Postman Basics: Guide for API Testing

Introduction

Postman is a popular HTTP client for API testing. This guide covers Postman basics for developers of all levels.

Making Your First Request

1. Open Postman and create a new tab.
2. Select an HTTP Method.
3. Enter the API Endpoint URL.
4. Click 'Send' to execute.

Example: GET Request

1. Select GET method.
2. Enter https://api.example.com/users.
3. Click 'Send'.
4. Review the response.

HTTP Methods and Status Codes

Common Methods

• GET: Retrieve data
• POST: Submit new data
• PUT: Update existing data
• DELETE: Remove data

Status Codes

• 200 OK: Successful
• 201 Created: Resource created
• 400 Bad Request: Client error
• 401 Unauthorized: Authentication required
• 404 Not Found: Resource not found
• 500 Internal Server Error: Server error

Headers

Key headers:

• Content-Type: Media type of resource
• Authorization: Authentication credentials
• Accept: Acceptable media types
• User-Agent: Client software identifier

Query Parameters

Add parameters via the 'Params' button next to the URL bar.

Example: https://api.example.com/users?role=admin

Workspaces, Environments, and Collections

Workspaces

• Personal: Individual projects
• Team: Collaborative projects

Environments

Define variables for different setups (development, staging, production).

Collections

Group related API requests for organization and sharing.

Sharing

Exporting

1. Right-click on collection/environment.
2. Select 'Export'.
3. Choose format and save.

Importing

1. Click 'Import'.
2. Upload or drag and drop file.

Automation with JavaScript

Use the Tests tab to automate tasks like token extraction.

Example:

const json = JSON.parse(responseBody);
pm.environment.set("TOKEN", json.token);