Refactor batch fetch module

sqlalchemy_utils/batch.py

@@ -11,7 +11,10 @@ from sqlalchemy_utils.generic import (
     GenericRelationshipProperty, class_from_table_name
 )
 from sqlalchemy_utils.functions.orm import (
-    local_column_names, remote_column_names
+    local_values,
+    local_column_names,
+    remote_column_names,
+    remote_values
 )
 
 
@@ -225,10 +228,7 @@ class CompositeFetcher(object):
     def fetch(self):
         for entity in self.related_entities:
             for fetcher in self.fetchers:
-                if any(
+                if any(remote_values(entity, fetcher.prop)):
-                    getattr(entity, name)
-                    for name in remote_column_names(fetcher.prop)
-                ):
                     fetcher.append_entity(entity)
 
     def populate(self):
@@ -240,16 +240,10 @@ class AbstractFetcher(object):
     @property
     def local_values_list(self):
         return [
-            self.local_values(entity)
+            local_values(entity, self.prop)
             for entity in self.path.entities
         ]
 
-    def local_values(self, entity):
-        return tuple(
-            getattr(entity, name)
-            for name in local_column_names(self.prop)
-        )
-
 
 class Fetcher(AbstractFetcher):
     def __init__(self, path):
@@ -260,12 +254,6 @@ class Fetcher(AbstractFetcher):
         else:
             self.parent_dict = defaultdict(lambda: None)
 
-    def parent_key(self, entity):
-        return tuple(
-            getattr(entity, name)
-            for name in remote_column_names(self.prop)
-        )
-
     @property
     def relation_query_base(self):
         return self.path.session.query(self.path.model)
@@ -279,11 +267,11 @@ class Fetcher(AbstractFetcher):
         Populates backrefs for given related entities.
         """
         backref_dict = dict(
-            (self.local_values(value[0]), [])
+            (local_values(value[0], self.prop), [])
             for value in related_entities
         )
         for value in related_entities:
-            backref_dict[self.local_values(value[0])].append(
+            backref_dict[local_values(value[0], self.prop)].append(
                 self.path.session.query(self.path.parent_model).get(
                     tuple(value[1:])
                 )
@@ -292,7 +280,7 @@ class Fetcher(AbstractFetcher):
             set_committed_value(
                 value[0],
                 self.prop.back_populates,
-                backref_dict[self.local_values(value[0])]
+                backref_dict[local_values(value[0], self.prop)]
             )
 
     def populate(self):
@@ -303,7 +291,7 @@ class Fetcher(AbstractFetcher):
             set_committed_value(
                 entity,
                 self.prop.key,
-                self.parent_dict[self.local_values(entity)]
+                self.parent_dict[local_values(entity, self.prop)]
             )
 
         if self.path.populate_backrefs:
@@ -359,7 +347,7 @@ class GenericRelationshipFetcher(AbstractFetcher):
         return (entity.__tablename__, getattr(entity, 'id'))
 
     def append_entity(self, entity):
-        self.parent_dict[self.parent_key(entity)] = entity
+        self.parent_dict[remote_values(entity, self.prop)] = entity
 
     def populate(self):
         """
@@ -369,7 +357,7 @@ class GenericRelationshipFetcher(AbstractFetcher):
             set_committed_value(
                 entity,
                 self.prop.key,
-                self.parent_dict[self.local_values(entity)]
+                self.parent_dict[local_values(entity, self.prop)]
             )
 
     @property
@@ -424,11 +412,11 @@ class ManyToManyFetcher(Fetcher):
 
 class ManyToOneFetcher(Fetcher):
     def append_entity(self, entity):
-        self.parent_dict[self.parent_key(entity)] = entity
+        self.parent_dict[remote_values(entity, self.prop)] = entity
 
 
 class OneToManyFetcher(Fetcher):
     def append_entity(self, entity):
-        self.parent_dict[self.parent_key(entity)].append(
+        self.parent_dict[remote_values(entity, self.prop)].append(
             entity
         )

sqlalchemy_utils/functions/orm.py

@@ -1,3 +1,4 @@
+from functools import partial
 import sqlalchemy as sa
 
 
@@ -46,6 +47,18 @@ def table_name(obj):
         pass
 
 
+def getattrs(obj, attrs):
+    return map(partial(getattr, obj), attrs)
+
+
+def local_values(entity, prop):
+    return tuple(getattrs(entity, local_column_names(prop)))
+
+
+def remote_values(entity, prop):
+    return tuple(getattrs(entity, remote_column_names(prop)))
+
+
 def local_column_names(prop):
     if not hasattr(prop, 'secondary'):
         yield prop._discriminator_col.key
@@ -62,7 +75,10 @@ def local_column_names(prop):
 
 
 def remote_column_names(prop):
-    if not hasattr(prop, 'secondary') or prop.secondary is None:
+    if not hasattr(prop, 'secondary'):
+        yield '__tablename__'
+        yield 'id'
+    elif prop.secondary is None:
         for _, remote in prop.local_remote_pairs:
             yield remote.name
     else: