Postman API Testing Tutorial | Postman Tutorial For Beginners 2022

Introduction

This tutorial is designed to help beginners understand how to use Postman for API testing. Postman is a powerful tool that facilitates sending requests to APIs, allowing users to test and debug them effectively. By the end of this guide, you will be equipped with the knowledge to perform various types of API requests and utilize Postman's core features.

Step 1: Installing Postman

• Visit the Postman website.
• Download the appropriate version for your operating system (Windows, macOS, or Linux).
• Install the application by following the on-screen instructions.

Step 2: Creating a New Request

• Open Postman and create a new workspace if prompted.
• Click on the "+ New" button to start a new request.
• Choose "Request" from the options provided.

Step 3: Sending GET Requests

• Select "GET" from the dropdown menu next to the request URL field.
• Enter the API endpoint URL you want to test.
• Click the "Send" button to execute the request.
• Review the response in the lower section of the window, which includes status code, response time, and data returned.

Step 4: Sending POST Requests

• Change the method from "GET" to "POST."
• Enter the API endpoint URL.
• Navigate to the "Body" tab below the URL field.
• Select "raw" and choose "JSON" from the dropdown menu.
• Input the data you wish to send in JSON format, e.g.:

  {
    "title": "New Book",
    "author": "Author Name"
  }
  

• Click "Send" to submit the request and check the response.

Step 5: Sending PUT Requests

• Switch the method to "PUT."
• Enter the appropriate API endpoint.
• Use the "Body" tab to input the updated data in JSON format.
• Click "Send" and review the response to confirm the changes.

Step 6: Sending DELETE Requests

• Select "DELETE" from the method dropdown.
• Enter the API endpoint that you wish to delete.
• Click "Send" and check the response to ensure the resource was deleted successfully.

Step 7: Using Query Parameters

• When making a GET request, you can add query parameters directly in the URL.
• For example, to filter results, append ?search=book to your endpoint.
• You can also use the "Params" tab to add key-value pairs for cleaner management.

Step 8: Uploading Files

• For POST or PUT requests, switch to the "Body" tab.
• Select "form-data" from the options.
• Add a key for your file upload and choose the type as "File."
• Click "Select Files" and choose the file from your computer.
• Click "Send" to upload the file to the API.

Practical Tips

• Always verify the API documentation for the correct endpoint and required parameters.
• Use environment variables in Postman to manage different configurations (like URLs or authentication tokens).
• Take advantage of collections to organize your requests.

Common Pitfalls to Avoid

• Forgetting to set the correct HTTP method for the request.
• Not including necessary headers like Content-Type for JSON or form-data requests.
• Failing to check the response status codes to diagnose API issues.

Conclusion

You now have a foundational understanding of how to use Postman for API testing. From sending various types of requests to utilizing query parameters and file uploads, you can effectively interact with APIs. As a next step, explore more advanced features of Postman, such as testing scripts and automation, to enhance your API testing skills further. Happy testing!