Fix getdotattr list handling

sqlalchemy_utils/functions/orm.py

@@ -220,6 +220,9 @@ def declarative_base(model):
     return model
 
 
+from operator import attrgetter
+
+
 def getdotattr(obj_or_class, dot_path):
     """
     Allow dot-notated strings to be passed to `getattr`.
@@ -234,16 +237,23 @@ def getdotattr(obj_or_class, dot_path):
     :param obj_or_class: Any object or class
     :param dot_path: Attribute path with dot mark as separator
     """
-    def get_attr(mixed, attr):
-        if isinstance(mixed, InstrumentedAttribute):
-            return getattr(
-                mixed.property.mapper.class_,
-                attr
-            )
-        else:
-            return getattr(mixed, attr)
+    last = obj_or_class
 
-    return six.moves.reduce(get_attr, dot_path.split('.'), obj_or_class)
+    for path in dot_path.split('.'):
+        getter = attrgetter(path)
+        if isinstance(last, list):
+            tmp = []
+            for el in last:
+                if isinstance(el, list):
+                    tmp.extend(map(getter, el))
+                else:
+                    tmp.append(getter(el))
+            last = tmp
+        elif isinstance(last, InstrumentedAttribute):
+            last = getter(last.property.mapper.class_)
+        else:
+            last = getter(last)
+    return last
 
 
 def has_changes(obj, attr):

tests/functions/test_getdotattr.py

@@ -9,13 +9,11 @@ class TestGetDotAttr(TestCase):
             __tablename__ = 'document'
             id = sa.Column(sa.Integer, primary_key=True)
             name = sa.Column(sa.Unicode(255))
-            locale = sa.Column(sa.String(10))
 
         class Section(self.Base):
             __tablename__ = 'section'
             id = sa.Column(sa.Integer, primary_key=True)
             name = sa.Column(sa.Unicode(255))
-            locale = sa.Column(sa.String(10))
 
             document_id = sa.Column(
                 sa.Integer, sa.ForeignKey(Document.id)
@@ -27,7 +25,6 @@ class TestGetDotAttr(TestCase):
             __tablename__ = 'subsection'
             id = sa.Column(sa.Integer, primary_key=True)
             name = sa.Column(sa.Unicode(255))
-            locale = sa.Column(sa.String(10))
 
             section_id = sa.Column(
                 sa.Integer, sa.ForeignKey(Section.id)
@@ -35,11 +32,26 @@ class TestGetDotAttr(TestCase):
 
             section = sa.orm.relationship(Section, backref='subsections')
 
+        class SubSubSection(self.Base):
+            __tablename__ = 'subsubsection'
+            id = sa.Column(sa.Integer, primary_key=True)
+            name = sa.Column(sa.Unicode(255))
+            locale = sa.Column(sa.String(10))
+
+            subsection_id = sa.Column(
+                sa.Integer, sa.ForeignKey(SubSection.id)
+            )
+
+            subsection = sa.orm.relationship(
+                SubSection, backref='subsubsections'
+            )
+
         self.Document = Document
         self.Section = Section
         self.SubSection = SubSection
+        self.SubSubSection = SubSubSection
 
-    def test_getdotattr_for_objects(self):
+    def test_simple_objects(self):
         document = self.Document(name=u'some document')
         section = self.Section(document=document)
         subsection = self.SubSection(section=section)
@@ -49,7 +61,20 @@ class TestGetDotAttr(TestCase):
             'section.document.name'
         ) == u'some document'
 
-    def test_getdotattr_for_class_paths(self):
+    def test_with_instrumented_lists(self):
+        document = self.Document(name=u'some document')
+        section = self.Section(document=document)
+        subsection = self.SubSection(section=section)
+        subsubsection = self.SubSubSection(subsection=subsection)
+
+        assert getdotattr(document, 'sections.subsections') == [
+            [subsection]
+        ]
+        assert getdotattr(document, 'sections.subsections.subsubsections') == [
+            [subsubsection]
+        ]
+
+    def test_class_paths(self):
         assert getdotattr(self.Section, 'document') is self.Section.document
         assert (
             getdotattr(self.SubSection, 'section.document') is