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Improved the advice on using QuerySets in extra_context based on feedback from 

Luke Plant.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@2949 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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Malcolm Tredinnick 2006-05-21 12:44:58 +00:00
parent 35869c53ef
commit 690f9ad8f0
1 changed files with 21 additions and 56 deletions
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77
docs/generic_views.txt
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@ -62,6 +62,15 @@ Most generic views require the ``queryset`` key, which is a ``QuerySet``
instance; see the `database API docs`_ for more information about ``Queryset`` instance; see the `database API docs`_ for more information about ``Queryset``
objects. objects.
Most views also take an optional ``extra_context`` dictionary that you can use
to pass any auxiliary information you wish to the view. The values in the
``extra_context`` dictionary can be either functions (or other callables) or
other objects. Functions are evaluated just before they are passed to the
template. However, note that QuerySets retrieve and cache their data when they
are first evaluated, so if you want to pass in a QuerySet via
``extra_context`` that is always fresh you need to wrap it in a function or
lambda that returns the QuerySet.
.. _database API docs: http://www.djangoproject.com/documentation/db_api/ .. _database API docs: http://www.djangoproject.com/documentation/db_api/
"Simple" generic views "Simple" generic views
@ -161,13 +170,9 @@ a date in the *future* are not included.
template. By default, it's ``django.template.loader``. template. By default, it's ``django.template.loader``.
* ``extra_context``: A dictionary of values to add to the template * ``extra_context``: A dictionary of values to add to the template
context. By default, this is an empty dictionary. If a value in the context. By default, this is an empty dictionary.
dictionary is callable, the generic view will call it dictionary is callable, the generic view will call it
just before rendering the template. If it is not callable, it will be just before rendering the template.
evaluated once, at import time. Note that QuerySets are not callable, so
if you want to pass in a QuerySet in ``extra_context`` and have it
evaluated at render time, you need to wrap it in a function (that
returns the QuerySet).
* ``allow_empty``: A boolean specifying whether to display the page if no * ``allow_empty``: A boolean specifying whether to display the page if no
objects are available. If this is ``False`` and no objects are available, objects are available. If this is ``False`` and no objects are available,
@ -232,11 +237,7 @@ with a date in the *future* are not displayed.
* ``extra_context``: A dictionary of values to add to the template * ``extra_context``: A dictionary of values to add to the template
context. By default, this is an empty dictionary. If a value in the context. By default, this is an empty dictionary. If a value in the
dictionary is callable, the generic view will call it dictionary is callable, the generic view will call it
just before rendering the template. If it is not callable, it will be just before rendering the template.
evaluated once, at import time. Note that QuerySets are not callable, so
if you want to pass in a QuerySet in ``extra_context`` and have it
evaluated at render time, you need to wrap it in a function (that
returns the QuerySet).
* ``allow_empty``: A boolean specifying whether to display the page if no * ``allow_empty``: A boolean specifying whether to display the page if no
objects are available. If this is ``False`` and no objects are available, objects are available. If this is ``False`` and no objects are available,
@ -298,11 +299,7 @@ date in the *future* are not displayed.
* ``extra_context``: A dictionary of values to add to the template * ``extra_context``: A dictionary of values to add to the template
context. By default, this is an empty dictionary. If a value in the context. By default, this is an empty dictionary. If a value in the
dictionary is callable, the generic view will call it dictionary is callable, the generic view will call it
just before rendering the template. If it is not callable, it will be just before rendering the template.
evaluated once, at import time. Note that QuerySets are not callable, so
if you want to pass in a QuerySet in ``extra_context`` and have it
evaluated at render time, you need to wrap it in a function (that
returns the QuerySet).
* ``allow_empty``: A boolean specifying whether to display the page if no * ``allow_empty``: A boolean specifying whether to display the page if no
objects are available. If this is ``False`` and no objects are available, objects are available. If this is ``False`` and no objects are available,
@ -375,11 +372,7 @@ in the *future* are not displayed.
* ``extra_context``: A dictionary of values to add to the template * ``extra_context``: A dictionary of values to add to the template
context. By default, this is an empty dictionary. If a value in the context. By default, this is an empty dictionary. If a value in the
dictionary is callable, the generic view will call it dictionary is callable, the generic view will call it
just before rendering the template. If it is not callable, it will be just before rendering the template.
evaluated once, at import time. Note that QuerySets are not callable, so
if you want to pass in a QuerySet in ``extra_context`` and have it
evaluated at render time, you need to wrap it in a function (that
returns the QuerySet).
* ``allow_empty``: A boolean specifying whether to display the page if no * ``allow_empty``: A boolean specifying whether to display the page if no
objects are available. If this is ``False`` and no objects are available, objects are available. If this is ``False`` and no objects are available,
@ -455,11 +448,7 @@ a 404 error, regardless of whether any objects exist for future days.
* ``extra_context``: A dictionary of values to add to the template * ``extra_context``: A dictionary of values to add to the template
context. By default, this is an empty dictionary. If a value in the context. By default, this is an empty dictionary. If a value in the
dictionary is callable, the generic view will call it dictionary is callable, the generic view will call it
just before rendering the template. If it is not callable, it will be just before rendering the template.
evaluated once, at import time. Note that QuerySets are not callable, so
if you want to pass in a QuerySet in ``extra_context`` and have it
evaluated at render time, you need to wrap it in a function (that
returns the QuerySet).
* ``allow_empty``: A boolean specifying whether to display the page if no * ``allow_empty``: A boolean specifying whether to display the page if no
objects are available. If this is ``False`` and no objects are available, objects are available. If this is ``False`` and no objects are available,
@ -566,11 +555,7 @@ A page representing an individual object.
* ``extra_context``: A dictionary of values to add to the template * ``extra_context``: A dictionary of values to add to the template
context. By default, this is an empty dictionary. If a value in the context. By default, this is an empty dictionary. If a value in the
dictionary is callable, the generic view will call it dictionary is callable, the generic view will call it
just before rendering the template. If it is not callable, it will be just before rendering the template.
evaluated once, at import time. Note that QuerySets are not callable, so
if you want to pass in a QuerySet in ``extra_context`` and have it
evaluated at render time, you need to wrap it in a function (that
returns the QuerySet).
* ``context_processors``: A list of template-context processors to apply to * ``context_processors``: A list of template-context processors to apply to
the view's template. See the `RequestContext docs`_. the view's template. See the `RequestContext docs`_.
@ -627,11 +612,7 @@ A page representing a list of objects.
* ``extra_context``: A dictionary of values to add to the template * ``extra_context``: A dictionary of values to add to the template
context. By default, this is an empty dictionary. If a value in the context. By default, this is an empty dictionary. If a value in the
dictionary is callable, the generic view will call it dictionary is callable, the generic view will call it
just before rendering the template. If it is not callable, it will be just before rendering the template.
evaluated once, at import time. Note that QuerySets are not callable, so
if you want to pass in a QuerySet in ``extra_context`` and have it
evaluated at render time, you need to wrap it in a function (that
returns the QuerySet).
* ``allow_empty``: A boolean specifying whether to display the page if no * ``allow_empty``: A boolean specifying whether to display the page if no
objects are available. If this is ``False`` and no objects are available, objects are available. If this is ``False`` and no objects are available,
@ -728,11 +709,7 @@ A page representing an individual object.
* ``extra_context``: A dictionary of values to add to the template * ``extra_context``: A dictionary of values to add to the template
context. By default, this is an empty dictionary. If a value in the context. By default, this is an empty dictionary. If a value in the
dictionary is callable, the generic view will call it dictionary is callable, the generic view will call it
just before rendering the template. If it is not callable, it will be just before rendering the template.
evaluated once, at import time. Note that QuerySets are not callable, so
if you want to pass in a QuerySet in ``extra_context`` and have it
evaluated at render time, you need to wrap it in a function (that
returns the QuerySet).
* ``context_processors``: A list of template-context processors to apply to * ``context_processors``: A list of template-context processors to apply to
the view's template. See the `RequestContext docs`_. the view's template. See the `RequestContext docs`_.
@ -799,11 +776,7 @@ automatic manipulators that come with Django models.
* ``extra_context``: A dictionary of values to add to the template * ``extra_context``: A dictionary of values to add to the template
context. By default, this is an empty dictionary. If a value in the context. By default, this is an empty dictionary. If a value in the
dictionary is callable, the generic view will call it dictionary is callable, the generic view will call it
just before rendering the template. If it is not callable, it will be just before rendering the template.
evaluated once, at import time. Note that QuerySets are not callable, so
if you want to pass in a QuerySet in ``extra_context`` and have it
evaluated at render time, you need to wrap it in a function (that
returns the QuerySet).
* ``context_processors``: A list of template-context processors to apply to * ``context_processors``: A list of template-context processors to apply to
the view's template. See the `RequestContext docs`_. the view's template. See the `RequestContext docs`_.
@ -882,11 +855,7 @@ object. This uses the automatic manipulators that come with Django models.
* ``extra_context``: A dictionary of values to add to the template * ``extra_context``: A dictionary of values to add to the template
context. By default, this is an empty dictionary. If a value in the context. By default, this is an empty dictionary. If a value in the
dictionary is callable, the generic view will call it dictionary is callable, the generic view will call it
just before rendering the template. If it is not callable, it will be just before rendering the template.
evaluated once, at import time. Note that QuerySets are not callable, so
if you want to pass in a QuerySet in ``extra_context`` and have it
evaluated at render time, you need to wrap it in a function (that
returns the QuerySet).
* ``context_processors``: A list of template-context processors to apply to * ``context_processors``: A list of template-context processors to apply to
the view's template. See the `RequestContext docs`_. the view's template. See the `RequestContext docs`_.
@ -967,11 +936,7 @@ contain a form that POSTs to the same URL.
* ``extra_context``: A dictionary of values to add to the template * ``extra_context``: A dictionary of values to add to the template
context. By default, this is an empty dictionary. If a value in the context. By default, this is an empty dictionary. If a value in the
dictionary is callable, the generic view will call it dictionary is callable, the generic view will call it
just before rendering the template. If it is not callable, it will be just before rendering the template.
evaluated once, at import time. Note that QuerySets are not callable, so
if you want to pass in a QuerySet in ``extra_context`` and have it
evaluated at render time, you need to wrap it in a function (that
returns the QuerySet).
* ``context_processors``: A list of template-context processors to apply to * ``context_processors``: A list of template-context processors to apply to
the view's template. See the `RequestContext docs`_. the view's template. See the `RequestContext docs`_.