=================== Using generic views =================== Writing Web applications can be monotonous, because we repeat certain patterns again and again. In Django, the most common of these patterns have been abstracted into "generic views" that let you quickly provide common views of an object without actually needing to write any views. Django's generic views contain the following: * A set of views for doing list/detail interfaces (for example, Django's `documentation index`_ and `detail pages`_). * A set of views for year/month/day archive pages and associated detail and "latest" pages (for example, the Django weblog's year_, month_, day_, detail_, and latest_ pages). * A set of views for creating, editing, and deleting objects. .. _`documentation index`: http://www.djangoproject.com/documentation/ .. _`detail pages`: http://www.djangoproject.com/documentation/faq/ .. _year: http://www.djangoproject.com/weblog/2005/ .. _month: http://www.djangoproject.com/weblog/2005/jul/ .. _day: http://www.djangoproject.com/weblog/2005/jul/20/ .. _detail: http://www.djangoproject.com/weblog/2005/jul/20/autoreload/ .. _latest: http://www.djangoproject.com/weblog/ All of these views are used by creating configuration dictionaries in your URLconf files and passing those dictionaries as the third member of the URLconf tuple. For example, here's the URLconf for the simple weblog app that drives the blog on djangoproject.com:: from django.conf.urls.defaults import * info_dict = { 'app_label': 'blog', 'module_name': 'entries', 'date_field': 'pub_date', } urlpatterns = patterns('django.views.generic.date_based', (r'^(?P\d{4})/(?P[a-z]{3})/(?P\w{1,2})/(?P[-\w]+)/$', 'object_detail', dict(info_dict, slug_field='slug')), (r'^(?P\d{4})/(?P[a-z]{3})/(?P\w{1,2})/$', 'archive_day', info_dict), (r'^(?P\d{4})/(?P[a-z]{3})/$', 'archive_month', info_dict), (r'^(?P\d{4})/$', 'archive_year', info_dict), (r'^/?$', 'archive_index', info_dict), ) As you can see, this URLconf defines a few options in ``info_dict`` that tell the generic view which model to use (``blog.entries`` in this case), as well as some extra information. Documentation of each generic view follows, along with a list of all keyword arguments that a generic view expects. Remember that as in the example above, arguments may either come from the URL pattern (as ``month``, ``day``, ``year``, etc. do above) or from the additional-information dictionary (as for ``app_label``, ``module_name``, etc.). Most of the generic views that follow require the ``app_label`` and ``module_name`` keys. These values are easiest to explain through example:: >>> from django.models.blog import entries In the above line, ``blog`` is the ``app_label`` (the name of the file that holds all your model definitions) and ``entries`` is the ``module_name`` (either a pluralized, lowercased version of the model class name, or the value of the ``module_name`` option of your model). In the docs below, these keys will not be repeated, but each generic view requires them. Using "simple" generic views ============================ The ``django.views.generic.simple`` module contains simple views to handle a couple of common cases: rendering a template when no view logic is needed, and issuing a redirect. These views are: ``direct_to_template`` Renders a given template, passing it a ``{{ params }}`` template variable, which is a dictionary of the parameters captured in the URL. This requires the ``template`` argument. For example, given the following URL patterns:: urlpatterns = patterns('django.views.generic.simple', (r'^foo/$', 'direct_to_template', {'template': 'foo_index'}), (r'^foo/(?P\d+)/$', 'direct_to_template', {'template': 'foo_detail'}), ) ... a request to ``/foo/`` would cause the ``foo_index`` template to be rendered, and a request to ``/foo/15/`` would cause the ``foo_detail`` template to be rendered with a context variable ``{{ params.id }}`` that is set to ``15``. ``redirect_to`` Issue a redirect to a given URL. The given URL may contain dict-style string formatting, which will be interpolated against the params in the URL. For example, to redirect from ``/foo//`` to ``/bar//``, you could use the following urlpattern:: urlpatterns = patterns('django.views.generic.simple', ('^foo/(?p\d+)/$', 'redirect_to', {'url' : '/bar/%(id)s/'}), ) If the given URL is ``None``, an ``HttpResponseGone`` (410) will be issued. Using date-based generic views ============================== Date-based generic views (in the module ``django.views.generic.date_based``) feature six functions for dealing with date-based data. Besides ``app_label`` and ``module_name``, all date-based generic views require that the ``date_field`` argument be passed to them. This is the name of the field that stores the date the objects should key off of. Additionally, all date-based generic views have the following optional arguments: ======================= ================================================== Argument Description ======================= ================================================== ``template_name`` Overrides the default template name used for the view. ``extra_lookup_kwargs`` A dictionary of extra lookup parameters (see the `database API docs`_). ``extra_context`` A dictionary of extra data to put into the template's context. ``processors`` A tuple of processors to apply to the ``DjangoContext`` of this view's template. See the `DjangoContext docs`_ ======================= ================================================== .. _database API docs: http://www.djangoproject.com/documentation/db_api/ .. _DjangoContext docs: http://www.djangoproject.com/documentation/templates_python/#subclassing-context-djangocontext The date-based generic functions are: ``archive_index`` A top-level index page showing the "latest" objects. Takes the following optional arguments: ======================= ================================================= Argument Description ======================= ================================================= ``num_latest`` The number of items to display on the page. Defaults to 15. ``allow_empty`` If ``False`` and there are no objects to display, the view will raise a 404 instead of displaying an empty index page. ``False`` is default. ======================= ================================================= Uses the template ``app_label/module_name_archive`` by default. Has the following template context: ``date_list`` List of years with objects ``latest`` Latest objects by date ``archive_year`` Yearly archive. Requires that the ``year`` argument be present in the URL pattern. **New in Django development version:** Takes an optional ``allow_empty`` parameter, as ``archive_index``. Uses the template ``app_label/module_name_archive_year`` by default. Has the following template context: ``date_list`` List of months in the given year with objects ``year`` The given year (an integer) ``archive_month`` Monthly archive. Requires that ``year`` and ``month`` arguments be given. You can pass the additional option ``month_format`` if you'd like to change the way months are specified in the URL. ``month_format`` is a format string in the same syntax accepted by Python's ``time.strftime``. (See the `strftime docs`_.) It's set to ``"%b"`` by default, which is a three-letter month abbreviation. To change it to use numbers, use ``"%m"``. **New in Django development version:** Takes an optional ``allow_empty`` parameter, as ``archive_index``. **New in Django development version:** Takes an optional ``template_object_name`` parameter, which designates the name of the template variable to use. Default is ``'object'``. Uses the template ``app_label/module_name_archive_month`` by default. Has the following template context: ``month`` The given month (a datetime.date object) ``next_month`` **New in Django development version.** The first day of the next month, or None if the next month is in the future (a datetime.date object) ``previous_month`` **New in Django development version.** The first day of the previous month (a datetime.date object) ``object_list`` List of objects published in the given month. In the Django development version, you can change this variable name from ``object_list`` by using the ``template_object_name`` parameter. (See above.) For example, if ``template_object_name`` is ``foo``, the variable will be ``foo_list``. ``archive_day`` Daily archive. Requires that ``year``, ``month``, and ``day`` arguments be given. As in ``archive_month``, you can pass an optional ``month_format``. You can also pass ``day_format``, which defaults to ``"%d"`` (day of the month as a decimal number, 01-31). **New in Django development version:** Takes an optional ``template_object_name`` parameter, which designates the name of the template variable to use. Default is ``'object'``. Uses the template ``app_label/module_name_archive_day`` by default. Has the following template context: ``object_list`` List of objects published on the given day. In the Django development version, you can change this variable name from ``object_list`` by using the ``template_object_name`` parameter. (See above.) For example, if ``template_object_name`` is ``foo``, the variable will be ``foo_list``. ``day`` The given day (a datetime.datetime object) ``previous_day`` The previous day (a datetime.datetime object) ``next_day`` The next day (a datetime.datetime object), or None if the given day is today ``archive_today`` List of objects for today. Exactly the same as ``archive_day``, except the year/month/day arguments are not given, and today's date is used instead. ``object_detail`` Individual object page. Requires ``year``/``month``/``day`` arguments like ``archive_day``. This function can be used with two types of URLs: either ``/year/month/day/slug/`` or ``/year/month/day/object_id/``. If you're using the slug-style URLs, you'll need to have a ``slug`` item in your URLconf, and you'll need to pass a ``slug_field`` key in your info dictionary to indicate the name of the slug field. If you're using the object_id-style URLs, you'll just need to give the URL pattern an ``object_id`` field. You can also pass the ``template_name_field`` argument to indicate that the the object stores the name of its template in a field on the object itself. As in ``archive_day``, ``object_detail`` takes optional ``month_format`` and ``day_format`` parameters. **New in Django development version:** Takes an optional ``template_object_name`` parameter, which designates the name of the template variable to use. Default is ``'object'``. .. _strftime docs: http://www.python.org/doc/current/lib/module-time.html#l2h-1941 Using list/detail generic views =============================== The list-detail generic-view framework (in the ``django.views.generic.list_detail`` module) is similar to the date-based one, except the former simply has two views: a list of objects and an individual object page. All these views take the same four optional arguments as the date-based ones -- and, clearly, they don't accept the ``date_field`` argument. Individual views are: ``object_list`` List of objects. Takes the following optional arguments: ======================== ================================================= Argument Description ======================== ================================================= ``paginate_by`` If set to an integer, the view will paginate objects with ``paginate_by`` objects per page. The view will expect a ``page`` GET param with the (zero-indexed) page number. ``allow_empty`` If ``False`` and there are no objects to display, the view will raise a 404 instead of displaying an empty index page. ``False`` is default. ``template_object_name`` **New in Django development version.** Designates the name of the object template variable. Default is ``'object'``. ======================== ================================================= Uses the template ``app_label/module_name_list`` by default. Has the following template context: ``object_list`` List of objects. In the Django development version, you can change this variable name from ``object_list`` by using the ``template_object_name`` parameter. (See above.) For example, if ``template_object_name`` is ``foo``, the variable will be ``foo_list``. ``is_paginated`` Are the results paginated? Either True or False If the results are paginated, the context will have some extra variables: ``results_per_page`` Number of objects per page ``has_next`` Is there a next page? ``has_previous`` Is there a previous page? ``page`` The current page number ``next`` The next page number ``previous`` The previous page ``pages`` Number of pages total ``hits`` Total number of objects ``object_detail`` Object detail page. This works like and takes the same arguments as the date-based ``object_detail`` above, except this one, obviously, does not take the year/month/day arguments. Using create/update/delete generic views ======================================== The ``django.views.generic.create_update`` module contains a set of functions for creating, editing and deleting objects. These views take the same global arguments as the above sets of generic views. They also have a ``login_required`` argument which, if ``True``, requires the user to be logged in to have access to the page. (``login_required`` defaults to ``False``.) The create/update/delete views are: ``create_object`` Create a new object. Has an extra optional argument, ``post_save_redirect``, which is a URL to which the view will redirect after saving the object. It defaults to ``object.get_absolute_url()``. ``post_save_redirect`` may contain dictionary string formatting, which will be interpolated against the object's field attributes. For example, you could use ``post_save_redirect="/polls/%(slug)s/"``. Uses the template ``app_label/module_name_form`` by default. This is the same template as the ``update_object`` view below. Your template can tell the difference by the presence or absence of ``{{ object }}`` in the context. Has the following template context: form The form wrapper for the object .. admonition:: Note See the `manipulator and formfield documentation`_ for more information about using form wrappers in templates. .. _`manipulator and formfield documentation`: http://www.djangoproject.com/documentation/forms/ ``update_object`` Edit an existing object. Has the same extra slug/ID parameters as ``list_detail.object_detail`` does (see above), and the same ``post_save_redirect`` as ``create_object`` does. **New in Django development version:** Takes an optional ``template_object_name`` parameter, which designates the name of the template variable to use. Default is ``'object'``. Uses the template ``app_label/module_name_form`` by default. Has the following template context: form The form wrapper for the object object The original object being edited. In the Django development version, you can change this variable name from ``object`` by using the ``template_object_name`` parameter. (See above.) For example, if ``template_object_name`` is ``foo``, the variable will be ``foo`` instead of ``object``. ``delete_object`` Delete an existing object. The given object will only actually be deleted if the request method is POST. If this view is fetched with GET, it will display a confirmation page that should contain a form that POSTs to the same URL. You must provide the ``post_delete_redirect`` argument to this function, so that the view knows where to go after the object is deleted. If fetched with GET, it uses the template ``app_label/module_name_confirm_delete`` by default. It uses no template if POSTed -- it simply deletes the object and redirects. **New in Django development version:** Takes an optional ``template_object_name`` parameter, which designates the name of the template variable to use. Default is ``'object'``. Has the following template context: object The object about to be deleted In the Django development version, you can change this variable name from ``object`` by using the ``template_object_name`` parameter. (See above.) For example, if ``template_object_name`` is ``foo``, the variable will be ``foo`` instead of ``object``.