PHP language has become one of the standards for Internet application development, and Symfony, as an efficient and flexible PHP framework, is favored by more and more PHP developers. Symfony provides a rich set of components and tools that enable developers to quickly build high-quality web applications. In this article, we will introduce how to use Symfony framework in PHP programming.

1. Installing Symfony
   The easiest way to install the Symfony framework is to use Composer. Composer is a PHP dependency manager that can help us download and install the Symfony framework. First, you need to make sure Composer is installed, and then enter the following command in the terminal:

composer create-project symfony/skeleton my-project

This command will create a new Symfony project named my-project in the current directory. After this, you can start the Symfony application by running the following command:

cd my-project
php -S localhost:8000 -t public

2. Using Controllers
   In Symfony, controllers are used to handle HTTP requests and generate responses. The controller can be a class or a closure function. In the Symfony framework, controller classes need to inherit the SymfonyBundleFrameworkBundleControllerAbstractController class.

A simple controller example is as follows:

Copy after login

In the above example, we created a class named HelloController and created a method named index, This method returns a response containing the string "Hello Symfony".

In order for the controller to be accessible, routes need to be defined in the router. The router maps the request to the correct controller. In the controller, we use annotations to define routes. The following is a simple router example:

add('hello', '/hello')
        ->controller([HelloController::class, 'index']);
};

In the above router, we define a route named "hello", its path is "/hello", and the request will be routed to the index of HelloController method.

3. Using Twig templates
   Twig is a modern, flexible and efficient PHP template engine that is seamlessly integrated with the Symfony framework. The Twig template engine can help you organize your code more efficiently and also improve code reusability. The following is a simple Twig template example:

    
        
    

    
        
{{ message }}
    

In the above template example, we use a template that contains a message variable. The Twig template engine will automatically inject the necessary variables. The following are the modifications to the controller and router:

render('hello.html.twig', [
            'message' => 'Hello Symfony'
        ]);
    }
}

add('hello', '/hello')
        ->controller([HelloController::class, 'index'])
        ->methods(['GET'])
        ->defaults(['_format' => 'html']);
};

In the above example, we modified the index function in HelloController so that it returns a rendered Twig template. At the same time, we also added a default HTML format item in the router so that Twig templates can be rendered correctly.

4. Using Doctrine ORM
   Doctrine is a popular PHP object-relational mapping tool that helps you map PHP classes to database tables. Using Doctrine ORM, we can easily use databases in Symfony applications.

The following is a simple entity example used to represent user information:

id;
    }

    public function getName(): ?string
    {
        return $this->name;
    }

    public function setName(string $name): self
    {
        $this->name = $name;

        return $this;
    }
}

In the above example, we define an entity class named User, which corresponds to A database table named users. We also define an auto-increasing integer column called id, and a string column called name.

In Symfony, we can use Doctrine ORM to easily query and modify entities in the database. Here is a simple query example:

getDoctrine()
            ->getRepository(User::class)
            ->find($id);

        if (!$user) {
            throw $this->createNotFoundException(
                'No user found for id '.$id
            );
        }

        return $this->render('user/show.html.twig', [
            'user' => $user,
        ]);
    }
}

In the above example, we have defined a controller class called UserController, which has a method called show, which accepts an ID parameter and returns An HTML page containing user information.

In short, the Symfony framework is a very powerful and efficient PHP framework that can help us build high-quality web applications. Using Symfony, we can quickly write efficient, reusable code and integrate with external frameworks and tools, such as Twig templates and Doctrine ORM. If you are a PHP developer, I believe you will greatly appreciate using Symfony to write code.

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