In this section, we will explore the fundamental HTTP methods used in API requests. Understanding these methods is crucial for interacting with APIs effectively, as they define the action to be performed on the server.

1. GET

   • Purpose: Retrieve data from a server.
   • Characteristics:
     • Safe and idempotent (does not alter the state of the server).
     • Can be cached.
   • Example: Fetching a list of users from a database.
   • Code Example:

     GET /users HTTP/1.1
     Host: api.example.com
     

   • Explanation: This request asks the server to return a list of users. The server responds with the requested data without making any changes to its state.

2. POST

   • Purpose: Send data to the server to create a new resource.
   • Characteristics:
     • Not idempotent (repeated requests can create multiple resources).
     • Often used to submit form data.
   • Example: Creating a new user account.
   • Code Example:

     POST /users HTTP/1.1
     Host: api.example.com
     Content-Type: application/json
     
     {
       "name": "John Doe",
       "email": "[email protected]"
     }
     

   • Explanation: This request sends user data to the server, which processes it to create a new user account.

3. PUT

   • Purpose: Update an existing resource or create a resource if it does not exist.
   • Characteristics:
     • Idempotent (repeated requests have the same effect as a single request).
   • Example: Updating user information.
   • Code Example:

     PUT /users/1 HTTP/1.1
     Host: api.example.com
     Content-Type: application/json
     
     {
       "name": "Jane Doe",
       "email": "[email protected]"
     }
     

   • Explanation: This request updates the user with ID 1. If the user does not exist, it may create a new user with the provided data.

4. DELETE

   • Purpose: Remove a resource from the server.
   • Characteristics:
     • Idempotent (repeated requests have the same effect as a single request).
   • Example: Deleting a user account.
   • Code Example:

     DELETE /users/1 HTTP/1.1
     Host: api.example.com
     

   • Explanation: This request deletes the user with ID 1 from the server.

5. PATCH

   • Purpose: Apply partial modifications to a resource.
   • Characteristics:
     • Not necessarily idempotent.
   • Example: Updating a user's email address.
   • Code Example:

     PATCH /users/1 HTTP/1.1
     Host: api.example.com
     Content-Type: application/json
     
     {
       "email": "[email protected]"
     }
     

   • Explanation: This request updates only the email address of the user with ID 1.

Exercise: Use Postman to send a GET request to a public API endpoint and retrieve data.

1. Open Postman and create a new request.
2. Set the request type to GET.
3. Enter the URL: https://jsonplaceholder.typicode.com/posts.
4. Click "Send" to execute the request.
5. Observe the response data in the Postman interface.

Solution Explanation:

• The GET request retrieves a list of posts from the JSONPlaceholder API, a free online REST API for testing and prototyping. The response should include an array of post objects, each with properties like userId, id, title, and body.

• Mistake: Using GET instead of POST for creating resources.

  • Tip: Remember that GET is for retrieving data, while POST is for sending data to create resources.

• Mistake: Forgetting to set the correct Content-Type header for POST and PUT requests.

  • Tip: Always specify Content-Type: application/json when sending JSON data.

Understanding HTTP methods is essential for effective API interaction. Each method serves a specific purpose and has unique characteristics that dictate how it should be used. Mastering these methods will enable you to perform a wide range of operations on APIs, from retrieving data to creating and updating resources. In the next section, we will introduce you to Postman, a powerful tool for testing APIs.