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

=========================
Class-based generic views
=========================

.. versionadded:: 1.3

.. note::
    Prior to Django 1.3, generic views were implemented as functions. The
    function-based implementation has been removed in favor of the
    class-based approach described here.

Writing Web applications can be monotonous, because we repeat certain patterns
again and again. Django tries to take away some of that monotony at the model
and template layers, but Web developers also experience this boredom at the view
level.

A general introduction to class-based generic views can be found in the
:doc:`topic guide </topics/class-based-views>`.

This reference contains details of Django's built-in generic views, along with
a list of the keyword arguments that each generic view expects. Remember that
arguments may either come from the URL pattern or from the ``extra_context``
additional-information dictionary.

Most generic views require the ``queryset`` key, which is a ``QuerySet``
instance; see :doc:`/topics/db/queries` for more information about ``QuerySet``
objects.

Mixins
======

A mixin class is a way of using the inheritance capabilities of
classes to compose a class out of smaller pieces of behavior. Django's
class-based generic views are constructed by composing mixins into
usable generic views.

For example, the :class:`~django.views.generic.base.detail.DetailView`
is composed from:

* :class:`~django.db.views.generic.base.View`, which provides the
  basic class-based behavior
* :class:`~django.db.views.generic.detail.SingleObjectMixin`, which
  provides the utilities for retrieving and displaying a single object
* :class:`~django.db.views.generic.detail.SingleObjectTemplateResponseMixin`,
  which provides the tools for rendering a single object into a
  template-based response.

When combined, these mixins provide all the pieces necessary to
provide a view over a single object that renders a template to produce
a response.

Django provides a range of mixins. If you want to write your own
generic views, you can build classes that compose these mixins in
interesting ways. Alternatively, you can just use the pre-mixed
`Generic views`_ that Django provides.

.. note::

    When the documentation for a view gives the list of mixins, that view
    inherits all the properties and methods of that mixin.

Simple mixins
-------------

.. currentmodule:: django.views.generic.base

TemplateResponseMixin
~~~~~~~~~~~~~~~~~~~~~
.. class:: TemplateResponseMixin()

    .. attribute:: template_name

        The path to the template to use when rendering the view.

    .. attribute:: response_class

        The response class to be returned by ``render_to_response`` method.
        Default is
        :class:`TemplateResponse <django.template.response.TemplateResponse>`.
        The template and context of ``TemplateResponse`` instances can be
        altered later (e.g. in
        :ref:`template response middleware <template-response-middleware>`).

        If you need custom template loading or custom context object
        instantiation, create a ``TemplateResponse`` subclass and assign it to
        ``response_class``.

    .. method:: render_to_response(context, **response_kwargs)

        Returns a ``self.response_class`` instance.

        If any keyword arguments are provided, they will be
        passed to the constructor of the response class.

        Calls :meth:`~TemplateResponseMixin.get_template_names()` to obtain the
        list of template names that will be searched looking for an existent
        template.

    .. method:: get_template_names()

        Returns a list of template names to search for when rendering the
        template.

        If :attr:`TemplateResponseMixin.template_name` is specified, the
        default implementation will return a list containing
        :attr:`TemplateResponseMixin.template_name` (if it is specified).


Single object mixins
--------------------

.. currentmodule:: django.views.generic.detail

SingleObjectMixin
~~~~~~~~~~~~~~~~~
.. class:: SingleObjectMixin()

    .. attribute:: model

        The model that this view will display data for. Specifying ``model
        = Foo`` is effectively the same as specifying ``queryset =
        Foo.objects.all()``.

    .. attribute:: queryset

        A ``QuerySet`` that represents the objects. If provided, the value of
        :attr:`SingleObjectMixin.queryset` supersedes the value provided for
        :attr:`SingleObjectMixin.model`.

    .. attribute:: slug_field

        The name of the field on the model that contains the slug. By default,
        ``slug_field`` is ``'slug'``.

    .. attribute:: slug_url_kwarg

        .. versionadded:: 1.4

        The name of the URLConf keyword argument that contains the slug. By
        default, ``slug_url_kwarg`` is ``'slug'``.

    .. attribute:: pk_url_kwarg

        .. versionadded:: 1.4

        The name of the URLConf keyword argument that contains the primary key.
        By default, ``pk_url_kwarg`` is ``'pk'``.

    .. attribute:: context_object_name

        Designates the name of the variable to use in the context.

    .. method:: get_object(queryset=None)

        Returns the single object that this view will display. If
        ``queryset`` is provided, that queryset will be used as the
        source of objects; otherwise,
        :meth:`~SingleObjectMixin.get_queryset` will be used.
        ``get_object()`` looks for a
        :attr:`SingleObjectMixin.pk_url_kwarg` argument in the arguments
        to the view; if this argument is found, this method performs a
        primary-key based lookup using that value. If this argument is not
        found, it looks for a :attr:`SingleObjectMixin.slug_url_kwarg`
        argument, and performs a slug lookup using the
        :attr:`SingleObjectMixin.slug_field`.

    .. method:: get_queryset()

        Returns the queryset that will be used to retrieve the object that
        this view will display. By default,
        :meth:`~SingleObjectMixin.get_queryset` returns the value of the
        :attr:`~SingleObjectMixin.queryset` attribute if it is set, otherwise
        it constructs a :class:`QuerySet` by calling the `all()` method on the
        :attr:`~SingleObjectMixin.model` attribute's default manager.

    .. method:: get_context_object_name(obj)

        Return the context variable name that will be used to contain the
        data that this view is manipulating. If
        :attr:`~SingleObjectMixin.context_object_name` is not set, the context
        name will be constructed from the ``object_name`` of the model that
        the queryset is composed from. For example, the model ``Article``
        would have context object named ``'article'``.

    .. method:: get_context_data(**kwargs)

        Returns context data for displaying the list of objects.

    **Context**

    * ``object``: The object 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``.

SingleObjectTemplateResponseMixin
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. class:: SingleObjectTemplateResponseMixin()

    A mixin class that performs template-based response rendering for views
    that operate upon a single object instance. Requires that the view it is
    mixed with provides ``self.object``, the object instance that the view is
    operating on. ``self.object`` will usually be, but is not required to be,
    an instance of a Django model. It may be ``None`` if the view is in the
    process of constructing a new instance.

    **Extends**

    * :class:`~django.views.generic.base.TemplateResponseMixin`

    .. attribute:: template_name_field

        The field on the current object instance that can be used to determine
        the name of a candidate template. If either ``template_name_field`` or
        the value of the ``template_name_field`` on the current object instance
        is ``None``, the object will not be interrogated for a candidate
        template name.

    .. attribute:: template_name_suffix

        The suffix to append to the auto-generated candidate template name.
        Default suffix is ``_detail``.

    .. 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)
        * the contents of the ``template_name_field`` field on the
          object instance that the view is operating upon (if available)
        * ``<app_label>/<object_name><template_name_suffix>.html``

Multiple object mixins
----------------------

.. currentmodule:: django.views.generic.list

MultipleObjectMixin
~~~~~~~~~~~~~~~~~~~
.. class:: 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::

        (r'^objects/page(?P<page>[0-9]+)/$', 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.

    .. 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()``.

    .. attribute:: queryset

        A ``QuerySet`` that represents the objects. If provided, the value of
        :attr:`MultipleObjectMixin.queryset` supersedes the value provided for
        :attr:`MultipleObjectMixin.model`.

    .. attribute:: paginate_by

        An integer specifying how many objects should be displayed per page. If
        this is given, the view will paginate objects with
        :attr:`MultipleObjectMixin.paginate_by` objects per page. The view will
        expect either a ``page`` query string parameter (via ``GET``) or a
        ``page`` variable specified in the URLconf.

    .. 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:`MultipleObjectMixin.get_paginator`.

    .. attribute:: context_object_name

        Designates the name of the variable to use in the context.

    .. method:: get_queryset()

        Returns the queryset that represents the data this view will display.

    .. 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 simply returns the value of
        :attr:`MultipleObjectMixin.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_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:`~MultipleObjectMixin.context_object_name` is not set,
        the context name will be the ``object_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:: 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`

    .. 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>/<object_name><template_name_suffix>.html``

Editing mixins
--------------

.. currentmodule:: django.views.generic.edit

FormMixin
~~~~~~~~~
.. class:: FormMixin()

    A mixin class that provides facilities for creating and displaying forms.

    .. attribute:: initial

        A dictionary containing initial data for the form.

    .. attribute:: form_class

        The form class to instantiate.

    .. attribute:: success_url

        The URL to redirect to when the form is successfully processed.

    .. method:: get_initial()

        Retrieve initial data for the form. By default, returns a copy of
        :attr:`.initial`.

    .. admonition:: Changed in 1.4

        In Django 1.3, this method was returning the :attr:`initial` class
        variable itself.

    .. method:: get_form_class()

        Retrieve the form class to instantiate. By default
        :attr:`.form_class`.

    .. method:: get_form(form_class)

        Instantiate an instance of ``form_class`` using
        :meth:`.get_form_kwargs`.

    .. method:: get_form_kwargs()

        Build the keyword arguments required to instantiate the form.

        The ``initial`` argument is set to :meth:`.get_initial`. If the
        request is a ``POST`` or ``PUT``, the request data (``request.POST``
        and ``request.FILES``) will also be provided.

    .. method:: get_success_url()

        Determine the URL to redirect to when the form is successfully
        validated. Returns :attr:`.success_url` by default.

    .. method:: form_valid(form)

        Redirects to :meth:`.get_success_url`.

    .. method:: form_invalid(form)

        Renders a response, providing the invalid form as context.

    .. method:: get_context_data(**kwargs)

        Populates a context containing the contents of ``kwargs``.

    **Context**

    * ``form``: The form instance that was generated for the view.

    .. note::

        Views mixing :class:`FormMixin` must
        provide an implementation of :meth:`.form_valid` and
        :meth:`.form_invalid`.

ModelFormMixin
~~~~~~~~~~~~~~
.. class:: ModelFormMixin()

    A form mixin that works on ModelForms, rather than a standalone form.

    Since this is a subclass of
    :class:`~django.views.generic.detail.SingleObjectMixin`, instances of this
    mixin have access to the :attr:`~SingleObjectMixin.model` and
    :attr:`~SingleObjectMixin.queryset` attributes, describing the type of
    object that the ModelForm is manipulating. The view also provides
    ``self.object``, the instance being manipulated. If the instance is being
    created, ``self.object`` will be ``None``.

    **Mixins**

    * :class:`django.views.generic.edit.FormMixin`
    * :class:`django.views.generic.detail.SingleObjectMixin`

    .. attribute:: success_url

        The URL to redirect to when the form is successfully processed.

        ``success_url`` may contain dictionary string formatting, which
        will be interpolated against the object's field attributes. For
        example, you could use ``success_url="/polls/%(slug)s/"`` to
        redirect to a URL composed out of the ``slug`` field on a model.

    .. method:: get_form_class()

        Retrieve the form class to instantiate. If
        :attr:`FormMixin.form_class` is provided, that class will be used.
        Otherwise, a ModelForm will be instantiated using the model associated
        with the :attr:`~SingleObjectMixin.queryset`, or with the
        :attr:`~SingleObjectMixin.model`, depending on which attribute is
        provided.

    .. method:: get_form_kwargs()

        Add the current instance (``self.object``) to the standard
        :meth:`FormMixin.get_form_kwargs`.

    .. method:: get_success_url()

        Determine the URL to redirect to when the form is successfully
        validated. Returns :attr:`FormMixin.success_url` if it is provided;
        otherwise, attempts to use the ``get_absolute_url()`` of the object.

    .. method:: form_valid(form)

        Saves the form instance, sets the current object for the view, and
        redirects to :meth:`.get_success_url`.

    .. method:: form_invalid()

        Renders a response, providing the invalid form as context.

ProcessFormView
~~~~~~~~~~~~~~~
.. class:: ProcessFormView()

    A mixin that provides basic HTTP GET and POST workflow.

    .. method:: get(request, *args, **kwargs)

        Constructs a form, then renders a response using a context that
        contains that form.

    .. method:: post(request, *args, **kwargs)

        Constructs a form, checks the form for validity, and handles it
        accordingly.

    The PUT action is also handled, as an analog of POST.

DeletionMixin
~~~~~~~~~~~~~
.. class:: DeletionMixin()

    Enables handling of the ``DELETE`` http action.

    .. attribute:: success_url

        The url to redirect to when the nominated object has been
        successfully deleted.

    .. method:: get_success_url(obj)

        Returns the url to redirect to when the nominated object has been
        successfully deleted. Returns
        :attr:`~django.views.generic.edit.DeletionMixin.success_url` by
        default.

Date-based mixins
-----------------

.. currentmodule:: django.views.generic.dates

YearMixin
~~~~~~~~~
.. class:: YearMixin()

    A mixin that can be used to retrieve and provide parsing information for a
    year component of a date.

    .. attribute:: year_format

        The :func:`~time.strftime` format to use when parsing the year.
        By default, this is ``'%Y'``.

    .. attribute:: year

        **Optional** The value for the year (as a string). By default, set to
        ``None``, which means the year will be determined using other means.

    .. method:: get_year_format()

        Returns the :func:`~time.strftime` format to use when parsing the year. Returns
        :attr:`YearMixin.year_format` by default.

    .. method:: get_year()

        Returns the year for which this view will display data. Tries the
        following sources, in order:

        * The value of the :attr:`YearMixin.year` attribute.
        * The value of the `year` argument captured in the URL pattern
        * The value of the `year` GET query argument.

        Raises a 404 if no valid year specification can be found.

MonthMixin
~~~~~~~~~~
.. class:: MonthMixin()

    A mixin that can be used to retrieve and provide parsing information for a
    month component of a date.

    .. attribute:: month_format

        The :func:`~time.strftime` format to use when parsing the month. By default, this is
        ``'%b'``.

    .. attribute:: month

        **Optional** The value for the month (as a string). By default, set to
        ``None``, which means the month will be determined using other means.

    .. method:: get_month_format()

        Returns the :func:`~time.strftime` format to use when parsing the month. Returns
        :attr:`MonthMixin.month_format` by default.

    .. method:: get_month()

        Returns the month for which this view will display data. Tries the
        following sources, in order:

        * The value of the :attr:`MonthMixin.month` attribute.
        * The value of the `month` argument captured in the URL pattern
        * The value of the `month` GET query argument.

        Raises a 404 if no valid month specification can be found.

    .. method:: get_next_month(date)

        Returns a date object containing the first day of the month after the
        date provided. Returns ``None`` if mixed with a view that sets
        ``allow_future = False``, and the next month is in the future. If
        ``allow_empty = False``, returns the next month that contains data.

    .. method:: get_prev_month(date)

        Returns a date object containing the first day of the month before the
        date provided. If ``allow_empty = False``, returns the previous month
        that contained data.

DayMixin
~~~~~~~~~
.. class:: DayMixin()

    A mixin that can be used to retrieve and provide parsing information for a
    day component of a date.

    .. attribute:: day_format

        The :func:`~time.strftime` format to use when parsing the day. By default, this is
        ``'%d'``.

    .. attribute:: day

        **Optional** The value for the day (as a string). By default, set to
        ``None``, which means the day will be determined using other means.

    .. method:: get_day_format()

        Returns the :func:`~time.strftime` format to use when parsing the day. Returns
        :attr:`DayMixin.day_format` by default.

    .. method:: get_day()

        Returns the day for which this view will display data. Tries the
        following sources, in order:

        * The value of the :attr:`DayMixin.day` attribute.
        * The value of the `day` argument captured in the URL pattern
        * The value of the `day` GET query argument.

        Raises a 404 if no valid day specification can be found.

    .. method:: get_next_day(date)

        Returns a date object containing the next day after the date provided.
        Returns ``None`` if mixed with a view that sets ``allow_future = False``,
        and the next day is in the future. If ``allow_empty = False``, returns
        the next day that contains data.

    .. method:: get_prev_day(date)

        Returns a date object containing the previous day. If
        ``allow_empty = False``, returns the previous day that contained data.

WeekMixin
~~~~~~~~~
.. class:: WeekMixin()

    A mixin that can be used to retrieve and provide parsing information for a
    week component of a date.

    .. attribute:: week_format

        The :func:`~time.strftime` format to use when parsing the week. By default, this is
        ``'%U'``.

    .. attribute:: week

        **Optional** The value for the week (as a string). By default, set to
        ``None``, which means the week will be determined using other means.

    .. method:: get_week_format()

        Returns the :func:`~time.strftime` format to use when parsing the week. Returns
        :attr:`WeekMixin.week_format` by default.

    .. method:: get_week()

        Returns the week for which this view will display data. Tries the
        following sources, in order:

        * The value of the :attr:`WeekMixin.week` attribute.
        * The value of the `week` argument captured in the URL pattern
        * The value of the `week` GET query argument.

        Raises a 404 if no valid week specification can be found.


DateMixin
~~~~~~~~~
.. class:: DateMixin()

    A mixin class providing common behavior for all date-based views.

    .. attribute:: date_field

        The name of the ``DateField`` or ``DateTimeField`` in the
        ``QuerySet``'s model that the date-based archive should use to
        determine the objects on the page.

        When :doc:`time zone support </topics/i18n/timezones>` is enabled and
        ``date_field`` is a ``DateTimeField``, dates are assumed to be in the
        current time zone. As a consequence, if you have implemented per-user
        time zone selection, users living in different time zones may view a
        different set of objects at the same URL.

    .. attribute:: allow_future

        A boolean specifying whether to include "future" objects on this page,
        where "future" means objects in which the field specified in
        ``date_field`` is greater than the current date/time. By default, this
        is ``False``.

    .. method:: get_date_field()

        Returns the name of the field that contains the date data that this
        view will operate on. Returns :attr:`DateMixin.date_field` by default.

    .. method:: get_allow_future()

        Determine whether to include "future" objects on this page, where
        "future" means objects in which the field specified in ``date_field``
        is greater than the current date/time. Returns
        :attr:`DateMixin.allow_future` by default.

BaseDateListView
~~~~~~~~~~~~~~~~
.. class:: BaseDateListView()

    A base class that provides common behavior for all date-based views. There
    won't normally be a reason to instantiate
    :class:`~django.views.generic.dates.BaseDateListView`; instantiate one of
    the subclasses instead.

    While this view (and it's subclasses) are executing, ``self.object_list``
    will contain the list of objects that the view is operating upon, and
    ``self.date_list`` will contain the list of dates for which data is
    available.

    **Mixins**

    * :class:`~django.views.generic.dates.DateMixin`
    * :class:`~django.views.generic.list.MultipleObjectMixin`

    .. attribute:: allow_empty

        A boolean specifying whether to display the page if no objects are
        available. If this is ``True`` and no objects are available, the view
        will display an empty page instead of raising a 404. By default, this
        is ``False``.

    .. method:: get_dated_items():

        Returns a 3-tuple containing (``date_list``, ``object_list``,
        ``extra_context``).

        ``date_list`` is the list of dates for which data is available.
        ``object_list`` is the list of objects. ``extra_context`` is a
        dictionary of context data that will be added to any context data
        provided by the
        :class:`~django.views.generic.list.MultipleObjectMixin`.

    .. method:: get_dated_queryset(**lookup)

        Returns a queryset, filtered using the query arguments defined by
        ``lookup``. Enforces any restrictions on the queryset, such as
        ``allow_empty`` and ``allow_future``.

    .. method:: get_date_list(queryset, date_type)

        Returns the list of dates of type ``date_type`` for which
        ``queryset`` contains entries. For example, ``get_date_list(qs,
        'year')`` will return the list of years for which ``qs`` has entries.
        See :meth:`~django.db.models.query.QuerySet.dates()` for the
        ways that the ``date_type`` argument can be used.


Generic views
=============

Simple generic views
--------------------

.. currentmodule:: django.views.generic.base

View
~~~~
.. class:: View()

    The master class-based base view. All other generic class-based views
    inherit from this base class.

    Each request served by a :class:`~django.views.generic.base.View` has an
    independent state; therefore, it is safe to store state variables on the
    instance (i.e., ``self.foo = 3`` is a thread-safe operation).

    A class-based view is deployed into a URL pattern using the
    :meth:`~View.as_view()` classmethod::

        urlpatterns = patterns('',
                (r'^view/$', MyView.as_view(size=42)),
            )

    Any argument passed into :meth:`~View.as_view()` will be assigned onto the
    instance that is used to service a request. Using the previous example,
    this means that every request on ``MyView`` is able to interrogate
    ``self.size``.

    .. admonition:: Thread safety with view arguments

        Arguments passed to a view are shared between every instance of a view.
        This means that you shoudn't use a list, dictionary, or any other
        variable object as an argument to a view. If you did, the actions of
        one user visiting your view could have an effect on subsequent users
        visiting the same view.

    .. 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 HTTP method it doesn't support, this method
        is called instead.

        The default implementation returns ``HttpResponseNotAllowed`` with list
        of allowed methods in plain text.

TemplateView
~~~~~~~~~~~~
.. class:: TemplateView()

    Renders a given template, passing it a ``{{ params }}`` template variable,
    which is a dictionary of the parameters captured in the URL.

    **Mixins**

    * :class:`django.views.generic.base.TemplateResponseMixin`

    .. 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.

RedirectView
~~~~~~~~~~~~
.. class:: 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).

    .. 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.

Detail views
------------

.. currentmodule:: django.views.generic.detail

DetailView
~~~~~~~~~~
.. class:: BaseDetailView()
.. class:: DetailView()

    A page representing an individual object.

    While this view is executing, ``self.object`` will contain the object that
    the view is operating upon.

    :class:`~django.views.generic.base.BaseDetailView` implements the same
    behavior as :class:`~django.views.generic.base.DetailView`, but doesn't
    include the
    :class:`~django.views.generic.detail.SingleObjectTemplateResponseMixin`.

    **Mixins**

    * :class:`django.views.generic.detail.SingleObjectMixin`
    * :class:`django.views.generic.detail.SingleObjectTemplateResponseMixin`

List views
----------

.. currentmodule:: django.views.generic.list

ListView
~~~~~~~~
.. class:: BaseListView()
.. class:: ListView()

    A page representing a list of objects.

    While this view is executing, ``self.object_list`` will contain the list of
    objects (usually, but not necessarily a queryset) that the view is
    operating upon.

    :class:`~django.views.generic.list.BaseListView` implements the same
    behavior as :class:`~django.views.generic.list.ListView`, but doesn't
    include the
    :class:`~django.views.generic.list.MultipleObjectTemplateResponseMixin`.

    **Mixins**

    * :class:`django.views.generic.list.MultipleObjectMixin`
    * :class:`django.views.generic.list.MultipleObjectTemplateResponseMixin`


Editing views
-------------

.. currentmodule:: django.views.generic.edit

FormView
~~~~~~~~
.. class:: BaseFormView()
.. class:: FormView()

    A view that displays a form. On error, redisplays the form with validation
    errors; on success, redirects to a new URL.

    :class:`~django.views.generic.edit.BaseFormView` implements the same
    behavior as :class:`~django.views.generic.edit.FormView`, but doesn't
    include the :class:`~django.views.generic.base.TemplateResponseMixin`.

    **Mixins**

    * :class:`django.views.generic.edit.FormMixin`
    * :class:`django.views.generic.edit.ProcessFormView`

CreateView
~~~~~~~~~~
.. class:: BaseCreateView()
.. class:: CreateView()

    A view that displays a form for creating an object, redisplaying the form
    with validation errors (if there are any) and saving the object.

    :class:`~django.views.generic.edit.BaseCreateView` implements the same
    behavior as :class:`~django.views.generic.edit.CreateView`, but doesn't
    include the :class:`~django.views.generic.base.TemplateResponseMixin`.

    **Mixins**

    * :class:`django.views.generic.edit.ModelFormMixin`
    * :class:`django.views.generic.edit.ProcessFormView`

UpdateView
~~~~~~~~~~
.. class:: BaseUpdateView()
.. class:: UpdateView()

    A view that displays a form for editing an existing object, redisplaying
    the form with validation errors (if there are any) and saving changes to
    the object. This uses a form automatically generated from the object's
    model class (unless a form class is manually specified).

    :class:`~django.views.generic.edit.BaseUpdateView` implements the same
    behavior as :class:`~django.views.generic.edit.UpdateView`, but doesn't
    include the :class:`~django.views.generic.base.TemplateResponseMixin`.

    **Mixins**

    * :class:`django.views.generic.edit.ModelFormMixin`
    * :class:`django.views.generic.edit.ProcessFormView`

DeleteView
~~~~~~~~~~
.. class:: BaseDeleteView()
.. class:: DeleteView()

    A view that displays a confirmation page and deletes an existing object.
    The given object will only be deleted if the request method is ``POST``. If
    this view is fetched via ``GET``, it will display a confirmation page that
    should contain a form that POSTs to the same URL.

    :class:`~django.views.generic.edit.BaseDeleteView` implements the same
    behavior as :class:`~django.views.generic.edit.DeleteView`, but doesn't
    include the :class:`~django.views.generic.base.TemplateResponseMixin`.

    **Mixins**

    * :class:`django.views.generic.edit.DeletionMixin`
    * :class:`django.views.generic.detail.BaseDetailView`

    **Notes**

    * The delete confirmation page displayed to a GET request uses a
      ``template_name_suffix`` of ``'_confirm_delete'``.

Date-based views
----------------

Date-based generic views (in the module :mod:`django.views.generic.dates`)
are views for displaying drilldown pages for date-based data.

.. currentmodule:: django.views.generic.dates

ArchiveIndexView
~~~~~~~~~~~~~~~~
.. class:: BaseArchiveIndexView()
.. class:: ArchiveIndexView()

    A top-level index page showing the "latest" objects, by date. Objects with
    a date in the *future* are not included unless you set ``allow_future`` to
    ``True``.

    :class:`~django.views.generic.dates.BaseArchiveIndexView` implements the
    same behavior as :class:`~django.views.generic.dates.ArchiveIndexView`, but
    doesn't include the
    :class:`~django.views.generic.list.MultipleObjectTemplateResponseMixin`.

    **Mixins**

    * :class:`django.views.generic.dates.BaseDateListView`
    * :class:`django.views.generic.list.MultipleObjectTemplateResponseMixin`

    **Notes**

    * Uses a default ``context_object_name`` of ``latest``.
    * Uses a default ``template_name_suffix`` of ``_archive``.

YearArchiveView
~~~~~~~~~~~~~~~
.. class:: BaseYearArchiveView()
.. class:: YearArchiveView()

    A yearly archive page showing all available months in a given year. Objects
    with a date in the *future* are not displayed unless you set
    ``allow_future`` to ``True``.

    :class:`~django.views.generic.dates.BaseYearArchiveView` implements the
    same behavior as :class:`~django.views.generic.dates.YearArchiveView`, but
    doesn't include the
    :class:`~django.views.generic.list.MultipleObjectTemplateResponseMixin`.

    **Mixins**

    * :class:`django.views.generic.list.MultipleObjectTemplateResponseMixin`
    * :class:`django.views.generic.dates.YearMixin`
    * :class:`django.views.generic.dates.BaseDateListView`

    .. attribute:: make_object_list

        A boolean specifying whether to retrieve the full list of objects for
        this year and pass those to the template. If ``True``, the list of
        objects will be made available to the context. By default, this is
        ``False``.

    .. method:: get_make_object_list()

        Determine if an object list will be returned as part of the context. If
        ``False``, the ``None`` queryset will be used as the object list.

    **Context**

    In addition to the context provided by
    :class:`django.views.generic.list.MultipleObjectMixin` (via
    :class:`django.views.generic.dates.BaseDateListView`), the template's
    context will be:

    * ``date_list``: A ``DateQuerySet`` object containing all months that
      have objects available according to ``queryset``, represented as
      ``datetime.datetime`` objects, in ascending order.

    * ``year``: The given year, as a four-character string.

    **Notes**

    * Uses a default ``template_name_suffix`` of ``_archive_year``.

MonthArchiveView
~~~~~~~~~~~~~~~~
.. class:: BaseMonthArchiveView()
.. class:: MonthArchiveView()

    A monthly archive page showing all objects in a given month. Objects with a
    date in the *future* are not displayed unless you set ``allow_future`` to
    ``True``.

    :class:`~django.views.generic.dates.BaseMonthArchiveView` implements
    the same behavior as
    :class:`~django.views.generic.dates.MonthArchiveView`, but doesn't
    include the
    :class:`~django.views.generic.list.MultipleObjectTemplateResponseMixin`.

    **Mixins**

    * :class:`django.views.generic.list.MultipleObjectTemplateResponseMixin`
    * :class:`django.views.generic.dates.YearMixin`
    * :class:`django.views.generic.dates.MonthMixin`
    * :class:`django.views.generic.dates.BaseDateListView`

    **Context**

    In addition to the context provided by
    :class:`~django.views.generic.list.MultipleObjectMixin` (via
    :class:`~django.views.generic.dates.BaseDateListView`), the template's
    context will be:

    * ``date_list``: A ``DateQuerySet`` object containing all days that
      have objects available in the given month, according to ``queryset``,
      represented as ``datetime.datetime`` objects, in ascending order.

    * ``month``: A ``datetime.date`` object representing the given month.

    * ``next_month``: A ``datetime.date`` object representing the first day
      of the next month. If the next month is in the future, this will be
      ``None``.

    * ``previous_month``: A ``datetime.date`` object representing the first
      day of the previous month. Unlike ``next_month``, this will never be
      ``None``.

    **Notes**

    * Uses a default ``template_name_suffix`` of ``_archive_month``.

WeekArchiveView
~~~~~~~~~~~~~~~
.. class:: BaseWeekArchiveView()
.. class:: WeekArchiveView()

    A weekly archive page showing all objects in a given week. Objects with a
    date in the *future* are not displayed unless you set ``allow_future`` to
    ``True``.

    :class:`~django.views.generic.dates.BaseWeekArchiveView` implements the
    same behavior as :class:`~django.views.generic.dates.WeekArchiveView`, but
    doesn't include the
    :class:`~django.views.generic.list.MultipleObjectTemplateResponseMixin`.

    **Mixins**

    * :class:`django.views.generic.list.MultipleObjectTemplateResponseMixin`
    * :class:`django.views.generic.dates.YearMixin`
    * :class:`django.views.generic.dates.MonthMixin`
    * :class:`django.views.generic.dates.BaseDateListView`

    **Context**

    In addition to the context provided by
    :class:`~django.views.generic.list.MultipleObjectMixin` (via
    :class:`~django.views.generic.dates.BaseDateListView`), the template's
    context will be:

    * ``week``: A ``datetime.date`` object representing the first day of
      the given week.

    **Notes**

    * Uses a default ``template_name_suffix`` of ``_archive_week``.

DayArchiveView
~~~~~~~~~~~~~~
.. class:: BaseDayArchiveView()
.. class:: DayArchiveView()

    A day archive page showing all objects in a given day. Days in the future
    throw a 404 error, regardless of whether any objects exist for future days,
    unless you set ``allow_future`` to ``True``.

    :class:`~django.views.generic.dates.BaseDayArchiveView` implements the same
    behavior as :class:`~django.views.generic.dates.DayArchiveView`, but
    doesn't include the
    :class:`~django.views.generic.list.MultipleObjectTemplateResponseMixin`.

    **Mixins**

    * :class:`django.views.generic.list.MultipleObjectTemplateResponseMixin`
    * :class:`django.views.generic.dates.YearMixin`
    * :class:`django.views.generic.dates.MonthMixin`
    * :class:`django.views.generic.dates.DayMixin`
    * :class:`django.views.generic.dates.BaseDateListView`

    **Context**

    In addition to the context provided by
    :class:`~django.views.generic.list.MultipleObjectMixin` (via
    :class:`~django.views.generic.dates.BaseDateListView`), the template's
    context will be:

    * ``day``: A ``datetime.date`` object representing the given day.

    * ``next_day``: A ``datetime.date`` object representing the next day.
      If the next day is in the future, this will be ``None``.

    * ``previous_day``: A ``datetime.date`` object representing the
      previous day. Unlike ``next_day``, this will never be ``None``.

    * ``next_month``: A ``datetime.date`` object representing the first day
      of the next month. If the next month is in the future, this will be
      ``None``.

    * ``previous_month``: A ``datetime.date`` object representing the first
      day of the previous month. Unlike ``next_month``, this will never be
      ``None``.

    **Notes**

    * Uses a default ``template_name_suffix`` of ``_archive_day``.

TodayArchiveView
~~~~~~~~~~~~~~~~
.. class:: BaseTodayArchiveView()
.. class:: TodayArchiveView()

    A day archive page showing all objects for *today*. This is exactly the
    same as :class:`django.views.generic.dates.DayArchiveView`, except today's
    date is used instead of the ``year``/``month``/``day`` arguments.

    :class:`~django.views.generic.dates.BaseTodayArchiveView` implements the
    same behavior as :class:`~django.views.generic.dates.TodayArchiveView`, but
    doesn't include the
    :class:`~django.views.generic.list.MultipleObjectTemplateResponseMixin`.

    **Mixins**

    * :class:`django.views.generic.list.MultipleObjectTemplateResponseMixin`
    * :class:`django.views.generic.dates.BaseDayArchiveView`

DateDetailView
~~~~~~~~~~~~~~
.. class:: BaseDateDetailView()
.. class:: DateDetailView()

    A page representing an individual object. If the object has a date value in
    the future, the view will throw a 404 error by default, unless you set
    ``allow_future`` to ``True``.

    :class:`~django.views.generic.dates.BaseDateDetailView` implements the same
    behavior as :class:`~django.views.generic.dates.DateDetailView`, but
    doesn't include the
    :class:`~django.views.generic.detail.SingleObjectTemplateResponseMixin`.

    **Mixins**

    * :class:`django.views.generic.detail.SingleObjectTemplateResponseMixin`
    * :class:`django.views.generic.detail.BaseDetailView`
    * :class:`django.views.generic.dates.DateMixin`
    * :class:`django.views.generic.dates.YearMixin`
    * :class:`django.views.generic.dates.MonthMixin`
    * :class:`django.views.generic.dates.DayMixin`