========== Base views ========== The following three classes provide much of the functionality needed to create Django views. You may think of them as *parent* views, which can be used by themselves or inherited from. They may not provide all the capabilities required for projects, in which case there are Mixins and Generic class-based views. Many of Django's built-in class-based views inherit from other class-based views or various mixins. Because this inheritance chain is very important, the ancestor classes are documented under the section title of **Ancestors (MRO)**. MRO is an acronym for Method Resolution Order. ``View`` ======== .. class:: django.views.generic.base.View The base view class. All other class-based views inherit from this base class. It isn't strictly a generic view and thus can also be imported from ``django.views``. **Method Flowchart** #. :meth:`setup()` #. :meth:`dispatch()` #. :meth:`http_method_not_allowed()` #. :meth:`options()` **Example views.py**:: from django.http import HttpResponse from django.views import View class MyView(View): def get(self, request, *args, **kwargs): return HttpResponse('Hello, World!') **Example urls.py**:: from django.urls import path from myapp.views import MyView urlpatterns = [ path('mine/', MyView.as_view(), name='my-view'), ] **Attributes** .. attribute:: http_method_names The list of HTTP method names that this view will accept. Default:: ['get', 'post', 'put', 'patch', 'delete', 'head', 'options', 'trace'] **Methods** .. classmethod:: as_view(**initkwargs) Returns a callable view that takes a request and returns a response:: response = MyView.as_view()(request) The returned view has ``view_class`` and ``view_initkwargs`` attributes. When the view is called during the request/response cycle, the :meth:`setup` method assigns the :class:`~django.http.HttpRequest` to the view's ``request`` attribute, and any positional and/or keyword arguments :ref:`captured from the URL pattern ` to the ``args`` and ``kwargs`` attributes, respectively. Then :meth:`dispatch` is called. If a ``View`` subclass defines asynchronous (``async def``) method handlers, ``as_view()`` will mark the returned callable as a coroutine function. An ``ImproperlyConfigured`` exception will be raised if both asynchronous (``async def``) and synchronous (``def``) handlers are defined on a single view-class. .. method:: setup(request, *args, **kwargs) Performs key view initialization prior to :meth:`dispatch`. If overriding this method, you must call ``super()``. .. method:: dispatch(request, *args, **kwargs) The ``view`` part of the view -- the method that accepts a ``request`` argument plus arguments, and returns an HTTP response. The default implementation will inspect the HTTP method and attempt to delegate to a method that matches the HTTP method; a ``GET`` will be delegated to ``get()``, a ``POST`` to ``post()``, and so on. By default, a ``HEAD`` request will be delegated to ``get()``. If you need to handle ``HEAD`` requests in a different way than ``GET``, you can override the ``head()`` method. See :ref:`supporting-other-http-methods` for an example. .. method:: http_method_not_allowed(request, *args, **kwargs) If the view was called with an HTTP method it doesn't support, this method is called instead. The default implementation returns ``HttpResponseNotAllowed`` with a list of allowed methods in plain text. .. method:: options(request, *args, **kwargs) Handles responding to requests for the OPTIONS HTTP verb. Returns a response with the ``Allow`` header containing a list of the view's allowed HTTP method names. If the other HTTP methods handlers on the class are asynchronous (``async def``) then the response will be wrapped in a coroutine function for use with ``await``. ``TemplateView`` ================ .. class:: django.views.generic.base.TemplateView Renders a given template, with the context containing parameters captured in the URL. **Ancestors (MRO)** This view inherits methods and attributes from the following views: * :class:`django.views.generic.base.TemplateResponseMixin` * :class:`django.views.generic.base.ContextMixin` * :class:`django.views.generic.base.View` **Method Flowchart** #. :meth:`~django.views.generic.base.View.setup()` #. :meth:`~django.views.generic.base.View.dispatch()` #. :meth:`~django.views.generic.base.View.http_method_not_allowed()` #. :meth:`~django.views.generic.base.ContextMixin.get_context_data()` **Example views.py**:: from django.views.generic.base import TemplateView from articles.models import Article class HomePageView(TemplateView): template_name = "home.html" def get_context_data(self, **kwargs): context = super().get_context_data(**kwargs) context['latest_articles'] = Article.objects.all()[:5] return context **Example urls.py**:: from django.urls import path from myapp.views import HomePageView urlpatterns = [ path('', HomePageView.as_view(), name='home'), ] **Context** * Populated (through :class:`~django.views.generic.base.ContextMixin`) with the keyword arguments captured from the URL pattern that served the view. * You can also add context using the :attr:`~django.views.generic.base.ContextMixin.extra_context` keyword argument for :meth:`~django.views.generic.base.View.as_view`. ``RedirectView`` ================ .. class:: django.views.generic.base.RedirectView Redirects to a given URL. The given URL may contain dictionary-style string formatting, which will be interpolated against the parameters captured in the URL. Because keyword interpolation is *always* done (even if no arguments are passed in), any ``"%"`` characters in the URL must be written as ``"%%"`` so that Python will convert them to a single percent sign on output. If the given URL is ``None``, Django will return an ``HttpResponseGone`` (410). **Ancestors (MRO)** This view inherits methods and attributes from the following view: * :class:`django.views.generic.base.View` **Method Flowchart** #. :meth:`~django.views.generic.base.View.setup()` #. :meth:`~django.views.generic.base.View.dispatch()` #. :meth:`~django.views.generic.base.View.http_method_not_allowed()` #. :meth:`get_redirect_url()` **Example views.py**:: from django.shortcuts import get_object_or_404 from django.views.generic.base import RedirectView from articles.models import Article class ArticleCounterRedirectView(RedirectView): permanent = False query_string = True pattern_name = 'article-detail' def get_redirect_url(self, *args, **kwargs): article = get_object_or_404(Article, pk=kwargs['pk']) article.update_counter() return super().get_redirect_url(*args, **kwargs) **Example urls.py**:: from django.urls import path from django.views.generic.base import RedirectView from article.views import ArticleCounterRedirectView, ArticleDetailView urlpatterns = [ path('counter//', ArticleCounterRedirectView.as_view(), name='article-counter'), path('details//', ArticleDetailView.as_view(), name='article-detail'), path('go-to-django/', RedirectView.as_view(url='https://www.djangoproject.com/'), name='go-to-django'), ] **Attributes** .. attribute:: url The URL to redirect to, as a string. Or ``None`` to raise a 410 (Gone) HTTP error. .. attribute:: pattern_name The name of the URL pattern to redirect to. Reversing will be done using the same args and kwargs as are passed in for this view. .. attribute:: permanent Whether the redirect should be permanent. The only difference here is the HTTP status code returned. If ``True``, then the redirect will use status code 301. If ``False``, then the redirect will use status code 302. By default, ``permanent`` is ``False``. .. attribute:: query_string Whether to pass along the GET query string to the new location. If ``True``, then the query string is appended to the URL. If ``False``, then the query string is discarded. By default, ``query_string`` is ``False``. **Methods** .. method:: get_redirect_url(*args, **kwargs) Constructs the target URL for redirection. The ``args`` and ``kwargs`` arguments are positional and/or keyword arguments :ref:`captured from the URL pattern `, respectively. The default implementation uses :attr:`url` as a starting string and performs expansion of ``%`` named parameters in that string using the named groups captured in the URL. If :attr:`url` is not set, ``get_redirect_url()`` tries to reverse the :attr:`pattern_name` using what was captured in the URL (both named and unnamed groups are used). If requested by :attr:`query_string`, it will also append the query string to the generated URL. Subclasses may implement any behavior they wish, as long as the method returns a redirect-ready URL string.