165 lines
11 KiB
HTML
165 lines
11 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>Hooks : CodeIgniter User Guide</title>
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<style type='text/css' media='all'>@import url('../userguide.css');</style>
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<link rel='stylesheet' type='text/css' media='all' href='../userguide.css' />
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<script type="text/javascript" src="../nav/nav.js"></script>
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<script type="text/javascript" src="../nav/prototype.lite.js"></script>
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<script type="text/javascript" src="../nav/moo.fx.js"></script>
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<script type="text/javascript" src="../nav/user_guide_menu.js"></script>
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<meta http-equiv='expires' content='-1' />
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<meta http-equiv= 'pragma' content='no-cache' />
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<meta name='robots' content='all' />
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<meta name='author' content='ExpressionEngine Dev Team' />
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<meta name='description' content='CodeIgniter User Guide' />
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</head>
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<body>
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<!-- START NAVIGATION -->
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<div id="nav"><div id="nav_inner"><script type="text/javascript">create_menu('../');</script></div></div>
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<div id="nav2"><a name="top"></a><a href="javascript:void(0);" onclick="myHeight.toggle();"><img src="../images/nav_toggle_darker.jpg" width="154" height="43" border="0" title="Toggle Table of Contents" alt="Toggle Table of Contents" /></a></div>
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<div id="masthead">
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<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
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<tr>
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<td><h1>CodeIgniter User Guide Version 2.1.3</h1></td>
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<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
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</tr>
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</table>
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</div>
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<!-- END NAVIGATION -->
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<!-- START BREADCRUMB -->
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<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
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<tr>
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<td id="breadcrumb">
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<a href="http://codeigniter.com/">CodeIgniter Home</a> ›
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<a href="../index.html">User Guide Home</a> ›
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Hooks - Extending the Framework Core
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</td>
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<td id="searchbox"><form method="get" action="http://www.google.com/search"><input type="hidden" name="as_sitesearch" id="as_sitesearch" value="codeigniter.com/user_guide/" />Search User Guide <input type="text" class="input" style="width:200px;" name="q" id="q" size="31" maxlength="255" value="" /> <input type="submit" class="submit" name="sa" value="Go" /></form></td>
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</tr>
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</table>
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<!-- END BREADCRUMB -->
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<br clear="all" />
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<!-- START CONTENT -->
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<div id="content">
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<h1>Hooks - Extending the Framework Core</h1>
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<p>CodeIgniter's Hooks feature provides a means to tap into and modify the inner workings of the framework without hacking the core files.
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When CodeIgniter runs it follows a specific execution process, diagramed in the <a href="../overview/appflow.html">Application Flow</a> page.
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There may be instances, however, where you'd like to cause some action to take place at a particular stage in the execution process.
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For example, you might want to run a script right before your controllers get loaded, or right after, or you might want to trigger one of
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your own scripts in some other location.
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</p>
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<h2>Enabling Hooks</h2>
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<p>The hooks feature can be globally enabled/disabled by setting the following item in the <kbd>application/config/config.php</kbd> file:</p>
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<code>$config['enable_hooks'] = TRUE;</code>
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<h2>Defining a Hook</h2>
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<p>Hooks are defined in <dfn>application/config/hooks.php</dfn> file. Each hook is specified as an array with this prototype:</p>
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<code>
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$hook['pre_controller'] = array(<br />
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'class' => 'MyClass',<br />
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'function' => 'Myfunction',<br />
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'filename' => 'Myclass.php',<br />
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'filepath' => 'hooks',<br />
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'params' => array('beer', 'wine', 'snacks')<br />
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);</code>
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<p><strong>Notes:</strong><br />The array index correlates to the name of the particular hook point you want to
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use. In the above example the hook point is <kbd>pre_controller</kbd>. A list of hook points is found below.
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The following items should be defined in your associative hook array:</p>
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<ul>
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<li><strong>class</strong> The name of the class you wish to invoke. If you prefer to use a procedural function instead of a class, leave this item blank.</li>
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<li><strong>function</strong> The function name you wish to call.</li>
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<li><strong>filename</strong> The file name containing your class/function.</li>
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<li><strong>filepath</strong> The name of the directory containing your script. Note: Your script must be located in a directory INSIDE your <kbd>application</kbd> folder, so the file path is relative to that folder. For example, if your script is located in <dfn>application/hooks</dfn>, you will simply use <samp>hooks</samp> as your filepath. If your script is located in <dfn>application/hooks/utilities</dfn> you will use <samp>hooks/utilities</samp> as your filepath. No trailing slash.</li>
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<li><strong>params</strong> Any parameters you wish to pass to your script. This item is optional.</li>
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</ul>
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<h2>Multiple Calls to the Same Hook</h2>
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<p>If want to use the same hook point with more then one script, simply make your array declaration multi-dimensional, like this:</p>
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<code>
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$hook['pre_controller']<kbd>[]</kbd> = array(<br />
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'class' => 'MyClass',<br />
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'function' => 'Myfunction',<br />
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'filename' => 'Myclass.php',<br />
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'filepath' => 'hooks',<br />
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'params' => array('beer', 'wine', 'snacks')<br />
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);<br />
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<br />
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$hook['pre_controller']<kbd>[]</kbd> = array(<br />
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'class' => 'MyOtherClass',<br />
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'function' => 'MyOtherfunction',<br />
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'filename' => 'Myotherclass.php',<br />
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'filepath' => 'hooks',<br />
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'params' => array('red', 'yellow', 'blue')<br />
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);</code>
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<p>Notice the brackets after each array index:</p>
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<code>$hook['pre_controller']<kbd>[]</kbd></code>
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<p>This permits you to have the same hook point with multiple scripts. The order you define your array will be the execution order.</p>
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<h2>Hook Points</h2>
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<p>The following is a list of available hook points.</p>
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<ul>
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<li><strong>pre_system</strong><br />
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Called very early during system execution. Only the benchmark and hooks class have been loaded at this point. No routing or other processes have happened.</li>
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<li><strong>pre_controller</strong><br />
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Called immediately prior to any of your controllers being called. All base classes, routing, and security checks have been done.</li>
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<li><strong>post_controller_constructor</strong><br />
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Called immediately after your controller is instantiated, but prior to any method calls happening.</li>
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<li><strong>post_controller</strong><br />
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Called immediately after your controller is fully executed.</li>
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<li><strong>display_override</strong><br />
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Overrides the <dfn>_display()</dfn> function, used to send the finalized page to the web browser at the end of system execution. This permits you to
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use your own display methodology. Note that you will need to reference the CI superobject with <dfn>$this->CI =& get_instance()</dfn> and then the finalized data will be available by calling <dfn>$this->CI->output->get_output()</dfn></li>
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<li><strong>cache_override</strong><br />
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Enables you to call your own function instead of the <dfn>_display_cache()</dfn> function in the output class. This permits you to use your own cache display mechanism.</li>
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<li><strong>post_system</strong><br />
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Called after the final rendered page is sent to the browser, at the end of system execution after the finalized data is sent to the browser.</li>
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</ul>
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</div>
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<!-- END CONTENT -->
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<div id="footer">
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<p>
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Previous Topic: <a href="core_classes.html">Creating Core Classes</a>
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·
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<a href="#top">Top of Page</a> ·
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<a href="../index.html">User Guide Home</a> ·
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Next Topic: <a href="autoloader.html">Auto-loading Resources</a>
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</p>
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<p><a href="http://codeigniter.com">CodeIgniter</a> · Copyright © 2006 - 2012 · <a href="http://ellislab.com/">EllisLab, Inc.</a></p>
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</div>
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</body>
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</html>
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