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Django Exceptions

An exception is an abnormal event that leads to program failure. To deal with this situation, Django uses its own exception classes and supports all core Python exceptions as well.

Django core exceptions classes are defined in django.core.exceptions module. This module contains the following classes.

Django Exception Classes

Exception Description
AppRegistryNotReady It is raised when attempting to use models before the app loading process.
ObjectDoesNotExist The base class for DoesNotExist exceptions.
EmptyResultSet If a query does not return any result, this exception is raised.
FieldDoesNotExist It raises when the requested field does not exist.
MultipleObjectsReturned This exception is raised by a query if only one object is expected, but multiple objects are returned.
SuspiciousOperation This exception is raised when a user has performed an operation that should be considered suspicious from a security perspective.
PermissionDenied It is raised when a user does not have permission to perform the action requested.
ViewDoesNotExist It is raised by django.urls when a requested view does not exist.
MiddlewareNotUsed It is raised when a middleware is not used in the server configuration.
ImproperlyConfigured The ImproperlyConfigured exception is raised when Django is somehow improperly configured.
FieldError It is raised when there is a problem with a model field.
ValidationError It is raised when data validation fails form or model field validation.

Django URL Resolver Exceptions

These exceptions are defined in django.urls module.

Exception Description
Resolver404 This exception raised when the path passed to resolve() function does not map to a view.
NoReverseMatch It is raised when a matching URL in your URLconf cannot be identified based on the parameters supplied.

Django Database Exceptions

The following exceptions are defined in django.db module.

Exception Description
DatabaseError It occurs when the database is not available.
IntegrityError It occurs when an insertion query executes.
DataError It raises when data related issues come into the database.

Django Http Exceptions

The following exceptions are defined in django.http module.

Exception Description
UnreadablePostError It is raised when a user cancels an upload.

Django Transaction Exceptions

The transaction exceptions are defined in django.db.transaction.

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

Django Exception Example

Suppose, we want to get employee record where id = 12, our view function will look below. It raises a DoesNotExist exception if data not found. This is Django's built-in exception.

// views.py

// urls.py

It shows the following exception because no record is available at id 12.

Output:

Django Exception example

We can handle it by using try and except, now let's handle this exception.

// Views.py

Output:

Django Exception output
Next TopicDjango Session




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