[Understanding APIs] Function-Based and Class-Based Views

Coursera

• This is a API course is one part of the overall Meta Back-end Developer course

1. Introduction

• Django is to server HTTP responses to HTTP requests

• Django allows us to views that is just a callable that accepts a request and return a response

2. Function-based views (FBVs)

• Similar to Django, being simple and intuitive

• @api_view decorator

  automatic handling of request data parsing and response data rendering can be achieved in FBVs

    from rest_framework.decorators import api_view
    from rest_framework.response import Response
  
    @api_view(['GET'])
    def hello_world(request):
        return Response({"message": "Hello, World!"})
  

3. Class-based views (CBVs)

• It is more suitable for implementing more complex web API logic, enhancing code resuability, and better organizing code structure.

• DRF provides base classes (APIView and ViewSet) that allow easy handling of various HTTP methods and URL patterns.

    from rest_framework.views import APIView
    from rest_framework.response import Response
  
    class HelloWorldView(APIView):
        def get(self, request):
            return Response({"message": "Hello, World!"})
  

  • HelloWorldView class inherits from the APIView class

  • get method that handles HTTP GET requests

  • The CBVs is used in conjunction with DRF’s routing system to automatically call the appropriate method based on the URL pattern.

4. Code Flow

1. Django’s URL dispatcher routes the HTTP requests to the HelloWorldView. Selected according to the URL pattern

   • URL dispatcher is responsible for connecting all incoming HTTP requests. This is done according to Django’s URLconf settings, where each URL path is mapped to a specific view function or class.

   • meaning of routes -> connecting an HTTP request to the view class

     Django's URL dispatcher routes the HTTP request to HelloWorldView means that the URL dispatcher in Django connects the HTTP request received from the client to a view class called HelloWorldView.

     At this point, the URL pattern determines which view class the request will be connected to.

2. as_view() is a class method that instantiates the class and receives an HttpRequest object to call the appropriate method.

3. Inside the as_view() method, the setup() method and the dispatch() method are called.

   The setup() method initializes the view, and the dispatch() method checks the type of HTTP request (GET, POST, etc.) and calls the appropriate handler method.

4. The dispatch() method calls the get() method. This get() method handles the HTTP GET request and returns a Response object.

   This Response object is sent to the client as an HTTP response.

5. If the dispatch() method receives an unknown HTTP method, the http_method_not_allowed() method is called. This method returns a 405 Method Not Allowed response.
   

Summary

• In summary, the flow of the code is that an HttpRequest is routed to the HelloWorldView, the as_view() method is called to call the appropriate handler method (get()), and this handler method returns an HttpResponse.