Repository: django/django
File: django/core/serializers/xml_serializer.py (Python)

Code before:
                    m2m_data[field.name] = value
            elif field.remote_field and isinstance(
                field.remote_field, models.ManyToOneRel
            ):
                value = self._handle_fk_field_node(field_node, field)
                if value == base.DEFER_FIELD:
                    deferred_fields[field] = [
                        (
                            None
                            if k.getElementsByTagName("None")
                            else getInnerText(k).strip()
                        )
                        for k in field_node.getElementsByTagName("natural")
                    ]
                else:
                    data[field.attname] = value
            else:
                if field_node.getElementsByTagName("None"):
                    value = None
                else:
                    value = field.to_python(getInnerText(field_node).strip())
                    # Load value since JSONField.to_python() outputs strings.
                    if field.get_internal_type() == "JSONField":
                        value = json.loads(value, cls=field.decoder)
                data[field.name] = value

        obj = base.build_instance(Model, data, self.db)

        # Return a DeserializedObject so that the m2m data has a place to live.
        return base.DeserializedObject(obj, m2m_data, deferred_fields)

    def _handle_fk_field_node(self, node, field):
        """
        Handle a <field> node for a ForeignKey
        """
        model = field.remote_field.model
        if hasattr(model._default_manager, "get_by_natural_key"):
            keys = node.getElementsByTagName("natural")
            if keys:
                # If there are 'natural' subelements, it must be a natural
                # key
                field_value = [
                    None if k.getElementsByTagName("None") else getInnerText(k).strip()
                    for k in keys
                ]
                try:
                    obj = model._default_manager.db_manager(self.db).get_by_natural_key(
                        *field_value
                    )
                except ObjectDoesNotExist:
                    if self.handle_forward_references:

Review comment (suggestion):
For the sake of having a much smaller diff, I would suggest leaving most of this where it was and just fix the condition. (e.g. lift up `keys = ...` and then check `... and not keys: return None`, perhaps improving the variable name `keys`).

Your version has a terser if condition, but this code is touched so infrequently that I think we should prioritize a smaller diff and more understandable blames over more readable if conditions.

Code after:
                    m2m_data[field.name] = value
            elif field.remote_field and isinstance(
                field.remote_field, models.ManyToOneRel
            ):
                value = self._handle_fk_field_node(field_node, field)
                if value == base.DEFER_FIELD:
                    deferred_fields[field] = [
                        (
                            None
                            if k.getElementsByTagName("None")
                            else getInnerText(k).strip()
                        )
                        for k in field_node.getElementsByTagName("natural")
                    ]
                else:
                    data[field.attname] = value
            else:
                if field_node.getElementsByTagName("None"):
                    value = None
                else:
                    value = field.to_python(getInnerText(field_node).strip())
                    # Load value since JSONField.to_python() outputs strings.
                    if field.get_internal_type() == "JSONField":
                        value = json.loads(value, cls=field.decoder)
                data[field.name] = value

        obj = base.build_instance(Model, data, self.db)

        # Return a DeserializedObject so that the m2m data has a place to live.
        return base.DeserializedObject(obj, m2m_data, deferred_fields)

    def _handle_fk_field_node(self, node, field):
        """
        Handle a <field> node for a ForeignKey
        """
        # Check if there is a child node named 'None', returning None if so.
        natural_keys = node.getElementsByTagName("natural")
        if node.getElementsByTagName("None") and not natural_keys:
            return None
        else:
            model = field.remote_field.model
            if hasattr(model._default_manager, "get_by_natural_key"):
                if natural_keys:
                    # If there are 'natural' subelements, it must be a natural
                    # key
                    field_value = []
                    for k in natural_keys:
                        if k.getElementsByTagName("None"):
                            field_value.append(None)
                        else:
                            field_value.append(getInnerText(k).strip())