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admin05186612006-10-28 03:28:01 +0000[diff] [blame]36<td><h1>Code Igniter User Guide Version 1.5.0</h1></td>
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50Hooks - Extending the Framework Core
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63<h1>Hooks - Extending the Framework Core</h1>
64
admine334c472006-10-21 19:44:22 +0000[diff] [blame]65<p>Code Igniter's Hooks feature provides a means to tap into and modify the inner workings of the framework without hacking the core files.
66When Code Igniter runs it follows a specific execution process, diagramed in the <a href="../overview/appflow.html">Application Flow</a> page.
67There may be instances, however, where you'd like to cause some action to take place at a particular stage in the execution process.
68For 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]69your own scripts in some other location.
70</p>
71
admin2ed76d52006-09-02 17:34:52 +0000[diff] [blame]72<h2>Enabling Hooks</h2>
73
74<p>The hooks feature can be globally enabled/disabled by setting the following item in the <kbd>application/config/config.php</kbd> file:</p>
75
76<code>$config['enable_hooks'] = TRUE;</code>
77
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]78
79<h2>Defining a Hook</h2>
80
81<p>Hooks are defined in <dfn>application/config/hooks.php</dfn> file. Each hook is specified as an array with this prototype:</p>
82
83<code>
84$hook['pre_controller'] = array(<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;'class'&nbsp;&nbsp;&nbsp;&nbsp;=> 'MyClass',<br />
admine334c472006-10-21 19:44:22 +0000[diff] [blame]86&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&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]87&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&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 />
88&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&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 />
89&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&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 />
90&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&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>
91
admine334c472006-10-21 19:44:22 +0000[diff] [blame]92<p><strong>Notes:</strong><br />The array index correlates to the name of the particular hook point you want to
93use. 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]94The following items should be defined in your associative hook array:</p>
95
96<ul>
97<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>
98<li><strong>function</strong>&nbsp; The function name you wish to call.</li>
99<li><strong>filename</strong>&nbsp; The file name containing your class/function.</li>
100<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>
101<li><strong>params</strong>&nbsp; Any parameters you wish to pass to your script. This item is optional.</li>
102</ul>
103
104
105<h2>Multiple Calls to the Same Hook</h2>
106
107<p>If want to use the same hook point with more then one script, simply make your array declaration multi-dimensional, like this:
108
109<code>
110$hook['pre_controller']<kbd>[]</kbd> = array(<br />
111&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'class'&nbsp;&nbsp;&nbsp;&nbsp;=> 'MyClass',<br />
admine334c472006-10-21 19:44:22 +0000[diff] [blame]112&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'function' => 'Myfunction',<br />
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]113&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'filename' => 'Myclass.php',<br />
114&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'filepath' => 'hooks',<br />
115&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;'params'&nbsp;&nbsp;&nbsp;=> array('beer', 'wine', 'snacks')<br />
116&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;);<br />
117<br />
118$hook['pre_controller']<kbd>[]</kbd> = array(<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;'class'&nbsp;&nbsp;&nbsp;&nbsp;=> 'MyOtherClass',<br />
admine334c472006-10-21 19:44:22 +0000[diff] [blame]120&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&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]121&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&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 />
122&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&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 />
123&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&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 />
124&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&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>
125
126<p>Notice the brackets after each array index:</p>
127
128<code>$hook['pre_controller']<kbd>[]</kbd></code>
129
130<p>This permits you to the same hook point with multiple scripts. The order you define your array will be the execution order.</p>
131
132
133<h2>Hook Points</h2>
134
135The following is a list of available hook points.</p>
136
137<ul>
138
139<li><strong>pre_system</strong><br />
140Called very early during system execution. Only the benchmark and hooks class have been loaded at this point. No routing or other processes have happened.</li>
141
142<li><strong>pre_controller</strong><br />
143Called immediately prior to any of your controllers being called. All base classes, routing, and security checks have been done.</li>
144
admina16e8832006-09-06 02:48:30 +0000[diff] [blame]145<li><strong>post_controller_constructor</strong><br />
admin17a890d2006-09-27 20:42:42 +0000[diff] [blame]146Called immediately after your controller is instantiated, but prior to any method calls happening.</li>
admina16e8832006-09-06 02:48:30 +0000[diff] [blame]147
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]148<li><strong>post_controller</strong><br />
admin17a890d2006-09-27 20:42:42 +0000[diff] [blame]149Called immediately after your controller is fully executed.</li>
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]150
151<li><strong>display_override</strong><br />
admine334c472006-10-21 19:44:22 +0000[diff] [blame]152Overrides the <dfn>_display()</dfn> function, used to send the finalized page to the web browser at the end of system execution. This permits you to
adminb0dd10f2006-08-25 17:25:49 +0000[diff] [blame]153use your own display methodology. Note that the finalized data will be available by calling <dfn>$this->output->get_output()</dfn></li>
154
155<li><strong>cache_override</strong><br />
156Enables 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>
157
158<li><strong>scaffolding_override</strong><br />
159Permits a scaffolding request to trigger your own script instead.</li>
160
161<li><strong>post_system</strong><br />
162Called 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>
163
164
165</ul>
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