64 lines
2.2 KiB
Plaintext
64 lines
2.2 KiB
Plaintext
=====================
|
|
Model class reference
|
|
=====================
|
|
|
|
.. currentmodule:: django.db.models
|
|
|
|
This document covers features of the :class:`~django.db.models.Model` class.
|
|
For more information about models, see :doc:`the complete list of Model
|
|
reference guides </ref/models/index>`.
|
|
|
|
Attributes
|
|
==========
|
|
|
|
``DoesNotExist``
|
|
----------------
|
|
|
|
.. exception:: Model.DoesNotExist
|
|
|
|
This exception is raised by the ORM when an expected object is not found.
|
|
For example, :meth:`.QuerySet.get` will raise it when no object is found
|
|
for the given lookups.
|
|
|
|
Django provides a ``DoesNotExist`` exception as an attribute of each model
|
|
class to identify the class of object that could not be found, allowing you
|
|
to catch exceptions for a particular model class. The exception is a
|
|
subclass of :exc:`django.core.exceptions.ObjectDoesNotExist`.
|
|
|
|
``MultipleObjectsReturned``
|
|
---------------------------
|
|
|
|
.. exception:: Model.MultipleObjectsReturned
|
|
|
|
This exception is raised by :meth:`.QuerySet.get` when multiple objects are
|
|
found for the given lookups.
|
|
|
|
Django provides a ``MultipleObjectsReturned`` exception as an attribute of
|
|
each model class to identify the class of object for which multiple objects
|
|
were found, allowing you to catch exceptions for a particular model class.
|
|
The exception is a subclass of
|
|
:exc:`django.core.exceptions.MultipleObjectsReturned`.
|
|
|
|
``objects``
|
|
-----------
|
|
|
|
.. attribute:: Model.objects
|
|
|
|
Each non-abstract :class:`~django.db.models.Model` class must have a
|
|
:class:`~django.db.models.Manager` instance added to it.
|
|
Django ensures that in your model class you have at least a
|
|
default ``Manager`` specified. If you don't add your own ``Manager``,
|
|
Django will add an attribute ``objects`` containing default
|
|
:class:`~django.db.models.Manager` instance. If you add your own
|
|
:class:`~django.db.models.Manager` instance attribute, the default one does
|
|
not appear. Consider the following example::
|
|
|
|
from django.db import models
|
|
|
|
class Person(models.Model):
|
|
# Add manager with another name
|
|
people = models.Manager()
|
|
|
|
For more details on model managers see :doc:`Managers </topics/db/managers>`
|
|
and :ref:`Retrieving objects <retrieving-objects>`.
|