diff options
Diffstat (limited to 'lib/sqlalchemy/ext/declarative.py')
| -rw-r--r-- | lib/sqlalchemy/ext/declarative.py | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/lib/sqlalchemy/ext/declarative.py b/lib/sqlalchemy/ext/declarative.py index 784236662..62691a906 100644 --- a/lib/sqlalchemy/ext/declarative.py +++ b/lib/sqlalchemy/ext/declarative.py @@ -161,7 +161,7 @@ from sqlalchemy.schema import Table, SchemaItem, Column, MetaData from sqlalchemy.orm import synonym as _orm_synonym, mapper, comparable_property from sqlalchemy.orm.interfaces import MapperProperty from sqlalchemy.orm.properties import PropertyLoader, ColumnProperty -from sqlalchemy import util +from sqlalchemy import util, exceptions __all__ = ['declarative_base', 'synonym_for', 'comparable_using', 'declared_synonym'] @@ -237,7 +237,10 @@ def _deferred_relation(cls, prop): if isinstance(prop, PropertyLoader) and isinstance(prop.argument, basestring): arg = prop.argument def return_cls(): - return cls._decl_class_registry[arg] + try: + return cls._decl_class_registry[arg] + except KeyError: + raise exceptions.InvalidRequestError("When compiling mapper %s, could not locate a declarative class named %r. Consider adding this property to the %r class after both dependent classes have been defined." % (prop.parent, arg, prop.parent.class_)) prop.argument = return_cls return prop |