Add column observers for generates

sqlalchemy_utils/decorators.py

@@ -67,14 +67,64 @@ class AttributeValueGenerator(object):
                     attr = getdotattr(class_, str(path))
 
                     if isinstance(attr.property, sa.orm.ColumnProperty):
-                        for attr in path[0:-1]:
+                        for attr in path:
+                            self.generate_property_observer(
+                                path,
+                                attr,
+                                column_key
+                            )
+
+    def generate_property_observer(self, path, attr, property_key):
+        """
+        Generate SQLAlchemy listener that observes given attr within given
+        path space.
+        """
         @sa.event.listens_for(attr, 'set')
         def receive_attr_set(target, value, oldvalue, initiator):
+            index = path.index(attr)
+            if not index:
                 setattr(
                     target,
-                                    column_key,
+                    property_key,
-                                    getattr(value, path[-1].key)
+                    getdotattr(value, str(path[1:]))
                 )
+            elif index == len(path) - 1:
+                inversed_path = ~path[0:-1]
+                entities = list(
+                    getdotattr(
+                        target,
+                        str(inversed_path)
+                    )
+                )
+                for entity in entities:
+                    if isinstance(entity, list):
+                        for e in entity:
+                            setattr(
+                                e,
+                                property_key,
+                                value
+                            )
+                    else:
+                        setattr(
+                            entity,
+                            property_key,
+                            value
+                        )
+            else:
+                inversed_path = ~path[0:-1]
+                entities = list(
+                    getdotattr(
+                        target,
+                        str(inversed_path[index:])
+                    )
+                )
+                for entity in entities:
+                    setattr(
+                        entity,
+                        property_key,
+                        getdotattr(value, str(path[(index + 1):]))
+                    )
+
 
     def update_generated_properties(self, session, ctx, instances):
         for obj in itertools.chain(session.new, session.dirty):

sqlalchemy_utils/path.py

@@ -1,3 +1,4 @@
+import sqlalchemy as sa
 from sqlalchemy.orm.attributes import InstrumentedAttribute
 from .utils import str_coercible
 
@@ -86,8 +87,13 @@ class AttrPath(object):
                 )
             return backref
 
+        if isinstance(self.parts[-1].property, sa.orm.ColumnProperty):
+            class_ = self.parts[-1].class_
+        else:
+            class_ = self.parts[-1].mapper.class_
+
         return self.__class__(
-            self.parts[-1].mapper.class_,
+            class_,
             '.'.join(map(get_backref, reversed(self.parts)))
         )
 

tests/test_generates.py

@@ -126,7 +126,7 @@ class TestGeneratesWithSourcePath(DeepPathGeneratesTestCase):
 
 
 
-class TestTwoWayAttributeValueGeneration(DeepPathGeneratesTestCase):
+class TestInstantAttributeValueGeneration(TestCase):
     def create_models(self):
         class Document(self.Base):
             __tablename__ = 'document'
@@ -144,7 +144,7 @@ class TestTwoWayAttributeValueGeneration(DeepPathGeneratesTestCase):
                 sa.Integer, sa.ForeignKey(Document.id)
             )
 
-            document = sa.orm.relationship(Document)
+            document = sa.orm.relationship(Document, backref='sections')
 
         class SubSection(self.Base):
             __tablename__ = 'subsection'
@@ -156,7 +156,7 @@ class TestTwoWayAttributeValueGeneration(DeepPathGeneratesTestCase):
                 sa.Integer, sa.ForeignKey(Section.id)
             )
 
-            section = sa.orm.relationship(Section)
+            section = sa.orm.relationship(Section, backref='subsections')
 
             @generates(locale, source='section.document.locale')
             def copy_locale(self, value):
@@ -169,6 +169,10 @@ class TestTwoWayAttributeValueGeneration(DeepPathGeneratesTestCase):
     def test_change_parent_attribute(self):
         document = self.Document(name=u'Document 1', locale='en')
         section = self.Section(name=u'Section 1', document=document)
-        assert section.locale == 'en'
         subsection = self.SubSection(name=u'Section 1', section=section)
         assert subsection.locale == 'en'
+        document.locale = 'fi'
+        assert subsection.locale == 'fi'
+        section.document = self.Document(name=u'Document 2', locale='sv')
+        assert subsection.locale == 'sv'
+