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| <td><h1>Code Igniter User Guide Version 1.4.0</h1></td> | |
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| Hooks - Extending the Framework Core | |
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| <h1>Hooks - Extending the Framework Core</h1> | |
| <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. | |
| When Code Igniter runs it follows a specific execution process, diagramed in the <a href="../overview/appflow.html">Application Flow</a> page. | |
| There may be instances, however, where you'd like to cause some action to take place at a particular stage in the execution process. | |
| 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 | |
| your own scripts in some other location. | |
| </p> | |
| <h2>Defining a Hook</h2> | |
| <p>Hooks are defined in <dfn>application/config/hooks.php</dfn> file. Each hook is specified as an array with this prototype:</p> | |
| <code> | |
| $hook['pre_controller'] = array(<br /> | |
| 'class' => 'MyClass',<br /> | |
| 'function' => 'Myfunction',<br /> | |
| 'filename' => 'Myclass.php',<br /> | |
| 'filepath' => 'hooks',<br /> | |
| 'params' => array('beer', 'wine', 'snacks')<br /> | |
| );</code> | |
| <p><strong>Notes:</strong><br />The array index correlates to the name of the particular hook point you want to | |
| use. In the above example the hook point is <kbd>pre_controller</kbd>. A list of hook points is found below. | |
| The following items should be defined in your associative hook array:</p> | |
| <ul> | |
| <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> | |
| <li><strong>function</strong> The function name you wish to call.</li> | |
| <li><strong>filename</strong> The file name containing your class/function.</li> | |
| <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> | |
| <li><strong>params</strong> Any parameters you wish to pass to your script. This item is optional.</li> | |
| </ul> | |
| <h2>Multiple Calls to the Same Hook</h2> | |
| <p>If want to use the same hook point with more then one script, simply make your array declaration multi-dimensional, like this: | |
| <code> | |
| $hook['pre_controller']<kbd>[]</kbd> = array(<br /> | |
| 'class' => 'MyClass',<br /> | |
| 'function' => 'Myfunction',<br /> | |
| 'filename' => 'Myclass.php',<br /> | |
| 'filepath' => 'hooks',<br /> | |
| 'params' => array('beer', 'wine', 'snacks')<br /> | |
| );<br /> | |
| <br /> | |
| $hook['pre_controller']<kbd>[]</kbd> = array(<br /> | |
| 'class' => 'MyOtherClass',<br /> | |
| 'function' => 'MyOtherfunction',<br /> | |
| 'filename' => 'Myotherclass.php',<br /> | |
| 'filepath' => 'hooks',<br /> | |
| 'params' => array('red', 'yellow', 'blue')<br /> | |
| );</code> | |
| <p>Notice the brackets after each array index:</p> | |
| <code>$hook['pre_controller']<kbd>[]</kbd></code> | |
| <p>This permits you to the same hook point with multiple scripts. The order you define your array will be the execution order.</p> | |
| <h2>Hook Points</h2> | |
| The following is a list of available hook points.</p> | |
| <ul> | |
| <li><strong>pre_system</strong><br /> | |
| 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> | |
| <li><strong>pre_controller</strong><br /> | |
| Called immediately prior to any of your controllers being called. All base classes, routing, and security checks have been done.</li> | |
| <li><strong>post_controller</strong><br /> | |
| Called immediately after the controller is called.</li> | |
| <li><strong>display_override</strong><br /> | |
| 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 | |
| use your own display methodology. Note that the finalized data will be available by calling <dfn>$this->output->get_output()</dfn></li> | |
| <li><strong>cache_override</strong><br /> | |
| 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> | |
| <li><strong>scaffolding_override</strong><br /> | |
| Permits a scaffolding request to trigger your own script instead.</li> | |
| <li><strong>post_system</strong><br /> | |
| 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> | |
| </ul> | |
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