In today's digital landscape, APIs (Application Programming Interfaces) have become the backbone of integration between different systems. Whether you are developing a web application or working on microservices, managing API requests in an efficient manner is crucial. This is where creating collections and automating these requests can streamline your workflow.

Understanding Postman Collections

Postman is an intuitive tool that allows developers to test API requests easily. Collections in Postman are groups of API requests that allow you to organize your work better. Instead of managing heaps of individual requests, collections help you bundle related requests together. This is especially useful when working with APIs that require multiple calls for a single feature.

Why Use Collections?

1. Organization: Collections help keep your requests organized, making it easier to locate and manage them.
2. Collaboration: Teams can share collections with each other, ensuring everyone has access to the same set of requests.
3. Version Control: You can keep track of changes made to requests over time.
4. Testing: You can run all requests in a collection at once, making it easy to test functionalities.

Automating API Requests

Automation is a key part of modern development, allowing you to run repetitive tasks without human intervention. Postman allows you to automate requests within collections using the built-in scripting feature. You can write JavaScript code in the "Pre-request Script" or "Tests" tabs to manipulate requests or process responses, making it much easier to handle complex workflows.

Example: Creating a Collection and Automating Requests

Let’s walk through a practical example where we will create a collection to automate requests to a public REST API. For this example, we’ll use the JSONPlaceholder API, a fake online REST API for testing and prototyping.

Step 1: Setting Up Postman

1. Download and Install Postman: If you don’t already have Postman, download it from Postman's official website and install it.
2. Create an Account: Create a Postman account to access features like collections and collaboration.

Step 2: Create a New Collection

1. Open Postman and click on the "Collections" tab on the left sidebar.
2. Click on the "New Collection" button.
3. Name your collection, e.g., “JSONPlaceholder Testing,” and add a description if desired.

Step 3: Create Requests

1. Inside your new collection, click on "Add Request."
2. Name your request, e.g., “Get All Posts.”
3. Set the request type to GET and enter the URL: https://jsonplaceholder.typicode.com/posts.
4. Click Save to add it to your collection.

Repeat these steps to create additional requests, such as:

• Get Post by ID: GET https://jsonplaceholder.typicode.com/posts/1
• Create a Post: POST https://jsonplaceholder.typicode.com/posts with a JSON body.

Step 4: Automate the Requests

To automate requests, we will write a simple script to fetch all posts, then create a new post and log the response.

1. Click on the request “Get All Posts” in your collection.
2. Go to the Tests tab.
3. Paste the code below into the “Tests” editor:

pm.sendRequest("https://jsonplaceholder.typicode.com/posts", function(err, res) {
    if (err) {
        console.log(err);
        return;
    }
    console.log("All Posts:", res.json());

    // Now create a new post
    let newPost = {
        title: 'foo',
        body: 'bar',
        userId: 1
    };

    pm.sendRequest({
        url: 'https://jsonplaceholder.typicode.com/posts',
        method: 'POST',
        header: {
            'Content-Type': 'application/json'
        },
        body: {
            mode: 'raw',
            raw: JSON.stringify(newPost)
        }
    }, function(err, res) {
        if (err) {
            console.log(err);
            return;
        }
        console.log("New Post Created:", res.json());
    });
});

Step 5: Running the Collection

• Click on the "Runner" button on the top left corner and select your collection.
• Click Run. This will execute all the requests in your collection sequentially and display the results in the console.

Result

After running the collection, you should see logs in the console showing all fetched posts and details of the newly created post. This demonstrates a simple automation scenario where you Fetch data and utilize the results programmatically.

With these steps, you have learned how to create collections in Postman and automate your API requests. This not only enhances your productivity but also allows for better API management and testing. Happy coding!