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Helper Functions

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Helpers, as the name suggests, help you with tasks. Each helper file is simply a collection of functions in a particular -category. There are URL Helpers, that assist in creating links, there are Form Helpers -that help you create form elements, Text Helpers perform various text formatting routines, -Cookie Helpers set and read cookies, File Helpers help you deal with files, etc. -

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Unlike most other systems in CodeIgniter, Helpers are not written in an Object Oriented format. They are simple, procedural functions. -Each helper function performs one specific task, with no dependence on other functions.

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CodeIgniter does not load Helper Files by default, so the first step in using -a Helper is to load it. Once loaded, it becomes globally available in your controller and views.

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Helpers are typically stored in your system/helpers, or application/helpers directory. CodeIgniter will look first in your application/helpers -directory. If the directory does not exist or the specified helper is not located there CI will instead look in your global -system/helpers folder.

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Loading a Helper

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Loading a helper file is quite simple using the following function:

- -$this->load->helper('name'); - -

Where name is the file name of the helper, without the .php file extension or the "helper" part.

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For example, to load the URL Helper file, which is named url_helper.php, you would do this:

- -$this->load->helper('url'); - -

A helper can be loaded anywhere within your controller functions (or even within your View files, although that's not a good practice), -as long as you load it before you use it. You can load your helpers in your controller constructor so that they become available -automatically in any function, or you can load a helper in a specific function that needs it.

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Note: The Helper loading function above does not return a value, so don't try to assign it to a variable. Just use it as shown.

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Loading Multiple Helpers

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If you need to load more than one helper you can specify them in an array, like this:

- -$this->load->helper( array('helper1', 'helper2', 'helper3') ); - -

Auto-loading Helpers

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If you find that you need a particular helper globally throughout your application, you can tell CodeIgniter to auto-load it during system initialization. -This is done by opening the application/config/autoload.php file and adding the helper to the autoload array.

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Using a Helper

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Once you've loaded the Helper File containing the function you intend to use, you'll call it the way you would a standard PHP function.

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For example, to create a link using the anchor() function in one of your view files you would do this:

- -<?php echo anchor('blog/comments', 'Click Here');?> - -

Where "Click Here" is the name of the link, and "blog/comments" is the URI to the controller/function you wish to link to.

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"Extending" Helpers

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To "extend" Helpers, create a file in your application/helpers/ folder with an identical name to the existing Helper, but prefixed with MY_ (this item is configurable. See below.).

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If all you need to do is add some functionality to an existing helper - perhaps add a function or two, or change how a particular - helper function operates - then it's overkill to replace the entire helper with your version. In this case it's better to simply - "extend" the Helper. The term "extend" is used loosely since Helper functions are procedural and discrete and cannot be extended - in the traditional programmatic sense. Under the hood, this gives you the ability to add to the functions a Helper provides, - or to modify how the native Helper functions operate.

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For example, to extend the native Array Helper you'll create a file named application/helpers/MY_array_helper.php, and add or override functions:

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-// any_in_array() is not in the Array Helper, so it defines a new function

-function any_in_array($needle, $haystack)

-{

-    $needle = (is_array($needle)) ? $needle : array($needle);

-	

-    foreach ($needle as $item)

-    {

-        if (in_array($item, $haystack))

-        {

-            return TRUE;

-        }

-        }

-	

-    return FALSE;

-}

-

-// random_element() is included in Array Helper, so it overrides the native function

-function random_element($array)

-{

-    shuffle($array);

-    return array_pop($array);

-}

-

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Setting Your Own Prefix

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The filename prefix for "extending" Helpers is the same used to extend libraries and Core classes. To set your own prefix, open your application/config/config.php file and look for this item:

- -$config['subclass_prefix'] = 'MY_'; - -

Please note that all native CodeIgniter libraries are prefixed with CI_ so DO NOT use that as your prefix.

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Now What?

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In the Table of Contents you'll find a list of all the available Helper Files. Browse each one to see what they do.

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CodeIgniter User Guide Version 2.0.3

Helper Functions

Loading a Helper

Loading Multiple Helpers

Auto-loading Helpers

Using a Helper

"Extending" Helpers

Setting Your Own Prefix

Now What?