django/tests/select_for_update/models.py

from django.db import models


class Country(models.Model):
    name = models.CharField(max_length=30)


class City(models.Model):
    name = models.CharField(max_length=30)
    country = models.ForeignKey(Country, models.CASCADE)


class Person(models.Model):
    name = models.CharField(max_length=30)
    born = models.ForeignKey(City, models.CASCADE, related_name='+')
    died = models.ForeignKey(City, models.CASCADE, related_name='+')