Solve OneToOne Caching Issue

model.py

from dynamorm import DynaModel, OneToOne

from marshmallow.fields import String


class Device(DynaModel):
    class Table:
        name = 'Device'
        hash_key = 'device_id'

    class Schema:
        device_id = String(required=True)
        device_name = String()
        device_location = String()


class User(DynaModel):
    _device = None

    class Table:
        name = 'User'
        hash_key = 'user_id'

    class Schema:
        user_id = String(required=True)
        device_id = String(required=True)

    @property
    def device(self):
        if self._device is None:
            self._device = OneToOne(
                Device,
                query=lambda user: dict(device_id=user.device_id),
            ).__get__(self, type(self))
        return self._device


Device(device_id='Device_1').save()
Device(device_id='Device_2').save()

User(user_id='Alice', device_id='Device_1').save()
User(user_id='Bob', device_id='Device_2').save()

alice = User.get(user_id='Alice')
assert alice.device.device_id == 'Device_1'

bob = User.get(user_id='Bob')
assert bob.device.device_id == 'Device_2'