django/docs/ref/class-based-views/base.txt

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==========
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.
View
----
.. class:: django.views.generic.base.View
The master class-based base view. All other class-based views inherit from
this base class.
**Method Flowchart**
1. :meth:`dispatch()`
2. :meth:`http_method_not_allowed()`
**Example views.py**::
from django.http import HttpResponse
from django.views.generic import View
class MyView(View):
def get(self, request, *args, **kwargs):
return HttpResponse('Hello, World!')
**Example urls.py**::
from django.conf.urls import patterns, url
from myapp.views import MyView
urlpatterns = patterns('',
url(r'^mine/$', MyView.as_view(), name='my-view'),
)
**Methods**
.. method:: dispatch(request, *args, **kwargs)
The ``view`` part of the view -- the method that accepts a ``request``
argument plus arguments, and returns a 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 :meth:`~View.get()`, a ``POST`` to :meth:`~View.post()`,
and so on.
The default implementation also sets ``request``, ``args`` and
``kwargs`` as instance variables, so any method on the view can know
the full details of the request that was made to invoke the view.
.. method:: http_method_not_allowed(request, *args, **kwargs)
If the view was called with a HTTP method it doesn't support, this
method is called instead.
The default implementation returns ``HttpResponseNotAllowed`` with list
of allowed methods in plain text.
.. note::
Documentation on class-based views is a work in progress. As yet, only the
methods defined directly on the class are documented here, not methods
defined on superclasses.
TemplateView
------------
.. class:: django.views.generic.base.TemplateView
Renders a given template, passing it a ``{{ params }}`` template variable,
which is a dictionary of the parameters captured in the URL.
**Ancestors (MRO)**
* :class:`django.views.generic.base.TemplateView`
* :class:`django.views.generic.base.TemplateResponseMixin`
* :class:`django.views.generic.base.View`
**Method Flowchart**
1. :meth:`dispatch()`
2. :meth:`http_method_not_allowed()`
3. :meth:`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(HomePageView, self).get_context_data(**kwargs)
context['latest_articles'] = Article.objects.all()[:5]
return context
**Example urls.py**::
from django.conf.urls import patterns, url
from myapp.views import HomePageView
urlpatterns = patterns('',
url(r'^$', HomePageView.as_view(), name='home'),
)
**Methods and Attributes**
.. attribute:: template_name
The full name of a template to use.
.. method:: get_context_data(**kwargs)
Return a context data dictionary consisting of the contents of
``kwargs`` stored in the context variable ``params``.
**Context**
* ``params``: The dictionary of keyword arguments captured from the URL
pattern that served the view.
.. note::
Documentation on class-based views is a work in progress. As yet, only the
methods defined directly on the class are documented here, not methods
defined on superclasses.
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)**
* :class:`django.views.generic.base.View`
**Method Flowchart**
1. :meth:`dispatch()`
2. :meth:`http_method_not_allowed()`
3. :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
def get_redirect_url(self, pk):
article = get_object_or_404(Article, pk=pk)
article.update_counter()
return reverse('product_detail', args=(pk,))
**Example urls.py**::
from django.conf.urls import patterns, url
from django.views.generic.base import RedirectView
from article.views import ArticleCounterRedirectView
urlpatterns = patterns('',
url(r'r^(?P<pk>\d+)/$', ArticleCounterRedirectView.as_view(), name='article-counter'),
url(r'^go-to-django/$', RedirectView.as_view(url='http://djangoproject.com'), name='go-to-django'),
)
**Methods and Attributes**
.. attribute:: url
The URL to redirect to, as a string. Or ``None`` to raise a 410 (Gone)
HTTP error.
.. 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 ``True``.
.. 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``.
.. method:: get_redirect_url(**kwargs)
Constructs the target URL for redirection.
The default implementation uses :attr:`~RedirectView.url` as a starting
string, performs expansion of ``%`` parameters in that string, as well
as the appending of query string if requested by
:attr:`~RedirectView.query_string`. Subclasses may implement any
behavior they wish, as long as the method returns a redirect-ready URL
string.
.. note::
Documentation on class-based views is a work in progress. As yet, only the
methods defined directly on the class are documented here, not methods
defined on superclasses.