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246 lines
7.8 KiB
Plaintext
246 lines
7.8 KiB
Plaintext
==========
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Base views
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==========
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The following three classes provide much of the functionality needed to create
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Django views. You may think of them as *parent* views, which can be used by
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themselves or inherited from. They may not provide all the capabilities
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required for projects, in which case there are Mixins and Generic class-based
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views.
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Many of Django's built-in class-based views inherit from other class-based
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views or various mixins. Because this inheritence chain is very important, the
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ancestor classes are documented under the section title of **Ancestors (MRO)**.
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MRO is an acronym for Method Resolution Order.
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View
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----
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.. class:: django.views.generic.base.View
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The master class-based base view. All other class-based views inherit from
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this base class.
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**Method Flowchart**
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1. :meth:`dispatch()`
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2. :meth:`http_method_not_allowed()`
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3. :meth:`options()`
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**Example views.py**::
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from django.http import HttpResponse
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from django.views.generic import View
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class MyView(View):
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def get(self, request, *args, **kwargs):
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return HttpResponse('Hello, World!')
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**Example urls.py**::
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from django.conf.urls import patterns, url
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from myapp.views import MyView
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urlpatterns = patterns('',
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url(r'^mine/$', MyView.as_view(), name='my-view'),
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)
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**Attributes**
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.. attribute:: http_method_names
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The list of HTTP method names that this view will accept.
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Default::
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['get', 'post', 'put', 'delete', 'head', 'options', 'trace']
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**Methods**
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.. classmethod:: as_view(**initkwargs)
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Returns a callable view that takes a request and returns a response::
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response = MyView.as_view()(request)
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.. method:: dispatch(request, *args, **kwargs)
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The ``view`` part of the view -- the method that accepts a ``request``
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argument plus arguments, and returns a HTTP response.
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The default implementation will inspect the HTTP method and attempt to
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delegate to a method that matches the HTTP method; a ``GET`` will be
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delegated to ``get()``, a ``POST`` to ``post()``, and so on.
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By default, a ``HEAD`` request will be delegated to ``get()``.
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If you need to handle ``HEAD`` requests in a different way than ``GET``,
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you can override the ``head()`` method. See
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:ref:`supporting-other-http-methods` for an example.
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The default implementation also sets ``request``, ``args`` and
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``kwargs`` as instance variables, so any method on the view can know
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the full details of the request that was made to invoke the view.
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.. method:: http_method_not_allowed(request, *args, **kwargs)
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If the view was called with a HTTP method it doesn't support, this
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method is called instead.
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The default implementation returns ``HttpResponseNotAllowed`` with a
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list of allowed methods in plain text.
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.. method:: options(request, *args, **kwargs)
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Handles responding to requests for the OPTIONS HTTP verb. Returns a
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list of the allowed HTTP method names for the view.
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TemplateView
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------------
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.. class:: django.views.generic.base.TemplateView
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Renders a given template, with the context containing parameters captured
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in the URL.
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.. versionchanged:: 1.5
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The context used to be populated with a ``{{ params }}`` dictionary of
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the parameters captured in the URL. Now those parameters are first-level
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context variables.
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**Ancestors (MRO)**
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This view inherits methods and attributes from the following views:
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* :class:`django.views.generic.base.TemplateView`
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* :class:`django.views.generic.base.TemplateResponseMixin`
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* :class:`django.views.generic.base.View`
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**Method Flowchart**
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1. :meth:`~django.views.generic.base.View.dispatch()`
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2. :meth:`~django.views.generic.base.View.http_method_not_allowed()`
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3. :meth:`~django.views.generic.base.ContextMixin.get_context_data()`
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**Example views.py**::
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from django.views.generic.base import TemplateView
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from articles.models import Article
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class HomePageView(TemplateView):
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template_name = "home.html"
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def get_context_data(self, **kwargs):
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context = super(HomePageView, self).get_context_data(**kwargs)
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context['latest_articles'] = Article.objects.all()[:5]
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return context
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**Example urls.py**::
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from django.conf.urls import patterns, url
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from myapp.views import HomePageView
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urlpatterns = patterns('',
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url(r'^$', HomePageView.as_view(), name='home'),
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)
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**Context**
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* ``params``: The dictionary of keyword arguments captured from the URL
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pattern that served the view.
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RedirectView
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------------
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.. class:: django.views.generic.base.RedirectView
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Redirects to a given URL.
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The given URL may contain dictionary-style string formatting, which will be
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interpolated against the parameters captured in the URL. Because keyword
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interpolation is *always* done (even if no arguments are passed in), any
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``"%"`` characters in the URL must be written as ``"%%"`` so that Python
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will convert them to a single percent sign on output.
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If the given URL is ``None``, Django will return an ``HttpResponseGone``
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(410).
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**Ancestors (MRO)**
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This view inherits methods and attributes from the following view:
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* :class:`django.views.generic.base.View`
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**Method Flowchart**
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1. :meth:`~django.views.generic.base.View.dispatch()`
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2. :meth:`~django.views.generic.base.View.http_method_not_allowed()`
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3. :meth:`get_redirect_url()`
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**Example views.py**::
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from django.shortcuts import get_object_or_404
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from django.views.generic.base import RedirectView
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from articles.models import Article
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class ArticleCounterRedirectView(RedirectView):
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permanent = False
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query_string = True
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def get_redirect_url(self, pk):
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article = get_object_or_404(Article, pk=pk)
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article.update_counter()
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return reverse('product_detail', args=(pk,))
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**Example urls.py**::
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from django.conf.urls import patterns, url
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from django.views.generic.base import RedirectView
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from article.views import ArticleCounterRedirectView
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urlpatterns = patterns('',
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url(r'r^(?P<pk>\d+)/$', ArticleCounterRedirectView.as_view(), name='article-counter'),
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url(r'^go-to-django/$', RedirectView.as_view(url='http://djangoproject.com'), name='go-to-django'),
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)
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**Attributes**
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.. attribute:: url
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The URL to redirect to, as a string. Or ``None`` to raise a 410 (Gone)
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HTTP error.
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.. attribute:: permanent
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Whether the redirect should be permanent. The only difference here is
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the HTTP status code returned. If ``True``, then the redirect will use
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status code 301. If ``False``, then the redirect will use status code
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302. By default, ``permanent`` is ``True``.
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.. attribute:: query_string
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Whether to pass along the GET query string to the new location. If
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``True``, then the query string is appended to the URL. If ``False``,
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then the query string is discarded. By default, ``query_string`` is
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``False``.
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**Methods**
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.. method:: get_redirect_url(**kwargs)
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Constructs the target URL for redirection.
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The default implementation uses :attr:`url` as a starting
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string, performs expansion of ``%`` parameters in that string, as well
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as the appending of query string if requested by :attr:`query_string`.
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Subclasses may implement any behavior they wish, as long as the method
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returns a redirect-ready URL string.
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