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- =================
- Class-based views
- =================
- Class-based views API reference. For introductory material, see
- :doc:`/topics/class-based-views/index`.
- .. toctree::
- :maxdepth: 3
- base
- generic-display
- generic-editing
- generic-date-based
- mixins
- flattened-index
- Specification
- -------------
- Each request served by a class-based 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:`~django.views.generic.base.View.as_view()` classmethod::
- urlpatterns = patterns('',
- (r'^view/$', MyView.as_view(size=42)),
- )
- .. 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
- mutable object as an argument to a view. If you do and the shared object
- is modified, the actions of one user visiting your view could have an
- effect on subsequent users visiting the same view.
- Any argument passed into :meth:`~django.views.generic.base.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 use
- ``self.size``.
- Base vs Generic views
- ---------------------
- Base class-based views can be thought of as *parent* views, which can be
- used by themselves or inherited from. They may not provide all the
- capabilities required for projects, in which case there are Mixins which
- extend what base views can do.
- Django’s generic views are built off of those base views, and were developed
- as a shortcut for common usage patterns such as displaying the details of an
- object. They take certain common idioms and patterns found in view
- development and abstract them so that you can quickly write common views of
- data without having to repeat yourself.
- Most generic views require the ``queryset`` key, which is a ``QuerySet``
- instance; see :doc:`/topics/db/queries` for more information about ``QuerySet``
- objects.
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