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320 lines
9.1 KiB
Plaintext
320 lines
9.1 KiB
Plaintext
=========================
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Django shortcut functions
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=========================
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.. module:: django.shortcuts
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:synopsis:
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Convenience shortcuts that span multiple levels of Django's MVC stack.
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.. index:: shortcuts
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The package ``django.shortcuts`` collects helper functions and classes that
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"span" multiple levels of MVC. In other words, these functions/classes
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introduce controlled coupling for convenience's sake.
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``render()``
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============
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.. function:: render(request, template_name, context=None, content_type=None, status=None, using=None)
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Combines a given template with a given context dictionary and returns an
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:class:`~django.http.HttpResponse` object with that rendered text.
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Django does not provide a shortcut function which returns a
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:class:`~django.template.response.TemplateResponse` because the constructor
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of :class:`~django.template.response.TemplateResponse` offers the same level
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of convenience as :func:`render()`.
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Required arguments
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------------------
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``request``
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The request object used to generate this response.
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``template_name``
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The full name of a template to use or sequence of template names. If a
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sequence is given, the first template that exists will be used. See the
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:ref:`template loading documentation <template-loading>` for more
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information on how templates are found.
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Optional arguments
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------------------
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``context``
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A dictionary of values to add to the template context. By default, this
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is an empty dictionary. If a value in the dictionary is callable, the
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view will call it just before rendering the template.
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``content_type``
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The MIME type to use for the resulting document. Defaults to
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``'text/html'``.
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``status``
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The status code for the response. Defaults to ``200``.
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``using``
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The :setting:`NAME <TEMPLATES-NAME>` of a template engine to use for
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loading the template.
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Example
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-------
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The following example renders the template ``myapp/index.html`` with the
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MIME type :mimetype:`application/xhtml+xml`::
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from django.shortcuts import render
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def my_view(request):
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# View code here...
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return render(
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request,
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"myapp/index.html",
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{
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"foo": "bar",
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},
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content_type="application/xhtml+xml",
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)
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This example is equivalent to::
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from django.http import HttpResponse
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from django.template import loader
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def my_view(request):
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# View code here...
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t = loader.get_template("myapp/index.html")
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c = {"foo": "bar"}
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return HttpResponse(t.render(c, request), content_type="application/xhtml+xml")
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``redirect()``
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==============
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.. function:: redirect(to, *args, permanent=False, preserve_request=False, **kwargs)
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Returns an :class:`~django.http.HttpResponseRedirect` to the appropriate URL
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for the arguments passed.
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The arguments could be:
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* A model: the model's :meth:`~django.db.models.Model.get_absolute_url()`
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function will be called.
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* A view name, possibly with arguments: :func:`~django.urls.reverse` will be
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used to reverse-resolve the name.
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* An absolute or relative URL, which will be used as-is for the redirect
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location.
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By default, a temporary redirect is issued with a 302 status code. If
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``permanent=True``, a permanent redirect is issued with a 301 status code.
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If ``preserve_request=True``, the response instructs the user agent to
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preserve the method and body of the original request when issuing the
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redirect. In this case, temporary redirects use a 307 status code, and
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permanent redirects use a 308 status code. This is better illustrated in the
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following table:
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========= ================ ================
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permanent preserve_request HTTP status code
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========= ================ ================
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``True`` ``False`` 301
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``False`` ``False`` 302
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``False`` ``True`` 307
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``True`` ``True`` 308
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========= ================ ================
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.. versionchanged:: 5.2
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The argument ``preserve_request`` was added.
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Examples
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--------
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You can use the :func:`redirect` function in a number of ways.
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#. By passing some object; that object's
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:meth:`~django.db.models.Model.get_absolute_url` method will be called
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to figure out the redirect URL::
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from django.shortcuts import redirect
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def my_view(request):
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...
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obj = MyModel.objects.get(...)
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return redirect(obj)
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#. By passing the name of a view and optionally some positional or
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keyword arguments; the URL will be reverse resolved using the
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:func:`~django.urls.reverse` method::
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def my_view(request):
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...
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return redirect("some-view-name", foo="bar")
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#. By passing a hardcoded URL to redirect to:
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::
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def my_view(request):
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...
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return redirect("/some/url/")
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This also works with full URLs:
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::
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def my_view(request):
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...
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return redirect("https://example.com/")
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By default, :func:`redirect` returns a temporary redirect. All of the above
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forms accept a ``permanent`` argument; if set to ``True`` a permanent redirect
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will be returned::
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def my_view(request):
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...
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obj = MyModel.objects.get(...)
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return redirect(obj, permanent=True)
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Additionally, the ``preserve_request`` argument can be used to preserve the
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original HTTP method::
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def my_view(request):
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# ...
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obj = MyModel.objects.get(...)
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if request.method in ("POST", "PUT"):
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# Redirection preserves the original request method.
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return redirect(obj, preserve_request=True)
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# ...
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``get_object_or_404()``
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=======================
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.. function:: get_object_or_404(klass, *args, **kwargs)
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.. function:: aget_object_or_404(klass, *args, **kwargs)
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*Asynchronous version*: ``aget_object_or_404()``
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Calls :meth:`~django.db.models.query.QuerySet.get()` on a given model
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manager, but it raises :class:`~django.http.Http404` instead of the model's
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:class:`~django.db.models.Model.DoesNotExist` exception.
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Arguments
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---------
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``klass``
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A :class:`~django.db.models.Model` class,
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a :class:`~django.db.models.Manager`,
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or a :class:`~django.db.models.query.QuerySet` instance from which to get
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the object.
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``*args``
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:class:`Q objects <django.db.models.Q>`.
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``**kwargs``
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Lookup parameters, which should be in the format accepted by ``get()`` and
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``filter()``.
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Example
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-------
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The following example gets the object with the primary key of 1 from
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``MyModel``::
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from django.shortcuts import get_object_or_404
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def my_view(request):
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obj = get_object_or_404(MyModel, pk=1)
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This example is equivalent to::
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from django.http import Http404
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def my_view(request):
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try:
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obj = MyModel.objects.get(pk=1)
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except MyModel.DoesNotExist:
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raise Http404("No MyModel matches the given query.")
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The most common use case is to pass a :class:`~django.db.models.Model`, as
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shown above. However, you can also pass a
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:class:`~django.db.models.query.QuerySet` instance::
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queryset = Book.objects.filter(title__startswith="M")
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get_object_or_404(queryset, pk=1)
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The above example is a bit contrived since it's equivalent to doing::
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get_object_or_404(Book, title__startswith="M", pk=1)
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but it can be useful if you are passed the ``queryset`` variable from somewhere
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else.
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Finally, you can also use a :class:`~django.db.models.Manager`. This is useful
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for example if you have a
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:ref:`custom manager<custom-managers>`::
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get_object_or_404(Book.dahl_objects, title="Matilda")
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You can also use
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:class:`related managers<django.db.models.fields.related.RelatedManager>`::
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author = Author.objects.get(name="Roald Dahl")
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get_object_or_404(author.book_set, title="Matilda")
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Note: As with ``get()``, a
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:class:`~django.core.exceptions.MultipleObjectsReturned` exception
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will be raised if more than one object is found.
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``get_list_or_404()``
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=====================
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.. function:: get_list_or_404(klass, *args, **kwargs)
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.. function:: aget_list_or_404(klass, *args, **kwargs)
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*Asynchronous version*: ``aget_list_or_404()``
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Returns the result of :meth:`~django.db.models.query.QuerySet.filter()` on
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a given model manager cast to a list, raising :class:`~django.http.Http404`
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if the resulting list is empty.
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Arguments
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---------
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``klass``
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A :class:`~django.db.models.Model`, :class:`~django.db.models.Manager` or
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:class:`~django.db.models.query.QuerySet` instance from which to get the
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list.
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``*args``
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:class:`Q objects <django.db.models.Q>`.
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``**kwargs``
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Lookup parameters, which should be in the format accepted by ``get()`` and
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``filter()``.
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Example
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-------
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The following example gets all published objects from ``MyModel``::
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from django.shortcuts import get_list_or_404
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def my_view(request):
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my_objects = get_list_or_404(MyModel, published=True)
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This example is equivalent to::
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from django.http import Http404
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def my_view(request):
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my_objects = list(MyModel.objects.filter(published=True))
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if not my_objects:
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raise Http404("No MyModel matches the given query.")
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