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271 lines
8.1 KiB
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271 lines
8.1 KiB
Plaintext
=================
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Django Exceptions
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=================
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Django raises some of its own exceptions as well as standard Python exceptions.
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Django Core Exceptions
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======================
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.. module:: django.core.exceptions
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:synopsis: Django core exceptions
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Django core exception classes are defined in ``django.core.exceptions``.
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``ObjectDoesNotExist`` and ``DoesNotExist``
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-------------------------------------------
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.. exception:: DoesNotExist
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The ``DoesNotExist`` exception is raised when an object is not found for
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the given parameters of a query. Django provides a ``DoesNotExist``
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exception as an attribute of each model class to identify the class of
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object that could not be found and to allow you to catch a particular model
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class with ``try/except``.
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.. exception:: ObjectDoesNotExist
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The base class for ``DoesNotExist`` exceptions; a ``try/except`` for
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``ObjectDoesNotExist`` will catch ``DoesNotExist`` exceptions for all
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models.
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See :meth:`~django.db.models.query.QuerySet.get()` for further information
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on :exc:`ObjectDoesNotExist` and :exc:`DoesNotExist`.
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``FieldDoesNotExist``
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---------------------
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.. exception:: FieldDoesNotExist
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The ``FieldDoesNotExist`` exception is raised by a model's
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``_meta.get_field()`` method when the requested field does not exist on the
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model or on the model's parents.
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.. versionchanged:: 1.8
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This exception was previously defined only in
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``django.db.models.fields`` and wasn't part of the public API.
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``MultipleObjectsReturned``
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---------------------------
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.. exception:: MultipleObjectsReturned
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The :exc:`MultipleObjectsReturned` exception is raised by a query if only
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one object is expected, but multiple objects are returned. A base version
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of this exception is provided in :mod:`django.core.exceptions`; each model
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class contains a subclassed version that can be used to identify the
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specific object type that has returned multiple objects.
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See :meth:`~django.db.models.query.QuerySet.get()` for further information.
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``SuspiciousOperation``
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-----------------------
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.. exception:: SuspiciousOperation
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The :exc:`SuspiciousOperation` exception is raised when a user has
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performed an operation that should be considered suspicious from a security
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perspective, such as tampering with a session cookie. Subclasses of
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``SuspiciousOperation`` include:
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* ``DisallowedHost``
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* ``DisallowedModelAdminLookup``
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* ``DisallowedModelAdminToField``
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* ``DisallowedRedirect``
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* ``InvalidSessionKey``
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* ``SuspiciousFileOperation``
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* ``SuspiciousMultipartForm``
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* ``SuspiciousSession``
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If a ``SuspiciousOperation`` exception reaches the WSGI handler level it is
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logged at the ``Error`` level and results in
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a :class:`~django.http.HttpResponseBadRequest`. See the :doc:`logging
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documentation </topics/logging/>` for more information.
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``PermissionDenied``
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--------------------
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.. exception:: PermissionDenied
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The :exc:`PermissionDenied` exception is raised when a user does not have
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permission to perform the action requested.
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``ViewDoesNotExist``
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--------------------
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.. exception:: ViewDoesNotExist
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The :exc:`ViewDoesNotExist` exception is raised by
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:mod:`django.core.urlresolvers` when a requested view does not exist.
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``MiddlewareNotUsed``
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---------------------
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.. exception:: MiddlewareNotUsed
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The :exc:`MiddlewareNotUsed` exception is raised when a middleware is not
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used in the server configuration.
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``ImproperlyConfigured``
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------------------------
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.. exception:: ImproperlyConfigured
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The :exc:`ImproperlyConfigured` exception is raised when Django is
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somehow improperly configured -- for example, if a value in ``settings.py``
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is incorrect or unparseable.
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``FieldError``
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--------------
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.. exception:: FieldError
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The :exc:`FieldError` exception is raised when there is a problem with a
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model field. This can happen for several reasons:
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- A field in a model clashes with a field of the same name from an
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abstract base class
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- An infinite loop is caused by ordering
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- A keyword cannot be parsed from the filter parameters
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- A field cannot be determined from a keyword in the query
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parameters
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- A join is not permitted on the specified field
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- A field name is invalid
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- A query contains invalid order_by arguments
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``ValidationError``
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-------------------
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.. exception:: ValidationError
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The :exc:`ValidationError` exception is raised when data fails form or
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model field validation. For more information about validation, see
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:doc:`Form and Field Validation </ref/forms/validation>`,
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:ref:`Model Field Validation <validating-objects>` and the
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:doc:`Validator Reference </ref/validators>`.
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``NON_FIELD_ERRORS``
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~~~~~~~~~~~~~~~~~~~~
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.. data:: NON_FIELD_ERRORS
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``ValidationError``\s that don't belong to a particular field in a form
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or model are classified as ``NON_FIELD_ERRORS``. This constant is used
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as a key in dictionaries that otherwise map fields to their respective
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list of errors.
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.. currentmodule:: django.core.urlresolvers
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URL Resolver exceptions
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=======================
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URL Resolver exceptions are defined in ``django.core.urlresolvers``.
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``Resolver404``
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---------------
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.. exception:: Resolver404
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The :exc:`Resolver404` exception is raised by
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:func:`django.core.urlresolvers.resolve()` if the path passed to
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``resolve()`` doesn't map to a view. It's a subclass of
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:class:`django.http.Http404`.
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``NoReverseMatch``
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------------------
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.. exception:: NoReverseMatch
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The :exc:`NoReverseMatch` exception is raised by
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:mod:`django.core.urlresolvers` when a matching URL in your URLconf
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cannot be identified based on the parameters supplied.
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.. currentmodule:: django.db
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Database Exceptions
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===================
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Database exceptions may be imported from ``django.db``.
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Django wraps the standard database exceptions so that your Django code has a
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guaranteed common implementation of these classes.
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.. exception:: Error
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.. exception:: InterfaceError
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.. exception:: DatabaseError
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.. exception:: DataError
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.. exception:: OperationalError
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.. exception:: IntegrityError
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.. exception:: InternalError
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.. exception:: ProgrammingError
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.. exception:: NotSupportedError
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The Django wrappers for database exceptions behave exactly the same as
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the underlying database exceptions. See :pep:`249`, the Python Database API
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Specification v2.0, for further information.
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As per :pep:`3134`, a ``__cause__`` attribute is set with the original
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(underlying) database exception, allowing access to any additional
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information provided. (Note that this attribute is available under
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both Python 2 and Python 3, although :pep:`3134` normally only applies
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to Python 3.)
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.. exception:: models.ProtectedError
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Raised to prevent deletion of referenced objects when using
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:attr:`django.db.models.PROTECT`. :exc:`models.ProtectedError` is a subclass
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of :exc:`IntegrityError`.
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.. currentmodule:: django.http
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Http Exceptions
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===============
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Http exceptions may be imported from ``django.http``.
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``UnreadablePostError``
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-----------------------
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.. exception:: UnreadablePostError
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:exc:`UnreadablePostError` is raised when a user cancels an upload.
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Transaction Exceptions
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======================
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.. currentmodule:: django.db.transaction
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Transaction exceptions are defined in ``django.db.transaction``.
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``TransactionManagementError``
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------------------------------
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.. exception:: TransactionManagementError
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:exc:`TransactionManagementError` is raised for any and all problems
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related to database transactions.
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.. currentmodule:: django.test
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Testing Framework Exceptions
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============================
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Exceptions provided by the ``django.test`` package.
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``RedirectCycleError``
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----------------------
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.. exception:: client.RedirectCycleError
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.. versionadded:: 1.8
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:exc:`~client.RedirectCycleError` is raised when the test client detects a
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loop or an overly long chain of redirects.
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Python Exceptions
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=================
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Django raises built-in Python exceptions when appropriate as well. See the
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Python documentation for further information on the :ref:`bltin-exceptions`.
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