**Course Title:** Mastering Symfony: Building Enterprise-Level PHP Applications **Section Title:** Building RESTful APIs with Symfony **Topic:** Handling API requests and responses (JSON, XML) Handling API requests and responses is a critical aspect of building a RESTful API with Symfony. In this topic, we'll explore how to handle API requests and responses in JSON and XML formats. **Handling API Requests** When building an API, you'll typically handle two types of requests: `GET` requests to retrieve data and `POST`, `PUT`, and `DELETE` requests to create, update, and delete data. Symfony provides an `HttpRequest` object to handle incoming requests. ### Handling JSON Requests To handle JSON requests, you'll need to use the `JsonRequest` object, which is included in the `Symfony\Component\HttpFoundation` namespace. Here's an example: ```php use Symfony\Component\HttpFoundation\JsonResponse; use Symfony\Component\HttpFoundation\Request; public function handleJsonRequest(Request $request) { if ($request->getMethod() === 'POST') { $requestData = json_decode($request->getContent(), true); // Handle the request data return new JsonResponse($requestData); } return new JsonResponse(['error' => 'Invalid request method'], 400); } ``` In this example, we're using the `JsonResponse` object to return a JSON response. The `json_decode` function is used to parse the JSON data from the request. ### Handling XML Requests To handle XML requests, you'll need to use the `XmlEncoder` object, which is included in the `Symfony\Component\Serializer` namespace. Here's an example: ```php use Symfony\Component\HttpFoundation\Response; use Symfony\Component\Serializer\Encoder\XmlEncoder; use Symfony\Component\Serializer\Normalizer\ObjectNormalizer; public function handleXmlRequest(Request $request) { if ($request->getMethod() === 'POST') { $requestData = $request->getContent(); $encoder = new XmlEncoder(); $normalizer = new ObjectNormalizer(); $response = new Response($encoder->encode($requestData, 'xml'), 200); $response->headers->set('Content-Type', 'application/xml'); return $response; } return new Response('Invalid request method', 400); } ``` In this example, we're using the `XmlEncoder` object to encode the request data into XML format. The `ObjectNormalizer` is used to normalize the request data into an array. **Handling API Responses** When building an API, you'll need to return data in a format that's easily consumable by clients. Symfony provides a `Response` object to handle outgoing responses. ### Returning JSON Responses To return a JSON response, you can use the `JsonResponse` object. Here's an example: ```php use Symfony\Component\HttpFoundation\JsonResponse; public function getUsers() { $users = ['John Doe', 'Jane Doe']; return new JsonResponse($users); } ``` In this example, we're using the `JsonResponse` object to return a JSON response. ### Returning XML Responses To return an XML response, you can use the `Response` object and set the `Content-Type` header to `application/xml`. Here's an example: ```php use Symfony\Component\HttpFoundation\Response; public function getUsers() { $users = ['John Doe', 'Jane Doe']; $encoder = new XmlEncoder(); $response = new Response($encoder->encode($users, 'xml'), 200); $response->headers->set('Content-Type', 'application/xml'); return $response; } ``` In this example, we're using the `XmlEncoder` object to encode the response data into XML format. **Conclusion** In this topic, we covered how to handle API requests and responses in JSON and XML formats using Symfony. We explored how to use the `JsonRequest` object to handle JSON requests and the `XmlEncoder` object to handle XML requests. We also covered how to return JSON and XML responses using the `JsonResponse` and `Response` objects. For more information on handling API requests and responses, please refer to the official Symfony documentation: [https://symfony.com/doc/4.4/controller.html](https://symfony.com/doc/4.4/controller.html) **What's Next?** In the next topic, we'll cover how to implement API authentication using JWT (JSON Web Tokens) or OAuth2. Please provide your feedback on this topic by leaving a comment below or asking for help on any specific aspect of handling API requests and responses.