Question

我可以成功运行所有单元测试，如果运行独立服务器，甚至可以成功运行硒测试，但是当我尝试使用LiveServerTestCases以独立方式测试所有内容时，每个LiveServerTestCase测试都以以下错误结束完成tearDown功能后：

  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\db\backends\base\base.py", line 239, in _commit
    return self.connection.commit()
django.db.utils.IntegrityError: FOREIGN KEY constraint failed

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\test\testcases.py", line 209, in __call__
    self._post_teardown()
  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\test\testcases.py", line 908, in _post_teardown
    self._fixture_teardown()
  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\test\testcases.py", line 943, in _fixture_teardown
    inhibit_post_migrate=inhibit_post_migrate)
  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\core\management\__init__.py", line 148, in call_command
    return command.execute(*args, **defaults)
  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\core\management\base.py", line 353, in execute
    output = self.handle(*args, **options)
  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\core\management\commands\flush.py", line 80, in handle
    emit_post_migrate_signal(verbosity, interactive, database)
  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\core\management\sql.py", line 51, in emit_post_migrate_signal
    **kwargs
  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\dispatch\dispatcher.py", line 175, in send
    for receiver in self._live_receivers(sender)
  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\dispatch\dispatcher.py", line 175, in <listcomp>
    for receiver in self._live_receivers(sender)
  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\contrib\auth\management\__init__.py", line 79, in create_permissions
    Permission.objects.using(using).bulk_create(perms)
  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\db\models\query.py", line 471, in bulk_create
    obj_without_pk._state.db = self.db
  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\db\transaction.py", line 212, in __exit__
    connection.commit()
  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\db\backends\base\base.py", line 261, in commit
    self._commit()
  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\db\backends\base\base.py", line 239, in _commit
    return self.connection.commit()
  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\db\utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\db\backends\base\base.py", line 239, in _commit
    return self.connection.commit()
django.db.utils.IntegrityError: FOREIGN KEY constraint failed

我很确定我的数据库模型中没有任何错误，因为当我启动一个单独的服务器实例以并行运行时，所有单元测试运行良好，硒测试运行良好，所以猜猜它与硒有关吗？

我尝试使用Chrome网络驱动程序，IE网络驱动程序和Firefox网络驱动程序。结果相同。它似乎与我的数据库无关，因为该错误仅发生在LiveServerTestCases上。

环境详细信息

Django 2.1版
SQLite3版本3.20.0

Answer 1

有关 Django 版本，数据库 type 和 version 的更多信息连同您的代码试用版可以帮助我们更好地调试此问题。

但是，此错误消息...

File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\core\management\sql.py", line 51, in emit_post_migrate_signal **kwargs
.
File "C:\Users\Win7\.virtualenvs\lang-QbOXb8q_\lib\site-packages\django\db\backends\base\base.py", line 239, in _commit
    return self.connection.commit()
django.db.utils.IntegrityError: FOREIGN KEY constraint failed

...表示在尝试保存现有模型实例时引发了 IntegrityError 。

根据Django 2.0 release notes：

Foreign key constraints are now enabled on SQLite：这是向后不兼容的更改（ IntegrityError：FOREIGN KEY约束失败），如果尝试保存违反外键约束的现有模型实例。
外键现在使用可延期初始递延而不是可立即递延创建。因此，可能需要重建表以使用新定义重新创建外键，尤其是如果您使用以下模式；
```
from django.db import transaction

with transaction.atomic():
    Book.objects.create(author_id=1)
    Author.objects.create(id=1)
```
如果不将外键重新创建为 DEFERRED ，则第一个 create() 将失败，因为将强制执行外键约束。 / p>

discussion

@dirkgroten提供了一个示例，如下所示：
- 在您的代码中查找如下所示的模式：
```
 # in pagetree/models.py, line 810
 @classmethod
 def create_from_dict(cls, d):
    return cls.objects.create()  # what happens to d by the way?
```
- 这肯定会因ForeignKey constraint 错误而失败，因为PageBlock必须具有部分，所以您不能在未先分配它的情况下调用create。

django.db.utils.IntegrityError：通过Selenium和Python Django执行LiveServerTestCases时，FOREIGN KEY约束失败

环境详细信息

1 个答案: