? Overriding CBV Methods

? Quick Overview

Class-Based Views (CBVs) provide a structured way to organize view logic in Django. While CBVs offer many built-in methods for handling HTTP requests and responses, there are times when you may need to modify or extend the default behavior.

? Key Concepts

• CBVs encapsulate request handling logic into reusable classes
• Overriding methods allows precise customization
• Default behavior should usually be preserved using super()

? Why Override CBV Methods?

• Change how data is retrieved or processed
• Customize GET or POST request handling
• Modify template context
• Run logic before or after default behavior

? Common Methods to Override

• get_context_data()
• get_queryset()
• form_valid()
• get()
• post()

? Example: Overriding get_context_data

# Adding extra context data to template
from django.views.generic import DetailView
from .models import Book

class BookDetailView(DetailView):
    model = Book
    template_name = 'book_detail.html'
    context_object_name = 'book'

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['additional_info'] = "Some additional context data"
        return context

? Example: Overriding get_queryset

# Filtering queryset based on condition
from django.views.generic import ListView
from .models import Book

class BookListView(ListView):
    model = Book
    template_name = 'book_list.html'
    context_object_name = 'books'

    def get_queryset(self):
        return Book.objects.filter(pages__gt=100)

? Example: Overriding form_valid

# Custom action before saving form
from django.views.generic.edit import CreateView
from .models import Book

class BookCreateView(CreateView):
    model = Book
    template_name = 'book_form.html'
    fields = ['title', 'author', 'price']

    def form_valid(self, form):
        form.instance.created_by = self.request.user
        return super().form_valid(form)

? Live Explanation

Each overridden method allows you to inject custom logic while still leveraging Django’s built-in workflow. Using super() ensures the framework continues to handle routing, rendering, and validation correctly.

? Visual Flow (CBV Lifecycle)

? Use Cases

• Custom dashboards
• User-specific filtering
• Audit logging after form submission
• Dynamic template context