Async ForeignKeys

At the moment if you have model

class Model(peewee.Model):
    other_model = peewee.ForeignKey(OrderModel)

using it like this

model_instance.other_model

will trigger sync query.

I’ve already have this working so this issue is just to keep contribution in mind 😉

[anjianshi]

I have implemented get_related() method, maybe someone can use it.

import peewee_async


class ExtManager(peewee_async.Manager):
    async def get_related(self, instance, related_name, single_backref=False):
        """
        return related instance for foreign key relationship
        return query for backref or return related instance if single_backref is True
        """
        model_cls = type(instance)
        related_field = getattr(model_cls, related_name)

        if isinstance(related_field, ReverseRelationDescriptor):
            return await self._get_backrefs(instance, related_name, single_backref)
        else:
            return await self._get_foreign_key_target(instance, related_name)

    async def _get_foreign_key_target(self, instance, field_name):
        foreign_key_value = getattr(instance, field_name + "_id")

        model_cls = type(instance)
        foreign_key_field = getattr(model_cls, field_name)
        target_cls = foreign_key_field.rel_model
        target_field = foreign_key_field.to_field

        return await self.get(target_cls, target_field == foreign_key_value)

    async def _get_backrefs(self, instance, related_name, single_backref=False):
        query = getattr(instance, related_name)
        instances = await self.execute(query)

        if single_backref:
            for instance in instances:
                return instance
            raise query.model_class.DoesNotExist
        else:
            return instances

[jackfischer]

Thank you! I’m new to peewee and peewee async so this example is helpful. It might be a worthwhile addition to the docs. Thank you for all your work