1 files changed, 6 insertions, 9 deletions
diff --git a/lib/sqlalchemy/ext/declarative/api.py b/lib/sqlalchemy/ext/declarative/api.py
index 048533b92..713ea0aba 100644
--- a/lib/sqlalchemy/ext/declarative/api.py
+++ b/lib/sqlalchemy/ext/declarative/api.py
@@ -175,15 +175,12 @@ class declared_attr(interfaces._MappedAttribute, property):
                 "non-mapped class %s" %
                 (desc.fget.__name__, cls.__name__))
             return desc.fget(cls)
-        try:
-            reg = manager.info['declared_attr_reg']
-        except KeyError:
-            raise exc.InvalidRequestError(
-                "@declared_attr called outside of the "
-                "declarative mapping process; is declarative_base() being "
-                "used correctly?")
-
-        if desc in reg:
+
+        reg = manager.info.get('declared_attr_reg', None)
+
+        if reg is None:
+            return desc.fget(cls)
+        elif desc in reg:
             return reg[desc]
         else:
             reg[desc] = obj = desc.fget(cls)