[Python] Issue with Django CheckConstraint

I'm trying to add some new fields to an existing model and also a constraint related to those new fields:

class User(models.Model):
username = models.CharField(max_length=32)

# New fields ##################################
has_garden = models.BooleanField(default=False)
garden_description = models.CharField(
max_length=32,
null=True,
blank=True,
)

class Meta:
constraints = [
models.CheckConstraint(
check=Q(has_garden=models.Value(True))
& Q(garden_description__isnull=True),
name="garden_description_if_has_garden",
)
]



The problem is that when I run my migrations I get the following error:

django.db.utils.IntegrityError: check constraint "garden_description_if_has_garden" is violated by some row


But I don't understand how the constraint is being violated if no User has a has_garden, the field is just being created and also its default value is False .

I'm using django 3.2 with postgresql.

What is the proper way to add this constraint? If it's of any use here's the autogenerated migration:

# Generated by Django 3.2.25 on 2025-01-15 23:52

import django.db.models.expressions
from django.db import migrations, models


class Migration(migrations.Migration):

dependencies = [
("some_app", "0066_user"),
]

operations = [
migrations.AddField(
model_name="user",
name="garden_description",
field=models.CharField(blank=True, max_length=32, null=True),
),
migrations.AddField(
model_name="user",
name="has_garden",
field=models.BooleanField(default=False),
),
migrations.AddConstraint(
model_name="user",
constraint=models.CheckConstraint(
check=models.Q(
("has_garden", django.db.models.expressions.Value(True)),
("garden_description__isnull", True),
),
name="garden_description_if_has_garden",
),
),
]

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