In Django, a view is simply a Python function (or class) that takes a web request and returns a web response.

Key points

• Input: an HttpRequest object, which carries data about the incoming request (URL parameters, submitted form data, cookies, etc.).

• Output: an HttpResponse object, which could render an HTML template, redirect, raise a 404, stream a file, return JSON… anything you want to send back to the browser or client.

Types of views in django:

Django views come in two broad flavors:

1. Function‑Based Views (FBVs)

   • What they are: Plain Python functions that receive an HttpRequest and return an HttpResponse.

   • When to use:

     • Simple, custom logic that doesn’t fit a generic pattern.

     • You want full control over request handling without the abstraction layer of classes.

   • Example:

       from django.shortcuts import render, get_object_or_404
       from .models import Question
     
       def detail(request, question_id):
           q = get_object_or_404(Question, pk=question_id)
           return render(request, 'polls/detail.html', {'question': q})
     

2. Class‑Based Views (CBVs)

   • What they are: Python classes (subclasses of django.views.View) with methods like get(), post(), etc., that handle different HTTP verbs.

   • Why use them:

     • Promote reuse via inheritance and mixins.

     • Built‑in generic implementations for common patterns.

     • Cleaner separation of GET vs. POST logic.

   • Basic Structure:

       from django.views import View
       from django.shortcuts import render
     
       class HelloView(View):
           def get(self, request):
               return render(request, 'hello.html')
     

3. Generic Class‑Based Views (GCBVs)
   Django ships with a set of “batteries‑included” CBVs for the most common web‑app patterns:

   | View | Purpose | | --- | --- | | TemplateView | Renders a template with a context. | | ListView | Displays a list of objects (e.g. rows). | | DetailView | Shows detail for a single object. | | CreateView | Displays a form for creating an object; saves on valid POST. | | UpdateView | Form for editing an existing object. | | DeleteView | Asks for confirmation then deletes object. | | FormView | Renders a form and processes it. | | RedirectView | Immediately redirects to a different URL. |

    from django.views.generic import ListView
    from .models import Question
   
    class QuestionListView(ListView):
        model = Question
        template_name = 'polls/question_list.html'
        context_object_name = 'questions'
   

4. Mixins
   — Small building‑block classes that you can combine with CBVs to add behavior (e.g. LoginRequiredMixin, PermissionRequiredMixin, FormMixin).

    from django.contrib.auth.mixins import LoginRequiredMixin
    from django.views.generic import CreateView
    from .models import Choice
   
    class ChoiceCreateView(LoginRequiredMixin, CreateView):
        model = Choice
        fields = ['question', 'choice_text']
   

5. Decorator‑Based Views
   — You can apply decorators (like @login_required, @permission_required) to FBVs, or use mixins on CBVs, to enforce authentication, permissions, caching, etc.

6. REST‑Style/API Views (when using Django REST Framework)
   If you add DRF, you get:

   • APIView: the base class for REST endpoints.

   • Generic API views & ViewSets: e.g. ListCreateAPIView, ModelViewSet, which mirror Django’s generic CBVs but for JSON/serializers instead of HTML/templates.

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How to choose?

• FBV if your view logic is very simple or highly customized.

• CBV/GCBV if you see yourself repeating the same boilerplate (e.g. “show list → show detail → form to create → form to update”) and want to leverage inheritance/mixins.

• DRF’s APIView/ViewSet for building RESTful JSON APIs.