Override get_initial() rather than is_valid()

InvenTree/InvenTree/serializers.py

@@ -45,17 +45,15 @@ class InvenTreeModelSerializer(serializers.ModelSerializer):
     but also ensures that the underlying model class data are checked on validation.
     """
 
-    def is_valid(self, raise_exception=False):
+    def get_initial(self):
         """
-        Override the 'is_valid' method of the underlying ModelSerializer class.
-
-        - This is so we can intercept the data before save() is called.
-        - If we are creating a *new* model, replace any "missing" fields with the default values
-        - Default values are those specified by the database model
+        Construct initial data for the serializer.
+        Use the 'default' values specified by the django model definition
         """
 
-        # This serializer is *not* associated with a model instance
-        # This means that we are trying to *create* a new model
+        initials = super().get_initial()
+
+        # Are we creating a new instance?
         if self.instance is None:
             ModelClass = self.Meta.model
 
@@ -63,16 +61,10 @@ class InvenTreeModelSerializer(serializers.ModelSerializer):
 
             for field_name, field in fields.fields.items():
 
-                # Check if the field has a default value
                 if field.has_default():
+                    initials[field_name] = field.default
 
-                    # Value not specified?
-                    if field_name not in self.initial_data:
-                        
-                        self.initial_data[field_name] = field.default
-
-
-        return super().is_valid(raise_exception=raise_exception)
+        return initials
 
     def run_validation(self, data=empty):
         """ Perform serializer validation.