Django raises some of its own exceptions as well as standard Python exceptions.
Django Core Exceptions¶Django core exception classes are defined in django.core.exceptions
.
AppRegistryNotReady
¶
This exception is raised when attempting to use models before the app loading process, which initializes the ORM, is complete.
ObjectDoesNotExist
¶
The base class for Model.DoesNotExist
exceptions. A try/except
for ObjectDoesNotExist
will catch DoesNotExist
exceptions for all models.
See get()
.
ObjectNotUpdated
¶
New in Django Development version.
The base class for Model.NotUpdated
exceptions. A try/except
for ObjectNotUpdated
will catch NotUpdated
exceptions for all models.
See save()
.
EmptyResultSet
¶
EmptyResultSet
may be raised during query generation if a query won’t return any results. Most Django projects won’t encounter this exception, but it might be useful for implementing custom lookups and expressions.
FullResultSet
¶
FullResultSet
may be raised during query generation if a query will match everything. Most Django projects won’t encounter this exception, but it might be useful for implementing custom lookups and expressions.
FieldDoesNotExist
¶
The FieldDoesNotExist
exception is raised by a model’s _meta.get_field()
method when the requested field does not exist on the model or on the model’s parents.
MultipleObjectsReturned
¶
The base class for Model.MultipleObjectsReturned
exceptions. A try/except
for MultipleObjectsReturned
will catch MultipleObjectsReturned
exceptions for all models.
See get()
.
SuspiciousOperation
¶
The 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. Subclasses of SuspiciousOperation
include:
DisallowedHost
DisallowedModelAdminLookup
DisallowedModelAdminToField
DisallowedRedirect
InvalidSessionKey
RequestDataTooBig
SuspiciousFileOperation
SuspiciousMultipartForm
SuspiciousSession
TooManyFieldsSent
TooManyFilesSent
If a SuspiciousOperation
exception reaches the ASGI/WSGI handler level it is logged at the Error
level and results in a HttpResponseBadRequest
. See the logging documentation for more information.
PermissionDenied
¶
The PermissionDenied
exception is raised when a user does not have permission to perform the action requested.
ViewDoesNotExist
¶
The ViewDoesNotExist
exception is raised by django.urls
when a requested view does not exist.
MiddlewareNotUsed
¶
The MiddlewareNotUsed
exception is raised when a middleware is not used in the server configuration.
ImproperlyConfigured
¶
The ImproperlyConfigured
exception is raised when Django is somehow improperly configured – for example, if a value in settings.py
is incorrect or unparseable.
FieldError
¶
The 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
¶
The ValidationError
exception is raised when data fails form or model field validation. For more information about validation, see Form and Field Validation, Model Field Validation and the Validator Reference.
NON_FIELD_ERRORS
¶
ValidationError
s that don’t belong to a particular field in a form or model are classified as NON_FIELD_ERRORS
. This constant is used as a key in dictionaries that otherwise map fields to their respective list of errors.
BadRequest
¶
The BadRequest
exception is raised when the request cannot be processed due to a client error. If a BadRequest
exception reaches the ASGI/WSGI handler level it results in a HttpResponseBadRequest
.
RequestAborted
¶
The RequestAborted
exception is raised when an HTTP body being read in by the handler is cut off midstream and the client connection closes, or when the client does not send data and hits a timeout where the server closes the connection.
It is internal to the HTTP handler modules and you are unlikely to see it elsewhere. If you are modifying HTTP handling code, you should raise this when you encounter an aborted request to make sure the socket is closed cleanly.
SynchronousOnlyOperation
¶
The SynchronousOnlyOperation
exception is raised when code that is only allowed in synchronous Python code is called from an asynchronous context (a thread with a running asynchronous event loop). These parts of Django are generally heavily reliant on thread-safety to function and don’t work correctly under coroutines sharing the same thread.
If you are trying to call code that is synchronous-only from an asynchronous thread, then create a synchronous thread and call it in that. You can accomplish this is with asgiref.sync.sync_to_async()
.
URL Resolver exceptions are defined in django.urls
.
Resolver404
¶
The Resolver404
exception is raised by resolve()
if the path passed to resolve()
doesn’t map to a view. It’s a subclass of django.http.Http404
.
NoReverseMatch
¶
The NoReverseMatch
exception is raised by django.urls
when a matching URL in your URLconf cannot be identified based on the parameters supplied.
Database exceptions may be imported from django.db
.
Django wraps the standard database exceptions so that your Django code has a guaranteed common implementation of these classes.
The Django wrappers for database exceptions behave exactly the same as the underlying database exceptions. See PEP 249, the Python Database API Specification v2.0, for further information.
As per PEP 3134, a __cause__
attribute is set with the original (underlying) database exception, allowing access to any additional information provided.
Raised to prevent deletion of referenced objects when using django.db.models.PROTECT
. models.ProtectedError
is a subclass of IntegrityError
.
Raised to prevent deletion of referenced objects when using django.db.models.RESTRICT
. models.RestrictedError
is a subclass of IntegrityError
.
HTTP exceptions may be imported from django.http
.
UnreadablePostError
¶
UnreadablePostError
is raised when a user cancels an upload.
Sessions exceptions are defined in django.contrib.sessions.exceptions
.
SessionInterrupted
¶
SessionInterrupted
is raised when a session is destroyed in a concurrent request. It’s a subclass of BadRequest
.
Transaction exceptions are defined in django.db.transaction
.
TransactionManagementError
¶
TransactionManagementError
is raised for any and all problems related to database transactions.
Exceptions provided by the django.test
package.
RedirectCycleError
¶
RedirectCycleError
is raised when the test client detects a loop or an overly long chain of redirects.
Django raises built-in Python exceptions when appropriate as well. See the Python documentation for further information on the Built-in Exceptions.
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