Django elasticsearch DSL with custom model fields (hashid field)

Question

I have a model that uses django hashid fields for the id.

class Artwork(Model):

    id = HashidAutoField(primary_key=True, min_length=8, alphabet="0123456789abcdefghijklmnopqrstuvwxyz")

    title = ....

This is the related item of another model

class ArtworkFeedItem(FeedItem):
    artwork = models.OneToOneField('artwork.Artwork', related_name='artwork_feeditem', on_delete=models.CASCADE)

Now I'm trying to setup [django elasticsearch dsl] (https://github.com/django-es/django-elasticsearch-dsl) and to that end have the Document

@registry.register_document
class ArtworkFeedItemDocument(Document):
    class Index:
        name = 'feed'
        settings = {
            'number_of_shards': 1,
            'number_of_replicas': 0
        }

    artwork = fields.ObjectField(
        properties={
            'id': fields.TextField(),
            'title': fields.TextField(
                attr='title',
                fields={
                    'suggest': fields.Completion(),
                }
            )
        }

    )

    class Django:
        model = ArtworkFeedItem
        fields = []
        related_models = [Artwork]

However, when I try to rebuild indices with python manage.py search_index --rebuild I get the following exception

elasticsearch.exceptions.SerializationError: ({'index': {'_id': Hashid(135): l2vylzm9, '_index': 'feed'}}, TypeError("Unable to serialize Hashid(135): l2vylzm9 (type: <class 'hashid_field.hashid.Hashid'>)",))

Django elasticsearch dsl clearly does not know what to do with such a hashid field.

I thought maybe I could just make my own HashIdField like

from elasticsearch_dsl import Field
class HashIdField(Field):
    """
    Custom DSL field to support HashIds
    """

    name = "hashid"

    def _serialize(self, data):
        return data.hashid

then use it in 'id': HashIdField, but this gave me yet another exception

elasticsearch.exceptions.RequestError: RequestError(400, 'mapper_parsing_exception', 'No handler for type [hashid] declared on field [id]')

Does anyone know how I could get this to work?

Answer 1

For anyone interested, I managed to solve this by overriding the generate_id method of the Document so that the _id used is just a plain string:

    @classmethod
    def generate_id(cls, object_instance):
        return object_instance.id.hashid