Chaining Requests in Postman: 3 Practical Examples

Understanding Chaining Requests in Postman

Chaining requests in Postman allows you to execute multiple requests in a sequence, where the output of one request can be used as the input for the next. This is particularly useful in scenarios like authentication, where you need a token from one request to access another resource. Below are three practical examples of chaining requests in Postman.

Example 1: User Authentication and Data Retrieval

Use Case

In this example, we will authenticate a user and then retrieve their profile data using the obtained token.

You start by sending a POST request to the authentication endpoint to log in, which provides a token. This token will then be used in the subsequent GET request to fetch user data.

To set this up, proceed as follows:

1. POST Request: Send a request to the login endpoint.

   • URL: https://api.example.com/login
   • Body:

   {  
     "username": "testuser",  
     "password": "password123"  
   }  
   

2. In the Tests tab of the POST request, save the token to an environment variable:

   pm.environment.set("authToken", pm.response.json().token);  
   

3. GET Request: Use the token in a request to get user data.

   • URL: https://api.example.com/user
   • Headers:
     • Authorization: Bearer {{authToken}}

Notes

Ensure you have the environment variable set up in Postman. You can view the token in the Postman console for debugging.

Example 2: Creating an Item and Following Up with Retrieval

Use Case

Here, we will create a new item in a resource list and then retrieve it to confirm creation.

The process involves sending a POST request to create an item, followed by a GET request to fetch the newly created item.

1. POST Request: Create a new item.

   • URL: https://api.example.com/items
   • Body:

   {  
     "name": "New Item",  
     "type": "example"  
   }  
   

2. In the Tests tab, save the ID of the created item:

   pm.environment.set("itemId", pm.response.json().id);  
   

3. GET Request: Retrieve the created item.

   • URL: https://api.example.com/items/{{itemId}}

Notes

This approach is helpful for validating that the item was created successfully, especially if there are unique identifiers needed for subsequent operations.

Example 3: Updating a Resource and Validating the Update

Use Case

In this instance, we will update user information and then validate that the update was successful by retrieving the updated data.

The workflow consists of sending a PUT request to update the user’s details and then a GET request to fetch the updated information.

1. PUT Request: Update user information.

   • URL: https://api.example.com/user/{{userId}}
   • Body:

   {  
     "email": "newemail@example.com"  
   }  
   

2. In the Tests tab, confirm the response status is 200:

   pm.test("Update successful", function () {  
     pm.response.to.have.status(200);  
   });  
   

3. GET Request: Validate the updated information.

   • URL: https://api.example.com/user/{{userId}}

Notes

Using assertions in the Tests tab ensures that updates are functioning as expected, providing immediate feedback on the operation’s success.

These examples highlight the power and flexibility of chaining requests in Postman, making API testing smoother and more efficient.