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laravel running process

WBOYOriginal: 2023-05-26 15:25:09603browse

Laravel is currently one of the most popular PHP frameworks. Its design concept is simple and elegant, and it also provides many tools and functions that facilitate development. In Laravel, a request eventually becomes a response, and there are many components in this process to meet the needs of developers. This article will introduce the running process of Laravel in detail, from the beginning of the request to the end of the response, so that readers can understand how each step works.

Routing

The first component in Laravel is routing. Its purpose is to determine the corresponding processing logic based on the requested URL. In Laravel, the definition of routes is very simple. A series of routes can be defined in the routes/web.php file, as follows:

Route::get('/', function () {
    return view('welcome');
});

In the above code, we define a route that handles the root path. This route The processing logic is to return a template file named welcome.

Requests and middleware

When a request reaches the application, the application will first encapsulate the request into an IlluminateHttpRequest object. This object contains a series of useful methods and properties that allow us to easily obtain various parts of the request, such as GET parameters, POST parameters, etc.

After the request reaches the application, the next step is to go through a series of middleware. Middleware can be regarded as the processing layer between requests and responses. Some common processing logic can be implemented through middleware, such as verifying user permissions, cross-domain processing, sending emails, etc. In Laravel, middleware is defined in the app/Http/Middleware directory. The following is a sample code for defining middleware:

<?php

namespace AppHttpMiddleware;

use Closure;

class MyMiddleware
{
    public function handle($request, Closure $next)
    {
        // 在请求处理之前的自定义逻辑
        return $next($request);
    }
}

Controller

In Laravel , the controller is an important part of handling HTTP requests. It is the core piece that combines models, views, and other classes to make request logic more structured and maintainable. When a request passes through routing and middleware, the Laravel framework processes the request based on the controller class and its methods specified in the routing and returns a response.

The following is a simple controller sample code:

<?php

namespace AppHttpControllers;

use IlluminateHttpRequest;

class MyController extends Controller
{
    public function index(Request $request)
    {
        return view('my.view', ['key' => 'value']);
    }
}

In the above code, we define a MyController controller and define a method in it to handle index requests. This method returns the view of my.view and passes a parameter named key.

View

View is another important component in Laravel. They are the components that display the user interface, rendering HTML code that the user can see. In Laravel, view files are stored in the resources/views directory. When the controller returns a view, Laravel will automatically look for matching template files in this directory.

The following is a simple view sample code:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>My View</title>
</head>
<body>
    <p>The value of the key parameter is: {{ $key }}</p>
</body>
</html>

In the above code, we define a simple HTML file, and then output the controller pass through {{ $key }} passed parameters.

Response

The last component of the request is the response. There are many forms of responses in Laravel, which can be a plain text string, an HTML view, a JSON response, etc. In Laravel, response objects are instances of the SymfonyComponentHttpFoundationResponse class. When you return a response in your controller, Laravel converts it into a complete response object and sends it back to the client.

The following is a sample code that returns a JSON response:

<?php

namespace AppHttpControllers;

use IlluminateHttpRequest;

class MyController extends Controller
{
    public function index(Request $request)
    {
        return response()->json([
            'message' => 'Hello World!',
        ]);
    }
}

In the above code, we return a JSON response containing the message key and "Hello World!" value.

Summary

The above is the running process of Laravel. From the definition of routes to the sending of responses, each component plays its own unique role. Understanding how these components work will help you better use Laravel to develop your own applications, and it will also help you better understand the entire life cycle of PHP applications.

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