import datetime from django.db import models class Country(models.Model): # Table Column Fields name = models.CharField(max_length=50) def __str__(self): return self.name class Person(models.Model): # Table Column Fields name = models.CharField(max_length=128) person_country_id = models.IntegerField() # Relation Fields person_country = models.ForeignObject( Country, from_fields=['person_country_id'], to_fields=['id'], on_delete=models.CASCADE, ) friends = models.ManyToManyField('self', through='Friendship', symmetrical=False) class Meta: ordering = ('name',) def __str__(self): return self.name class Group(models.Model): # Table Column Fields name = models.CharField(max_length=128) group_country = models.ForeignKey(Country, models.CASCADE) members = models.ManyToManyField(Person, related_name='groups', through='Membership') class Meta: ordering = ('name',) def __str__(self): return self.name class Membership(models.Model): # Table Column Fields membership_country = models.ForeignKey(Country, models.CASCADE) date_joined = models.DateTimeField(default=datetime.datetime.now) invite_reason = models.CharField(max_length=64, null=True) person_id = models.IntegerField() group_id = models.IntegerField(blank=True, null=True) # Relation Fields person = models.ForeignObject( Person, from_fields=['person_id', 'membership_country'], to_fields=['id', 'person_country_id'], on_delete=models.CASCADE, ) group = models.ForeignObject( Group, from_fields=['group_id', 'membership_country'], to_fields=['id', 'group_country'], on_delete=models.CASCADE, ) class Meta: ordering = ('date_joined', 'invite_reason') def __str__(self): group_name = self.group.name if self.group_id else 'NULL' return "%s is a member of %s" % (self.person.name, group_name) class Friendship(models.Model): # Table Column Fields from_friend_country = models.ForeignKey(Country, models.CASCADE, related_name="from_friend_country") from_friend_id = models.IntegerField() to_friend_country_id = models.IntegerField() to_friend_id = models.IntegerField() # Relation Fields from_friend = models.ForeignObject( Person, on_delete=models.CASCADE, from_fields=['from_friend_country', 'from_friend_id'], to_fields=['person_country_id', 'id'], related_name='from_friend') to_friend_country = models.ForeignObject( Country, from_fields=['to_friend_country_id'], to_fields=['id'], related_name='to_friend_country', on_delete=models.CASCADE, ) to_friend = models.ForeignObject( Person, from_fields=['to_friend_country_id', 'to_friend_id'], to_fields=['person_country_id', 'id'], related_name='to_friend', on_delete=models.CASCADE, )