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How To Use Postman Rest Client In Chrome

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Getting Started with Postman REST Client in Chrome

Postman is a powerful tool for interacting with APIs, and it’s available as a Chrome extension. This guide will walk you through the basics of using Postman for API testing in your Chrome browser.

Download and Install Postman

  1. Open the Chrome Web Store by visiting https://chrome.google.com/webstore/category/extensions.
  2. Search for “Postman” and click on the Postman extension.
  3. Click on the “Add to Chrome” button.
  4. Once the extension is installed, you’ll see the Postman icon in your Chrome toolbar.

Launching Postman

  1. Click the Postman icon in your Chrome toolbar.
  2. This will open the Postman interface, which is divided into several sections:
    • Collections: Used for organizing requests and tests.
    • Workspaces: Allow you to collaborate with others.
    • History: Stores your recent requests.

Sending Your First Request

Let’s send a simple GET request to a public API, like the JSON Placeholder API:

  1. Create a new Request: Click on the “New” button in the upper left corner of the Postman interface.
  2. Select the Method: Choose “GET” from the dropdown menu in the top left.
  3. Enter the URL: Type the API endpoint URL, e.g. https://jsonplaceholder.typicode.com/posts, in the address bar.
  4. Send the Request: Click the “Send” button.

The response from the server will be displayed in the “Body” tab of the Postman window. You should see a JSON array of posts.

Understanding Request and Response

The Postman interface provides several sections to explore the request and response:

Request:

  • Headers: Additional information sent with the request, such as content type, authorization, or cookies.
  • Body: The data sent to the server. Depending on the method, you can use various formats like JSON, XML, or form data.
  • Params: Used to add parameters to your URL, typically for dynamic data retrieval.

Response:

  • Status Code: Indicates the outcome of the request (e.g., 200: OK, 404: Not Found).
  • Headers: Information about the server’s response, including the content type and encoding.
  • Body: The data returned by the server.

Working with Different HTTP Methods

Postman supports all HTTP methods:

  • GET: Retrieve data from a server.
  • POST: Send data to the server to create or update a resource.
  • PUT: Update an existing resource (entire data).
  • PATCH: Partially update an existing resource.
  • DELETE: Remove a resource from the server.

Example - POST request:

Let’s create a new post using the jsonplaceholder API:

  1. Create a new request and set the method to “POST”.
  2. In the “Body” tab, select “raw” and choose “JSON”.
  3. Enter the following JSON data:
{
    "userId": 1,
    "title": "New Post",
    "body": "This is the body of a new post."
}
  1. Click “Send”.

You should see a 201 Created status code as a response, indicating success.

Testing and Validation

Postman’s features allow you to test and validate your APIs:

Built-in Tests:

  • You can write JavaScript tests within Postman to validate the response data. For instance, checking if a status code is as expected or if a specific field in the response exists.

Example - a simple test:

pm.test("Status code is 200", function () {
    pm.response.to.have.status(200);
});

Pre-request Scripts:

  • You can run JavaScript code before sending a request.
    • This can be used to set up variables, add parameters, or modify headers.

Example - pre-request script to add a header:

pm.environment.set("Authorization", "Bearer your_token");

Organizing and Sharing Requests

Collections:

  • Create collections to group related requests.
  • This makes it easy to organize and manage your API tests.

Environment Variables:

  • Store dynamic values like API keys or base URLs in environment variables to avoid hard-coding.
  • This makes your requests reusable and adaptable.

Sharing and Collaboration:

  • Export your collections and environments as JSON files.
  • Import them into other Postman workspaces or share them with colleagues for streamlined collaboration.

Conclusion

Postman is a versatile and user-friendly tool for API testing. This guide covered some essential techniques for using Postman with Chrome, but there’s much more to explore. Experiment with Postman’s features and explore advanced functionalities like automated testing and integration with other tools to enhance your API workflow.

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