Postman Guide: Mastering the Evaluation of JSON Arrays

Question

Postman Guide: Mastering the Evaluation of JSON Arrays

One of the features in Postman allows users to save a specific field from the response body as a variable and then utilize that variable in a subsequent call.

For instance, after my initial call to the web service, the response body contains:

[ {
  "id" : "11111111-1111-1111-1111-111111111111",
  "username" : "<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="f386809681dec2b3968b929e839f96">[email protected]</a>",
}, {
  "id" : "22222222-2222-2222-2222-222222222222",
  "username" : "<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="c0b5b3a5b2edf280a5b8a1adb0aca5eea3afad">[email protected]</a>"
} ]

A test is added:

postman.setGlobalVariable("user_0_id", JSON.parse(responseBody)[0].id);

Subsequently, I send another request with the URL:

http://example.com/users/{{user_0_id}}

Postman replaces {{user_0_id}} with

11111111-1111-1111-1111-111111111111

.

This process works correctly. However, when I enhance the test for my first call with:

postman.setGlobalVariable("users", JSON.parse(responseBody));

In the second request to the webservice, using the URL:

http://example.com/users/{{users[0].id}}

The issue arises where {{users[0].id}} remains unchanged and does not get replaced by

11111111-1111-1111-1111-111111111111

.

What should be the correct syntax for this scenario?

javascript json postman

Answer 1

Answer №1

In order to store an array in a global or environment variable, it is necessary to use the JSON.stringify() method. According to information found in the Postman documentation on environments:

Both environment and global variables will always be saved as strings. When storing objects or arrays, it is important to stringify them before saving, and parse them when retrieving.

If you need to save the entire response for later use, you can follow these steps in your test script for the initial call:

var jsonData = JSON.parse(responseBody);
// perform tests on jsonData

postman.setGlobalVariable("users", JSON.stringify(jsonData));

To extract a user's ID from the global variable and incorporate it into the request URL, you must parse the global variable within the pre-request script of the second call and assign the value to a temporary variable to utilize in the URL:

postman.setGlobalVariable("temp", JSON.parse(postman.getEnvironmentVariable("users"))[0].id);

As a result, the URL for the second call would appear as follows:

http://example.com/users/{{temp}}

Remember to clear the temp variable at the conclusion of the tests for the second call:

postman.clearGlobalVariable("temp");

This approach should provide the desired outcome. At this time, there is no direct means to parse the global variable directly within the URL to access specific entries, such as attempting to use {{users[0].id}}.

Answer 2

In order to store an array in a global or environment variable, it is necessary to use the JSON.stringify() method. According to information found in the Postman documentation on environments:

Both environment and global variables will always be saved as strings. When storing objects or arrays, it is important to stringify them before saving, and parse them when retrieving.

If you need to save the entire response for later use, you can follow these steps in your test script for the initial call:

var jsonData = JSON.parse(responseBody);
// perform tests on jsonData

postman.setGlobalVariable("users", JSON.stringify(jsonData));

To extract a user's ID from the global variable and incorporate it into the request URL, you must parse the global variable within the pre-request script of the second call and assign the value to a temporary variable to utilize in the URL:

postman.setGlobalVariable("temp", JSON.parse(postman.getEnvironmentVariable("users"))[0].id);

As a result, the URL for the second call would appear as follows:

http://example.com/users/{{temp}}

Remember to clear the temp variable at the conclusion of the tests for the second call:

postman.clearGlobalVariable("temp");

This approach should provide the desired outcome. At this time, there is no direct means to parse the global variable directly within the URL to access specific entries, such as attempting to use {{users[0].id}}.

Postman Guide: Mastering the Evaluation of JSON Arrays

Answer №1

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