Django - 引发错误后在 transaction.atomic 块中操作数据库

Question

我想在 transaction.atomic() 块中对我的数据库执行操作，即使在引发错误的情况下也是如此。这是一些示例代码来演示我的问题：

示例代码

# Outer try block
try:

    # Enclose in atomic transaction for database rollbacks
    with transaction.atomic():

        # If this line fails, all database updates within the outer try: block should be rolled back
        u = UU.create(email='test@test.com')

        # Inner try block
        try:
            cc = CC.objects.get(id=1)
            perform_action(cc)

        # If this exception triggers, the 'cc' object should be deleted, but all other database updates within the outer try: block should be rolled back
        except:
            cc.delete()
            raise

        # If this line fails, all database updates within the outer try: block should be rolled back
        u = UU.create(email='test@test.com')

# If any exception triggers, this error should be printed
except:
    print("Error occured.")

如果我的内部try: 块中发生错误，我希望删除cc 对象，但要回滚外部try: 块中的所有其他数据库事务。但是，就目前的代码而言，如果内部 try: 块内发生任何错误，cc.delete() 事务将被回滚。

有什么建议吗？

Answer 1

您不能只保留数据库事务的一部分，也不能在回滚外部事务的同时保留内部事务。

相反，您可以使用自定义异常发出特定错误状态的信号，然后在回滚后捕获它时进行额外处理。比如：

class BadCCException(Exception):
    def __init__(self, badid):
        super().__init__()
        self.badid = badid

try:
    with transaction.atomic():
        u = UU.create(email='test@test.com')

        try:
            cc = CC.objects.get(id=1)
            perform_action(cc)
        except Exception as e:
            raise BadCCException(1) from e

        u = UU.create(email='test@test.com')
except BadCCException as e:
    CC.objects.filter(id=e.badid).delete()
    print("Error occured.")
except:
    print("Error occured.")