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# orm/exc.py
# Copyright (C) 2005-2021 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""SQLAlchemy ORM exceptions."""
from .. import exc as sa_exc
from .. import util
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.dependencies("sqlalchemy.orm.base")
def __init__(self, base, obj, msg=None):
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.dependencies("sqlalchemy.orm.base")
def __init__(self, base, state, msg=None):
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 NoResultFound(sa_exc.InvalidRequestError):
"""A database result was required but none was found."""
class MultipleResultsFound(sa_exc.InvalidRequestError):
"""A single database result was required but more than one were found."""
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.dependencies("sqlalchemy.orm.base")
def _default_unmapped(base, cls):
try:
mappers = base.manager_of_class(cls).mappers
except NO_STATE:
mappers = {}
except TypeError:
mappers = {}
name = _safe_cls_name(cls)
if not mappers:
return "Class '%s' is not mapped" % name
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