Use path variable as variable in mock server response

Ask the Experts and Postman Tips
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1

I’m building mocked APIs using examples.
The faker library to create random bits and pieces (https://learning.postman.com/docs/writing-scripts/script-references/variables-list/) is awesome to mock the creation of a new resource.

However a common pattern we have does not work with this.
We have a Restful API, so usually we have something along the lines: https://api.com/resource/:id

With Postman I can now nicely return a static JSON response and with that faker library I can even generate random data so that it is always looking different.
However what I would need to do is to have that :id from the path inside the JSON.

So that a request to https://api.com/resource/3 returns
{“id”: 3, …}
and one to to https://api.com/resource/341894 returns
{“id”: 341894, …}

So essentially a way to have the path variable as a variable for the response.

How can I achieve this? This would enable us to build mock APIs with ease!
Thank you

2

Hi @lukaswelte,

Welcome to the community! :clap:

This is a great question, and something that would make mocking even better. Fortunately, you should be able to do this, and I verified with my current testing.

The way you can go about this is to generate a fake ID with your faker library, and persist that as an environment variable using your pre-request script. Then, in your mocked example, include that variable for the id value, like so:

{ "id": {{fakerId}}, ... }

This should give you the functionality you are looking for.

Orest

3

Thank you for the response.
I’m glad that this is possible, but it seems quite hacky with having to pass this through a pre request script in order to use the request path variable in the response (would be really handy if those automatically get part of the response variables).

But I understand that this is what currently is available.
Thank you :slight_smile:

4

Certainly!

If you are interested in seeing this as a feature for Postman, you can create a feature request on github and the engineering team can review it that way.

Nonetheless, glad there is some way you can get this functionality you desire. Glad I can help :slight_smile: