# SQLAlchemy 0.7.1 Documentation

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Version: 0.7.1 Last Updated: 06/05/2011 13:13:59

# ORM Exceptions

SQLAlchemy ORM exceptions.

`sqlalchemy.orm.exc.``ConcurrentModificationError`

  alias of `StaleDataError`

exception `sqlalchemy.orm.exc.``DetachedInstanceError`

  Bases: `sqlalchemy.exc.SQLAlchemyError`

  An attempt to access unloaded attributes on a mapped instance that is detached.

exception `sqlalchemy.orm.exc.``FlushError`

  Bases: `sqlalchemy.exc.SQLAlchemyError`

  A invalid condition was detected during flush().

exception `sqlalchemy.orm.exc.``MultipleResultsFound`

  Bases: `sqlalchemy.exc.InvalidRequestError`

  A single database result was required but more than one were found.

`sqlalchemy.orm.exc.``NO_STATE`

  Exception types that may be raised by instrumentation implementations.

exception `sqlalchemy.orm.exc.``NoResultFound`

  Bases: `sqlalchemy.exc.InvalidRequestError`

  A database result was required but none was found.

exception `sqlalchemy.orm.exc.``ObjectDeletedError`

  Bases: `sqlalchemy.exc.InvalidRequestError`

  An refresh() operation failed to re-retrieve an object’s row.

exception `sqlalchemy.orm.exc.``ObjectDereferencedError`

  Bases: `sqlalchemy.exc.SQLAlchemyError`

  An operation cannot complete due to an object being garbage collected.

exception `sqlalchemy.orm.exc.``StaleDataError`

  Bases: `sqlalchemy.exc.SQLAlchemyError`

  An operation encountered database state that is unaccounted for.

  Two conditions cause this to happen:

  - A flush may have attempted to update or delete rows and an unexpected number of rows were matched during the UPDATE or DELETE statement. Note that when version_id_col is used, rows in UPDATE or DELETE statements are also matched against the current known version identifier.
  - A mapped object with version_id_col was refreshed, and the version number coming back from the database does not match that of the object itself.

exception `sqlalchemy.orm.exc.``UnmappedClassError`(cls, msg=None)

  Bases: `sqlalchemy.orm.exc.UnmappedError`

  An mapping operation was requested for an unknown class.

exception `sqlalchemy.orm.exc.``UnmappedColumnError`

  Bases: `sqlalchemy.exc.InvalidRequestError`

  Mapping operation was requested on an unknown column.

exception `sqlalchemy.orm.exc.``UnmappedError`

  Bases: `sqlalchemy.exc.InvalidRequestError`

  Base for exceptions that involve expected mappings not present.

exception `sqlalchemy.orm.exc.``UnmappedInstanceError`(obj, msg=None)

  Bases: `sqlalchemy.orm.exc.UnmappedError`

  An mapping operation was requested for an unknown instance.