TransactionManagementError“使用信号时，您只能在'atomic'块的末尾才能执行查询”，但仅限于单元测试期间

尝试保存Django用户模型实例时，我收到TransactionManagementError，并在其post_save信号中，保存了一些将用户作为外键的模型。

使用信号时，上下文和错误与此问题django TransactionManagementError非常相似

但是，在这种情况下，错误仅在单元测试时发生。

它在手动测试中效果很好，但是单元测试失败。

有什么我想念的吗？

以下是代码片段：

views.py

@csrf_exempt
def mobileRegister(request):
    if request.method == 'GET':
        response = {"error": "GET request not accepted!!"}
        return HttpResponse(json.dumps(response), content_type="application/json",status=500)
    elif request.method == 'POST':
        postdata = json.loads(request.body)
        try:
            # Get POST data which is to be used to save the user
            username = postdata.get('phone')
            password = postdata.get('password')
            email = postdata.get('email',"")
            first_name = postdata.get('first_name',"")
            last_name = postdata.get('last_name',"")
            user = User(username=username, email=email,
                        first_name=first_name, last_name=last_name)
            user._company = postdata.get('company',None)
            user._country_code = postdata.get('country_code',"+91")
            user.is_verified=True
            user._gcm_reg_id = postdata.get('reg_id',None)
            user._gcm_device_id = postdata.get('device_id',None)
            # Set Password for the user
            user.set_password(password)
            # Save the user
            user.save()

信号

def create_user_profile(sender, instance, created, **kwargs):
    if created:
        company = None
        companycontact = None
        try:   # Try to make userprofile with company and country code provided
            user = User.objects.get(id=instance.id)
            rand_pass = random.randint(1000, 9999)
            company = Company.objects.get_or_create(name=instance._company,user=user)
            companycontact = CompanyContact.objects.get_or_create(contact_type="Owner",company=company,contact_number=instance.username)
            profile = UserProfile.objects.get_or_create(user=instance,phone=instance.username,verification_code=rand_pass,company=company,country_code=instance._country_code)
            gcmDevice = GCMDevice.objects.create(registration_id=instance._gcm_reg_id,device_id=instance._gcm_reg_id,user=instance)
        except Exception, e:
            pass

tests.py

class AuthTestCase(TestCase):
    fixtures = ['nextgencatalogs/fixtures.json']
    def setUp(self):
        self.user_data={
            "phone":"0000000000",
            "password":"123",
            "first_name":"Gaurav",
            "last_name":"Toshniwal"
            }

    def test_registration_api_get(self):
        response = self.client.get("/mobileRegister/")
        self.assertEqual(response.status_code,500)

    def test_registration_api_post(self):
        response = self.client.post(path="/mobileRegister/",
                                    data=json.dumps(self.user_data),
                                    content_type="application/json")
        self.assertEqual(response.status_code,201)
        self.user_data['username']=self.user_data['phone']
        user = User.objects.get(username=self.user_data['username'])
        # Check if the company was created
        company = Company.objects.get(user__username=self.user_data['phone'])
        self.assertIsInstance(company,Company)
        # Check if the owner's contact is the same as the user's phone number
        company_contact = CompanyContact.objects.get(company=company,contact_type="owner")
        self.assertEqual(user.username,company_contact[0].contact_number)

追溯：

======================================================================
ERROR: test_registration_api_post (nextgencatalogs.apps.catalogsapp.tests.AuthTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/gauravtoshniwal1989/Developer/Web/Server/ngc/nextgencatalogs/apps/catalogsapp/tests.py", line 29, in test_registration_api_post
    user = User.objects.get(username=self.user_data['username'])
  File "/Users/gauravtoshniwal1989/Developer/Web/Server/ngc/ngcvenv/lib/python2.7/site-packages/django/db/models/manager.py", line 151, in get
    return self.get_queryset().get(*args, **kwargs)
  File "/Users/gauravtoshniwal1989/Developer/Web/Server/ngc/ngcvenv/lib/python2.7/site-packages/django/db/models/query.py", line 301, in get
    num = len(clone)
  File "/Users/gauravtoshniwal1989/Developer/Web/Server/ngc/ngcvenv/lib/python2.7/site-packages/django/db/models/query.py", line 77, in __len__
    self._fetch_all()
  File "/Users/gauravtoshniwal1989/Developer/Web/Server/ngc/ngcvenv/lib/python2.7/site-packages/django/db/models/query.py", line 854, in _fetch_all
    self._result_cache = list(self.iterator())
  File "/Users/gauravtoshniwal1989/Developer/Web/Server/ngc/ngcvenv/lib/python2.7/site-packages/django/db/models/query.py", line 220, in iterator
    for row in compiler.results_iter():
  File "/Users/gauravtoshniwal1989/Developer/Web/Server/ngc/ngcvenv/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 710, in results_iter
    for rows in self.execute_sql(MULTI):
  File "/Users/gauravtoshniwal1989/Developer/Web/Server/ngc/ngcvenv/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 781, in execute_sql
    cursor.execute(sql, params)
  File "/Users/gauravtoshniwal1989/Developer/Web/Server/ngc/ngcvenv/lib/python2.7/site-packages/django/db/backends/util.py", line 47, in execute
    self.db.validate_no_broken_transaction()
  File "/Users/gauravtoshniwal1989/Developer/Web/Server/ngc/ngcvenv/lib/python2.7/site-packages/django/db/backends/__init__.py", line 365, in validate_no_broken_transaction
    "An error occurred in the current transaction. You can't "
TransactionManagementError: An error occurred in the current transaction. You can't execute queries until the end of the 'atomic' block.

----------------------------------------------------------------------

我本人也遇到了同样的问题。这是由于在较新版本的Django中如何处理事务的古怪之处，加上故意触发异常的单元测试。

我有一个单元测试，通过有意触发IntegrityError异常来检查以确保实施了唯一的列约束：

def test_constraint(self):
    try:
        # Duplicates should be prevented.
        models.Question.objects.create(domain=self.domain, slug='barks')
        self.fail('Duplicate question allowed.')
    except IntegrityError:
        pass

    do_more_model_stuff()

在Django 1.4中，这可以正常工作。但是，在Django 1.5 / 1.6中，每个测试都包装在一个事务中，因此，如果发生异常，它将破坏该事务，直到您明确地将其回滚为止。因此，该事务中任何进一步的ORM操作（例如my do_more_model_stuff()）都将因该django.db.transaction.TransactionManagementError异常而失败。

就像注释中提到的caio一样，解决方案是使用以下方式捕获您的异常transaction.atomic：

from django.db import transaction
def test_constraint(self):
    try:
        # Duplicates should be prevented.
        with transaction.atomic():
            models.Question.objects.create(domain=self.domain, slug='barks')
        self.fail('Duplicate question allowed.')
    except IntegrityError:
        pass

这将防止故意抛出的异常破坏整个单元测试的事务。

由于@mkoistinen从未发表过他的评论（答案），因此我将发布他的建议，这样人们就不必再仔细研究评论了。

考虑只将测试类声明为TransactionTestCase而不是TestCase。

从文档：TransactionTestCase可以调用提交和回滚，并观察这些调用对数据库的影响。

如果使用pytest-django，则可以传递transaction=True给django_db装饰器以避免此错误。

请参阅https://pytest-django.readthedocs.io/en/latest/database.html#testing-transactions

Django本身具有TransactionTestCase，可让您测试事务并在两次测试之间刷新数据库以隔离它们。缺点是，由于需要刷新数据库，因此这些测试的建立速度要慢得多。pytest-django也支持这种测试风格，您可以使用django_db标记的参数进行选择：

@pytest.mark.django_db(transaction=True)
def test_spam():
    pass  # test relying on transactions

对我来说，建议的修复程序不起作用。在我的测试中，我打开了一些Popen用于分析/皮棉迁移的子流程（例如，一项测试检查是否没有模型更改）。

对我来说，从而SimpleTestCase不是继承TestCase确实可以解决问题。

请注意，SimpleTestCase不允许使用数据库。

尽管这不能回答最初的问题，但我希望这对某些人有帮助。

这是基于此问题的答案的另一种方法：

with transaction.atomic():
    self.assertRaises(IntegrityError, models.Question.objects.create, **{'domain':self.domain, 'slug':'barks'})

我在使用Django 1.9.7在create_test_data函数中运行单元测试时遇到此错误。它在Django的早期版本中工作。

它看起来像这样：

cls.localauth,_ = Organisation.objects.get_or_create(organisation_type=cls.orgtypeLA, name='LA for test', email_general='test@test.com', address='test', postcode='test', telephone='test')
cls.chamber,_ = Organisation.objects.get_or_create(organisation_type=cls.orgtypeC, name='chamber for test', email_general='test@test.com', address='test', postcode='test', telephone='test')
cls.lawfirm,_ = Organisation.objects.get_or_create(organisation_type=cls.orgtypeL, name='lawfirm for test', email_general='test@test.com', address='test', postcode='test', telephone='test')

cls.chamber.active = True
cls.chamber.save()

cls.localauth.active = True
cls.localauth.save()    <---- error here

cls.lawfirm.active = True
cls.lawfirm.save()

我的解决方案是改用update_or_create：

cls.localauth,_ = Organisation.objects.update_or_create(organisation_type=cls.orgtypeLA, name='LA for test', email_general='test@test.com', address='test', postcode='test', telephone='test', defaults={'active': True})
cls.chamber,_ = Organisation.objects.update_or_create(organisation_type=cls.orgtypeC, name='chamber for test', email_general='test@test.com', address='test', postcode='test', telephone='test', defaults={'active': True})
cls.lawfirm,_ = Organisation.objects.update_or_create(organisation_type=cls.orgtypeL, name='lawfirm for test', email_general='test@test.com', address='test', postcode='test', telephone='test', defaults={'active': True})

我有同样的问题，但with transaction.atomic()和TransactionTestCase我没有工作。

python manage.py test -r而不是python manage.py test对我来说没关系，也许执行顺序很关键

然后我找到了有关要在其中执行测试的Order的文档，其中提到了哪个测试将首先运行。

因此，我使用TestCase进行数据库交互，unittest.TestCase进行其他简单测试，现在可以使用！

@kdazzle的答案是正确的。我没有尝试过，因为人们说“ Django的TestCase类是TransactionTestCase的一个更常用的子类”，所以我认为它的用途是相同的。但是Jahongir Rahmonov的博客对此进行了更好的解释：

TestCase类将测试包装在两个嵌套的atomic（）块内：一个用于整个类，一个用于每个测试。这是应该使用TransactionTestCase的地方。它不使用atomic（）块包装测试，因此您可以测试需要事务的特殊方法，而不会出现任何问题。

编辑：这没有用，我想是的，但是没有。

他们可以在4年内解决此问题....................................

def test_wrong_user_country_db_constraint(self):
        """
        Check whether or not DB constraint doesnt allow to save wrong country code in DB.
        """
        self.test_user_data['user_country'] = 'XX'
        expected_constraint_name = "country_code_within_list_of_countries_check"

        with transaction.atomic():
            with self.assertRaisesRegex(IntegrityError, expected_constraint_name) as cm:
                get_user_model().objects.create_user(**self.test_user_data)

        self.assertFalse(
            get_user_model().objects.filter(email=self.test_user_data['email']).exists()
        )

with transaction.atomic() seems do the job correct

我遇到过同样的问题。

就我而言，我正在这样做

author.tasks.add(tasks)

所以将其转换为

author.tasks.add(*tasks)

删除了该错误。