move save mixins near one another and improve arg names

Author: claytondaley

drf_writable_nested/mixins.py

@@ -578,47 +578,14 @@ def _save_reverse_relations(self, related_objects, instance):
             field.save(**kwargs)
 
 
-class NestedSaveListSerializer(serializers.ListSerializer):
-    """Need a special save() method that cascades to the list of child instances"""
-
-    def save(self, **kwargs):
-        """
-        Save and return a list of object instances.
-        """
-        # Guard against incorrect use of `serializer.save(commit=False)`
-        assert 'commit' not in kwargs, (
-            "'commit' is not a valid keyword argument to the 'save()' method. "
-            "If you need to access data before committing to the database then "
-            "inspect 'serializer.validated_data' instead. "
-            "You can also pass additional keyword arguments to 'save()' if you "
-            "need to set extra attributes on the saved model instance. "
-            "For example: 'serializer.save(owner=request.user)'.'"
-        )
-
-        new_values = []
-
-        for item in self._validated_data:
-            # integrate save kwargs
-            self.child._validated_data = item
-            # since we reuse the serializer, we need to re-inject the new _validated_data using save kwargs
-            new_values.append(self.child.save(**kwargs))
-
-        return new_values
-
-    def run_validation(self, data=empty):
-        """Since a nested serializer is treated like a Field, `is_valid` will not be called so we need to set
-        _validated_data in the mixin."""
-        self._validated_data = super(NestedSaveListSerializer, self).run_validation(data)
-        return self._validated_data
-
-
 class FocalSaveMixin(FieldLookupMixin):
+    """Provides a framework for extracting the values needed to get or create the focal object."""
 
     @transaction.atomic
     def save(self, **kwargs):
         match_on = {}
         m2m_relations = {}
-        defaults = {}
+        create_values = {}
         for field_name, field in self.fields.items():
             if self.match_on == '__all__' or field_name in self.match_on:
                 # add to match_on dict
@@ -628,40 +595,74 @@ def save(self, **kwargs):
                 m2m_relations[field_name] = kwargs.get(field_name, self._validated_data.get(field_name))
             elif self.field_types[field_name] == self.TYPE_LOCAL:
                 # need to check kwargs since there's no pre-processing
-                defaults[field_name] = kwargs.get(field_name, self._validated_data.get(field_name))
+                create_values[field_name] = kwargs.get(field_name, self._validated_data.get(field_name))
             elif self.field_types[field_name] == self.TYPE_DIRECT:
                 # kwargs should have been injected when direct relations were saved
-                defaults[field_name] = self._validated_data.get(field_name)
+                create_values[field_name] = self._validated_data.get(field_name)
             # make reverse relations aren't sent to a create
         # a parent serializer may inject a value that isn't among the fields, but is in `match_on`
         for key in self.match_on:
             if key not in self.fields.keys():
                 match_on[key] = kwargs.get(key, None)
         try:
-            match, updated = self.do_save(match_on, defaults)
+            match, updated = self.do_save(match_on, create_values)
             if not updated:
-                updated = self.do_update(match, defaults)
+                updated = self.do_update(match, create_values)
             if updated:
                 match.save()
         except (TypeError, ValueError):
             self.fail('incorrect_type', data_type=type(self._validated_data).__name__)
         self.do_m2m_update(match, m2m_relations)
         return match
 
-    def do_save(self, match_on, defaults):
+    def do_save(self, match_on, create_values):
         """Returns the object requested by match_on and defaults."""
         raise NotImplementedError("Must use a SerializerMixin or provide a save behavior.")
 
-    def do_update(self, match, defaults):
+    def do_update(self, match, create_values):
         """Update the match (if appropriate) and returns a boolean indicating whether or not a save is required."""
         return False
 
     def do_m2m_update(self, match, m2m_relations):
         return  # no update
 
 
+class NestedSaveListSerializer(serializers.ListSerializer):
+    """Need a special save() method that cascades to the list of child instances"""
+
+    def save(self, **kwargs):
+        """
+        Save and return a list of object instances.
+        """
+        # Guard against incorrect use of `serializer.save(commit=False)`
+        assert 'commit' not in kwargs, (
+            "'commit' is not a valid keyword argument to the 'save()' method. "
+            "If you need to access data before committing to the database then "
+            "inspect 'serializer.validated_data' instead. "
+            "You can also pass additional keyword arguments to 'save()' if you "
+            "need to set extra attributes on the saved model instance. "
+            "For example: 'serializer.save(owner=request.user)'.'"
+        )
+
+        new_values = []
+
+        for item in self._validated_data:
+            # integrate save kwargs
+            self.child._validated_data = item
+            # since we reuse the serializer, we need to re-inject the new _validated_data using save kwargs
+            new_values.append(self.child.save(**kwargs))
+
+        return new_values
+
+    def run_validation(self, data=empty):
+        """Since a nested serializer is treated like a Field, `is_valid` will not be called so we need to set
+        _validated_data in the mixin."""
+        self._validated_data = super(NestedSaveListSerializer, self).run_validation(data)
+        return self._validated_data
+
+
 class NestedSaveSerializer(RelatedSaveMixin, FocalSaveMixin):
-    """Provides a general framework for nested serializers including argument validation and common save/update behaviors"""
+    """Provides a general framework for nested serializers including argument validation."""
 
     default_list_serializer = NestedSaveListSerializer
     DEFAULT_MATCH_ON = ['pk']
@@ -752,8 +753,8 @@ def create(self, validated_data):
 
 class UpdateDoSaveMixin(NestedSaveSerializer):
 
-    def do_update(self, match, defaults):
-        for k, v in defaults.items():
+    def do_update(self, match, create_values):
+        for k, v in create_values.items():
             setattr(match, k, v)
         return True
 
@@ -766,7 +767,7 @@ def do_m2m_update(self, match, m2m_relations):
 class GetOnlyNestedSerializerMixin(NestedSaveSerializer):
     """Gets (without updating) requetsed object or fails."""
 
-    def do_save(self, match_on, defaults):
+    def do_save(self, match_on, create_values):
         return self.queryset.select_for_update().get(**match_on), False
 
 
@@ -777,11 +778,11 @@ class UpdateOnlyNestedSerializerMixin(UpdateDoSaveMixin, GetOnlyNestedSerializer
 class GetOrCreateNestedSerializerMixin(GetOnlyNestedSerializerMixin):
     """Gets (without updating) or creates requested object."""
 
-    def do_save(self, match_on, defaults):
+    def do_save(self, match_on, create_values):
         try:
-            return super(GetOrCreateNestedSerializerMixin, self).do_save(match_on, defaults)
+            return super(GetOrCreateNestedSerializerMixin, self).do_save(match_on, create_values)
         except self.queryset.model.DoesNotExist:
-            return self.queryset.model(**defaults), True
+            return self.queryset.model(**create_values), True
 
 
 class UpdateOrCreateNestedSerializerMixin(UpdateDoSaveMixin, GetOrCreateNestedSerializerMixin):
@@ -791,5 +792,5 @@ class UpdateOrCreateNestedSerializerMixin(UpdateDoSaveMixin, GetOrCreateNestedSe
 class CreateOnlyNestedSerializerMixin(NestedSaveSerializer):
     """Creates requested object or fails."""
 
-    def do_save(self, match_on, defaults):
-        return self.queryset.model(**defaults), True
+    def do_save(self, match_on, create_values):
+        return self.queryset.model(**create_values), True