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authorEric Barnes <eric@ericlbarnes.com>2011-11-27 06:30:22 +0100
committerEric Barnes <eric@ericlbarnes.com>2011-11-27 06:30:22 +0100
commit7e66dda705743cbfe1d522ddb73e5694006ec42c (patch)
treec08b63deb28c09ec49d9173280f1ca234debfe50 /user_guide/general/helpers.html
parent7eceb03f083643254c7393c6b5ebe539e344a1ba (diff)
parente101593561a10632c1d63180436b19f1d7115046 (diff)
Merge branch 'refs/heads/develop' into feature/unit-tests
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-<h1>Helper Functions</h1>
-
-<p>Helpers, as the name suggests, help you with tasks. Each helper file is simply a collection of functions in a particular
-category. There are <dfn>URL Helpers</dfn>, that assist in creating links, there are <dfn>Form Helpers</dfn>
-that help you create form elements, <dfn>Text Helpers</dfn> perform various text formatting routines,
-<dfn>Cookie Helpers</dfn> set and read cookies, <dfn>File Helpers</dfn> help you deal with files, etc.
-</p>
-
-<p>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.</p>
-
-<p>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 <a href="../general/controllers.html">controller</a> and <a href="../general/views.html">views</a>.</p>
-
-<p>Helpers are typically stored in your <dfn>system/helpers</dfn>, or <dfn>application/helpers </dfn>directory. CodeIgniter will look first in your <dfn>application/helpers</dfn>
-directory. If the directory does not exist or the specified helper is not located there CI will instead look in your global
-<dfn>system/helpers</dfn> folder.</p>
-
-
-<h2>Loading a Helper</h2>
-
-<p>Loading a helper file is quite simple using the following function:</p>
-
-<code>$this->load->helper('<var>name</var>');</code>
-
-<p>Where <var>name</var> is the file name of the helper, without the .php file extension or the "helper" part.</p>
-
-<p>For example, to load the <dfn>URL Helper</dfn> file, which is named <var>url_helper.php</var>, you would do this:</p>
-
-<code>$this->load->helper('<var>url</var>');</code>
-
-<p>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.</p>
-
-<p class="important">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.</p>
-
-
-<h2>Loading Multiple Helpers</h2>
-
-<p>If you need to load more than one helper you can specify them in an array, like this:</p>
-
-<code>$this->load->helper( <samp>array(</samp>'<var>helper1</var>', '<var>helper2</var>', '<var>helper3</var>'<samp>)</samp> );</code>
-
-<h2>Auto-loading Helpers</h2>
-
-<p>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 <var>application/config/autoload.php</var> file and adding the helper to the autoload array.</p>
-
-
-<h2>Using a Helper</h2>
-
-<p>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.</p>
-
-<p>For example, to create a link using the <dfn>anchor()</dfn> function in one of your view files you would do this:</p>
-
-<code>&lt;?php echo anchor('blog/comments', 'Click Here');?&gt;</code>
-
-<p>Where "Click Here" is the name of the link, and "blog/comments" is the URI to the controller/function you wish to link to.</p>
-
-<h2>"Extending" Helpers</h2>
-
-<p>To "extend" Helpers, create a file in your <dfn>application/helpers/</dfn> folder with an identical name to the existing Helper, but prefixed with <kbd>MY_</kbd> (this item is configurable. See below.).</p>
-
-<p>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.</p>
-
-<p>For example, to extend the native <kbd>Array Helper</kbd> you'll create a file named <dfn>application/helpers/</dfn><kbd>MY_array_helper.php</kbd>, and add or override functions:</p>
-
-<code>
-// any_in_array() is not in the Array Helper, so it defines a new function<br />
-function any_in_array($needle, $haystack)<br />
-{<br />
-&nbsp;&nbsp;&nbsp;&nbsp;$needle = (is_array($needle)) ? $needle : array($needle);<br />
- <br />
-&nbsp;&nbsp;&nbsp;&nbsp;foreach ($needle as $item)<br />
-&nbsp;&nbsp;&nbsp;&nbsp;{<br />
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if (in_array($item, $haystack))<br />
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;{<br />
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return TRUE;<br />
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<br />
-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<br />
- <br />
-&nbsp;&nbsp;&nbsp;&nbsp;return FALSE;<br />
-}<br />
-<br />
-// random_element() is included in Array Helper, so it overrides the native function<br />
-function random_element($array)<br />
-{<br />
-&nbsp;&nbsp;&nbsp;&nbsp;shuffle($array);<br />
-&nbsp;&nbsp;&nbsp;&nbsp;return array_pop($array);<br />
-}<br />
-</code>
-
-<h3>Setting Your Own Prefix</h3>
-
-<p>The filename prefix for "extending" Helpers is the same used to extend libraries and Core classes. To set your own prefix, open your <dfn>application/config/config.php</dfn> file and look for this item:</p>
-
-<code>$config['subclass_prefix'] = 'MY_';</code>
-
-<p>Please note that all native CodeIgniter libraries are prefixed with <kbd>CI_</kbd> so DO NOT use that as your prefix.</p>
-
-
-<h2>Now What?</h2>
-
-<p>In the Table of Contents you'll find a list of all the available Helper Files. Browse each one to see what they do.</p>
-
-
-</div>
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