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from django.db import models
class Address(models.Model):
company = models.CharField(max_length=1)
customer_id = models.IntegerField()
class Meta:
unique_together = [
("company", "customer_id"),
]
class Customer(models.Model):
company = models.CharField(max_length=1)
customer_id = models.IntegerField()
address = models.ForeignObject(
Address,
models.CASCADE,
null=True,
# order mismatches the Contact ForeignObject.
from_fields=["company", "customer_id"],
to_fields=["company", "customer_id"],
)
class Meta:
unique_together = [
("company", "customer_id"),
]
class Contact(models.Model):
company_code = models.CharField(max_length=1)
customer_code = models.IntegerField()
customer = models.ForeignObject(
Customer,
models.CASCADE,
related_name="contacts",
to_fields=["customer_id", "company"],
from_fields=["customer_code", "company_code"],
)
class CustomerTab(models.Model):
customer_id = models.IntegerField()
customer = models.ForeignObject(
Customer,
from_fields=["customer_id"],
to_fields=["id"],
on_delete=models.CASCADE,
)
class Meta:
required_db_features = {"supports_table_check_constraints"}
constraints = [
models.CheckConstraint(
condition=models.Q(customer__lt=1000),
name="customer_id_limit",
),
]
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