Django developers talk about three kinds of views:
- function views (FV)
- class-based views (CBV)
- generic class-based views (GCBV)
People do not make always make the difference between CBV and GCBV, which is
unfortunate, as they serve different purposes (naming things is hard). When
Andréas states earlier in this thread that "(CBV) use a lot of defaults for
populating your templates, forms and views" that is not 100% precise. He means
GCBV---which provide default (generic) behavior---not CBV.
Let's break it down. Below is an example of a FV.
from django.http import HttpResponse
from django.views.decorators.http import (
require_http_methods
)
# below is equivalent to require_safe decorator
@require_http_methods(["GET", "HEAD"])
def hello_world(request):
"""Demonstrate HTTP Request/Response"""
return HttpResponse("Hello World")
Below is an example of an equivalent CBV.
from django.http import HttpResponse
from django.views import View
class HelloWorld(View):
"""Demonstrate HTTP Request/Response"""
def get(self, request):
"""Handle GET HTTP method"""
return HttpResponse("Hello World")
Formally, a CBV is any class that inherits from View. The only difference
between the two views above is that the View class being inherited will give
you automatic handling of HTTP OPTIONS.
Stated otherwise: FV and CBV are *equivalent* with the exception of automatic
OPTIONS handling in CBV.
GCBV are simply CBV that have been given behavior. For example, instead of
programming a view that shows a template with model data, you can instead
inherit a DetailView, and customize it by setting class variables and by
overriding methods. For more about that, I recommend looking at
https://ccbv.co.uk .
So, when should you use a FV, CBV, or GCBV?
If you are building a view that a GCBV provides behavior for, save yourself
time and use it! It's easy to add or slightly modify GCBV behavior, but
difficult to remove behavior. The moment you're thinking about removing
something a GCBV does, stick to a function or CBV.
So then, for choosing between FV or CBV: Do you need to handle multiple HTTP
methods? Is there shared behavior between how the resource is handled by those
HTTP methods? If yes, a CBV can help organize that logic and avoid duplicate
code.
However, if you have a simple view (typically only one or two HTTP methods must
be handled), then a FV will serve you fine (remember the view decorators!).
If you're not sure, start with a FV, and then switch to a CBV or GCBV if
appropriate (as complexity goes up or when you realize you can use a GCBV).
Hope that helps,
Andrew
https://jambonsw.com
https://django-unleashed.com
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