Tampilan berdasarkan-kelas

A view is a callable which takes a request and returns a response. This can be more than just a function, and Django provides an example of some classes which can be used as views. These allow you to structure your views and reuse code by harnessing inheritance and mixins. There are also some generic views for tasks which we'll get to later, but you may want to design your own structure of reusable views which suits your use case. For full details, see the class-based views reference documentation.

Contoh dasar

Django provides base view classes which will suit a wide range of applications. All views inherit from the View class, which handles linking the view into the URLs, HTTP method dispatching and other common features. RedirectView provides a HTTP redirect, and TemplateView extends the base class to make it also render a template.

Penggunaan dalam URLconf anda

The most direct way to use generic views is to create them directly in your URLconf. If you're only changing a few attributes on a class-based view, you can pass them into the as_view() method call itself:

from django.urls import path
from django.views.generic import TemplateView

urlpatterns = [
    path('about/', TemplateView.as_view(template_name="about.html")),
]

Apapun argumen dilewatkan ke as_view() akan menimpa atribut disetel pada kelas. Dalam contoh ini, kami menyetel template_name` pada TemplateView. Pola penibanan mirip dapat digunakan untuk atribut url pada RedirectView.

Mensubkelaskan tampilan umum

The second, more powerful way to use generic views is to inherit from an existing view and override attributes (such as the template_name) or methods (such as get_context_data) in your subclass to provide new values or methods. Consider, for example, a view that just displays one template, about.html. Django has a generic view to do this - TemplateView - so we can subclass it, and override the template name:

# some_app/views.py
from django.views.generic import TemplateView

class AboutView(TemplateView):
    template_name = "about.html"

Then we need to add this new view into our URLconf. TemplateView is a class, not a function, so we point the URL to the as_view() class method instead, which provides a function-like entry to class-based views:

# urls.py
from django.urls import path
from some_app.views import AboutView

urlpatterns = [
    path('about/', AboutView.as_view()),
]

Untuk informasi lebih pada bagaimana menggunakan tampilan umum siap pakai, obrolkan topik selanjutnya di generic class-based views.

mendukung cara HTTP lain

Misalkan seseorang ingin mengakses pustaka buku kami terhadap HTTP menggunakan tampilan sebagai sebuah klien API akan terhubung setiap sekarang kemudian dan mengunduh buku untuk buku diterbitkan sejak kunjugan terakhir. Tetapi jika tidak ada buku baru muncul sejak itu, itu adalah pembuangan dari waktu CPU dan lebar pita untuk mengambil buku-buku dari basisdata, mengirim tanggapan penuh dan mengirim itu ke klien. Itu mungkin lebih baik untuk menanyakan API ketika kebanyakan buku saat ini telah diterbitkan.

Kami memetakan UTL pada tampilan daftar buku di URLconf:

from django.urls import path
from books.views import BookListView

urlpatterns = [
    path('books/', BookListView.as_view()),
]

Dan tampilan:

from django.http import HttpResponse
from django.views.generic import ListView
from books.models import Book

class BookListView(ListView):
    model = Book

    def head(self, *args, **kwargs):
        last_book = self.get_queryset().latest('publication_date')
        response = HttpResponse(
            # RFC 1123 date format.
            headers={'Last-Modified': last_book.publication_date.strftime('%a, %d %b %Y %H:%M:%S GMT')},
        )
        return response

If the view is accessed from a GET request, an object list is returned in the response (using the book_list.html template). But if the client issues a HEAD request, the response has an empty body and the Last-Modified header indicates when the most recent book was published. Based on this information, the client may or may not download the full object list.

Asynchronous class-based views

New in Django 4.1.

As well as the synchronous (def) method handlers already shown, View subclasses may define asynchronous (async def) method handlers to leverage asynchronous code using await:

import asyncio
from django.http import HttpResponse
from django.views import View

class AsyncView(View):
    async def get(self, request, *args, **kwargs):
        # Perform io-blocking view logic using await, sleep for example.
        await asyncio.sleep(1)
        return HttpResponse("Hello async world!")

Within a single view-class, all user-defined method handlers must be either synchronous, using def, or all asynchronous, using async def. An ImproperlyConfigured exception will be raised in as_view() if def and async def declarations are mixed.

Django will automatically detect asynchronous views and run them in an asynchronous context. You can read more about Django's asynchronous support, and how to best use async views, in Dukungan asinkronus.

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