+ +
+

Hooks - Extending the Framework Core

+

CodeIgniter’s Hooks feature provides a means to tap into and modify the +inner workings of the framework without hacking the core files. When +CodeIgniter runs it follows a specific execution process, diagramed in +the Application Flow 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.

+
+

Enabling Hooks

+

The hooks feature can be globally enabled/disabled by setting the +following item in the application/config/config.php file:

+
$config['enable_hooks'] = TRUE;
+
+
+
+
+

Defining a Hook

+

Hooks are defined in the application/config/hooks.php file. +Each hook is specified as an array with this prototype:

+
$hook['pre_controller'] = array(
+        'class'    => 'MyClass',
+        'function' => 'Myfunction',
+        'filename' => 'Myclass.php',
+        'filepath' => 'hooks',
+        'params'   => array('beer', 'wine', 'snacks')
+);
+
+
+

Notes:

+

The array index correlates to the name of the particular hook point you +want to use. In the above example the hook point is pre_controller. A +list of hook points is found below. The following items should be +defined in your associative hook array:

+
    +
  • class 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.
    • +
  • function The function (or method) name you wish to call.
    • +
  • filename The file name containing your class/function.
    • +
  • filepath The name of the directory containing your script. +Note: +Your script must be located in a directory INSIDE your application/ +directory, so the file path is relative to that directory. For example, +if your script is located in application/hooks/, you will simply use +‘hooks’ as your filepath. If your script is located in +application/hooks/utilities/ you will use ‘hooks/utilities’ as your +filepath. No trailing slash.
    • +
  • params Any parameters you wish to pass to your script. This item +is optional.
    • +
+

You can also use lambda/anoymous functions (or closures) as hooks, with +a simpler syntax:

+
$hook['post_controller'] = function()
+{
+        /* do something here */
+};
+
+
+
+
+

Multiple Calls to the Same Hook

+

If want to use the same hook point with more than one script, simply +make your array declaration multi-dimensional, like this:

+
$hook['pre_controller'][] = array(
+        'class'    => 'MyClass',
+        'function' => 'MyMethod',
+        'filename' => 'Myclass.php',
+        'filepath' => 'hooks',
+        'params'   => array('beer', 'wine', 'snacks')
+);
+
+$hook['pre_controller'][] = array(
+        'class'    => 'MyOtherClass',
+        'function' => 'MyOtherMethod',
+        'filename' => 'Myotherclass.php',
+        'filepath' => 'hooks',
+        'params'   => array('red', 'yellow', 'blue')
+);
+
+
+

Notice the brackets after each array index:

+
$hook['pre_controller'][]
+
+
+

This permits you to have the same hook point with multiple scripts. The +order you define your array will be the execution order.

+
+
+

Hook Points

+

The following is a list of available hook points.

+
    +
  • pre_system +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.
    • +
  • pre_controller +Called immediately prior to any of your controllers being called. +All base classes, routing, and security checks have been done.
    • +
  • post_controller_constructor +Called immediately after your controller is instantiated, but prior +to any method calls happening.
    • +
  • post_controller +Called immediately after your controller is fully executed.
    • +
  • display_override +Overrides the _display() method, 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 you will need to +reference the CI superobject with $this->CI =& get_instance() and +then the finalized data will be available by calling +$this->CI->output->get_output().
    • +
  • cache_override +Enables you to call your own method instead of the _display_cache() +method in the Output Library. This permits +you to use your own cache display mechanism.
    • +
  • post_system +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.
    • +
+
+
+ + +