Useful tricks and tips for working with POSTMAN

      Postman is a powerful graphical HTTP client helpful when working with APIs. In our day to day work, we use postman for our REST Service tests a lot. In this post I am going to discuss about few tips and tricks while using postman.

1. Variables:

    We can use variables to replace certain fields such as the URL, URL parameters, headers, authorization, request body, and header presets etc. in postman. These variable names are enclosed with double curly braces – like {{variable name}}. Postman uses string substitution to replace the current value of this variable.

There are multiple ways to initialize, retrieve, and define the scope of these variables. Below is the practical usage of this feature.

How I used variables:

    The most annoying problem we face in our everyday usage of postman is, updating the Auth token. As the auth token has limited validity, we have to replace the token every time when it gets expired. This hack helps the users to include this token generation in the run time, so that we don't need to update every time.

    First, we need to add the below script under "Pre-request Script" tab. (The Pre-request Script is a tab where one can write javascript code to hit any endpoint and extract data from a response to use this data in a subsequent request. So, if you include any script in this tab, this will be executed even before making your REST Call. Thus it initializes & loads the variable even before making your actual Call.)

const echoPostRequest = {

  url: 'http://ur.access.token.endpoint',

  method: '<GET or POST>',

  header: 'Content-Type:application/json'

};

var getToken = true;

console.log(pm.sendRequest);

if (getToken === true) {

    pm.sendRequest(echoPostRequest, function (err, res) {

        console.log(err ? err : res.json());

        if (!err) {

            pm.globals.set("token", res.json()["<field name of the response where your token is stored>"]);

        }

    });

}

In the above script, we are storing the token value in the variable called “token”. Now we use this variable in the header as the value of “Authorization” like below (You may be using different key for authorization. Use the same key here).

That's it. Now you can run this collection, whenever you want without worrying about replacing latest token.

2. Dynamic Variables:

     Postman has a few dynamic variables you can use in your requests. We can use them in the request builder as unique IDs, timestamps, or random integers. The syntax will be {{$timestamp}}. Below are those variables and their purposes.

{{$guid}} : Adds a v4 style guid

{{$timestamp}} : Adds the current timestamp

{{$randomInt}} : Adds a random integer between 0 and 1000

3. Data Variables:

   Data variables are available when using a data file with the collection runner. You can import the data as a CSV or JSON file, and then use the values from the data file inside HTTP requests and scripts. Here's an example of Inside pre-request and test scripts. Let's say you have the pm.iterationData.get("username") method inside pre-request and test scripts. The method would let you access the value of the username variable from a data file.

You can get more details on how to use data variables from the below link

https://learning.getpostman.com/docs/postman/collection_runs/working_with_data_files/