; $i++){
		// get contents of each text file specified
		$lines = file($args[$i]); 

		// get each line from each file an add to array
		for($j = 0; $j < count($lines); $j++){
			array_push($input,$lines[$j]);
		}
	}
	// sort alphabetically
	sort($input,SORT_STRING);		

	for($i = 0; $i < count($input); $i++){
		$value = str_replace(' ','_',strtolower(trim($input[$i])));
		echo '\n";
	}
}

Configuration and use

The variable $txtfile_or_files should be a comma-separated list of paths to plain text files. This function accepts multiple arguments, in case you want to string multiple files into one menu.

Each text file should contain one item per line. For example:

Red
Blue
Orange
Green

Add another line or two of code if you need to indicate whether the form field value has already been selected.

Review: Learning PHP Data Objects by Dennis Popel

tiffany — Tue, 23 Oct 2007 05:01:56 +0000

Packt Publishing graciously provided me with a copy of this book to review.

PHP supports more than a dozen database setups, including the SQLite library bundled with PHP 5. That’s a lot of databases, and each one has its own connection syntax and server-specific functions.

So what happens when you want to be able to swap one database for another? You turn to an abstraction library, such as PDO.

In Learning PHP Data Objects, Dennis Popel takes you through the process of building an application using PDO with MySQL and SQLite.

Aimed squarely at PHP developers who are new to PDO, Popel covers how to make connections, handle errors, and use prepared statements with PDO. He also discusses transactions, MVC development, and the appropriateness of using PDO versus other abstraction libraries.

Where Learning PHP Data Objects shines, however is in its code examples. They are easy to follow, and Popel smartly alerts readers to potential gotchas in developing the sample application.

The book assumes an understanding of OOPHP — necessary because PDO is entirely object-oriented. To get the most out of it, you should be familiar with object-oriented principles and syntax. While Appendix A does give readers a quick overview of OOPHP, for a more thorough treatment, you’ll need to look elsewhere.

It’s a solid, though not quite perfect book. For example, Popel only sort-of mentions a potentially huge gotcha: when you may need to specify a unix_socket parameter in the connection string. It’s a problem I think would be common enough and confusing enough to discuss and demonstrate. I also think Popel could have been a bit clearer about when and why to use PDOStatement->closeCursor().

Those are minor quibbles however, easily solved by consulting the documentation or doing a Google search. Overall, this book is nice introduction to the whys and hows of using PDO to develop database driven applications.

Quick facts

Learning PHP Data Objects
By Dennis Popel
Packt Publishing
September 2007
$39.99
ISBN number: 978-1-847192-66-0

Solution for “Can’t connect to local MySQL server through socket ‘/tmp/mysql.sock’” error when using PDO

tiffany — Mon, 22 Oct 2007 14:54:34 +0000

If you’re trying to get up-and-running with PDO, you may experience a “Can’t connect to local MySQL server through socket ‘/tmp/mysql.sock’” error when trying to connect to your database, even if your php.ini and my.cnf files contain a different default socket path for MySQL.

It’s counterintuitive to a degree, but it’s actually expected behavior. The good news is that the fix is easy. Simply include the unix socket path in your connection string.

$connection = new PDO("mysql:host=localhost;dbname=test;unix_socket=/path/to/socket/found_in_php.ini_or_my.cnf",'username','password');

Related: Notes from “Introduction to PDO,” a talk by Ilia Alshanetsky at NYPHPCon 2006.

Atlanta, Ga: php|works 2007

tiffany — Wed, 15 Aug 2007 17:39:13 +0000

Local PHP geeks rejoice! php|works 2007 is happening in our neck of the woods in about a month. Speakers include Atlanta PHP founder Ben Ramsey, PHP guru Sara Goleman and security expert Chris Shiflett.

Event details

When: Sept 13 – 14, 2007
Where: Sheraton Gateway Hotel
How much: US$650 and $200 for the tutorial add-on. Discounts available for students, non-profits, educators and groups
More info