Question

在Django 2.0项目中，我的单元测试存在以下问题，但我找不到原因。

- 更新：我使用的是Postgres 10.1。当我切换到sqlite3

时，不会发生此问题

我正在实施一个跟踪另一个模型的任何变化的模型

from django.db import models
from django.contrib.auth.models import User
from django.db.models.signals import post_save
from django.dispatch import receiver

class Investment(models.Model):
     """the main model"""
     status = models.IntegerField()


class InvestmentStatusTrack(models.Model):
    """track every change of status on an investment"""
    investment = models.ForeignKey(Investment, on_delete=models.CASCADE)
    status = models.IntegerField()
    modified_on = models.DateTimeField(
        blank=True, null=True, default=None, verbose_name=_('modified on'), db_index=True
    )
    modified_by = models.ForeignKey(
        User, blank=True, null=True, default=None, verbose_name=_('modified by'), on_delete=models.CASCADE
    )

    class Meta:
        ordering = ('-modified_on', )

    def __str__(self):
        return '{0} - {1}'.format(self.investment, self.status)


@receiver(post_save, sender=Investment)
def handle_status_track(sender, instance, created, **kwargs):
    """add a new track every time the investment status change"""
    request = get_request()  # a way to get the current request
    modified_by = None
    if request and request.user and request.user.is_authenticated:
        modified_by = request.user
    InvestmentStatusTrack.objects.create(
       investment=instance, status=instance.status, modified_on=datetime.now(), modified_by=modified_by
    )

我的大多数单元测试都失败并带有以下追溯

Traceback (most recent call last):
  File "/env/lib/python3.6/site-packages/django/test/testcases.py", line 209, in __call__
    self._post_teardown()
  File "/env/lib/python3.6/site-packages/django/test/testcases.py", line 893, in _post_teardown
    self._fixture_teardown()
  File "/env/lib/python3.6/site-packages/django/test/testcases.py", line 1041, in _fixture_teardown
    connections[db_name].check_constraints()
  File "/env/lib/python3.6/site-packages/django/db/backends/postgresql/base.py", line 235, in check_constraints
    self.cursor().execute('SET CONSTRAINTS ALL IMMEDIATE')
  File "/env/lib/python3.6/site-packages/django/db/backends/utils.py", line 68, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/env/lib/python3.6/site-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/env/lib/python3.6/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "/env/lib/python3.6/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/env/lib/python3.6/site-packages/django/db/backends/utils.py", line 83, in _execute
    return self.cursor.execute(sql)
django.db.utils.IntegrityError: insert or update on table "investments_investmentstatustrack" violates foreign key constraint "investments_investme_modified_by_id_3a12fb21_fk_auth_user"
DETAIL:  Key (modified_by_id)=(1) is not present in table "auth_user".

任何想法，如何解决这个问题？

- 更新：2单元测试，显示问题。

单独执行时两者都是成功的。似乎问题发生在单元测试tearDown上。外键约束此时失败，因为用户已被删除。

class TrackInvestmentStatusTest(ApiTestCase):

    def login(self, is_staff=False):
        password = "abc123"
        self.user = mommy.make(User, is_staff=is_staff, is_active=True)
        self.user.set_password(password)
        self.user.save()
        self.assertTrue(self.client.login(username=self.user.username, password=password))

    def test_add_investment(self):
        """it should add a new investment and add a track"""
        self.login()

        url = reverse('investments:investments-list')

        data = {}

        response = self.client.post(url, data=data)

        self.assertEqual(response.status_code, status.HTTP_201_CREATED)

        self.assertEqual(1, Investment.objects.count())
        investment = Investment.objects.all()[0]
        self.assertEqual(investment.status, Investment.STATUS_IN_PROJECT)

        self.assertEqual(1, InvestmentStatusTrack.objects.count())
        track = InvestmentStatusTrack.objects.all()[0]
        self.assertEqual(track.status, investment.status)
        self.assertEqual(track.investment, investment)
        self.assertEqual(track.modified_by, self.user)
        self.assertEqual(track.modified_on.date(), date.today())

    def test_save_status(self):
        """it should modify the investment and add a track"""

        self.login()

        investment_status = Investment.STATUS_IN_PROJECT

        investment = mommy.make(Investment, asset=asset, status=investment_status)
        investment_id = investment.id

        self.assertEqual(1, InvestmentStatusTrack.objects.count())
        track = InvestmentStatusTrack.objects.all()[0]
        self.assertEqual(track.status, investment.status)
        self.assertEqual(track.investment, investment)
        self.assertEqual(track.modified_by, None)
        self.assertEqual(track.modified_on.date(), date.today())

        url = reverse('investments:investments-detail', args=[investment.id])

        data = {
            'status': Investment.STATUS_ACCEPTED
        }

        response = self.client.patch(url, data=data)

        self.assertEqual(response.status_code, status.HTTP_200_OK)

        self.assertEqual(1, Investment.objects.count())
        investment = Investment.objects.all()[0]
        self.assertEqual(investment.id, investment_id)
        self.assertEqual(investment.status, Investment.STATUS_ACCEPTED)

        self.assertEqual(2, InvestmentStatusTrack.objects.count())
        track = InvestmentStatusTrack.objects.all()[0]
        self.assertEqual(track.status, Investment.STATUS_ACCEPTED)
        self.assertEqual(track.investment, investment)
        self.assertEqual(track.modified_by, self.user)
        self.assertEqual(track.modified_on.date(), date.today())

        track = InvestmentStatusTrack.objects.all()[1]
        self.assertEqual(track.status, Investment.STATUS_IN_PROJECT)
        self.assertEqual(track.investment, investment)
        self.assertEqual(track.modified_by, None)
        self.assertEqual(track.modified_on.date(), date.today())

Answer 1

我通过重构代码来解决问题。

现在我不在投资的GridLayoutManager manager = new GridLayoutManager(getContext(), 3, LinearLayoutManager.VERTICAL, false); manager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() { @Override public int getSpanSize(int position) { return position == 3 ? 3 : 1; } });方法内或save信号处理程序内创建轨道，而是在明确调用的方法中

我的代码如下：

models.py

post_save

<强> views.py

class Investment(models.Model):
    """the main model"""
    status = models.IntegerField()

    def handle_status_track(self):
        """add a new track every time the investment status change"""
        request = get_request()  # a way to get the current request
        modified_by = None
        if request and request.user and request.user.is_authenticated:
            modified_by = request.user
        InvestmentStatusTrack.objects.create(
            investment=self, status=self.status, modified_on=datetime.now(), modified_by=modified_by
        )


class InvestmentStatusTrack(models.Model):
    """track every change of status on an investment"""
    investment = models.ForeignKey(Investment, on_delete=models.CASCADE)
    status = models.IntegerField()
    modified_on = models.DateTimeField(
        blank=True, null=True, default=None, verbose_name=_('modified on'), db_index=True
    )
    modified_by = models.ForeignKey(
        User, blank=True, null=True, default=None, verbose_name=_('modified by'), on_delete=models.CASCADE
    )

    class Meta:
        ordering = ('-modified_on',)

问题是它不完全相同：我需要在保存对象的任何时候处理对方法的调用。我仍然想知道为什么class InvestmentViewSet(ViewSet): model = Investment serializer_class = InvestmentSerializer def perform_create(self, serializer): """save""" investment = serializer.save() investment.handle_status_track() def perform_update(self, serializer): """save""" investment = serializer.save() investment.handle_status_track()信号会导致此错误。

Django app：由于django.db.utils.IntegrityError

1 个答案: