Django 抽象模型 + DB 迁移 : tests throw "cannot ALTER TABLE because it has pending trigger events"

Question

我想编写一个抽象模型 mixin，我可以用它来创建 OneToOne - 与用户模型的关系。这是我的代码:

from django.conf import settings
from django.db import models


class Userable(models.Model):
    user = models.OneToOneField(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE
    )

    class Meta:
        abstract = True

我为此模型编写了以下测试:

class TestUserable(TestCase):

    mixin = Userable

    def setUp(self):
        user = User.objects.create_user(
            email="testuser@test.com",
            name="Test User",
            password="test1234test"
        )
        self.user = user
        self.model = ModelBase(
            '__TestModel__' + self.mixin.__name__, (self.mixin,),
            {'__module__': self.mixin.__module__}
        )

        with connection.schema_editor() as schema_editor:
            schema_editor.create_model(self.model)

    def test_user(self):
        self.model.objects.create(user=self.user)
        self.assertEqual(self.model.objects.count(), 1)

    def tearDown(self):
        with connection.schema_editor() as schema_editor:
            schema_editor.delete_model(self.model)

我的问题是，这个测试是 tearDown()方法抛出以下错误:

django.db.utils.OperationalError: cannot DROP TABLE "core___testmodel__userable" because it has pending trigger events

这可能是什么原因？我确实跑了 python manage.py makemigrations和 python manage.py migrate ，但没有挂起的迁移(正如预期的那样，因为这是一个抽象模型)。

编辑:它似乎与 OneToOneFields 或 ForeignKeys(关系)有关。如果我将此代码更改为常规字段，如 CharFields 或 IntegerFields，它会起作用。

EDIT2:如果您有另一种更好的方法来测试使用外键的抽象基本模型，请告诉我!

Answer 1

测试抽象模型的常见做法是为测试创建实际模型

这是 model-utils 中的示例项目https://github.com/jazzband/django-model-utils/blob/master/tests/test_models/test_timestamped_model.py

from tests.models import UserableTest

class TestUserable(TestCase):
    def setUp(self):
        user = User.objects.create_user(
            email="testuser@test.com",
            name="Test User",
            password="test1234test"
        )
        self.user = user

    def test_user(self):
        UserableTest.objects.create(user=self.user)
        self.assertEqual(UserableTest.objects.count(), 1)

在这个项目中，他们有单独的设置 DJANGO_SETTINGS_MODULE = tests.settings https://github.com/jazzband/django-model-utils/blob/master/tests/settings.py

INSTALLED_APPS = (
    'model_utils',
    'tests',
)
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3'
    }
}
SECRET_KEY = 'dummy'

模型在 https://github.com/jazzband/django-model-utils/blob/master/tests/models.py 中描述

from myapp.models import Userable

class UserableTest(Userable):
    pass