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Derek Allard404e35d2007-08-07 01:00:45 +0000[diff] [blame]5<title>CodeIgniter User Guide : Hooks</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>$hook['pre_controller']<kbd>[]</kbd></code>
124
125<p>This permits you to the same hook point with multiple scripts. The order you define your array will be the execution order.</p>
126
127
128<h2>Hook Points</h2>
129
130The following is a list of available hook points.</p>
131
132<ul>
133
134<li><strong>pre_system</strong><br />
135Called very early during system execution. Only the benchmark and hooks class have been loaded at this point. No routing or other processes have happened.</li>
136
137<li><strong>pre_controller</strong><br />
138Called immediately prior to any of your controllers being called. All base classes, routing, and security checks have been done.</li>
139
admina16e8832006-09-06 02:48:30 +0000[diff] [blame]140<li><strong>post_controller_constructor</strong><br />
admin17a890d2006-09-27 20:42:42 +0000[diff] [blame]141Called immediately after your controller is instantiated, but prior to any method calls happening.</li>
admina16e8832006-09-06 02:48:30 +0000[diff] [blame]142
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]143<li><strong>post_controller</strong><br />
admin17a890d2006-09-27 20:42:42 +0000[diff] [blame]144Called immediately after your controller is fully executed.</li>
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]145
146<li><strong>display_override</strong><br />
admine334c472006-10-21 19:44:22 +0000[diff] [blame]147Overrides the <dfn>_display()</dfn> function, used to send the finalized page to the web browser at the end of system execution. This permits you to
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]148use your own display methodology. Note that the finalized data will be available by calling <dfn>$this->output->get_output()</dfn></li>
149
150<li><strong>cache_override</strong><br />
151Enables 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>
152
153<li><strong>scaffolding_override</strong><br />
154Permits a scaffolding request to trigger your own script instead.</li>
155
156<li><strong>post_system</strong><br />
157Called 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>
158
159
160</ul>
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