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Derek Allard404e35d2007-08-07 01:00:45 +0000[diff] [blame]5<title>CodeIgniter User Guide : Helper Functions</title>
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]6
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Derek Allard39b622d2008-01-16 21:10:09 +0000[diff] [blame]31<td><h1>CodeIgniter User Guide Version 1.6.0</h1></td>
adminc0d5d522006-10-30 19:40:35 +0000[diff] [blame]32<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
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Derek Jones7a9193a2008-01-21 18:39:20 +0000[diff] [blame^]43<a href="http://codeigniter.com/">CodeIgniter Home</a> &nbsp;&#8250;&nbsp;
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]44<a href="../index.html">User Guide Home</a> &nbsp;&#8250;&nbsp;
45Helper Functions
46</td>
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57
58<h1>Helper Functions</h1>
59
60<p>Helpers, as the name suggests, help you with tasks. Each helper file is simply a collection of functions in a particular
61category. There are <dfn>URL Helpers</dfn>, that assist in creating links, there are <dfn>Form Helpers</dfn>
62that help you create form elements, <dfn>Text Helpers</dfn> perform various text formatting routines,
63<dfn>Cookie Helpers</dfn> set and read cookies, <dfn>File Helpers</dfn> help you deal with files, etc.
64</p>
65
Derek Allardd2df9bc2007-04-15 17:41:17 +0000[diff] [blame]66<p>Unlike most other systems in CodeIgniter, Helpers are not written in an Object Oriented format. They are simple, procedural functions.
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]67Each helper function performs one specific task, with no dependence on other functions.</p>
68
admine334c472006-10-21 19:44:22 +0000[diff] [blame]69<p>Helpers are intentionally kept very simple so that they can be used within your <strong>View Files</strong> with a minimal amount of code.
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]70This is important if you intend to have designers or non-programmer will be working with your view files, since it keeps the code to a minimum.
71</p>
72
Derek Allardd2df9bc2007-04-15 17:41:17 +0000[diff] [blame]73<p>CodeIgniter does not load Helper Files by default, so the first step in using
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]74a 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>
75
76<h2>Loading a Helper</h2>
77
78<p>Loading a helper file is quite simple using the following function:</p>
79
80<code>$this->load->helper('<var>name</var>');</code>
81
82<p>Where <var>name</var> is the file name of the helper, without the .php file extension or the "helper" part.</p>
83
84<p>For example, to load the <dfn>URL Helper</dfn> file, which is named <var>url_helper.php</var>, you would do this:</p>
85
86<code>$this->load->helper('<var>url</var>');</code>
87
88<p>A helper can be loaded anywhere within your controller functions (or even within your View files, although that's not a good practice),
89as long as you load it before you use it. You can load your helpers in your controller constructor so that they become available
90automatically in any function, or you can load a helper in a specific function that needs it.</p>
91
92<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>
93
94<h2>Auto-loading Helpers</h2>
95
Derek Allardd2df9bc2007-04-15 17:41:17 +0000[diff] [blame]96<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.
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]97This is done by opening the <var>application/config/autoload.php</var> file and adding the helper to the autoload array.</p>
98
99
100<h2>Using a Helper</h2>
101
102<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>
103
104<p>For example, to create a link using the <dfn>anchor()</dfn> function in one of your view files you would do this:</p>
105
106<code>&lt;?=anchor('blog/comments', 'Click Here');?&gt;</code>
107
108<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>
109
110
111<h2>Now What?</h2>
112
113<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>
114
115
116</div>
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118
119
120<div id="footer">
Derek Allardc6441282007-07-04 23:54:32 +0000[diff] [blame]121<p><a href="#top">Top of Page</a></p>
Derek Jones7a9193a2008-01-21 18:39:20 +0000[diff] [blame^]122<p><a href="http://codeigniter.com">CodeIgniter</a> &nbsp;&middot;&nbsp; Copyright &#169; 2007 &nbsp;&middot;&nbsp; <a href="http://ellislab.com/">Ellislab, Inc.</a></p>
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