Tank_data = TankData.objects.filter(tank=tank, controller__isnull=False).order_by('record_time').first() hourly = TankDataHourly.objects.create( tank_id=tank.id,

Question

Tank_data = TankData.objects.filter(tank=tank, controller__isnull=False).order_by('record_time').first() hourly = TankDataHourly.objects.create( tank_id=tank.id,

record_time=tank_data.record_time,
controller_id=tank_data.controller.id,
)

выдает ошибку
django.db.utils.IntegrityError: null value in column "record_time" violates not-null constraint
DETAIL: Failing row contains (2339, null, null, null, null, null, null, null, null, 2020-01-17 06:15:36.081519+00, null, 4).

почему выдает ошибку ?