Fixed #20249 - Removed a "feature" in the tutorial that doesn't actually work.
Thanks bmispelon for the report and draft patch.
This commit is contained in:
Tim Graham
parent
a6edde3260
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679a2ac843
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@ -185,7 +185,7 @@ conversion. We will:
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2. Delete some of the old, unneeded views.
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3. Fix up URL handling for the new views.
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3. Introduce new views based on Django's generic views.
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Read on for details.
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@ -205,32 +205,51 @@ Amend URLconf
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First, open the ``polls/urls.py`` URLconf and change it like so::
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from django.conf.urls import patterns, url
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from django.views.generic import DetailView, ListView
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from polls.models import Poll
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from polls import views
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urlpatterns = patterns('',
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url(r'^$',
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ListView.as_view(
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queryset=Poll.objects.order_by('-pub_date')[:5],
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context_object_name='latest_poll_list',
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template_name='polls/index.html'),
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name='index'),
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url(r'^(?P<pk>\d+)/$',
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DetailView.as_view(
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model=Poll,
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template_name='polls/detail.html'),
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name='detail'),
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url(r'^(?P<pk>\d+)/results/$',
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DetailView.as_view(
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model=Poll,
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template_name='polls/results.html'),
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name='results'),
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url(r'^(?P<poll_id>\d+)/vote/$', 'polls.views.vote', name='vote'),
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url(r'^$', views.IndexView.as_view(), name='index'),
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url(r'^(?P<pk>\d+)/$', views.DetailView.as_view(), name='detail'),
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url(r'^(?P<pk>\d+)/results/$', views.ResultsView.as_view(), name='results'),
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url(r'^(?P<poll_id>\d+)/vote/$', views.vote, name='vote'),
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)
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Amend views
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-----------
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Next, we're going to remove our old ``index``, ``detail``, and ``results``
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views and use Django's generic views instead. To do so, open the
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``polls/views.py`` file and change it like so::
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from django.shortcuts import get_object_or_404, render
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from django.http import HttpResponseRedirect
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from django.core.urlresolvers import reverse
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from django.views import generic
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from polls.models import Choice, Poll
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class IndexView(generic.ListView):
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template_name = 'polls/index.html'
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context_object_name = 'latest_poll_list'
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def get_queryset(self):
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"""Return the last five published polls."""
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return Poll.objects.order_by('-pub_date')[:5]
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class DetailView(generic.DetailView):
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model = Poll
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template_name = 'polls/detail.html'
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class ResultsView(generic.DetailView):
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model = Poll
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template_name = 'polls/results.html'
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def vote(request, poll_id):
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....
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We're using two generic views here:
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:class:`~django.views.generic.list.ListView` and
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:class:`~django.views.generic.detail.DetailView`. Respectively, those
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@ -238,7 +257,7 @@ two views abstract the concepts of "display a list of objects" and
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"display a detail page for a particular type of object."
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* Each generic view needs to know what model it will be acting
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upon. This is provided using the ``model`` parameter.
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upon. This is provided using the ``model`` attribute.
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* The :class:`~django.views.generic.detail.DetailView` generic view
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expects the primary key value captured from the URL to be called
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@ -248,7 +267,7 @@ two views abstract the concepts of "display a list of objects" and
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By default, the :class:`~django.views.generic.detail.DetailView` generic
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view uses a template called ``<app name>/<model name>_detail.html``.
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In our case, it'll use the template ``"polls/poll_detail.html"``. The
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``template_name`` argument is used to tell Django to use a specific
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``template_name`` attribute is used to tell Django to use a specific
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template name instead of the autogenerated default template name. We
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also specify the ``template_name`` for the ``results`` list view --
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this ensures that the results view and the detail view have a
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@ -268,16 +287,11 @@ automatically -- since we're using a Django model (``Poll``), Django
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is able to determine an appropriate name for the context variable.
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However, for ListView, the automatically generated context variable is
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``poll_list``. To override this we provide the ``context_object_name``
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option, specifying that we want to use ``latest_poll_list`` instead.
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attribute, specifying that we want to use ``latest_poll_list`` instead.
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As an alternative approach, you could change your templates to match
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the new default context variables -- but it's a lot easier to just
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tell Django to use the variable you want.
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You can now delete the ``index()``, ``detail()`` and ``results()`` views from
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``polls/views.py``. We don't need them anymore -- they have been replaced by
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generic views. You can also delete the import for ``HttpResponse``, which is no
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longer required.
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Run the server, and use your new polling app based on generic views.
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For full details on generic views, see the :doc:`generic views documentation
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@ -378,45 +378,40 @@ Improving our view
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The list of polls shows polls that aren't published yet (i.e. those that have a
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``pub_date`` in the future). Let's fix that.
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In :doc:`Tutorial 4 </intro/tutorial04>` we deleted the view functions from
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``views.py`` in favor of a :class:`~django.views.generic.list.ListView` in
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``urls.py``::
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In :doc:`Tutorial 4 </intro/tutorial04>` we introduced a class-based view,
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based on :class:`~django.views.generic.list.ListView`::
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url(r'^$',
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ListView.as_view(
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queryset=Poll.objects.order_by('-pub_date')[:5],
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context_object_name='latest_poll_list',
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template_name='polls/index.html'),
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name='index'),
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class IndexView(generic.ListView):
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template_name = 'polls/index.html'
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context_object_name = 'latest_poll_list'
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def get_queryset(self):
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"""Return the last five published polls."""
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return Poll.objects.order_by('-pub_date')[:5]
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``response.context_data['latest_poll_list']`` extracts the data this view
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places into the context.
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We need to amend the line that gives us the ``queryset``::
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queryset=Poll.objects.order_by('-pub_date')[:5],
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Let's change the queryset so that it also checks the date by comparing it with
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``timezone.now()``. First we need to add an import::
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We need to amend the ``get_queryset`` method and change it so that it also
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checks the date by comparing it with ``timezone.now()``. First we need to add
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an import::
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from django.utils import timezone
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and then we must amend the existing ``url`` function to::
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and then we must amend the ``get_queryset`` method like so::
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url(r'^$',
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ListView.as_view(
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queryset=Poll.objects.filter(pub_date__lte=timezone.now) \
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.order_by('-pub_date')[:5],
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context_object_name='latest_poll_list',
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template_name='polls/index.html'),
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name='index'),
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def get_queryset(self):
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"""
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Return the last five published polls (not including those set to be
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published in the future).
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"""
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return Poll.objects.filter(
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pub_date__lte=timezone.now()
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).order_by('-pub_date')[:5]
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``Poll.objects.filter(pub_date__lte=timezone.now)`` returns a queryset
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``Poll.objects.filter(pub_date__lte=timezone.now())`` returns a queryset
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containing Polls whose ``pub_date`` is less than or equal to - that is, earlier
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than or equal to - ``timezone.now``. Notice that we use a callable queryset
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argument, ``timezone.now``, which will be evaluated at request time. If we had
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included the parentheses, ``timezone.now()`` would be evaluated just once when
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the web server is started.
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than or equal to - ``timezone.now``.
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Testing our new view
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--------------------
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@ -527,20 +522,18 @@ Testing the ``DetailView``
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What we have works well; however, even though future polls don't appear in the
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*index*, users can still reach them if they know or guess the right URL. So we
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need similar constraints in the ``DetailViews``, by adding::
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need to add a similar constraint to ``DetailView``::
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queryset=Poll.objects.filter(pub_date__lte=timezone.now)
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to them - for example::
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class DetailView(generic.DetailView):
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...
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def get_queryset(self):
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"""
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Excludes any polls that aren't published yet.
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"""
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return Poll.objects.filter(pub_date__lte=timezone.now())
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url(r'^(?P<pk>\d+)/$',
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DetailView.as_view(
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queryset=Poll.objects.filter(pub_date__lte=timezone.now),
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model=Poll,
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template_name='polls/detail.html'),
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name='detail'),
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and of course, we will add some tests, to check that a ``Poll`` whose
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And of course, we will add some tests, to check that a ``Poll`` whose
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``pub_date`` is in the past can be displayed, and that one with a ``pub_date``
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in the future is not::
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@ -566,9 +559,9 @@ in the future is not::
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Ideas for more tests
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--------------------
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We ought to add similar ``queryset`` arguments to the other ``DetailView``
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URLs, and create a new test class for each view. They'll be very similar to
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what we have just created; in fact there will be a lot of repetition.
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We ought to add a similar ``get_queryset`` method to ``ResultsView`` and
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create a new test class for that view. It'll be very similar to what we have
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just created; in fact there will be a lot of repetition.
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We could also improve our application in other ways, adding tests along the
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way. For example, it's silly that ``Polls`` can be published on the site that
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