How To Use Graphql Variables In Postman

How to Use GraphQL Variables in Postman

Postman is a powerful tool for API testing, and it offers excellent support for GraphQL queries. One of the key features of GraphQL is the ability to use variables to make your queries more flexible and dynamic. This guide will walk you through how to use GraphQL variables in Postman, along with practical examples and step-by-step instructions.

1. Setting up Your GraphQL Request in Postman

Create a new request: Start by creating a new request in Postman.
Select the ‘GraphQL’ tab: In the request editor, select the ‘GraphQL’ tab. This provides a dedicated interface for writing and executing GraphQL queries.
Enter your GraphQL endpoint: In the ‘URL’ field, specify the URL of your GraphQL server.
Write your GraphQL query: In the ‘Query’ section, start building your GraphQL query.

2. Defining GraphQL Variables

Variables section: There’s a dedicated ‘Variables’ section in the GraphQL tab of Postman. This is where you define your variables.
Variable name and value: For each variable, provide a name and a value. This value can be a static value or a dynamic value using Postman’s variable syntax (e.g., {{my_variable}}).

3. Using Variables in Your GraphQL Query

Using variables in the query: In your GraphQL query, use the dollar sign ($) followed by the variable name within curly braces to indicate variable usage:
```
query getProducts($category: String!) {
    products(category: $category) {
        name
        price
    }
}
```

4. Example: Fetching Products by Category

Step 1: Defining the GraphQL Query

query getProducts($category: String!) {
    products(category: $category) {
        name
        price
    }
}

Step 2: Setting up Variables

Add a variable named category with the value electronics. You can modify this to test with different product categories.

Step 3: Sending the GraphQL Request

Click on the ‘Send’ button in Postman. The request will be sent to your GraphQL server, using the defined ‘category’ variable.

5. Using Environment Variables for Dynamic Testing

For more advanced testing, consider using environment variables. This lets you quickly change the values of your GraphQL variables without editing the request directly.

Step 1: Define Environment Variables

Go to the Environment tab in Postman and define variables like category, productId, etc., and specify their values.

Step 2: Use Environment Variables in Variables Section

In the ‘Variables’ section, use the double curly brace syntax to reference environment variables:

{{category}}

This makes it easy to switch between different testing scenarios by simply modifying environment variables.

6. Tips for Effective Testing with GraphQL Variables

Test with different scenarios: Use a good mix of positive and negative test cases by modifying your variables to cover edge cases and boundary conditions.
Use validation: In Postman’s ‘Tests’ tab, add assertions to validate the response data, ensuring that your GraphQL variables are working correctly.
Documentation: Document the variables and their expected values in your test suite, making it easier to understand and maintain your GraphQL testing efforts.

By incorporating GraphQL variables and environment variables into your Postman workflows, you can significantly enhance your GraphQL API testing process, making it more efficient, flexible, and robust.