How to Format a JSON Array of Objects for Postman Tests

Описание: Learn how to transform the results from one Postman request into a well-structured JSON format for easier data handling in your API tests.
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Introduction to JSON Formatting in Postman

When working with APIs using Postman, you might encounter a situation where you need to manipulate data returned from one request to use as input for another. This is a frequent requirement when the responses are in a JSON format that contains arrays of objects.

In this guide, we will discuss a common problem faced by developers: formatting a JSON array of objects obtained from one request in Postman into a simpler object structure for another request.

The Problem

Imagine you have a JSON response from your first API call (let's call it Request 1) structured like this:

[[See Video to Reveal this Text or Code Snippet]]

You want to convert this response into another format that provides a simpler output resembling the following:

[[See Video to Reveal this Text or Code Snippet]]

This format allows for easier access to the data by using the feature names as keys. The challenge lies in the fact that there might be multiple objects in the response, and their count can change over time.

The Solution

Step 1: Extracting Data in Request 1

To tackle this requirement, you need to write some JavaScript code in the Tests tab of Request 1 that processes the JSON response. Here’s how you can do it:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code:

Parsing the Response: const res = pm.response.json();
Here, you parse the JSON response from the first request.

Variables for Storage: let log = ""; let pre = "";
You create variables to store the keyField values for "Logging" and "Premium".

Filtering the Data: Using the filter method, you go through each object (item) in the response. If the featureField matches "Logging" or "Premium", you assign the corresponding keyField to the respective variable.

Setting Environment Variables: Finally, you utilize pm.environment.set() to save these key values so they can be used in later requests.

Step 2: Using Data in Request 2

Now that you have stored the required values in environment variables, you can incorporate them into Request 2. This is how your body for the second request will look:

[[See Video to Reveal this Text or Code Snippet]]

Key Points

Environment Variables: Using {{variableName}} allows you to insert the values stored in environment variables dynamically.

Scalability: While we have hardcoded the featureField names, you can easily modify the filter loop to accommodate additional featureFields as needed.

Conclusion

Formatting a JSON array of objects in Postman doesn't have to be daunting. By utilizing a combination of JavaScript functions and environment variables, you can transform API responses into a format that is easier to work with in subsequent requests.

Now, when you run your requests, you can expect the structured output that simplifies your testing process. Experiment with this approach, and you'll find it streamlines how you handle JSON data in Postman!