CodeIgniter Hooks

Enabling Hooks 

By modifying the value of the following item in the application/config/config.php file, the hooks in Codeigniter can be globally enabled or disabled:

$config['enable_hooks'] = TRUE;

Defining Hooks 

In the application/config/hooks.php file, a hook can be specified. Each hook is defined as an array with the terms listed below. 

$hook['pre_controller'] = array(  
            'class' => MyCodingClass,  
            'function' => MyCodingFunction ,  
            'filename' => Coding.php',  
            'filepath' => 'hooks',  
            'params' => array('ele1', 'ele2', 'ele3')  
            );  

Notes:

The name of the hook point you want to use corresponds to the array index. The hook point in the aforementioned example is the pre-controller. Below is a list of hook points. You should define the following items in your associative hook array: 

• Class: the class name you want to invoke. Leave this item blank if you'd instead utilize a procedural function than a class.
   
• Function: The name of the function (or method) you want to call.
   
• Filename: your class's or function's class/function file name.
   
• Filepath: The name of the directory where your script is located. The file path is 
  relative to where your script must be found, which must be inside your application/ directory. For Instance, if your script is placed at application/hooks/, your file path will be ‘hooks.' You should use 'hooks/utilities' as your file path if your script is placed in the application/hooks/utilities/ directory. Not a trailing slash.
   
• Params: Any input you want to give your script. This is an optional item.
   

 Closures or lambda/anonymous functions can also be used as hooks and have a more compact syntax: 

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

Multiple Calls to the Same Hook

Make your array declaration multidimensional like follows if you wish to use the same hook point with many scripts:

$hook['pre_controller'][] = array(
        'class'    => MyCodingClass1,
        'function' => 'MyCodingFunction1’,
        'filename' => 'Coding1.php',
        'filepath' => 'hooks',
        'params'   => array('ele1', 'ele2', 'ele3') 
);


$hook['pre_controller'][] = array(
        'class'    => 'MyCodingClass2',
        'function' => 'MyOtherMethod2',
        'filename' => 'Coding2.php',
        'filepath' => 'hooks',
        'params'   => array('ele4', 'ele5', 'ele6')
);

Notice the brackets after each array index:

$hook['pre_controller'][]

This allows you to use the same hook point across different scripts. The execution order will be in the order that you define your array.

Hook points  

The hook points that are accessible are listed below. 

Hook Example

In CodeIgniter, hooks provide a mechanism for executing custom code at specific points during the application's lifecycle. Hooks allow developers to extend or modify the core functionality of the framework without directly modifying the framework's source code.

Here's a detailed explanation of how hooks work in CodeIgniter:

1. Configuration: Before using hooks, you need to configure them in the application/config/hooks.php file. This file contains an array where you can define the hooks and their respective settings.

2. Defining Hooks: In the hooks.php configuration file, each hook is defined as an array element with the following structure:

$hook['pre_controller'] = array(
   'class'    => 'MyHookClass',
   'function' => 'MyHookMethod',
   'filename' => 'MyHook.php',
   'filepath' => 'hooks',
   'params'   => array('param1', 'param2')
);

• pre_controller: This is the name of the hook point. CodeIgniter provides several predefined hook points such as pre_controller, post_controller_constructor, post_controller, etc.
• class: The name of the class containing the hook method.
• function: The name of the method to be called.
• filename: The filename of the PHP file containing the hook class.
• filepath: The directory where the hook class file is located.
• params: Optional parameters that can be passed to the hook method.
   

3. Creating Hook Classes: You need to create PHP classes containing the hook methods. These classes should be placed in the directory specified by the filepath configuration.

// application/hooks/MyHook.php
class MyHookClass {
   public function MyHookMethod($param1, $param2) {
       // Custom code to be executed
   }
}

4. Execution Flow: When CodeIgniter reaches a hook point during the request lifecycle, it loads and executes the corresponding hook methods. For example, if a hook is defined at the pre_controller point, the associated hook method will be executed before the controller's constructor is called.

5. Use Cases: Hooks can be used for various purposes such as:

• Authentication: Perform user authentication before executing controller methods.
• Logging: Log information about each request or response.
• Profiling: Measure the execution time of controller methods for performance analysis.
• Customization: Extend core functionality by injecting custom logic at specific points.

6. Flexibility: Hooks provide flexibility and extensibility to the CodeIgniter framework, allowing developers to tailor the application's behavior to their specific requirements without modifying the core files.

Frequently asked questions 

What is CodeIgniter?

An open-source web application framework is called Codeigniter. It is used to create PHP-powered websites. In comparison to other PHP frameworks, it is simple to use and loosely based on the MVC pattern. 

How to use middleware in CodeIgniter 3?

Define custom middleware classes in the application/middleware directory and register them in application/config/autoload.php or within controllers.

What are libraries in CodeIgniter?

Libraries are reusable components providing commonly used functionalities, accessed through the load method, aiding in code organization and modularity.

Describe what CodeIgniter's helpers are and how to load a helper file.

Helpers in CodeIgniter are a collection of functions that fall under a specific category and help you carry out particular tasks. Numerous helpers in CodeIgniter, such as URL helpers, facilitate the creation of links. Various text formatting functions are performed by text helpers. Cookies are set and read by text helpers.

Using the command $this->load->helper ('name'), you can load a helper file. 

How does routing work in Codeigniter? 

PHP files are served differently in CodeIgniter than they are when accessed directly from the browser. We refer to this procedure as routing. In CodeIgniter, routing gives you the flexibility to change the default URL pattern to use your own URL pattern depending on the situation.

As a result, whenever a request is made and it matches our pattern of URLs, it will automatically direct to the designated controller and function.

Describe how to add or load a model in CodeIgniter. 

Models are typically loaded within your controller functions; you will use the function 

'Model Name' in $this->load->model;

Conclusion

In this blog, we discussed everything about hooks in codeigniter, and how to enable and define the hooks.

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