Variables in Postman | Scope, Use Cases, and Advanced Features

Variables in Postman play an important role in increasing flexibility and efficiency in API development and testing. In this article, we will walk you through the concept of variables in Postman, focusing on practical steps and real-world examples to empower developers and testers to maximize the potential of variables in Postman.

Variables in Postman are placeholders that store and manage values used in different requests and environments. They provide flexibility and efficiency in API development and testing by enabling users to reuse values, store data, and create dynamic workflows.

Step 1: Environment in Postman

1. It allows you to Create Environments in Postman facilitating the organization of variables based on different contexts (e.g., development, production).

Step 2: Creating an Environment

1. Open Postman and go to the “Environment” tab.
2. Click “Add Environment” and name it (for example, “JSONPlaceholder“).
3. Define variables like “BaseURL” and set their corresponding values to “https://jsonplaceholder.typicode.com“

Step 3: Environment Variable in Postman

In each request, use environment variables by enclosing them in double curly braces, like {{baseURL}}. This allows seamless switching between environments.

1. Now, create a new request to the “https://jsonplaceholder.typicode.com/albums” endpoint.
2. In the request, use the environment variable by enclosing it in double curly braces, like {{BaseURL}}/albums.

Step 4: Creating an Environment Variable in Postman

1. Navigate to the created environment and click “Add new variable” Define a new variable (e.g., “apiKey“) and set its value.

Step 5: Global Variables in Postman

1. Global variables are accessible across all environments. Create them by going to the “Globals” tab and adding variables like “authToken.”

Step 6: Creating a Global Variable in Postman

1. Similar to environment variables, define global variables by clicking “Add” in the “Globals” tab.

Step 7: Using a Global Variable in Postman

1. Utilize global variables in requests, enhancing reusability and consistency across different environments.

Variable Scopes

Variables in Postman have different scopes, which determine where they can be accessed and modified. Let’s explore the different types of variables available in Postman:

Variable Scopes

1. Local Variables: Local variables are kept within the collection within the scope of a specific request or script. They are temporary and accessible only in the context of the request or script where they are defined.
2. Data Variables: Data variables, also known as data files, are used for data-driven testing in Postman. They allow users to parameterize requests with different sets of data, iterating over each set during test execution.
3. Environment Variables: Environment variables are limited to a specific environment and can be accessed by all requests within that environment. They allow easy configuration of different environments such as development, staging, and production.
4. Collection Variables: Collection variables are scoped to a specific collection and can be accessed by all requests to that collection. They provide a convenient way to share data between requests belonging to the same collection.
5. Global Variables: Global variables have a global scope and are accessible by all requests and scripts in all collections and environments. They provide a centralized storage mechanism to store commonly used data, such as authentication tokens or API keys.

Use Cases

1. Dynamic Request URLs: Variables enable data-driven testing by allowing users to parameterize requests with different sets of data, facilitating broader test coverage.
2. Authorization Headers: Using variables to handle authorization headers, allowing easy switching between authentication tokens.
3. Test Data Management: The role of variables in managing test data, ensuring efficient and organized data-driven testing.
4. Automated Testing Workflows: Variables contribute to automated testing workflow, increasing reusability and maintainability of scripts.

Advanced Features

1. Dynamic Data Generation: Postman allows to generation of dynamic data using scripts and libraries like Faker.js. This feature is especially useful for creating realistic testing scenarios with random or sequential data.
2. Chaining Requests: Variables can be used to extract data from a response and pass it as input to subsequent requests, enabling the chaining of requests in a workflow.
3. Environment Inheritance: The Postman environment supports inheritance, allowing variables to be inherited from the parent environment, and providing a hierarchical structure for managing variables.
4. Data-Driven Testing: Variables enable data-driven testing by allowing users to parameterize requests with different sets of data, facilitating broader test coverage.

Conclusion

Variables play an important role in increasing the flexibility and efficiency of API testing and development in Postman. By understanding how to effectively initialize and use variables, users can optimize their workflow, create dynamic test scenarios, and streamline their testing processes. With the ability to define environment-specific and global variables, as well as advanced features like dynamic data generation and request chaining, Postman provides a robust platform to easily create and execute API tests.

Frequently Asked Questions

1. How do I create a variable in Postman?

To create a variable:

1. Open Postman.
2. Switch to the “Environment” or “Globals” tab.
3. Click “Add Environment” or “Add” in the desired tab.
4. Name the variable.
5. Assign a value to a variable.

2. Can I use variables in request URLs in Postman?

Yes, you can use variables in the request URL by enclosing them in double curly braces, such as {{variableName}}. It allows dynamic and adaptable URLs.

3. What is the scope of global variables in Postman?

Global variables have a global scope and are accessible by all requests and scripts in all collections and environments.

4. How can I use variables for data-driven testing in Postman?

Use data variables or data files to parameterize requests with different sets of data, iterating over each set during test execution.

5. What are some of the postman’s advanced variable features?

Examples of advanced features are the use of scripts for dynamic data generation, data extraction and passing of chaining requests, support for environmental inheritance, and data-driven testing.