1
0
mirror of https://github.com/django/django.git synced 2024-12-29 12:36:08 +00:00
django/docs/ref/class-based-views/mixins-multiple-object.txt
Tobias Kunze 4a954cfd11 Fixed #30573 -- Rephrased documentation to avoid words that minimise the involved difficulty.
This patch does not remove all occurrences of the words in question.
Rather, I went through all of the occurrences of the words listed
below, and judged if they a) suggested the reader had some kind of
knowledge/experience, and b) if they added anything of value (including
tone of voice, etc). I left most of the words alone. I looked at the
following words:

- simply/simple
- easy/easier/easiest
- obvious
- just
- merely
- straightforward
- ridiculous

Thanks to Carlton Gibson for guidance on how to approach this issue, and
to Tim Bell for providing the idea. But the enormous lion's share of
thanks go to Adam Johnson for his patient and helpful review.
2019-09-06 13:27:46 +02:00

222 lines
8.3 KiB
Plaintext
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

======================
Multiple object mixins
======================
``MultipleObjectMixin``
=======================
.. class:: django.views.generic.list.MultipleObjectMixin
A mixin that can be used to display a list of objects.
If ``paginate_by`` is specified, Django will paginate the results returned
by this. You can specify the page number in the URL in one of two ways:
* Use the ``page`` parameter in the URLconf. For example, this is what
your URLconf might look like::
path('objects/page<int:page>/', PaginatedView.as_view()),
* Pass the page number via the ``page`` query-string parameter. For
example, a URL would look like this::
/objects/?page=3
These values and lists are 1-based, not 0-based, so the first page would be
represented as page ``1``.
For more on pagination, read the :doc:`pagination documentation
</topics/pagination>`.
As a special case, you are also permitted to use ``last`` as a value for
``page``::
/objects/?page=last
This allows you to access the final page of results without first having to
determine how many pages there are.
Note that ``page`` *must* be either a valid page number or the value
``last``; any other value for ``page`` will result in a 404 error.
**Extends**
* :class:`django.views.generic.base.ContextMixin`
**Methods and Attributes**
.. attribute:: allow_empty
A boolean specifying whether to display the page if no objects are
available. If this is ``False`` and no objects are available, the view
will raise a 404 instead of displaying an empty page. By default, this
is ``True``.
.. attribute:: model
The model that this view will display data for. Specifying ``model
= Foo`` is effectively the same as specifying ``queryset =
Foo.objects.all()``, where ``objects`` stands for ``Foo``s
:ref:`default manager <default-managers>`.
.. attribute:: queryset
A ``QuerySet`` that represents the objects. If provided, the value of
``queryset`` supersedes the value provided for :attr:`model`.
.. warning::
``queryset`` is a class attribute with a *mutable* value so care
must be taken when using it directly. Before using it, either call
its :meth:`~django.db.models.query.QuerySet.all` method or
retrieve it with :meth:`get_queryset` which takes care of the
cloning behind the scenes.
.. attribute:: ordering
A string or list of strings specifying the ordering to apply to the ``queryset``.
Valid values are the same as those for :meth:`~django.db.models.query.QuerySet.order_by`.
.. attribute:: paginate_by
An integer specifying how many objects should be displayed per page. If
this is given, the view will paginate objects with
``paginate_by`` objects per page. The view will
expect either a ``page`` query string parameter (via ``request.GET``)
or a ``page`` variable specified in the URLconf.
.. attribute:: paginate_orphans
An integer specifying the number of "overflow" objects the last page
can contain. This extends the :attr:`paginate_by` limit on the last
page by up to ``paginate_orphans``, in order to keep the last page from
having a very small number of objects.
.. attribute:: page_kwarg
A string specifying the name to use for the page parameter.
The view will expect this parameter to be available either as a query
string parameter (via ``request.GET``) or as a kwarg variable specified
in the URLconf. Defaults to ``page``.
.. attribute:: paginator_class
The paginator class to be used for pagination. By default,
:class:`django.core.paginator.Paginator` is used. If the custom paginator
class doesn't have the same constructor interface as
:class:`django.core.paginator.Paginator`, you will also need to
provide an implementation for :meth:`get_paginator`.
.. attribute:: context_object_name
Designates the name of the variable to use in the context.
.. method:: get_queryset()
Get the list of items for this view. This must be an iterable and may
be a queryset (in which queryset-specific behavior will be enabled).
.. method:: get_ordering()
Returns a string (or iterable of strings) that defines the ordering that
will be applied to the ``queryset``.
Returns :attr:`ordering` by default.
.. method:: paginate_queryset(queryset, page_size)
Returns a 4-tuple containing (``paginator``, ``page``, ``object_list``,
``is_paginated``).
Constructed by paginating ``queryset`` into pages of size ``page_size``.
If the request contains a ``page`` argument, either as a captured URL
argument or as a GET argument, ``object_list`` will correspond to the
objects from that page.
.. method:: get_paginate_by(queryset)
Returns the number of items to paginate by, or ``None`` for no
pagination. By default this returns the value of :attr:`paginate_by`.
.. method:: get_paginator(queryset, per_page, orphans=0, allow_empty_first_page=True)
Returns an instance of the paginator to use for this view. By default,
instantiates an instance of :attr:`paginator_class`.
.. method:: get_paginate_orphans()
An integer specifying the number of "overflow" objects the last page
can contain. By default this returns the value of
:attr:`paginate_orphans`.
.. method:: get_allow_empty()
Return a boolean specifying whether to display the page if no objects
are available. If this method returns ``False`` and no objects are
available, the view will raise a 404 instead of displaying an empty
page. By default, this is ``True``.
.. method:: get_context_object_name(object_list)
Return the context variable name that will be used to contain
the list of data that this view is manipulating. If
``object_list`` is a queryset of Django objects and
:attr:`context_object_name` is not set,
the context name will be the ``model_name`` of the model that
the queryset is composed from, with postfix ``'_list'``
appended. For example, the model ``Article`` would have a
context object named ``article_list``.
.. method:: get_context_data(**kwargs)
Returns context data for displaying the list of objects.
**Context**
* ``object_list``: The list of objects that this view is displaying. If
``context_object_name`` is specified, that variable will also be set
in the context, with the same value as ``object_list``.
* ``is_paginated``: A boolean representing whether the results are
paginated. Specifically, this is set to ``False`` if no page size has
been specified, or if the available objects do not span multiple
pages.
* ``paginator``: An instance of
:class:`django.core.paginator.Paginator`. If the page is not
paginated, this context variable will be ``None``.
* ``page_obj``: An instance of
:class:`django.core.paginator.Page`. If the page is not paginated,
this context variable will be ``None``.
``MultipleObjectTemplateResponseMixin``
=======================================
.. class:: django.views.generic.list.MultipleObjectTemplateResponseMixin
A mixin class that performs template-based response rendering for views
that operate upon a list of object instances. Requires that the view it is
mixed with provides ``self.object_list``, the list of object instances that
the view is operating on. ``self.object_list`` may be, but is not required
to be, a :class:`~django.db.models.query.QuerySet`.
**Extends**
* :class:`~django.views.generic.base.TemplateResponseMixin`
**Methods and Attributes**
.. attribute:: template_name_suffix
The suffix to append to the auto-generated candidate template name.
Default suffix is ``_list``.
.. method:: get_template_names()
Returns a list of candidate template names. Returns the following list:
* the value of ``template_name`` on the view (if provided)
* ``<app_label>/<model_name><template_name_suffix>.html``