django/docs/ref/models/options.txt

.. _ref-models-options:

======================
Model ``Meta`` options
======================

This document explains all the possible :ref:`metadata options <meta-options>`  that you can give your model in its internal
``class Meta``.

Available ``Meta`` options
==========================

.. currentmodule:: django.db.models

``abstract``
------------

.. attribute:: Options.abstract

If ``True``, this model will be an :ref:`abstract base class <abstract-base-classes>`.

``db_table``
------------

.. attribute:: Options.db_table

The name of the database table to use for the model::

    db_table = 'music_album'

.. _table-names:

Table names
~~~~~~~~~~~

To save you time, Django automatically derives the name of the database table
from the name of your model class and the app that contains it. A model's
database table name is constructed by joining the model's "app label" -- the
name you used in ``manage.py startapp`` -- to the model's class name, with an
underscore between them.

For example, if you have an app ``bookstore`` (as created by
``manage.py startapp bookstore``), a model defined as ``class Book`` will have
a database table named ``bookstore_book``.

To override the database table name, use the ``db_table`` parameter in
``class Meta``.

If your database table name is an SQL reserved word, or contains characters that
aren't allowed in Python variable names -- notably, the hyphen -- that's OK.
Django quotes column and table names behind the scenes.

``db_tablespace``
-----------------

.. attribute:: Options.db_tablespace

.. versionadded:: 1.0

The name of the database tablespace to use for the model. If the backend doesn't
support tablespaces, this option is ignored.

``get_latest_by``
-----------------

.. attribute:: Options.get_latest_by

The name of a :class:`DateField` or :class:`DateTimeField` in the model. This
specifies the default field to use in your model :class:`Manager`'s
:class:`~QuerySet.latest` method.

Example::

    get_latest_by = "order_date"

See the docs for :meth:`~django.db.models.QuerySet.latest` for more.

``managed``
-----------------------

.. attribute:: Options.managed

.. versionadded:: 1.1

If ``False``, no database table creation or deletion operations will be
performed for this model. This is useful if the model represents an existing
table or a database view that has been created by some other means.

The default value is ``True``, meaning Django will create the appropriate
database tables in :ref:`django-admin-syncdb` and remove them as part of a
:ref:`reset <django-admin-reset>` management command.

If a model contains a :class:`~django.db.models.ManyToManyField` and has
``managed=False``, the intermediate table for the many-to-many join will also
not be created. Should you require the intermediate table to be created, set
it up as an explicit model and use the :attr:`ManyToManyField.through`
attribute.

For tests involving models with ``managed=False``, it's up to you to ensure
the correct tables are created as part of the test setup.

If you're interested in changing the Python-level behaviour of a model class,
you *could* use ``managed=True`` and create a copy of an existing model.
However, there's a better approach for that situation: :ref:`proxy-models`.

``order_with_respect_to``
-------------------------

.. attribute:: Options.order_with_respect_to

Marks this object as "orderable" with respect to the given field. This is almost
always used with related objects to allow them to be ordered with respect to a
parent object. For example, if an ``Answer`` relates to a ``Question`` object,
and a question has more than one answer, and the order of answers matters, you'd
do this::

    class Answer(models.Model):
        question = models.ForeignKey(Question)
        # ...

        class Meta:
            order_with_respect_to = 'question'

``ordering``
------------

.. attribute:: Options.ordering

The default ordering for the object, for use when obtaining lists of objects::

    ordering = ['-order_date']

This is a tuple or list of strings. Each string is a field name with an optional
"-" prefix, which indicates descending order. Fields without a leading "-" will
be ordered ascending. Use the string "?" to order randomly.

.. note:: 

    Regardless of how many fields are in :attr:`~Options.ordering`, the admin
    site uses only the first field.

For example, to order by a ``pub_date`` field ascending, use this::

    ordering = ['pub_date']

To order by ``pub_date`` descending, use this::

    ordering = ['-pub_date']

To order by ``pub_date`` descending, then by ``author`` ascending, use this::

    ordering = ['-pub_date', 'author']

``permissions``
---------------

.. attribute:: Options.permissions

Extra permissions to enter into the permissions table when creating this object.
Add, delete and change permissions are automatically created for each object
that has ``admin`` set. This example specifies an extra permission,
``can_deliver_pizzas``::

    permissions = (("can_deliver_pizzas", "Can deliver pizzas"),)

This is a list or tuple of 2-tuples in the format ``(permission_code,
human_readable_permission_name)``.

``proxy``
---------

.. attribute:: Options.proxy

.. versionadded: 1.1

If set to ``True``, a model which subclasses another model will be treated as
a :ref:`proxy model <proxy-models>`.

``unique_together``
-------------------

.. attribute:: Options.unique_together

Sets of field names that, taken together, must be unique::

    unique_together = (("driver", "restaurant"),)

This is a list of lists of fields that must be unique when considered together.
It's used in the Django admin and is enforced at the database level (i.e., the
appropriate ``UNIQUE`` statements are included in the ``CREATE TABLE``
statement).

.. versionadded:: 1.0

For convenience, unique_together can be a single list when dealing with a single
set of fields::

    unique_together = ("driver", "restaurant")

``verbose_name``
----------------

.. attribute:: Options.verbose_name

A human-readable name for the object, singular::

    verbose_name = "pizza"

If this isn't given, Django will use a munged version of the class name:
``CamelCase`` becomes ``camel case``.

``verbose_name_plural``
-----------------------

.. attribute:: Options.verbose_name_plural

The plural name for the object::

    verbose_name_plural = "stories"

If this isn't given, Django will use :attr:`~Options.verbose_name` + ``"s"``.