**Course Title:** Mastering Yii Framework: Building Scalable Web Applications **Section Title:** RESTful API Development with Yii **Topic:** Handling API requests and responses (JSON format) **Overview** In this topic, we will explore how to handle API requests and responses in Yii, focusing on JSON format. We will cover the basics of JSON, how to send and receive JSON data in API requests and responses, and how to use Yii's built-in features to handle JSON data. **JSON Basics** JSON (JavaScript Object Notation) is a lightweight data interchange format that is easy to read and write. It is commonly used for exchanging data between web servers, web applications, and mobile apps. JSON data is represented as a collection of key-value pairs, arrays, and objects. Here is an example of a simple JSON object: ```json { "name": "John Doe", "age": 30, "city": "New York" } ``` **Sending JSON Data in API Requests** When sending JSON data in API requests, you need to specify the `Content-Type` header as `application/json`. You can use the `Yii::$app->request->post()` method to send JSON data in the request body. Here is an example of sending JSON data in a POST request: ```php $data = [ 'name' => 'John Doe', 'age' => 30, 'city' => 'New York' ]; Yii::$app->request->post($data); ``` **Receiving JSON Data in API Responses** When receiving JSON data in API responses, you can use the `Yii::$app->response->data` property to access the JSON data. Here is an example of receiving JSON data in a GET request: ```php $data = Yii::$app->response->data; print_r($data); ``` This would output: ```json { "name": "John Doe", "age": 30, "city": "New York" } ``` **Handling JSON Data in Yii** Yii provides several features to handle JSON data, including: * **JSON encoding and decoding**: Yii provides the `json_encode()` and `json_decode()` functions to encode and decode JSON data. * **JSON validation**: Yii provides the `yii\validators\JsonValidator` class to validate JSON data. * **JSON formatting**: Yii provides the `yii\helpers\Json` class to format JSON data. Here is an example of using the `json_encode()` function to encode JSON data: ```php $data = [ 'name' => 'John Doe', 'age' => 30, 'city' => 'New York' ]; $jsonData = json_encode($data); print_r($jsonData); ``` This would output: ```json {"name":"John Doe","age":30,"city":"New York"} ``` **Conclusion** In this topic, we covered how to handle API requests and responses in Yii, focusing on JSON format. We learned how to send and receive JSON data in API requests and responses, and how to use Yii's built-in features to handle JSON data. **What's Next?** In the next topic, we will explore API authentication techniques, including JWT and OAuth2. **Leave a comment or ask for help if you have any questions or need further clarification on any of the concepts covered in this topic.** **External Resources:** * [JSON specification](https://www.json.org/json-en.html) * [Yii documentation: JSON encoding and decoding](https://www.yiiframework.com/doc/api/2.0/yii-base-json) * [Yii documentation: JSON validation](https://www.yiiframework.com/doc/api/2.0/yii-validators-jsonvalidator) * [Yii documentation: JSON formatting](https://www.yiiframework.com/doc/api/2.0/yii-helpers-json)