Setting variables in scripts in Postman

Introduction

Setting variables in scripts helps you save and reuse data during your tests. It makes your tests flexible and easier to manage.

You want to save a value from a response to use in later requests.

You need to store user input or test data temporarily during a test run.

You want to share data between different requests in a collection.

You want to change values dynamically without editing the request manually.

Syntax

Postman

// Set a variable
pm.variables.set('variableName', 'value');

// Get a variable
let value = pm.variables.get('variableName');

Use pm.variables.set to create or update a variable.

Use pm.variables.get to read the variable's value.

Examples

This sets a variable named token with the value 12345abcde.

Postman

pm.variables.set('token', '12345abcde');

This retrieves the value of token and prints it to the console.

Postman

let token = pm.variables.get('token');
console.log(token);

This sets an environment variable userId with value 789. Environment variables last longer than local variables.

Postman

pm.environment.set('userId', '789');

This gets the environment variable userId.

Postman

let userId = pm.environment.get('userId');

Sample Program

This script saves the id from the response JSON into a variable called userId. Then it retrieves and prints it. Finally, it checks if the variable was set correctly.

Postman

// Example: Save a value from response and reuse it

// Assume response JSON: { "id": "abc123", "name": "John" }

// Save 'id' from response to a variable
let jsonData = pm.response.json();
pm.variables.set('userId', jsonData.id);

// Later, get the variable and print it
let savedId = pm.variables.get('userId');
console.log(`Saved userId is: ${savedId}`);

// Test to check if variable is set correctly
pm.test('userId variable is set', function () {
    pm.expect(savedId).to.eql('abc123');
});

Important Notes

Variables set with pm.variables.set exist only during the request execution.

Use pm.environment.set or pm.collectionVariables.set to save variables longer.

Always check if the response contains the data before setting variables to avoid errors.

Summary

Setting variables lets you store and reuse data during tests.

Use pm.variables.set and pm.variables.get for local variables.

Variables help make tests dynamic and easier to maintain.