Django2.0手册:Django Exceptions

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¶

exception AppRegistryNotReady[source]

This exception is raised when attempting to use models before the app
loading process
, which initializes the ORM, is
complete.

ObjectDoesNotExist¶

exception ObjectDoesNotExist[source]

The base class for DoesNotExist exceptions;
a try/except for ObjectDoesNotExist will catch
DoesNotExist exceptions for all models.

See get() for further information
on ObjectDoesNotExist and DoesNotExist.

EmptyResultSet¶

exception EmptyResultSet[source]

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.

Changed in Django 1.11:

In older versions, it’s only importable from django.db.models.sql.

FieldDoesNotExist¶

exception FieldDoesNotExist[source]

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¶

exception MultipleObjectsReturned[source]

The 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 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 get() for further information.

SuspiciousOperation¶

exception SuspiciousOperation[source]

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

If a SuspiciousOperation exception reaches the WSGI handler level it is
logged at the Error level and results in
a HttpResponseBadRequest. See the logging
documentation
for more information.

PermissionDenied¶

exception PermissionDenied[source]

The PermissionDenied exception is raised when a user does not have
permission to perform the action requested.

ViewDoesNotExist¶

exception ViewDoesNotExist[source]

The ViewDoesNotExist exception is raised by
django.urls when a requested view does not exist.

MiddlewareNotUsed¶

exception MiddlewareNotUsed[source]

The MiddlewareNotUsed exception is raised when a middleware is not
used in the server configuration.

ImproperlyConfigured¶

exception ImproperlyConfigured[source]

The 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[source]

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¶

exception ValidationError[source]

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

NON_FIELD_ERRORS

ValidationErrors 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.

URL Resolver exceptions¶

URL Resolver exceptions are defined in django.urls.

Resolver404¶

exception Resolver404[source]

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¶

exception NoReverseMatch[source]

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¶

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.

exception Error[source]
exception InterfaceError[source]
exception DatabaseError[source]
exception DataError[source]
exception OperationalError[source]
exception IntegrityError[source]
exception InternalError[source]
exception ProgrammingError[source]
exception NotSupportedError[source]

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.

exception models.ProtectedError

Raised to prevent deletion of referenced objects when using
django.db.models.PROTECT. models.ProtectedError is a subclass
of IntegrityError.

Http Exceptions¶

Http exceptions may be imported from django.http.

UnreadablePostError¶

exception UnreadablePostError[source]

UnreadablePostError is raised when a user cancels an upload.

Transaction Exceptions¶

Transaction exceptions are defined in django.db.transaction.

TransactionManagementError¶

exception TransactionManagementError[source]

TransactionManagementError is raised for any and all problems
related to database transactions.

Testing Framework Exceptions¶

Exceptions provided by the django.test package.

RedirectCycleError¶

exception client.RedirectCycleError

RedirectCycleError is raised when the test client detects a
loop or an overly long chain of redirects.

Python Exceptions¶

Django raises built-in Python exceptions when appropriate as well. See the
Python documentation for further information on the Built-in Exceptions.