Hello Symfony!¶

In this post, we will create a simply Somfony project and running the application.

Symfony follows the famous MVC pattern to handle request. The controller role is responsible for handling incoming request, updating models and sending results to the HTTP response.

Creating Controller¶

Here we will create a simple Controller to experience Symfony request handling.

class HelloController
{
    /**
     * @param Request $request
     * @return Response
     */
    #[Route('/hello', name: 'hello', methods:['GET'])]
    public function sayHello(Request $request): Response
    {
        $name = $request->get("name") ?? "Symfony";
        $data = ['message' => 'Hello ' . $name];

        return new JsonResponse($data, 200, [], true);
    }
}

Attribute is a new feature introduced in PHP 8.0, here we use Route attribute to define the routing rule for the HelloController.

Configuring Routes¶

According to the Route attribute defined in the sayHello method, if the incoming request path is matched with /hello and the request method is GET, it will be handled by HelloController.sayHello method. The request argument will be filled before invoking this method, it includes all request data in this request context. Every handling method return a Reponse, including the response status, view data, etc.

Symfony provides several approaches to configure the routes, such as YAML, annotations, XML, JSON, etc. But the PHP official Attribute will be the trend in future. We do not cover other methods in this tutorial.

To use the newest PHP 8 Attribute to configure the routing rules, apply the following changes in the project configuration.

Open config/packages/doctrine.yaml, remove doctrine/orm/mapping/App/type node in the configuration tree or change its value to attribute.
Open composer.json, make sure the PHP version set to >=8.0.0.

Rendering JSON Response¶

To render the response body into a JSON string, use a JsonReponse to wrap the response. The first parameter of JsonReponse accepts an array as data. In PHP, it is a little tedious to convert an object to an array.

Symfony provides a simple AbstractController which includes several functions to simplfy the response building and adopt the container and dependency injection management.

Change the above controller, make it to extend from AbstractController.

class HelloController extends AbstractController
{
    /**
     * @param Request $request
     * @return Response
     */
    #[Get('/hello', name: 'hello')]
    public function sayHello(Request $request): Response
    {
        $name = $request->get("name") ?? "Symfony";
        $data = Greeting::of('Hello ' . $name);
        return $this->json($data);
    }
}

It simply invoke $this->json to accept an object and render the response in JSON format, no need to transform the data to an array before rendering response.

The Greeting is a plain PHP class.

class Greeting
{
    private string $message;

    static function of(string $message): Greeting
    {
        $data = new Greeting();
        return $data->setMessage($message);
    }

    // use IDE to generate setters and getters
}

Run the application, use curl to test the /hello endpoint.

$ curl http://localhost:8000/hello
{"message":"Hello Symfony"}
$ curl http://localhost:8000/hello?name=Hantsy
{"message":"Hello Hantsy"}