multiple Many to Many constraints - ProgrammingError column xy_id does not exists

Using Django
1

Hi everyone,

I’m trying to add contraints to a model with multiple many to many fields.

Basically i would like to ensure that at least one value is entered for tenant_person OR for tenant_company. An d the same for the landord_tenant and landolord_company

I did write this constraints:
class Meta:
constraints = [
models.CheckConstraint(
name="%(app_label)s_%(class)s_tenant_not_null",
check=(models.Q(tenant_person__isnull=False) | models.Q(tenant_company__isnull=False))
),
models.CheckConstraint(
name="%(app_label)s_%(class)s_landlord_not_null",
check=(models.Q(landlord_person__isnull=False) | models.Q(landlord_company__isnull=False))
)
]

When I make the migrations everything is fine but when I migrate I get this error:

django.db.utils.ProgrammingError: column “person_id” does not exist

My DB backend is Postgres in a docker

I looked around in the doc, stackoverflow and the forum… I guess that it might be related to the type (ManyToMany) of the fields.

Any help, direction to the right documentation would be much appreciated

Axel

Here is my full model:

class RentContract(models.Model):
#
# BANK_TRANSFER = 'bank transfer'
# BLOCKED_ACCOUNT = 'blocked account'
# CASH = 'cash'
# DEPOSIT_TYPE = [
#     (BANK_TRANSFER, 'Bank transfer'),
#     (BLOCKED_ACCOUNT, 'Blocked account'),
#     (CASH, 'Cash'),
# ]

property = models.ForeignKey('real_estate.Property', on_delete=models.PROTECT)
tenant_person = models.ManyToManyField('address_book.Person', related_name='tenant_person', default=None,
                                       blank=True)
tenant_company = models.ManyToManyField('address_book.Company', related_name='tenant_company', default=None,
                                        blank=True)
tenant_representative = models.ForeignKey('address_book.Person', on_delete=models.PROTECT,
                                          related_name='tenant_representative', default=None, null=True, blank=True)

landlord_person = models.ManyToManyField('address_book.Person', related_name='landlord_person', default=None,
                                         blank=True)
landlord_company = models.ManyToManyField('address_book.Company', related_name='landlord_company', default=None,
                                          blank=True)
landlord_representative = models.ForeignKey('address_book.Person', on_delete=models.PROTECT,
                                            related_name='landlord_representative', default=None, null=True,
                                            blank=True)
date_signed = models.DateField()
date_start = models.DateField()
length = models.IntegerField(default=None, blank=True, null=True)
date_stop = models.DateField(default=None, blank=True, null=True)
renew_auto = models.BooleanField()
stop_normal_notification = models.IntegerField(default=2)
stop_normal_indemnity = models.FloatField(default=2)
stop_pro_notification = models.IntegerField(default=1)
stop_pro_indemnity = models.FloatField(default=1)
rent = models.FloatField()
expanses = models.FloatField()
payment_target_account = models.ForeignKey('accounting.BankAccount', on_delete=models.PROTECT)
# deposit = models.FloatField()
# deposit_type = models.CharField(max_length=25, choices=DEPOSIT_TYPE, default=BLOCKED_ACCOUNT)

timestamp_updated = models.DateTimeField(auto_now=True)
timestamp_created = models.DateField(auto_now_add=True)
comment = models.TextField(default=None, blank=True, null=True)
note = models.TextField(default=None, blank=True, null=True)

def __str__(self):
    return f"{self.property.name} - {self.date_start}"

class Meta:
    constraints = [
        models.CheckConstraint(
            name="%(app_label)s_%(class)s_tenant_not_null",
            check=(models.Q(tenant_person__isnull=False) | models.Q(tenant_company__isnull=False))
        ),
        models.CheckConstraint(
            name="%(app_label)s_%(class)s_landlord_not_null",
            check=(models.Q(landlord_person__isnull=False) | models.Q(landlord_company__isnull=False))
        )
    ]
2

It’s probably going to be helpful to see the migration file that is failing, and possibly helpful to see the Person and Company models.

3

Thank you for your reply and your time …

Here is the migration:

Generated by Django 3.1.5 on 2021-03-27 15:38

from django.db import migrations, models


class Migration(migrations.Migration):

    dependencies = [
        ('renting', '0004_auto_20210327_1415'),
    ]

    operations = [
        migrations.AddConstraint(
            model_name='rentcontract',
            constraint=models.CheckConstraint(check=models.Q(('tenant_person__isnull', False), ('tenant_company__isnull', False), _connector='OR'), name='renting_rentcontract_tenant_not_null'),
        ),
        migrations.AddConstraint(
            model_name='rentcontract',
            constraint=models.CheckConstraint(check=models.Q(('landlord_person__isnull', False), ('landlord_company__isnull', False), _connector='OR'), name='renting_rentcontract_landlord_not_null'),
        ),
    ]

Here is the Person model:

class Person(models.Model):
    firstname = models.CharField(max_length=100)
    lastname = models.CharField(max_length=100)
    address = models.ForeignKey(Address, on_delete=models.PROTECT, default=None, null=True, blank=True)
    company = models.ManyToManyField(Company, through='Position', default=None, blank=True)
    phone = models.CharField(max_length=50, default=None, blank=True, null=True)
    email = models.EmailField(default=None, blank=True, null=True)

    timestamp_updated = models.DateTimeField(auto_now=True)
    timestamp_created = models.DateField(auto_now_add=True)
    comment = models.TextField(default=None, blank=True, null=True)
    note = models.TextField(default=None, blank=True, null=True)

    def __str__(self):
        return f"{self.lastname} {self.firstname}"

    class Meta:
        ordering = ('lastname',)

and finaly the Company model:

class Company(models.Model):
    name = models.CharField(max_length=100)
    legal_form = models.CharField(max_length=35, default=None, blank=True, null=True)
    address = models.ForeignKey(Address, on_delete=models.PROTECT, default=None, null=True, blank=True)
    vat_number = models.CharField(max_length=100, default=None, null=True, blank=True)
    registration_number = models.CharField(max_length=100, default=None, null=True, blank=True)
    phone = models.CharField(max_length=50, default=None, blank=True, null=True)
    email = models.EmailField(default=None, blank=True, null=True)
    internal_uuid = models.CharField(max_length=35, default=None, null=True, blank=True)

    timestamp_updated = models.DateTimeField(auto_now=True)
    timestamp_created = models.DateField(auto_now_add=True)
    comment = models.TextField(default=None, blank=True, null=True)
    note = models.TextField(default=None, blank=True, null=True)

    def __str__(self):
        return f"{self.name} {self.legal_form}"

    class Meta:
        verbose_name_plural = 'Companies'
        ordering = ('name',)