docs/topics/http/shortcuts.txt
=========================
Django shortcut functions
=========================
.. module:: django.shortcuts
:synopsis:
Convenience shortcuts that span multiple levels of Django's MVC stack.
.. index:: shortcuts
The package ``django.shortcuts`` collects helper functions and classes that
"span" multiple levels of MVC. In other words, these functions/classes
introduce controlled coupling for convenience's sake.
``render()``
============
.. function:: render(request, template_name, context=None, content_type=None, status=None, using=None)
Combines a given template with a given context dictionary and returns an
:class:`~django.http.HttpResponse` object with that rendered text.
Django does not provide a shortcut function which returns a
:class:`~django.template.response.TemplateResponse` because the constructor
of :class:`~django.template.response.TemplateResponse` offers the same level
of convenience as :func:`render()`.
Required arguments
------------------
``request``
The request object used to generate this response.
``template_name``
The full name of a template to use or sequence of template names. If a
sequence is given, the first template that exists will be used. See the
:ref:`template loading documentation <template-loading>` for more
information on how templates are found.
Optional arguments
------------------
``context``
A dictionary of values to add to the template context. By default, this
is an empty dictionary. If a value in the dictionary is callable, the
view will call it just before rendering the template.
``content_type``
The MIME type to use for the resulting document. Defaults to
``'text/html'``.
``status``
The status code for the response. Defaults to ``200``.
``using``
The :setting:`NAME <TEMPLATES-NAME>` of a template engine to use for
loading the template.
Example
-------
The following example renders the template ``myapp/index.html`` with the
MIME type :mimetype:`application/xhtml+xml`::
from django.shortcuts import render
def my_view(request):
# View code here...
return render(
request,
"myapp/index.html",
{
"foo": "bar",
},
content_type="application/xhtml+xml",
)
This example is equivalent to::
from django.http import HttpResponse
from django.template import loader
def my_view(request):
# View code here...
t = loader.get_template("myapp/index.html")
c = {"foo": "bar"}
return HttpResponse(t.render(c, request), content_type="application/xhtml+xml")
``redirect()``
==============
.. function:: redirect(to, *args, permanent=False, **kwargs)
Returns an :class:`~django.http.HttpResponseRedirect` to the appropriate URL
for the arguments passed.
The arguments could be:
* A model: the model's :meth:`~django.db.models.Model.get_absolute_url()`
function will be called.
* A view name, possibly with arguments: :func:`~django.urls.reverse` will be
used to reverse-resolve the name.
* An absolute or relative URL, which will be used as-is for the redirect
location.
By default issues a temporary redirect; pass ``permanent=True`` to issue a
permanent redirect.
Examples
--------
You can use the :func:`redirect` function in a number of ways.
#. By passing some object; that object's
:meth:`~django.db.models.Model.get_absolute_url` method will be called
to figure out the redirect URL::
from django.shortcuts import redirect
def my_view(request):
...
obj = MyModel.objects.get(...)
return redirect(obj)
#. By passing the name of a view and optionally some positional or
keyword arguments; the URL will be reverse resolved using the
:func:`~django.urls.reverse` method::
def my_view(request):
...
return redirect("some-view-name", foo="bar")
#. By passing a hardcoded URL to redirect to:
::
def my_view(request):
...
return redirect("/some/url/")
This also works with full URLs:
::
def my_view(request):
...
return redirect("https://example.com/")
By default, :func:`redirect` returns a temporary redirect. All of the above
forms accept a ``permanent`` argument; if set to ``True`` a permanent redirect
will be returned::
def my_view(request):
...
obj = MyModel.objects.get(...)
return redirect(obj, permanent=True)
``get_object_or_404()``
=======================
.. function:: get_object_or_404(klass, *args, **kwargs)
.. function:: aget_object_or_404(klass, *args, **kwargs)
*Asynchronous version*: ``aget_object_or_404()``
Calls :meth:`~django.db.models.query.QuerySet.get()` on a given model
manager, but it raises :class:`~django.http.Http404` instead of the model's
:class:`~django.db.models.Model.DoesNotExist` exception.
Arguments
---------
``klass``
A :class:`~django.db.models.Model` class,
a :class:`~django.db.models.Manager`,
or a :class:`~django.db.models.query.QuerySet` instance from which to get
the object.
``*args``
:class:`Q objects <django.db.models.Q>`.
``**kwargs``
Lookup parameters, which should be in the format accepted by ``get()`` and
``filter()``.
Example
-------
The following example gets the object with the primary key of 1 from
``MyModel``::
from django.shortcuts import get_object_or_404
def my_view(request):
obj = get_object_or_404(MyModel, pk=1)
This example is equivalent to::
from django.http import Http404
def my_view(request):
try:
obj = MyModel.objects.get(pk=1)
except MyModel.DoesNotExist:
raise Http404("No MyModel matches the given query.")
The most common use case is to pass a :class:`~django.db.models.Model`, as
shown above. However, you can also pass a
:class:`~django.db.models.query.QuerySet` instance::
queryset = Book.objects.filter(title__startswith="M")
get_object_or_404(queryset, pk=1)
The above example is a bit contrived since it's equivalent to doing::
get_object_or_404(Book, title__startswith="M", pk=1)
but it can be useful if you are passed the ``queryset`` variable from somewhere
else.
Finally, you can also use a :class:`~django.db.models.Manager`. This is useful
for example if you have a
:ref:`custom manager<custom-managers>`::
get_object_or_404(Book.dahl_objects, title="Matilda")
You can also use
:class:`related managers<django.db.models.fields.related.RelatedManager>`::
author = Author.objects.get(name="Roald Dahl")
get_object_or_404(author.book_set, title="Matilda")
Note: As with ``get()``, a
:class:`~django.core.exceptions.MultipleObjectsReturned` exception
will be raised if more than one object is found.
.. versionchanged:: 5.0
``aget_object_or_404()`` function was added.
``get_list_or_404()``
=====================
.. function:: get_list_or_404(klass, *args, **kwargs)
.. function:: aget_list_or_404(klass, *args, **kwargs)
*Asynchronous version*: ``aget_list_or_404()``
Returns the result of :meth:`~django.db.models.query.QuerySet.filter()` on
a given model manager cast to a list, raising :class:`~django.http.Http404`
if the resulting list is empty.
Arguments
---------
``klass``
A :class:`~django.db.models.Model`, :class:`~django.db.models.Manager` or
:class:`~django.db.models.query.QuerySet` instance from which to get the
list.
``*args``
:class:`Q objects <django.db.models.Q>`.
``**kwargs``
Lookup parameters, which should be in the format accepted by ``get()`` and
``filter()``.
Example
-------
The following example gets all published objects from ``MyModel``::
from django.shortcuts import get_list_or_404
def my_view(request):
my_objects = get_list_or_404(MyModel, published=True)
This example is equivalent to::
from django.http import Http404
def my_view(request):
my_objects = list(MyModel.objects.filter(published=True))
if not my_objects:
raise Http404("No MyModel matches the given query.")
.. versionchanged:: 5.0
``aget_list_or_404()`` function was added.