# Django 4.1.8.dev20230308103347 ドキュメント

# Django の例外

Django は普通の Python の例外の他に、いくつか独自の例外も起こします。

## Django Core 例外

Django core 例外クラスは `django.core.exceptions` で定義されています。

### `AppRegistryNotReady`

exception `AppRegistryNotReady`

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

### `ObjectDoesNotExist`

exception `ObjectDoesNotExist`

  The base class for `Model.DoesNotExist` exceptions. A `try/except` for `ObjectDoesNotExist` will catch `DoesNotExist` exceptions for all models.

  See `get()`.

### `EmptyResultSet`

exception `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.

### `FieldDoesNotExist`

exception `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`

exception `MultipleObjectsReturned`

  The base class for `Model.MultipleObjectsReturned` exceptions. A `try/except` for `MultipleObjectsReturned` will catch `MultipleObjectsReturned` exceptions for all models.

  See `get()`.

### `SuspiciousOperation`

exception `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.

Changed in Django 3.2.18:

`SuspiciousOperation` is raised when too many files are submitted.

### `PermissionDenied`

exception `PermissionDenied`

  `PermissionDenied` 例外は、ユーザーにリクエストされたアクションを実行する権限がない場合に発生します。

### `ViewDoesNotExist`

exception `ViewDoesNotExist`

  `ViewDoesNotExist` 例外は、リクエストされたビューが存在しないい場合に、`django.urls` によって発生します。

### `MiddlewareNotUsed`

exception `MiddlewareNotUsed`

  `MiddlewareNotUsed` 例外は、サーバーの設定の中でミドルウェアが使用されなかった時に発生します。

### `ImproperlyConfigured`

exception `ImproperlyConfigured`

  `ImproperlyConfigured` 例外は、Django が何らかの点で不適切に設定されている場合に発生します。たとえば、`settings.py` に含まれる値が不正であったり、パースできないような場合が考えられます。

### `FieldError`

exception `FieldError`

  `FieldError` 例外は、モデルのフィールドに問題がある時に発生します。発生理由としては、次のようないくつかの理由が考えられます。

  - 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`

  `ValidationError` 例外は、データがフォームまたはモデルのフィールド検証に失敗すると発生します。検証 (validation) のより詳しい情報については、Form and Field Validation や Model Field Validation、Validator Reference を参照してください。

#### `NON_FIELD_ERRORS`

`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`

exception `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`

exception `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`

exception `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 の例外

URL Resolver の例外は `django.urls` で定義されています。

### `Resolver404`

exception `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`

exception `NoReverseMatch`

  The `NoReverseMatch` exception is raised by `django.urls` when a matching URL in your URLconf cannot be identified based on the parameters supplied.

## データベースの例外

データベースの例外は `django.db` からインポートできます。

Django wraps the standard database exceptions so that your Django code has a guaranteed common implementation of these classes.

exception `Error`

exception `InterfaceError`

exception `DatabaseError`

exception `DataError`

exception `OperationalError`

exception `IntegrityError`

exception `InternalError`

exception `ProgrammingError`

exception `NotSupportedError`

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`.

exception `models.``RestrictedError`

Raised to prevent deletion of referenced objects when using `django.db.models.RESTRICT`. `models.RestrictedError` is a subclass of `IntegrityError`.

## HTTP Exceptions

HTTP exceptions may be imported from `django.http`.

### `UnreadablePostError`

exception `UnreadablePostError`

  `UnreadablePostError` は、ユーザーがアップロードをキャンセルすると発生します。

## Sessions Exceptions

Sessions exceptions are defined in `django.contrib.sessions.exceptions`.

### `SessionInterrupted`

exception `SessionInterrupted`

  `SessionInterrupted` is raised when a session is destroyed in a concurrent request. It's a subclass of `BadRequest`.

## トランザクションの例外

トランザクションの例外は `django.db.transaction` で定義されています。

### `TransactionManagementError`

exception `TransactionManagementError`

  `TransactionManagementError` が発生するのは、データベースのトランザクションに関するあらゆる問題に対してです。

## テストフレームワークの例外

`django.test` パッケージが提供する例外です。

### `RedirectCycleError`

exception `client.``RedirectCycleError`

  `RedirectCycleError` は、テストクライアントがループまたは過度に長いリダイレクトチェーンを検出した時に発生します。

## Python の例外

Django は、十分適切な場合にはビルトインの Python の例外を起こします。詳しい情報については、Python のドキュメント Built-in Exceptions を読んでください。