I have to +1 Carstens answer. In short, I too find CB views to be too "magical".
=) On Thu, 22 Nov 2018 at 11:53, Carsten Fuchs <carsten.fu...@cafu.de> wrote: > Hi Andrew, > > many thanks for your clear and detailed explanation! > > Having used Django for several years, FVs are still my favorite approach > over CBVs and GCBVs. In the past, I made several starts with CBVs, but > never found or understood why CBVs and GCBVs seem to be in many people's > center of attention. > > FVs are not only the most simple of the three, but they also have the > virtue of emphasizing the basic generic HTML web functionality and the > way how forms work: The three logical paths that form processing can > take are clearly shown in e.g. this (modified) example from > https://django-book.readthedocs.io/en/latest/chapter07.html > > def contact(request): > if request.method == 'POST': > form = ContactForm(request.POST) > if form.is_valid(): > # success, now use form.cleaned_data > return HttpResponseRedirect('/contact/thanks/') > else: > form = ContactForm() > > # We get here both for GET requests and POST requests > # with invalid forms. > return render(request, 'contact_form.html', {'form': form}) > > When I was new to Django (and in fact new to serious web development), > understanding this concept, as step by step explained in the above > mentioned chapter, was one of the key insights for me. > > CBV and GCBV obscure this imho fundamental concept. Personally, I've > never found the CBV's help with DRY outweigh the clarity of FVs. With > all the attention and efforts that are spent on making getting started > with Django easier for beginners, I was really surprised when even the > official Django tutorials were changed from FVs to CBVs. > > I write this email to thank you for your explanation, but also to add > the above thoughts, which I have long been pondering but never found a > place to write down. ;-) > > Best regards, > Carsten > > > Am 21.11.18 um 21:39 schrieb Andrew Pinkham: > > 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 > > > > -- > You received this message because you are subscribed to the Google Groups > "Django users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to django-users+unsubscr...@googlegroups.com. > To post to this group, send email to django-users@googlegroups.com. > Visit this group at https://groups.google.com/group/django-users. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-users/3e4ce109-2f24-edfa-0eb3-3426cc52816d%40cafu.de > . > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Django users" group. 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