2.1. What is a REST API?

REST APIs provide data over HTTP. Each "resource" has a URL, and you interact with it using HTTP methods: ● GET: retrieve data ● POST: send data ● PUT: update data ● DELETE: remove data

REST, or Representational State Transfer, is an architectural style for designing networked applications. A REST API allows different applications to communicate with each other over the internet using standard HTTP protocols. Each resource, which is any piece of data (like a user or a product), is identified by a unique URL. You can perform actions on these resources using specific HTTP methods: GET fetches data, POST sends new data, PUT updates existing data, and DELETE removes data.

Think of a REST API as a restaurant menu: the menu lists different dishes (resources) available. When you want to order a dish, you tell the waiter (the HTTP method) what you want (GET for just looking at the menu, POST for ordering a new dish, PUT for modifying an existing order, and DELETE if you want to remove an item from your order).

import requests
url = "https://jsonplaceholder.typicode.com/posts/1"
response = requests.get(url)
if response.status_code == 200:
    data = response.json()
    print(data["title"])

In this example, we use the Python 'requests' library to perform a GET request. The URL points to a specific resource (a post in a blog). When we send this request, if the server successfully processes it (indicated by a status code 200), we then convert the response from JSON format into a Python dictionary, allowing us to access specific details easily, such as the title of the post.

Imagine you're calling a library to ask for a specific book (GET request). If they have it (status code 200), they tell you the title and maybe some other details about the book over the phone (JSON data).

payload = {"title": "foo", "body": "bar", "userId": 1}
response = requests.post("https://jsonplaceholder.typicode.com/posts",
                             json=payload)
print(response.status_code) # 201 means created
print(response.json())

Here, we're using a POST request to send data to a server. The 'payload' is a dictionary containing information we want to create (like a blog post with a title and body). When we make this request, we send this data in JSON format. If our request is successful, we would receive a status code of 201, indicating that a new resource was successfully created, and we can see the details returned in the response.

Think of this as filling out a form to submit a new recipe to a cooking website (POST request). After you submit the form, the website confirms that your recipe has been added (status code 201), and it might show you what details it saved on its end.

headers = {"Authorization": "Bearer YOUR_API_KEY"}
response = requests.get("https://api.example.com/protected",
                      headers=headers)

In many cases, when accessing APIs, you need to prove that you're authorized to do so, especially with private data. APIs often require authentication through headers. The 'Authorization' header typically contains an API key (like a password) that the server checks to decide if you should be allowed access to the requested resource.

This is similar to having a membership card for a club. When you arrive at the entrance (API), you present your card (API key) to confirm you have permission to enter and access member-only areas (protected resources).

Always handle timeouts, status codes, and error checking when working with APIs.

When working with APIs, it's crucial to handle potential errors gracefully. This includes setting timeouts to avoid indefinitely waiting for a response, checking the status code to know if the request was successful, and implementing error checking to manage cases where the request fails, ensuring your application behaves predictably.

Imagine planting a seed (making an API request) and waiting for it to grow (getting a response). If it takes too long, you might check to ensure there isn’t an issue with the soil or light (timeouts and error checking). You wouldn’t want to just stand there waiting with no plan; you'd need to take action or decide to try a different spot.

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