A view is a callable which takes a request and returns a\nresponse. This can be more than just a function, and Django provides\nan example of some classes which can be used as views. These allow you\nto structure your views and reuse code by harnessing inheritance and\nmixins. There are also some generic views for tasks which we’ll get to later,\nbut you may want to design your own structure of reusable views which suits\nyour use case. For full details, see the class-based views reference\ndocumentation.
\nDjango provides base view classes which will suit a wide range of applications.\nAll views inherit from the View class, which\nhandles linking the view into the URLs, HTTP method dispatching and other\ncommon features. RedirectView provides a\nHTTP redirect, and TemplateView extends the\nbase class to make it also render a template.
The most direct way to use generic views is to create them directly in your\nURLconf. If you’re only changing a few attributes on a class-based view, you\ncan pass them into the as_view() method\ncall itself:
from django.urls import path\nfrom django.views.generic import TemplateView\n\nurlpatterns = [\n path('about/', TemplateView.as_view(template_name="about.html")),\n]\nAny arguments passed to as_view() will\noverride attributes set on the class. In this example, we set template_name\non the TemplateView. A similar overriding pattern can be used for the\nurl attribute on RedirectView.
The second, more powerful way to use generic views is to inherit from an\nexisting view and override attributes (such as the template_name) or\nmethods (such as get_context_data) in your subclass to provide new values\nor methods. Consider, for example, a view that just displays one template,\nabout.html. Django has a generic view to do this -\nTemplateView - so we can subclass it, and\noverride the template name:
# some_app/views.py\nfrom django.views.generic import TemplateView\n\nclass AboutView(TemplateView):\n template_name = "about.html"\nThen we need to add this new view into our URLconf.\nTemplateView is a class, not a function, so\nwe point the URL to the as_view() class\nmethod instead, which provides a function-like entry to class-based views:
# urls.py\nfrom django.urls import path\nfrom some_app.views import AboutView\n\nurlpatterns = [\n path('about/', AboutView.as_view()),\n]\nFor more information on how to use the built in generic views, consult the next\ntopic on generic class-based views.
\nSuppose somebody wants to access our book library over HTTP using the views\nas an API. The API client would connect every now and then and download book\ndata for the books published since last visit. But if no new books appeared\nsince then, it is a waste of CPU time and bandwidth to fetch the books from the\ndatabase, render a full response and send it to the client. It might be\npreferable to ask the API when the most recent book was published.
\nWe map the URL to book list view in the URLconf:
\nfrom django.urls import path\nfrom books.views import BookListView\n\nurlpatterns = [\n path('books/', BookListView.as_view()),\n]\nAnd the view:
\nfrom django.http import HttpResponse\nfrom django.views.generic import ListView\nfrom books.models import Book\n\nclass BookListView(ListView):\n model = Book\n\n def head(self, *args, **kwargs):\n last_book = self.get_queryset().latest('publication_date')\n response = HttpResponse(\n # RFC 1123 date format.\n headers={'Last-Modified': last_book.publication_date.strftime('%a, %d %b %Y %H:%M:%S GMT')},\n )\n return response\nIf the view is accessed from a GET request, an object list is returned in\nthe response (using the book_list.html template). But if the client issues\na HEAD request, the response has an empty body and the Last-Modified\nheader indicates when the most recent book was published. Based on this\ninformation, the client may or may not download the full object list.