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- # orm/exc.py
- # Copyright (C) 2005-2022 the SQLAlchemy authors and contributors
- # <see AUTHORS file>
- #
- # This module is part of SQLAlchemy and is released under
- # the MIT License: https://www.opensource.org/licenses/mit-license.php
- """SQLAlchemy ORM exceptions."""
- from .. import exc as sa_exc
- from .. import util
- from ..exc import MultipleResultsFound # noqa
- from ..exc import NoResultFound # noqa
- NO_STATE = (AttributeError, KeyError)
- """Exception types that may be raised by instrumentation implementations."""
- class StaleDataError(sa_exc.SQLAlchemyError):
- """An operation encountered database state that is unaccounted for.
- Conditions which cause this to happen include:
- * 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.
- * A object is detached from its parent object, however
- the object was previously attached to a different parent
- identity which was garbage collected, and a decision
- cannot be made if the new parent was really the most
- recent "parent".
- """
- ConcurrentModificationError = StaleDataError
- class FlushError(sa_exc.SQLAlchemyError):
- """A invalid condition was detected during flush()."""
- class UnmappedError(sa_exc.InvalidRequestError):
- """Base for exceptions that involve expected mappings not present."""
- class ObjectDereferencedError(sa_exc.SQLAlchemyError):
- """An operation cannot complete due to an object being garbage
- collected.
- """
- class DetachedInstanceError(sa_exc.SQLAlchemyError):
- """An attempt to access unloaded attributes on a
- mapped instance that is detached."""
- code = "bhk3"
- class UnmappedInstanceError(UnmappedError):
- """An mapping operation was requested for an unknown instance."""
- @util.preload_module("sqlalchemy.orm.base")
- def __init__(self, obj, msg=None):
- base = util.preloaded.orm_base
- if not msg:
- try:
- base.class_mapper(type(obj))
- name = _safe_cls_name(type(obj))
- msg = (
- "Class %r is mapped, but this instance lacks "
- "instrumentation. This occurs when the instance "
- "is created before sqlalchemy.orm.mapper(%s) "
- "was called." % (name, name)
- )
- except UnmappedClassError:
- msg = _default_unmapped(type(obj))
- if isinstance(obj, type):
- msg += (
- "; was a class (%s) supplied where an instance was "
- "required?" % _safe_cls_name(obj)
- )
- UnmappedError.__init__(self, msg)
- def __reduce__(self):
- return self.__class__, (None, self.args[0])
- class UnmappedClassError(UnmappedError):
- """An mapping operation was requested for an unknown class."""
- def __init__(self, cls, msg=None):
- if not msg:
- msg = _default_unmapped(cls)
- UnmappedError.__init__(self, msg)
- def __reduce__(self):
- return self.__class__, (None, self.args[0])
- class ObjectDeletedError(sa_exc.InvalidRequestError):
- """A refresh operation failed to retrieve the database
- row corresponding to an object's known primary key identity.
- A refresh operation proceeds when an expired attribute is
- accessed on an object, or when :meth:`_query.Query.get` is
- used to retrieve an object which is, upon retrieval, detected
- as expired. A SELECT is emitted for the target row
- based on primary key; if no row is returned, this
- exception is raised.
- The true meaning of this exception is simply that
- no row exists for the primary key identifier associated
- with a persistent object. The row may have been
- deleted, or in some cases the primary key updated
- to a new value, outside of the ORM's management of the target
- object.
- """
- @util.preload_module("sqlalchemy.orm.base")
- def __init__(self, state, msg=None):
- base = util.preloaded.orm_base
- if not msg:
- msg = (
- "Instance '%s' has been deleted, or its "
- "row is otherwise not present." % base.state_str(state)
- )
- sa_exc.InvalidRequestError.__init__(self, msg)
- def __reduce__(self):
- return self.__class__, (None, self.args[0])
- class UnmappedColumnError(sa_exc.InvalidRequestError):
- """Mapping operation was requested on an unknown column."""
- class LoaderStrategyException(sa_exc.InvalidRequestError):
- """A loader strategy for an attribute does not exist."""
- def __init__(
- self,
- applied_to_property_type,
- requesting_property,
- applies_to,
- actual_strategy_type,
- strategy_key,
- ):
- if actual_strategy_type is None:
- sa_exc.InvalidRequestError.__init__(
- self,
- "Can't find strategy %s for %s"
- % (strategy_key, requesting_property),
- )
- else:
- sa_exc.InvalidRequestError.__init__(
- self,
- 'Can\'t apply "%s" strategy to property "%s", '
- 'which is a "%s"; this loader strategy is intended '
- 'to be used with a "%s".'
- % (
- util.clsname_as_plain_name(actual_strategy_type),
- requesting_property,
- util.clsname_as_plain_name(applied_to_property_type),
- util.clsname_as_plain_name(applies_to),
- ),
- )
- def _safe_cls_name(cls):
- try:
- cls_name = ".".join((cls.__module__, cls.__name__))
- except AttributeError:
- cls_name = getattr(cls, "__name__", None)
- if cls_name is None:
- cls_name = repr(cls)
- return cls_name
- @util.preload_module("sqlalchemy.orm.base")
- def _default_unmapped(cls):
- base = util.preloaded.orm_base
- try:
- mappers = base.manager_of_class(cls).mappers
- except (TypeError,) + NO_STATE:
- mappers = {}
- name = _safe_cls_name(cls)
- if not mappers:
- return "Class '%s' is not mapped" % name
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