Make model save and create methods more customizable in serializers

rest_framework/serializers.py

@@ -661,6 +661,9 @@ class ModelSerializer(Serializer):
     })
     _related_class = PrimaryKeyRelatedField
 
+    def create_instance(self, model_class, validated_data):
+        return model_class.objects.create(**validated_data)
+
     def create(self, validated_data):
         """
         We have a bit of extra checking around this in order to provide
@@ -696,7 +699,7 @@ class ModelSerializer(Serializer):
                 many_to_many[field_name] = validated_data.pop(field_name)
 
         try:
-            instance = ModelClass.objects.create(**validated_data)
+            instance = self.create_instance(ModelClass, validated_data)
         except TypeError as exc:
             msg = (
                 'Got a `TypeError` when calling `%s.objects.create()`. '
@@ -721,13 +724,15 @@ class ModelSerializer(Serializer):
 
         return instance
 
+    def save_instance(self, instance):
+        instance.save()
+
     def update(self, instance, validated_data):
         raise_errors_on_nested_writes('update', self)
 
         for attr, value in validated_data.items():
             setattr(instance, attr, value)
-        instance.save()
-
+        self.save_instance(instance)
         return instance
 
     def get_validators(self):