How to handle Conditional Requests/Branching in Postman ?

Conditional requests or branching in Postman allows you to create logic within your requests to handle different scenarios based on conditions. This feature is useful for executing specific actions or tests depending on the response received from an API endpoint.

In this article, we’ll explore how to handle conditional requests or branching in Postman.

Understanding Pre-request Scripts and Tests:

Postman offers two key areas where you can implement conditional logic: Pre-request Scripts and Tests. These areas allow you to write JavaScript code to perform actions before sending a request (Pre-request Scripts) and after receiving a response (Tests).

Characteristics of Pre-request Scripts:

• These scripts run before the actual request is sent.
• Can be used to set variables, modify request headers, or perform any actions needed before sending the request.
• Ideal for defining conditions based on which the request will be modified.

Characteristics of Tests Scripts:

• Run after the response is received.
• Suitable for evaluating the response data and deciding subsequent actions based on the outcome.
• Allows conditional logic based on the response status code, headers, or body content.

Implementing Conditional Requests in Postman

Let’s consider an example where we want to create a new user only if the user doesn’t exist; otherwise, we update the existing user data.

1. Create Requests:

For this scenario we would require creating three requests in Postman:

Request 1 (GET): Fetches user data.

Request 2 (POST): Creates a new user.

Request 3 (PUT): Updates user data.

2. Pre-request Script in Request 1 (GET):

In the Pre-request Script of the first request (GET), set conditions to determine whether to create a new user or update existing user data:

3. Test Script in Request 2 (POST) and Request 3 (PUT):

In the Tests of the second request (POST) and third request (PUT), use postman.setNextRequest() to navigate to subsequent requests:

4. Execution:

Execute the first request (GET). Depending on the condition (whether the user exists or not), Postman will navigate to the appropriate subsequent request (either POST or PUT). After the execution of the subsequent request, the flow will continue to the first request or stop based on the conditions defined in the Test scripts.

5. Testing:

Test different scenarios by manipulating the conditions in the Pre-request Scripts and Tests. Ensure that the requests are sequenced correctly based on the conditions and the logic defined in the scripts.

Conclusion:

Handling conditional requests or branching in Postman involves using JavaScript code within Pre-request Scripts and Tests. These scripts allow you to set conditions, modify requests based on those conditions, and perform specific actions or tests depending on the received response. By effectively using these capabilities, you can create more robust API tests and simulate various scenarios to ensure your API behaves as expected under different conditions.