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You can include a newly calculated attribute obtained from a raw query into the serializer by first defining the attribute in the serializer as a serializer field. Then, you can override the to_representation method of your serializer to set the value of the attribute.

Here's an example:

# define the new attribute field in your serializer
class MySerializer(serializers.ModelSerializer):
    my_attribute = serializers.IntegerField(read_only=True)

    class Meta:
        model = MyModel
        fields = ['id', 'name', 'my_attribute']

    # override the to_representation method to set the value of the attribute
    def to_representation(self, instance):
        # get the value of the attribute from the raw query
        my_attribute_value = instance.my_raw_query_result

        # set the value of the attribute in the representation
        representation = super().to_representation(instance)
        representation['my_attribute'] = my_attribute_value

        return representation

In this example, my_attribute is defined as an IntegerField and marked as read_only to indicate that it is a calculated value that is not to be included in any request data. The to_representation method is then overridden to get the value of the attribute from the raw query and set it in the serializer representation that is returned to the client.