admin.txt

.. _ref-contrib-admin:

=====================
The Django admin site
=====================

One of the most powerful parts of Django is the automatic admin interface. It
reads metadata in your model to provide a powerful and production-ready
interface that content producers can immediately use to start adding content to
the site. In this document, we discuss how to activate, use and customize
Django's admin interface.

.. admonition:: Note

    The admin site has been refactored significantly since Django 0.96. This
    document describes the newest version of the admin site, which allows for
    much richer customization. If you follow the development of Django itself,
    you may have heard this described as "newforms-admin."

Overview
========

There are five steps in activating the Django admin site:

    1. Add ``django.contrib.admin`` to your ``INSTALLED_APPS`` setting.

    2. Determine which of your application's models should be editable in the
       admin interface.

    3. For each of those models, optionally create a ``ModelAdmin`` class that
       encapsulates the customized admin functionality and options for that
       particular model.

    4. Instantiate an ``AdminSite`` and tell it about each of your models and
       ``ModelAdmin`` classes.

    5. Hook the ``AdminSite`` instance into your URLconf.

``ModelAdmin`` objects
======================

The ``ModelAdmin`` class is the representation of a model in the admin
interface. These are stored in a file named ``admin.py`` in your application.
Let's take a look at a very simple example of the ``ModelAdmin``::

    from django.contrib import admin
    from myproject.myapp.models import Author

    class AuthorAdmin(admin.ModelAdmin):
        pass
    admin.site.register(Author, AuthorAdmin)

.. admonition:: Do you need a ``ModelAdmin`` object at all?

    In the preceding example, the ``ModelAdmin`` class doesn't define any
    custom values (yet). As a result, the default admin interface will be
    provided. If you are happy with the default admin interface, you don't
    need to define a ``ModelAdmin`` object at all -- you can register the
    model class without providing a ``ModelAdmin`` description. The
    preceding example could be simplified to::

        from django.contrib import admin
        from myproject.myapp.models import Author
    
        admin.site.register(Author)
    
``ModelAdmin`` Options
----------------------

The ``ModelAdmin`` is very flexible. It has several options for dealing with
customizing the interface. All options are defined on the ``ModelAdmin``
subclass::

    class AuthorAdmin(admin.ModelAdmin):
        date_hierarchy = 'pub_date'

``date_hierarchy``
~~~~~~~~~~~~~~~~~~

Set ``date_hierarchy`` to the name of a ``DateField`` or ``DateTimeField`` in
your model, and the change list page will include a date-based drilldown
navigation by that field.

Example::

    date_hierarchy = 'pub_date'

``form``
~~~~~~~~

By default a ``ModelForm`` is dynamically created for your model. It is used
to create the form presented on both the add/change pages. You can easily
provide your own ``ModelForm`` to override any default form behavior on the
add/change pages.

For an example see the section `Adding custom validation to the admin`_.

``fieldsets``
~~~~~~~~~~~~~

Set ``fieldsets`` to control the layout of admin "add" and "change" pages.

``fieldsets`` is a list of two-tuples, in which each two-tuple represents a
``<fieldset>`` on the admin form page. (A ``<fieldset>`` is a "section" of the
form.)

The two-tuples are in the format ``(name, field_options)``, where ``name`` is a
string representing the title of the fieldset and ``field_options`` is a
dictionary of information about the fieldset, including a list of fields to be
displayed in it.

A full example, taken from the ``django.contrib.flatpages.FlatPage`` model::

    class FlatPageAdmin(admin.ModelAdmin):
        fieldsets = (
            (None, {
                'fields': ('url', 'title', 'content', 'sites')
            }),
            ('Advanced options', {
                'classes': ('collapse',),
                'fields': ('enable_comments', 'registration_required', 'template_name')
            }),
        )

This results in an admin page that looks like:

    .. image:: _images/flatfiles_admin.png

If ``fieldsets`` isn't given, Django will default to displaying each field
that isn't an ``AutoField`` and has ``editable=True``, in a single fieldset,
in the same order as the fields are defined in the model.

The ``field_options`` dictionary can have the following keys:

    * ``fields``
        A tuple of field names to display in this fieldset. This key is
        required.
        
        Example::
        
            {
            'fields': ('first_name', 'last_name', 'address', 'city', 'state'),
            }
            
        To display multiple fields on the same line, wrap those fields in
        their own tuple. In this example, the ``first_name`` and ``last_name``
        fields will display on the same line::

            {
            'fields': (('first_name', 'last_name'), 'address', 'city', 'state'),
            }

    * ``classes``
        A list containing extra CSS classes to apply to the fieldset.
        
        Example::
        
            {
            'classes': ['wide', 'extrapretty'],
            }

        Two useful classes defined by the default admin site stylesheet are
        ``collapse`` and ``wide``. Fieldsets with the ``collapse`` style will
        be initially collapsed in the admin and replaced with a small
        "click to expand" link. Fieldsets with the ``wide`` style will be
        given extra horizontal space.

    * ``description``
        A string of optional extra text to be displayed at the top of each
        fieldset, under the heading of the fieldset.

        Note that this value is *not* HTML-escaped when it's displayed in
        the admin interface. This lets you include HTML if you so desire.
        Alternatively you can use plain text and
        ``django.utils.html.escape()`` to escape any HTML special
        characters.

``fields``
~~~~~~~~~~

Use this option as an alternative to ``fieldsets`` if the layout does not
matter and if you want to only show a subset of the available fields in the
form. For example, you could define a simpler version of the admin form for
the ``django.contrib.flatpages.FlatPage`` model as follows::

    class FlatPageAdmin(admin.ModelAdmin):
        fields = ('url', 'title', 'content')

In the above example, only the fields 'url', 'title' and 'content' will be
displayed, sequentially, in the form.

.. admonition:: Note

    This ``fields`` option should not be confused with the ``fields``
    dictionary key that is within the ``fieldsets`` option, as described in
    the previous section.

``exclude``
~~~~~~~~~~~

This attribute, if given, should be a list of field names to exclude from the
form.

For example, let's consider the following model::

    class Author(models.Model):
        name = models.CharField(max_length=100)
        title = models.CharField(max_length=3)
        birth_date = models.DateField(blank=True, null=True)

If you want a form for the ``Author`` model that includes only the ``name``
and ``title`` fields, you would specify ``fields`` or ``exclude`` like this::
    
    class AuthorAdmin(admin.ModelAdmin):
        fields = ('name', 'title')
    
    class AuthorAdmin(admin.ModelAdmin):
        exclude = ('birth_date',)

Since the Author model only has three fields, ``name``, ``title``, and
``birth_date``, the forms resulting from the above declarations will contain
exactly the same fields.

``filter_horizontal``
~~~~~~~~~~~~~~~~~~~~~

Use a nifty unobtrusive JavaScript "filter" interface instead of the
usability-challenged ``<select multiple>`` in the admin form. The value is a
list of fields that should be displayed as a horizontal filter interface. See
``filter_vertical`` to use a vertical interface.

``filter_vertical``
~~~~~~~~~~~~~~~~~~~

Same as ``filter_horizontal``, but is a vertical display of the filter
interface.

``list_display``
~~~~~~~~~~~~~~~~

Set ``list_display`` to control which fields are displayed on the change list
page of the admin.

Example::

    list_display = ('first_name', 'last_name')

If you don't set ``list_display``, the admin site will display a single column
that displays the ``__unicode__()`` representation of each object.

You have four possible values that can be used in ``list_display``:

    * A field of the model. For example::
    
          class PersonAdmin(admin.ModelAdmin):
              list_display = ('first_name', 'last_name')
    
    * A callable that accepts one parameter for the model instance. For
      example::
    
          def upper_case_name(obj):
              return "%s %s" % (obj.first_name, obj.last_name).upper()
          upper_case_name.short_description = 'Name'
        
          class PersonAdmin(admin.ModelAdmin):
              list_display = (upper_case_name,)
    
    * A string representing an attribute on the ``ModelAdmin``. This behaves
      same as the callable. For example::
      
          class PersonAdmin(admin.ModelAdmin):
              list_display = ('upper_case_name',)
              
              def upper_case_name(self, obj):
                return "%s %s" % (obj.first_name, obj.last_name).upper()
              upper_case_name.short_description = 'Name'
    
    * A string representing an attribute on the model. This behaves almost
      the same as the callable, but ``self`` in this context is the model
      instance. Here's a full model example::

          class Person(models.Model):
              name = models.CharField(max_length=50)
              birthday = models.DateField()

              def decade_born_in(self):
                  return self.birthday.strftime('%Y')[:3] + "0's"
              decade_born_in.short_description = 'Birth decade'

          class PersonAdmin(admin.ModelAdmin):
              list_display = ('name', 'decade_born_in')

A few special cases to note about ``list_display``:

    * If the field is a ``ForeignKey``, Django will display the
      ``__unicode__()`` of the related object.

    * ``ManyToManyField`` fields aren't supported, because that would entail
      executing a separate SQL statement for each row in the table. If you
      want to do this nonetheless, give your model a custom method, and add
      that method's name to ``list_display``. (See below for more on custom
      methods in ``list_display``.)

    * If the field is a ``BooleanField`` or ``NullBooleanField``, Django will
      display a pretty "on" or "off" icon instead of ``True`` or ``False``.

    * If the string given is a method of the model, ``ModelAdmin`` or a
      callable, Django will HTML-escape the output by default. If you'd rather
      not escape the output of the method, give the method an ``allow_tags``
      attribute whose value is ``True``.
      
      Here's a full example model::

          class Person(models.Model):
              first_name = models.CharField(max_length=50)
              last_name = models.CharField(max_length=50)
              color_code = models.CharField(max_length=6)

              def colored_name(self):
                  return '<span style="color: #%s;">%s %s</span>' % (self.color_code, self.first_name, self.last_name)
              colored_name.allow_tags = True

          class PersonAdmin(admin.ModelAdmin):
              list_display = ('first_name', 'last_name', 'colored_name')

    * If the string given is a method of the model, ``ModelAdmin`` or a
      callable that returns True or False Django will display a pretty "on" or
      "off" icon if you give the method a ``boolean`` attribute whose value is
      ``True``.

      Here's a full example model::

          class Person(models.Model):
              first_name = models.CharField(max_length=50)
              birthday = models.DateField()

              def born_in_fifties(self):
                  return self.birthday.strftime('%Y')[:3] == 5
              born_in_fifties.boolean = True

          class PersonAdmin(admin.ModelAdmin):
              list_display = ('name', 'born_in_fifties')


    * The ``__str__()`` and ``__unicode__()`` methods are just as valid in
      ``list_display`` as any other model method, so it's perfectly OK to do
      this::

          list_display = ('__unicode__', 'some_other_field')

    * Usually, elements of ``list_display`` that aren't actual database fields
      can't be used in sorting (because Django does all the sorting at the
      database level).

      However, if an element of ``list_display`` represents a certain database
      field, you can indicate this fact by setting the ``admin_order_field``
      attribute of the item.

      For example::

        class Person(models.Model):
            first_name = models.CharField(max_length=50)
            color_code = models.CharField(max_length=6)

            def colored_first_name(self):
                return '<span style="color: #%s;">%s</span>' % (self.color_code, self.first_name)
            colored_first_name.allow_tags = True
            colored_first_name.admin_order_field = 'first_name'

        class PersonAdmin(admin.ModelAdmin):
            list_display = ('first_name', 'colored_first_name')

      The above will tell Django to order by the ``first_name`` field when
      trying to sort by ``colored_first_name`` in the admin.

``list_display_links``
~~~~~~~~~~~~~~~~~~~~~~

Set ``list_display_links`` to control which fields in ``list_display`` should
be linked to the "change" page for an object.

By default, the change list page will link the first column -- the first field
specified in ``list_display`` -- to the change page for each item. But
``list_display_links`` lets you change which columns are linked. Set
``list_display_links`` to a list or tuple of field names (in the same format as
``list_display``) to link.

``list_display_links`` can specify one or many field names. As long as the
field names appear in ``list_display``, Django doesn't care how many (or how
few) fields are linked. The only requirement is: If you want to use
``list_display_links``, you must define ``list_display``.

In this example, the ``first_name`` and ``last_name`` fields will be linked on
the change list page::

    class PersonAdmin(admin.ModelAdmin):
        list_display = ('first_name', 'last_name', 'birthday')
        list_display_links = ('first_name', 'last_name')

Finally, note that in order to use ``list_display_links``, you must define
``list_display``, too.

``list_filter``
~~~~~~~~~~~~~~~

Set ``list_filter`` to activate filters in the right sidebar of the change list
page of the admin. This should be a list of field names, and each specified
field should be either a ``BooleanField``, ``CharField``, ``DateField``,
``DateTimeField``, ``IntegerField`` or ``ForeignKey``.

This example, taken from the ``django.contrib.auth.models.User`` model, shows
how both ``list_display`` and ``list_filter`` work::

    class UserAdmin(admin.ModelAdmin):
        list_display = ('username', 'email', 'first_name', 'last_name', 'is_staff')
        list_filter = ('is_staff', 'is_superuser')

The above code results in an admin change list page that looks like this:

    .. image:: _images/users_changelist.png

(This example also has ``search_fields`` defined. See below.)

``list_per_page``
~~~~~~~~~~~~~~~~~

Set ``list_per_page`` to control how many items appear on each paginated admin
change list page. By default, this is set to ``100``.

``list_select_related``
~~~~~~~~~~~~~~~~~~~~~~~

Set ``list_select_related`` to tell Django to use ``select_related()`` in
retrieving the list of objects on the admin change list page. This can save you
a bunch of database queries.

The value should be either ``True`` or ``False``. Default is ``False``.

Note that Django will use ``select_related()``, regardless of this setting,
if one of the ``list_display`` fields is a ``ForeignKey``.

For more on ``select_related()``, see
:ref:`the select_related() docs <select-related>`.

``inlines``
~~~~~~~~~~~

See ``InlineModelAdmin`` objects below.

``ordering``
~~~~~~~~~~~~

Set ``ordering`` to specify how objects on the admin change list page should be
ordered. This should be a list or tuple in the same format as a model's
``ordering`` parameter.

If this isn't provided, the Django admin will use the model's default ordering.

.. admonition:: Note

    Django will only honor the first element in the list/tuple; any others
    will be ignored.

``prepopulated_fields``
~~~~~~~~~~~~~~~~~~~~~~~

Set ``prepopulated_fields`` to a dictionary mapping field names to the fields
it should prepopulate from::

    class ArticleAdmin(admin.ModelAdmin):
        prepopulated_fields = {"slug": ("title",)}

When set, the given fields will use a bit of JavaScript to populate from the
fields assigned. The main use for this functionality is to automatically
generate the value for ``SlugField`` fields from one or more other fields. The
generated value is produced by concatenating the values of the source fields,
and then by transforming that result into a valid slug (e.g. substituting
dashes for spaces).

``prepopulated_fields`` doesn't accept ``DateTimeField``, ``ForeignKey``, nor
``ManyToManyField`` fields.

``radio_fields``
~~~~~~~~~~~~~~~~

By default, Django's admin uses a select-box interface (<select>) for
fields that are ``ForeignKey`` or have ``choices`` set. If a field is present
in ``radio_fields``, Django will use a radio-button interface instead.
Assuming ``group`` is a ``ForeignKey`` on the ``Person`` model::

    class PersonAdmin(admin.ModelAdmin):
        radio_fields = {"group": admin.VERTICAL}

You have the choice of using ``HORIZONTAL`` or ``VERTICAL`` from the
``django.contrib.admin`` module.

Don't include a field in ``radio_fields`` unless it's a ``ForeignKey`` or has
``choices`` set.

``raw_id_fields``
~~~~~~~~~~~~~~~~~

By default, Django's admin uses a select-box interface (<select>) for
fields that are ``ForeignKey``. Sometimes you don't want to incur the
overhead of having to select all the related instances to display in the
drop-down.

``raw_id_fields`` is a list of fields you would like to change
into a ``Input`` widget for either a ``ForeignKey`` or ``ManyToManyField``::

    class ArticleAdmin(admin.ModelAdmin):
        raw_id_fields = ("newspaper",)

``save_as``
~~~~~~~~~~~

Set ``save_as`` to enable a "save as" feature on admin change forms.

Normally, objects have three save options: "Save", "Save and continue editing"
and "Save and add another". If ``save_as`` is ``True``, "Save and add another"
will be replaced by a "Save as" button.

"Save as" means the object will be saved as a new object (with a new ID),
rather than the old object.

By default, ``save_as`` is set to ``False``.

``save_on_top``
~~~~~~~~~~~~~~~

Set ``save_on_top`` to add save buttons across the top of your admin change
forms.

Normally, the save buttons appear only at the bottom of the forms. If you set
``save_on_top``, the buttons will appear both on the top and the bottom.

By default, ``save_on_top`` is set to ``False``.

``search_fields``
~~~~~~~~~~~~~~~~~

Set ``search_fields`` to enable a search box on the admin change list page.
This should be set to a list of field names that will be searched whenever
somebody submits a search query in that text box.

These fields should be some kind of text field, such as ``CharField`` or
``TextField``. You can also perform a related lookup on a ``ForeignKey`` with
the lookup API "follow" notation::

    search_fields = ['foreign_key__related_fieldname']

When somebody does a search in the admin search box, Django splits the search
query into words and returns all objects that contain each of the words, case
insensitive, where each word must be in at least one of ``search_fields``. For
example, if ``search_fields`` is set to ``['first_name', 'last_name']`` and a
user searches for ``john lennon``, Django will do the equivalent of this SQL
``WHERE`` clause::

    WHERE (first_name ILIKE '%john%' OR last_name ILIKE '%john%')
    AND (first_name ILIKE '%lennon%' OR last_name ILIKE '%lennon%')

For faster and/or more restrictive searches, prefix the field name
with an operator:

``^``
    Matches the beginning of the field. For example, if ``search_fields`` is
    set to ``['^first_name', '^last_name']`` and a user searches for
    ``john lennon``, Django will do the equivalent of this SQL ``WHERE``
    clause::

        WHERE (first_name ILIKE 'john%' OR last_name ILIKE 'john%')
        AND (first_name ILIKE 'lennon%' OR last_name ILIKE 'lennon%')

    This query is more efficient than the normal ``'%john%'`` query, because
    the database only needs to check the beginning of a column's data, rather
    than seeking through the entire column's data. Plus, if the column has an
    index on it, some databases may be able to use the index for this query,
    even though it's a ``LIKE`` query.

``=``
    Matches exactly, case-insensitive. For example, if
    ``search_fields`` is set to ``['=first_name', '=last_name']`` and
    a user searches for ``john lennon``, Django will do the equivalent
    of this SQL ``WHERE`` clause::

        WHERE (first_name ILIKE 'john' OR last_name ILIKE 'john')
        AND (first_name ILIKE 'lennon' OR last_name ILIKE 'lennon')

    Note that the query input is split by spaces, so, following this example,
    it's currently not possible to search for all records in which
    ``first_name`` is exactly ``'john winston'`` (containing a space).

``@``
    Performs a full-text match. This is like the default search method but uses
    an index. Currently this is only available for MySQL.

``ModelAdmin`` methods
----------------------

``save_model(self, request, obj, form, change)``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The ``save_model`` method is given the ``HttpRequest``, a model instance,
a ``ModelForm`` instance and a boolean value based on whether it is adding or
changing the object. Here you can do any pre- or post-save operations.

For example to attach ``request.user`` to the object prior to saving::

    class ArticleAdmin(admin.ModelAdmin):
        def save_model(self, request, obj, form, change):
            obj.user = request.user
            obj.save()

``save_formset(self, request, form, formset, change)``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The ``save_formset`` method is given the ``HttpRequest``, the parent
``ModelForm`` instance and a boolean value based on whether it is adding or
changing the parent object.

For example to attach ``request.user`` to each changed formset
model instance::

    class ArticleAdmin(admin.ModelAdmin):
        def save_formset(self, request, form, formset, change):
            instances = formset.save(commit=False)
            for instance in instances:
                instance.user = request.user
                instance.save()
            formset.save_m2m()

``ModelAdmin`` media definitions
--------------------------------

There are times where you would like add a bit of CSS and/or JavaScript to
the add/change views. This can be accomplished by using a Media inner class
on your ``ModelAdmin``::

    class ArticleAdmin(admin.ModelAdmin):
        class Media:
            css = {
                "all": ("my_styles.css",)
            }
            js = ("my_code.js",)

Keep in mind that this will be prepended with ``MEDIA_URL``. The same rules
apply as :ref:`regular media definitions on forms <topics-forms-media>`.

Adding custom validation to the admin
-------------------------------------

Adding custom validation of data in the admin is quite easy. The automatic admin
interfaces reuses :mod:`django.forms`, and the ``ModelAdmin`` class gives you
the ability define your own form::

    class ArticleAdmin(admin.ModelAdmin):
        form = MyArticleAdminForm

``MyArticleAdminForm`` can be defined anywhere as long as you import where
needed. Now within your form you can add your own custom validation for
any field::
    
    class MyArticleAdminForm(forms.ModelForm):
        class Meta:
            model = Article
        
        def clean_name(self):
            # do something that validates your data
            return self.cleaned_data["name"]

It is important you use a ``ModelForm`` here otherwise things can break. See the
:ref:`forms <ref-forms-index>` documentation on :ref:`custom validation
<ref-forms-validation>` for more information.

.. _admin-inlines:

``InlineModelAdmin`` objects
============================

The admin interface has the ability to edit models on the same page as a
parent model. These are called inlines. You can add them to a model by
specifying them in a ``ModelAdmin.inlines`` attribute::

    class BookInline(admin.TabularInline):
        model = Book

    class AuthorAdmin(admin.ModelAdmin):
        inlines = [
            BookInline,
        ]

Django provides two subclasses of ``InlineModelAdmin`` and they are:

    * ``TabularInline``
    * ``StackedInline``

The difference between these two is merely the template used to render them.

``InlineModelAdmin`` options
-----------------------------

The ``InlineModelAdmin`` class is a subclass of ``ModelAdmin`` so it inherits
all the same functionality as well as some of its own:

``model``
~~~~~~~~~

The model in which the inline is using. This is required.

``fk_name``
~~~~~~~~~~~

The name of the foreign key on the model. In most cases this will be dealt
with automatically, but ``fk_name`` must be specified explicitly if there are
more than one foreign key to the same parent model.

``formset``
~~~~~~~~~~~

This defaults to ``BaseInlineFormSet``. Using your own formset can give you
many possibilities of customization. Inlines are built around
:ref:`model formsets <model-formsets>`.

``form``
~~~~~~~~

The value for ``form`` is inherited from ``ModelAdmin``. This is what is
passed through to ``formset_factory`` when creating the formset for this
inline.

``extra``
~~~~~~~~~

This controls the number of extra forms the formset will display in addition
to the initial forms. See the
:ref:`formsets documentation <topics-forms-formsets>` for more information.

``max_num``
~~~~~~~~~~~

This controls the maximum number of forms to show in the inline. This doesn't
directly correlate to the number of objects, but can if the value is small
enough. See :ref:`model-formsets-max-num` for more information.

``raw_id_fields``
~~~~~~~~~~~~~~~~~

By default, Django's admin uses a select-box interface (<select>) for
fields that are ``ForeignKey``. Sometimes you don't want to incur the
overhead of having to select all the related instances to display in the
drop-down.

``raw_id_fields`` is a list of fields you would like to change
into a ``Input`` widget for either a ``ForeignKey`` or ``ManyToManyField``::

    class BookInline(admin.TabularInline):
        model = Book
        raw_id_fields = ("pages",)

``template``
~~~~~~~~~~~~

The template used to render the inline on the page.

``verbose_name``
~~~~~~~~~~~~~~~~

An override to the ``verbose_name`` found in the model's inner ``Meta`` class.

``verbose_name_plural``
~~~~~~~~~~~~~~~~~~~~~~~

An override to the ``verbose_name_plural`` found in the model's inner ``Meta``
class.

Working with a model with two or more foreign keys to the same parent model
---------------------------------------------------------------------------

It is sometimes possible to have more than one foreign key to the same model.
Take this model for instance::

    class Friendship(models.Model):
        to_person = models.ForeignKey(Person, related_name="friends")
        from_person = models.ForeignKey(Person, related_name="from_friends")

If you wanted to display an inline on the ``Person`` admin add/change pages
you need to explicitly define the foreign key since it is unable to do so
automatically::

    class FriendshipInline(admin.TabularInline):
        model = Friendship
        fk_name = "to_person"

    class PersonAdmin(admin.ModelAdmin):
        inlines = [
            FriendshipInline,
        ]

Working with Many-to-Many Intermediary Models
----------------------------------------------

By default, admin widgets for many-to-many relations will be displayed inline
on whichever model contains the actual reference to the ``ManyToManyField``.
However, when you specify an intermediary model using the ``through``
argument to a ``ManyToManyField``, the admin will not display a widget by 
default. This is because each instance of that intermediary model requires
more information than could be displayed in a single widget, and the layout
required for multiple widgets will vary depending on the intermediate model.

However, we still want to be able to edit that information inline. Fortunately,
this is easy to do with inline admin models. Suppose we have the following
models::

    class Person(models.Model):
        name = models.CharField(max_length=128)
    
    class Group(models.Model):
        name = models.CharField(max_length=128)
        members = models.ManyToManyField(Person, through='Membership')

    class Membership(models.Model):
        person = models.ForeignKey(Person)
        group = models.ForeignKey(Group)
        date_joined = models.DateField()
        invite_reason = models.CharField(max_length=64)

The first step in displaying this intermediate model in the admin is to
define an inline class for the ``Membership`` model::

    class MembershipInline(admin.TabularInline):
        model = Membership
        extra = 1

This simple example uses the default ``InlineModelAdmin`` values for the
``Membership`` model, and limits the extra add forms to one. This could be
customized using any of the options available to ``InlineModelAdmin`` classes.

Now create admin views for the ``Person`` and ``Group`` models::

    class PersonAdmin(admin.ModelAdmin):
        inlines = (MembershipInline,)

    class GroupAdmin(admin.ModelAdmin):
        inlines = (MembershipInline,)

Finally, register your ``Person`` and ``Group`` models with the admin site::
    
    admin.site.register(Person, PersonAdmin)
    admin.site.register(Group, GroupAdmin)

Now your admin site is set up to edit ``Membership`` objects inline from
either the ``Person`` or the ``Group`` detail pages.

Using generic relations as an inline
------------------------------------

It is possible to use an inline with generically related objects. Let's say
you have the following models::

    class Image(models.Model):
        image = models.ImageField(upload_to="images")
        content_type = models.ForeignKey(ContentType)
        object_id = models.PositiveIntegerField()
        content_object = generic.GenericForeignKey("content_type", "object_id")
    
    class Product(models.Model):
        name = models.CharField(max_length=100)

If you want to allow editing and creating ``Image`` instance on the ``Product``
add/change views you can simply use ``GenericInlineModelAdmin`` provided by
``django.contrib.contenttypes.generic``. In your ``admin.py`` for this
example app::

    from django.contrib import admin
    from django.contrib.contenttypes import generic
    
    from myproject.myapp.models import Image, Product
    
    class ImageInline(generic.GenericTabularInline):
        model = Image
    
    class ProductAdmin(admin.ModelAdmin):
        inlines = [
            ImageInline,
        ]
    
    admin.site.register(Product, ProductAdmin)

``django.contrib.contenttypes.generic`` provides both a ``GenericTabularInline``
and ``GenericStackedInline`` and behave just like any other inline. See the
:ref:`contenttypes documentation <ref-contrib-contenttypes>` for more specific
information.

Overriding Admin Templates
==========================

It is relatively easy to override many of the templates which the admin module
uses to generate the various pages of an admin site. You can even override a few
of these templates for a specific app, or a specific model.

Set up your projects admin template directories
-----------------------------------------------

The admin template files are located in the ``contrib/admin/templates/admin``
directory.

In order to override one or more of them, first create an ``admin`` directory in
your project's ``templates`` directory. This can be any of the directories you
specified in ``TEMPLATE_DIRS``.

Within this ``admin`` directory, create sub-directories named after your app.
Within these app subdirectories create sub-directories named after your models.
Note, that the admin app will lowercase the model name when looking for the
directory, so make sure you name the directory in all lowercase if you are going
to run your app on a case-sensitive filesystem.

To override an admin template for a specific app, copy and edit the template
from the ``django/contrib/admin/templates/admin`` directory, and save it to one
of the directories you just created.

For example, if we wanted to add a tool to the change list view for all the
models in an app named ``my_app``, we would copy
``contrib/admin/templates/admin/change_list.html`` to the
``templates/admin/my_app/`` directory of our project, and make any necessary
changes.

If we wanted to add a tool to the change list view for only a specific model
named 'Page', we would copy that same file to the
``templates/admin/my_app/page`` directory of our project.

Overriding vs. replacing an admin template
------------------------------------------

Because of the modular design of the admin templates, it is usually neither
necessary nor advisable to replace an entire template. It is almost always
better to override only the section of the template which you need to change.

To continue the example above, we want to add a new link next to the ``History``
tool for the ``Page`` model. After looking at ``change_form.html`` we determine
that we only need to override the ``object-tools`` block. Therefore here is our
new ``change_form.html`` :

.. code-block:: html+django

    {% extends "admin/change_form.html" %}
    {% load i18n %}
    {% block object-tools %}
    {% if change %}{% if not is_popup %}
      <ul class="object-tools">
        <li><a href="history/" class="historylink">{% trans "History" %}</a></li>
        <li><a href="mylink/" class="historylink">My Link</a></li>
        {% if has_absolute_url %}
            <li><a href="../../../r/{{ content_type_id }}/{{ object_id }}/" class="viewsitelink">
                {% trans "View on site" %}</a>
            </li>
        {% endif%}
      </ul>
    {% endif %}{% endif %}
    {% endblock %}

And that's it! If we placed this file in the ``templates/admin/my_app``
directory, our link would appear on every model's change form.

Templates which may be overridden per app or model
--------------------------------------------------

Not every template in ``contrib\admin\templates\admin`` may be overridden per
app or per model. The following can:

    * ``change_form.html``
    * ``change_list.html``
    * ``delete_confirmation.html``
    * ``object_history.html``

For those templates that cannot be overridden in this way, you may still
override them for your entire project. Just place the new version in your
``templates/admin`` directory. This is particularly useful to create custom 404
and 500 pages.

.. note::

    Some of the admin templates, such as ``change_list_request.html`` are used
    to render custom inclusion tags. These may be overridden, but in such cases
    you are probably better off creating your own version of the tag in question
    and giving it a different name. That way you can use it selectively.

Root and login templates
------------------------

If you wish to change the index or login templates, you are better off creating
your own ``AdminSite`` instance (see below), and changing the ``index_template``
or ``login_template`` properties.

``AdminSite`` objects
=====================

A Django administrative site is represented by an instance of
``django.contrib.admin.sites.AdminSite``; by default, an instance of
this class is created as ``django.contrib.admin.site`` and you can
register your models and ``ModelAdmin`` instances with it.

If you'd like to set up your own administrative site with custom
behavior, however, you're free to subclass ``AdminSite`` and override
or add anything you like. Then, simply create an instance of your
``AdminSite`` subclass (the same way you'd instantiate any other
Python class), and register your models and ``ModelAdmin`` subclasses
with it instead of using the default.


Hooking ``AdminSite`` instances into your URLconf
-------------------------------------------------

The last step in setting up the Django admin is to hook your ``AdminSite``
instance into your URLconf. Do this by pointing a given URL at the
``AdminSite.root`` method.

In this example, we register the default ``AdminSite`` instance
``django.contrib.admin.site`` at the URL ``/admin/`` ::

    # urls.py
    from django.conf.urls.defaults import *
    from django.contrib import admin

    admin.autodiscover()

    urlpatterns = patterns('',
        ('^admin/(.*)', admin.site.root),
    )

Above we used ``admin.autodiscover()`` to automatically load the
``INSTALLED_APPS`` admin.py modules.

In this example, we register the ``AdminSite`` instance
``myproject.admin.admin_site`` at the URL ``/myadmin/`` ::

    # urls.py
    from django.conf.urls.defaults import *
    from myproject.admin import admin_site

    urlpatterns = patterns('',
        ('^myadmin/(.*)', admin_site.root),
    )

There is really no need to use autodiscover when using your own ``AdminSite``
instance since you will likely be importing all the per-app admin.py modules
in your ``myproject.admin`` module.

Note that the regular expression in the URLpattern *must* group everything in
the URL that comes after the URL root -- hence the ``(.*)`` in these examples.

Multiple admin sites in the same URLconf
----------------------------------------

It's easy to create multiple instances of the admin site on the same
Django-powered Web site. Just create multiple instances of ``AdminSite`` and
root each one at a different URL.

In this example, the URLs ``/basic-admin/`` and ``/advanced-admin/`` feature
separate versions of the admin site -- using the ``AdminSite`` instances
``myproject.admin.basic_site`` and ``myproject.admin.advanced_site``,
respectively::

    # urls.py
    from django.conf.urls.defaults import *
    from myproject.admin import basic_site, advanced_site

    urlpatterns = patterns('',
        ('^basic-admin/(.*)', basic_site.root),
        ('^advanced-admin/(.*)', advanced_site.root),
    )