Interview #152: Rest-Assured: How do you send a POST/PUT request with a payload?

RestAssured is a powerful Java library used for testing RESTful APIs. It provides a domain-specific language (DSL) for writing readable, maintainable, and efficient API tests. One of the most common operations when working with APIs is sending HTTP POST and PUT requests along with a payload (also called the request body). These requests are used to create or update resources on the server.

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Let’s explore in detail how to send POST/PUT requests with a payload using RestAssured.

1. Understanding POST and PUT Requests:

• POST Request: Used to create a new resource on the server. It sends data to the server, and the server typically returns the newly created resource or a confirmation response.

• PUT Request: Used to update an existing resource or create one if it does not exist. The full payload usually represents the updated resource.

Both require a request body (payload), which can be in formats like JSON, XML, or form-data. JSON is the most common format used in modern APIs.

2. Basic Structure of POST/PUT in RestAssured

RestAssured uses the following structure to send a request with a payload:

The same structure applies to PUT requests by replacing with .

3. Ways to Send the Payload

a. Using Raw JSON String:

This method is straightforward but can become hard to manage with large or dynamic data.

b. Using Java Map (automatically converted to JSON):

RestAssured uses Jackson or Gson under the hood to convert the map to JSON.

c. Using POJOs (Plain Old Java Objects):

Define a Java class representing the structure of your payload:

Then:

This approach is clean and maintainable, especially when testing large APIs.

4. Adding Headers (Optional):

Sometimes, APIs require additional headers like authentication tokens or custom headers:

5. Validating the Response:

After sending a POST or PUT request, you often want to validate the response body or extract data:

6. Handling Different Content Types:

If your API uses other formats (e.g., XML or form-encoded data), you can change the content type accordingly:

For XML:

For Form data:

Conclusion:

Sending a POST or PUT request with a payload in RestAssured is straightforward and highly flexible. You can send payloads as raw strings, Java Maps, or custom POJOs. Using proper content types and payload formats ensures that your request is understood by the server. Leveraging RestAssured's fluent syntax makes tests readable and easy to maintain. Whether you're testing simple endpoints or complex APIs, RestAssured provides the necessary tools to handle payload-based requests effectively.