Django flush引发“不能截断外键约束中引用的表”

考虑以下几点 models.py :

from django.db import models

class Foo(models.Model):
    bars = models.ManyToManyField(
        "Bar",
        blank=True
    )

class Bar(models.Model):
    foos = models.ManyToManyField(
        "Foo",
        blank=True,
        through="Foo_bars"
    )

以及相关的迁移:

from django.db import migrations, models


class Migration(migrations.Migration):
    initial = True

    dependencies = []

    operations = [
        migrations.CreateModel(
            name="Bar",
            fields=[
                (
                    "id",
                    models.BigAutoField(
                        auto_created=True,
                        primary_key=True,
                        serialize=False,
                        verbose_name="ID",
                    ),
                ),
            ],
        ),
        migrations.CreateModel(
            name="Foo",
            fields=[
                (
                    "id",
                    models.BigAutoField(
                        auto_created=True,
                        primary_key=True,
                        serialize=False,
                        verbose_name="ID",
                    ),
                ),
                ("bars", models.ManyToManyField(blank=True, to="demo.bar")),
            ],
        ),
        migrations.AddField(
            model_name="bar",
            name="foos",
            field=models.ManyToManyField(blank=True, to="demo.foo"),
        ),
    ]

跑步

python manage.py migrate && python manage.py flush --no-input --traceback

生成以下回溯

  File "/opt/venv/lib/python3.13/site-packages/psycopg/cursor.py", line 97, in execute
    raise ex.with_traceback(None)
django.db.utils.NotSupportedError: cannot truncate a table referenced in a foreign key constraint
DETAIL:  Table "demo_bar_foos" references "demo_foo".
HINT:  Truncate table "demo_bar_foos" at the same time, or use TRUNCATE ... CASCADE.

我该如何解决这个问题?如何添加级联?

完整的可复制示例可在 https://github.com/rgaiacs/django-flush-problem .