SelectFieldRenderer's that are on a relationship now use the default of the associated foreign key column

formalchemy/fields.py

@@ -15,7 +15,7 @@
 from sqlalchemy.orm.interfaces import ONETOMANY
 from sqlalchemy.orm import class_mapper, Query
 from sqlalchemy.orm.attributes import ScalarAttributeImpl, ScalarObjectAttributeImpl, CollectionAttributeImpl
-from sqlalchemy.orm.properties import CompositeProperty, ColumnProperty
+from sqlalchemy.orm.properties import CompositeProperty, ColumnProperty, RelationshipProperty
 from sqlalchemy import exceptions as sqlalchemy_exceptions
 from sqlalchemy.orm import object_session
 from formalchemy import helpers as h
@@ -174,8 +174,17 @@ def value(self):
             return v
 
         value = self.field.model_value
-        if value is None:
+
+        if value is None and _pk(self.field.parent.model) is None:
+            if (hasattr(self.field, '_property') and 
+                    isinstance(self.field._property, RelationshipProperty)):
+                try:
+                    value = self.field._property.local_side[0].default.arg          
+                except Exception:
+                    pass
+        elif value is None:
             return None
+
         if self.field.is_collection:
             return [self.stringify_value(v) for v in value]
         else:
@@ -830,6 +839,7 @@ def render(self, options, **kwargs):
                 L = [(k, self.stringify_value(v)) for k, v in L]
             else:
                 L = [_stringify(k) for k in L]
+
         return h.select(self.name, self.value, L, **kwargs)
 
     def render_readonly(self, options=None, **kwargs):