How To Use Delete Method In Postman

Understanding the DELETE Method in API Testing

The DELETE method is a fundamental HTTP method used to remove data from a server. In API testing, this method is crucial for verifying that your API can successfully delete existing resources. This guide will walk you through the process of using the DELETE method in Postman, providing practical examples and step-by-step instructions.

Sending a DELETE Request

Open Postman: Launch the Postman application and create a new request.
Select the DELETE Method: In the request tab, choose “DELETE” from the dropdown menu next to the URL input field.
Enter the Endpoint URL: Specify the complete URL of the resource you want to delete. For instance, if you’re deleting a user with the ID “123”, your URL might look like this:
```
https://api.example.com/users/123
```
Send the Request: Click the “Send” button to execute the DELETE request.

Example: Deleting a User

Let’s assume you have a user management API with the endpoint /users/{userId}. Here’s how to delete a user with the ID “123”:

Request:

Method: DELETE
URL: https://api.example.com/users/123
Headers: (Optional) You can include headers like Authorization if your API requires authentication.

Response:

Status Code: A successful DELETE request returns a 204 (No Content) status code, indicating that the resource was successfully deleted.
Body: The response body is typically empty.

Handling Authentication

Many APIs require authentication to access or modify data. Here’s how to incorporate authentication in your DELETE requests:

Choose Authentication Type: Postman supports various authentication methods like API keys, basic auth, OAuth 2.0, etc. Select the appropriate method from the “Authorization” tab.
Configure Credentials: Provide the necessary authentication details, such as API keys, username/password, or token information.

Example: DELETE with Basic Authentication

Request:

Method: DELETE
URL: https://api.example.com/users/123
Headers:
- Authorization: Basic your_username:your_password (base64 encoded)

Verifying Deletion with Assertions

To ensure the DELETE operation was successful, you can use Postman’s test features:

Add Tests: Click the “Tests” tab and add a test script.
Assert Status Code: Verify the returned status code is 204 (No Content) using the pm.test() function.

Example Test Script:

pm.test("Status code is 204", function () {
    pm.response.to.have.status(204);
});

Using the DELETE Method with Parameters

Sometimes, you need to pass additional information along with the DELETE request. Postman supports adding parameters to your URL or using the request body.

Example: DELETE with Query Parameter:

Request:

Method: DELETE
URL: https://api.example.com/users?filter=inactive
Headers: (Optional)
Body: (Optional)

Example: DELETE with Body Parameters:

Request:

Method: DELETE
URL: https://api.example.com/users/123
Headers: (Optional)
Body:
```
{
    "reason": "Inactive User"
}
```

Handling Error Scenarios

When testing your API, it’s vital to simulate various error conditions. Common DELETE method errors include:

404 (Not Found): The resource you’re trying to delete doesn’t exist.
401 (Unauthorized): You don’t have the necessary permissions to delete the resource.
403 (Forbidden): You’re authorized but lack the specific privileges to delete the resource.
409 (Conflict): The deletion operation failed due to a conflict.

Postman allows you to create tests that check for these error conditions and understand the API’s behavior when faced with unexpected situations.

Conclusion

Mastering the DELETE method in Postman is essential for comprehensive API testing. By following the steps outlined in this guide, you can confidently create and execute DELETE requests, verify the successful deletion of resources, and ensure the reliability of your API. Remember to always test with various scenarios, including successful and error cases, to gain a complete understanding of your API’s behavior.