391 lines
16 KiB
Plaintext
391 lines
16 KiB
Plaintext
===================
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Using generic views
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===================
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Writing Web applications can be monotonous, because we repeat certain patterns
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again and again. In Django, the most common of these patterns have been
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abstracted into "generic views" that let you quickly provide common views of
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an object without actually needing to write any views.
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Django's generic views contain the following:
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* A set of views for doing list/detail interfaces (for example,
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Django's `documentation index`_ and `detail pages`_).
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* A set of views for year/month/day archive pages and associated
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detail and "latest" pages (for example, the Django weblog's year_,
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month_, day_, detail_, and latest_ pages).
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* A set of views for creating, editing, and deleting objects.
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.. _`documentation index`: http://www.djangoproject.com/documentation/
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.. _`detail pages`: http://www.djangoproject.com/documentation/faq/
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.. _year: http://www.djangoproject.com/weblog/2005/
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.. _month: http://www.djangoproject.com/weblog/2005/jul/
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.. _day: http://www.djangoproject.com/weblog/2005/jul/20/
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.. _detail: http://www.djangoproject.com/weblog/2005/jul/20/autoreload/
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.. _latest: http://www.djangoproject.com/weblog/
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All of these views are used by creating configuration dictionaries in
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your URLconf files and passing those dictionaries as the third member of the
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URLconf tuple. For example, here's the URLconf for the simple weblog app that
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drives the blog on djangoproject.com::
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from django.conf.urls.defaults import *
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info_dict = {
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'app_label': 'blog',
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'module_name': 'entries',
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'date_field': 'pub_date',
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}
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urlpatterns = patterns('django.views.generic.date_based',
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(r'^(?P<year>\d{4})/(?P<month>[a-z]{3})/(?P<day>\w{1,2})/(?P<slug>[-\w]+)/$', 'object_detail', dict(info_dict, slug_field='slug')),
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(r'^(?P<year>\d{4})/(?P<month>[a-z]{3})/(?P<day>\w{1,2})/$', 'archive_day', info_dict),
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(r'^(?P<year>\d{4})/(?P<month>[a-z]{3})/$', 'archive_month', info_dict),
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(r'^(?P<year>\d{4})/$', 'archive_year', info_dict),
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(r'^/?$', 'archive_index', info_dict),
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)
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As you can see, this URLconf defines a few options in ``info_dict`` that tell
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the generic view which model to use (``blog.entries`` in this case), as well as
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some extra information.
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Documentation of each generic view follows, along with a list of all keyword
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arguments that a generic view expects. Remember that as in the example above,
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arguments may either come from the URL pattern (as ``month``, ``day``,
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``year``, etc. do above) or from the additional-information dictionary (as for
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``app_label``, ``module_name``, etc.).
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Most of the generic views that follow require the ``app_label`` and
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``module_name`` keys. These values are easiest to explain through example::
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>>> from django.models.blog import entries
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In the above line, ``blog`` is the ``app_label`` (the name of the file that
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holds all your model definitions) and ``entries`` is the ``module_name``
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(either a pluralized, lowercased version of the model class name, or the value
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of the ``module_name`` option of your model). In the docs below, these keys
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will not be repeated, but each generic view requires them.
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Using "simple" generic views
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============================
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The ``django.views.generic.simple`` module contains simple views to handle a
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couple of common cases: rendering a template when no view logic is needed,
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and issuing a redirect. These views are:
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``direct_to_template``
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Renders a given template, passing it a ``{{ params }}`` template variable,
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which is a dictionary of the parameters captured in the URL. This requires
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the ``template`` argument.
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For example, given the following URL patterns::
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urlpatterns = patterns('django.views.generic.simple',
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(r'^foo/$', 'direct_to_template', {'template': 'foo_index'}),
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(r'^foo/(?P<id>\d+)/$', 'direct_to_template', {'template': 'foo_detail'}),
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)
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... a request to ``/foo/`` would cause the ``foo_index`` template to be
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rendered, and a request to ``/foo/15/`` would cause the ``foo_detail``
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template to be rendered with a context variable ``{{ params.id }}`` that is
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set to ``15``.
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``redirect_to``
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Issue a redirect to a given URL.
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The given URL may contain dict-style string formatting, which will be
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interpolated against the params in the URL. For example, to redirect from
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``/foo/<id>/`` to ``/bar/<id>/``, you could use the following urlpattern::
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urlpatterns = patterns('django.views.generic.simple',
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('^foo/(?p<id>\d+)/$', 'redirect_to', {'url' : '/bar/%(id)s/'}),
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)
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If the given URL is ``None``, an ``HttpResponseGone`` (410) will be issued.
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Using date-based generic views
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==============================
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Date-based generic views (in the module ``django.views.generic.date_based``)
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feature six functions for dealing with date-based data. Besides ``app_label``
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and ``module_name``, all date-based generic views require that the
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``date_field`` argument be passed to them. This is the name of the field that
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stores the date the objects should key off of.
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Additionally, all date-based generic views have the following optional
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arguments:
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======================= ==================================================
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Argument Description
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======================= ==================================================
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``template_name`` Overrides the default template name used for the
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view.
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``extra_lookup_kwargs`` A dictionary of extra lookup parameters (see
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the `database API docs`_).
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``extra_context`` A dictionary of extra data to put into the
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template's context.
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``processors`` A tuple of processors to apply to the
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``DjangoContext`` of this view's template. See the
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`DjangoContext docs`_
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======================= ==================================================
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.. _database API docs: http://www.djangoproject.com/documentation/db_api/
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.. _DjangoContext docs: http://www.djangoproject.com/documentation/templates_python/#subclassing-context-djangocontext
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The date-based generic functions are:
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``archive_index``
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A top-level index page showing the "latest" objects.
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Takes the following optional arguments:
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======================= =================================================
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Argument Description
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======================= =================================================
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``num_latest`` The number of items to display on the page.
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Defaults to 15.
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``allow_empty`` If ``False`` and there are no objects to display,
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the view will raise a 404 instead of displaying
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an empty index page. ``False`` is default.
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======================= =================================================
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Uses the template ``app_label/module_name_archive`` by default.
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Has the following template context:
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``date_list``
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List of years with objects
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``latest``
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Latest objects by date
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``archive_year``
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Yearly archive. Requires that the ``year`` argument be present in the URL
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pattern.
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**New in Django development version:** Takes an optional ``allow_empty``
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parameter, as ``archive_index``.
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Uses the template ``app_label/module_name_archive_year`` by default.
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Has the following template context:
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``date_list``
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List of months in the given year with objects
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``year``
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The given year (an integer)
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``archive_month``
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Monthly archive. Requires that ``year`` and ``month`` arguments be given.
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You can pass the additional option ``month_format`` if you'd like to change
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the way months are specified in the URL.
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``month_format`` is a format string in the same syntax accepted by Python's
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``time.strftime``. (See the `strftime docs`_.) It's set to ``"%b"`` by
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default, which is a three-letter month abbreviation. To change it to use
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numbers, use ``"%m"``.
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**New in Django development version:** Takes an optional ``allow_empty``
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parameter, as ``archive_index``.
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Uses the template ``app_label/module_name_archive_month`` by default.
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Has the following template context:
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``month``
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The given month (a datetime.date object)
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``next_month``
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**New in Django development version.** The first day of the next
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month, or None if the next month is in the future (a datetime.date
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object)
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``previous_month``
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**New in Django development version.** The first day of the
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previous month (a datetime.date object)
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``object_list``
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List of objects published in the given month
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``archive_day``
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Daily archive. Requires that ``year``, ``month``, and ``day`` arguments be
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given.
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As in ``archive_month``, you can pass an optional ``month_format``. You can
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also pass ``day_format``, which defaults to ``"%d"`` (day of the month as a
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decimal number, 1-31).
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Uses the template ``app_label/module_name_archive_day`` by default.
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Has the following template context:
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``object_list``
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List of objects published this day
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``day``
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The given day (a datetime.datetime object)
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``previous_day``
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The previous day (a datetime.datetime object)
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``next_day``
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The next day (a datetime.datetime object), or None if the given
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day is today
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``archive_today``
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List of objects for today. Exactly the same as ``archive_day``, except
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the year/month/day arguments are not given, and today's date is used
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instead.
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``object_detail``
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Individual object page. Requires ``year``/``month``/``day`` arguments like
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``archive_day``. This function can be used with two types of URLs: either
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``/year/month/day/slug/`` or ``/year/month/day/object_id/``.
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If you're using the slug-style URLs, you'll need to have a ``slug`` item in
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your URLconf, and you'll need to pass a ``slug_field`` key in your info
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dictionary to indicate the name of the slug field.
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If your using the object_id-style URLs, you'll just need to give the URL
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pattern an ``object_id`` field.
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You can also pass the ``template_name_field`` argument to indicate that the
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the object stores the name of its template in a field on the object itself.
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As in ``archive_day``, ``object_detail`` takes optional ``month_format``
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and ``day_format`` parameters.
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.. _strftime docs: http://www.python.org/doc/current/lib/module-time.html#l2h-1941
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Using list/detail generic views
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===============================
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The list-detail generic-view framework (in the
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``django.views.generic.list_detail`` module) is similar to the date-based one,
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except the former simply has two views: a list of objects and an individual
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object page.
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All these views take the same four optional arguments as the date-based ones
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-- and, clearly, they don't accept the ``date_field`` argument.
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Individual views are:
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``object_list``
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List of objects.
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Takes the following optional arguments:
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======================= =================================================
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Argument Description
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======================= =================================================
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``paginate_by`` If set to an integer, the view will paginate
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objects with ``paginate_by`` objects per page.
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The view will expect a ``page`` GET param with
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the (zero-indexed) page number.
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``allow_empty`` If ``False`` and there are no objects to display,
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the view will raise a 404 instead of displaying
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an empty index page. ``False`` is default.
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======================= =================================================
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Uses the template ``app_label/module_name_list`` by default.
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Has the following template context:
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``object_list``
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List of objects
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``is_paginated``
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Are the results paginated? Either True or False
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If the results are paginated, the context will have some extra variables:
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``results_per_page``
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Number of objects per page
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``has_next``
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Is there a next page?
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``has_previous``
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Is there a previous page?
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``page``
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The current page number
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``next``
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The next page number
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``previous``
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The previous page
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``pages``
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Number of pages total
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``hits``
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Total number of objects
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``object_detail``
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Object detail page. This works like and takes the same arguments as
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the date-based ``object_detail`` above, except this one, obviously,
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does not take the year/month/day arguments.
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Using create/update/delete generic views
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========================================
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The ``django.views.generic.create_update`` module contains a set of functions
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for creating, editing and deleting objects. These views take the same global
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arguments as the above sets of generic views. They also have a
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``login_required`` argument which, if ``True``, requires the user to be logged
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in to have access to the page. (``login_required`` defaults to ``False``.)
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The create/update/delete views are:
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``create_object``
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Create a new object. Has an extra optional argument, ``post_save_redirect``,
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which is a URL to which the view will redirect after saving the object.
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It defaults to ``object.get_absolute_url()``.
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``post_save_redirect`` may contain dictionary string formatting, which will
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be interpolated against the object's field attributes. For example, you
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could use ``post_save_redirect="/polls/%(slug)s/"``.
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Uses the template ``app_label/module_name_form`` by default. This is the
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same template as the ``update_object`` view below. Your template can tell
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the difference by the presence or absence of ``{{ object }}`` in the
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context.
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Has the following template context:
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form
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The form wrapper for the object
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.. admonition:: Note
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See the `manipulator and formfield documentation`_ for more information
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about using form wrappers in templates.
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.. _`manipulator and formfield documentation`: http://www.djangoproject.com/documentation/forms/
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``update_object``
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Edit an existing object. Has the same extra slug/ID parameters as
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``list_detail.object_detail`` does (see above), and the same
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``post_save_redirect`` as ``create_object`` does.
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Uses the template ``app_label/module_name_form`` by default.
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Has the following template context:
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form
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The form wrapper for the object
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object
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The original object being edited
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``delete_object``
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Delete an existing object. The given object will only actually be deleted
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if the request method is POST. If this view is fetched with GET, it will
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display a confirmation page that should contain a form that POSTs to the
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same URL.
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You must provide the ``post_delete_redirect`` argument to this function, so
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that the view knows where to go after the object is deleted.
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If fetched with GET, it uses the template
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``app_label/module_name_confirm_delete`` by default. It uses no template
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if POSTed -- it simply deletes the object and redirects.
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Has the following template context:
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object
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The object about to be deleted
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