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Derek Jonesfd93d222008-05-06 15:18:50 +0000[diff] [blame]5<title>Hooks : CodeIgniter User Guide</title>
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45Hooks - Extending the Framework Core
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58<h1>Hooks - Extending the Framework Core</h1>
59
Derek Allardd2df9bc2007-04-15 17:41:17 +0000[diff] [blame]60<p>CodeIgniter's Hooks feature provides a means to tap into and modify the inner workings of the framework without hacking the core files.
61When CodeIgniter runs it follows a specific execution process, diagramed in the <a href="../overview/appflow.html">Application Flow</a> page.
admine334c472006-10-21 19:44:22 +0000[diff] [blame]62There may be instances, however, where you'd like to cause some action to take place at a particular stage in the execution process.
63For 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
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]64your own scripts in some other location.
65</p>
66
admin2ed76d52006-09-02 17:34:52 +0000[diff] [blame]67<h2>Enabling Hooks</h2>
68
69<p>The hooks feature can be globally enabled/disabled by setting the following item in the <kbd>application/config/config.php</kbd> file:</p>
70
71<code>$config['enable_hooks'] = TRUE;</code>
72
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]73
74<h2>Defining a Hook</h2>
75
76<p>Hooks are defined in <dfn>application/config/hooks.php</dfn> file. Each hook is specified as an array with this prototype:</p>
77
78<code>
79$hook['pre_controller'] = array(<br />
80&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'class'&nbsp;&nbsp;&nbsp;&nbsp;=> 'MyClass',<br />
admine334c472006-10-21 19:44:22 +0000[diff] [blame]81&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'function' => 'Myfunction',<br />
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]82&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'filename' => 'Myclass.php',<br />
83&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'filepath' => 'hooks',<br />
84&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'params'&nbsp;&nbsp;&nbsp;=> array('beer', 'wine', 'snacks')<br />
85&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;);</code>
86
admine334c472006-10-21 19:44:22 +0000[diff] [blame]87<p><strong>Notes:</strong><br />The array index correlates to the name of the particular hook point you want to
88use. In the above example the hook point is <kbd>pre_controller</kbd>. A list of hook points is found below.
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]89The following items should be defined in your associative hook array:</p>
90
91<ul>
92<li><strong>class</strong>&nbsp; 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>
93<li><strong>function</strong>&nbsp; The function name you wish to call.</li>
94<li><strong>filename</strong>&nbsp; The file name containing your class/function.</li>
95<li><strong>filepath</strong>&nbsp; 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>
96<li><strong>params</strong>&nbsp; Any parameters you wish to pass to your script. This item is optional.</li>
97</ul>
98
99
100<h2>Multiple Calls to the Same Hook</h2>
101
Derek Allardc6441282007-07-04 23:54:32 +0000[diff] [blame]102<p>If want to use the same hook point with more then one script, simply make your array declaration multi-dimensional, like this:</p>
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]103
104<code>
105$hook['pre_controller']<kbd>[]</kbd> = array(<br />
106&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'class'&nbsp;&nbsp;&nbsp;&nbsp;=> 'MyClass',<br />
admine334c472006-10-21 19:44:22 +0000[diff] [blame]107&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'function' => 'Myfunction',<br />
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]108&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'filename' => 'Myclass.php',<br />
109&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'filepath' => 'hooks',<br />
110&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'params'&nbsp;&nbsp;&nbsp;=> array('beer', 'wine', 'snacks')<br />
111&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;);<br />
112<br />
113$hook['pre_controller']<kbd>[]</kbd> = array(<br />
114&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'class'&nbsp;&nbsp;&nbsp;&nbsp;=> 'MyOtherClass',<br />
admine334c472006-10-21 19:44:22 +0000[diff] [blame]115&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'function' => 'MyOtherfunction',<br />
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]116&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'filename' => 'Myotherclass.php',<br />
117&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'filepath' => 'hooks',<br />
118&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'params'&nbsp;&nbsp;&nbsp;=> array('red', 'yellow', 'blue')<br />
119&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;);</code>
120
121<p>Notice the brackets after each array index:</p>
122
123<code>$hook['pre_controller']<kbd>[]</kbd></code>
124
Derek Allard1ea127a2008-04-04 12:26:46 +0000[diff] [blame]125<p>This permits you to have the same hook point with multiple scripts. The order you define your array will be the execution order.</p>
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]126
127
128<h2>Hook Points</h2>
129
Derek Allardce66d152008-03-04 20:55:55 +0000[diff] [blame]130<p>The following is a list of available hook points.</p>
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]131
132<ul>
Derek Allard1ea127a2008-04-04 12:26:46 +0000[diff] [blame]133 <li><strong>pre_system</strong><br />
134 Called very early during system execution. Only the benchmark and hooks class have been loaded at this point. No routing or other processes have happened.</li>
135 <li><strong>pre_controller</strong><br />
136 Called immediately prior to any of your controllers being called. All base classes, routing, and security checks have been done.</li>
137 <li><strong>post_controller_constructor</strong><br />
138 Called immediately after your controller is instantiated, but prior to any method calls happening.</li>
139 <li><strong>post_controller</strong><br />
140 Called immediately after your controller is fully executed.</li>
141 <li><strong>display_override</strong><br />
142 Overrides the <dfn>_display()</dfn> function, used to send the finalized page to the web browser at the end of system execution. This permits you to
143 use your own display methodology. Note that the finalized data will be available by calling <dfn>$this->output->get_output()</dfn></li>
144 <li><strong>cache_override</strong><br />
145 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>
146 <li><strong>scaffolding_override</strong><br />
147 Permits a scaffolding request to trigger your own script instead.</li>
148 <li><strong>post_system</strong><br />
149 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>
150 </ul>
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