How to implement custom middleware in CodeIgniter

How to implement custom middleware in CodeIgniter

Introduction:
In modern web development, middleware plays a vital role in applications. They can be used to perform some shared processing logic before or after the request reaches the controller. CodeIgniter, as a popular PHP framework, also supports the use of middleware. This article will introduce how to implement custom middleware in CodeIgniter and provide a simple code example.

Middleware Overview:
Middleware is a mechanism that performs some action before or after the request reaches the controller. They can be used to handle common business logic such as authentication, logging, access control, etc. In CodeIgniter, middleware can be thought of as an interceptor, capable of performing some additional logic before or after the request reaches the controller.

The steps to implement custom middleware are as follows:

Step 1: Create a custom middleware class
Create a middleware class, named MyMiddleware, and place it in application/middlewares Save in directory. This class needs to implement the CodeIgniterMiddlewareMiddlewareInterface interface and implement the handle() method. The handle() method is the core method of middleware and is used to handle specific logic.

<?php

namespace AppMiddlewares;

use CodeIgniterMiddlewareMiddlewareInterface;
use CodeIgniterHTTPRequestInterface;
use CodeIgniterHTTPResponseInterface;

class MyMiddleware implements MiddlewareInterface
{
    public function handle(RequestInterface $request, ResponseInterface $response, $arguments = null)
    {
        // 在请求到达控制器之前执行的代码
        // 可以在这里实现身份验证、日志记录、访问控制等逻辑

        // 继续处理请求
        $response = $this->next($request, $response);

        // 在请求到达控制器之后执行的代码
        // 可以在这里实现日志记录、响应处理等逻辑

        return $response;
    }
}

Step 2: Register middleware
Open the app/Config/Autoload.php file and add the following configuration in the $psr4 array to automatically load the middleware class:

$psr4 = [
    'App'         => APPPATH,                // 默认
    'Config'      => APPPATH . 'Config',
    'Modules'     => ROOTPATH . 'modules',    // 可选
    'AppMiddlewares' => APPPATH . 'middlewares' // 添加这一行
];

Then open the app/Config/Events.php file and add the class name of the middleware in the 'middleware' key of the $filters array, as shown below:

$filters = [
    'csrf'    => AppFiltersCSRF::class,
    'toolbar' => AppFiltersDebugToolbar::class,
    'honeypot' => AppFiltersHoneypot::class,
    'middleware' => AppMiddlewaresMyMiddleware::class // 添加这一行
];

Step 3: Use middleware
To To use middleware in a controller, just add the following code in the __construct() method of the controller:

public function __construct()
{
    $this->middleware('MyMiddleware');
}

Middleware will be executed in the order registered in the $filters array. You can also use $this->middleware([]) in the controller's __construct() method to add multiple middlewares and define their execution order.

Summary:
This article introduces how to implement custom middleware in CodeIgniter. By creating a custom middleware class and registering it with the application, we can perform some common processing logic before or after the request reaches the controller. I hope this article can help you better understand and use middleware in CodeIgniter.

Reference:

• CodeIgniter official documentation: https://codeigniter.com/user_guide/incoming/middleware.html

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