django/docs/ref/exceptions.txt

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=================
Django Exceptions
=================
Django raises some Django specific exceptions as well as many standard
Python exceptions.
Django-specific Exceptions
==========================
.. module:: django.core.exceptions
:synopsis: Django specific exceptions
ObjectDoesNotExist and DoesNotExist
-----------------------------------
.. exception:: DoesNotExist
.. exception:: ObjectDoesNotExist
The :exc:`DoesNotExist` exception is raised when an object is not found
for the given parameters of a query.
:exc:`ObjectDoesNotExist` is defined in :mod:`django.core.exceptions`.
:exc:`DoesNotExist` is a subclass of the base :exc:`ObjectDoesNotExist`
exception that is provided on every model class as a way of
identifying the specific type of object that could not be found.
See :meth:`~django.db.models.QuerySet.get()` for further information
on :exc:`ObjectDoesNotExist` and :exc:`DoesNotExist`.
MultipleObjectsReturned
-----------------------
.. exception:: MultipleObjectsReturned
The :exc:`MultipleObjectsReturned` exception is raised by a query if only
one object is expected, but multiple objects are returned. A base version
of this exception is provided in :mod:`django.core.exceptions`; each model
class contains a subclassed version that can be used to identify the
specific object type that has returned multiple objects.
See :meth:`~django.db.models.QuerySet.get()` for further information.
SuspiciousOperation
-------------------
.. exception:: SuspiciousOperation
The :exc:`SuspiciousOperation` exception is raised when a user has performed
an operation that should be considered suspicious from a security perspective,
such as tampering with a session cookie.
PermissionDenied
----------------
.. exception:: PermissionDenied
The :exc:`PermissionDenied` exception is raised when a user does not have
permission to perform the action requested.
ViewDoesNotExist
----------------
.. exception:: ViewDoesNotExist
The :exc:`ViewDoesNotExist` exception is raised by
:mod:`django.core.urlresolvers` when a requested view does not exist.
MiddlewareNotUsed
-----------------
.. exception:: MiddlewareNotUsed
The :exc:`MiddlewareNotUsed` exception is raised when a middleware is not
used in the server configuration.
ImproperlyConfigured
--------------------
.. exception:: ImproperlyConfigured
The :exc:`ImproperlyConfigured` exception is raised when Django is
somehow improperly configured -- for example, if a value in ``settings.py``
is incorrect or unparseable.
FieldError
----------
.. exception:: FieldError
The :exc:`FieldError` exception is raised when there is a problem with a
model field. This can happen for several reasons:
- A field in a model clashes with a field of the same name from an
abstract base class
- An infinite loop is caused by ordering
- A keyword cannot be parsed from the filter parameters
- A field cannot be determined from a keyword in the query
parameters
- A join is not permitted on the specified field
- A field name is invalid
- A query contains invalid order_by arguments
ValidationError
---------------
.. exception:: ValidationError
The :exc:`ValidationError` exception is raised when data fails form or
model field validation. For more information about validation, see
:doc:`Form and Field Validation </ref/forms/validation>`,
:ref:`Model Field Validation <validating-objects>` and the
:doc:`Validator Reference </ref/validators>`.
.. currentmodule:: django.core.urlresolvers
NoReverseMatch
--------------
.. exception:: NoReverseMatch
The :exc:`NoReverseMatch` exception is raised by
:mod:`django.core.urlresolvers` when a matching URL in your URLconf
cannot be identified based on the parameters supplied.
.. currentmodule:: django.db
Database Exceptions
===================
Django wraps the standard database exceptions :exc:`DatabaseError` and
:exc:`IntegrityError` so that your Django code has a guaranteed common
implementation of these classes. These database exceptions are
provided in :mod:`django.db`.
.. exception:: DatabaseError
.. exception:: IntegrityError
The Django wrappers for database exceptions behave exactly the same as
the underlying database exceptions. See `PEP 249 - Python Database API
Specification v2.0`_ for further information.
.. _`PEP 249 - Python Database API Specification v2.0`: http://www.python.org/dev/peps/pep-0249/
Python Exceptions
=================
Django raises built-in Python exceptions when appropriate as well. See
the Python `documentation`_ for further information on the built-in
exceptions.
.. _`documentation`: http://docs.python.org/lib/module-exceptions.html