当两个不同的用户在 Django 中向数据库插入新记录时的竞争条件
当我想创建模型 Order 的新实例时，会出现竞争条件情况。
有一个 daily_id 字段，任何类别的每一天都从 1 开始。这意味着每个类别都有自己的每日 ID。
class Order(models.Model):
daily_id = models.SmallIntegerField(default=0)
category = models.ForeignKey(Categoty, on_delete=models.PROTECT, related_name="orders")
declare_time = models.DateField()
...
}
使用这种方法计算新记录的 daily_id 字段：
def get_daily_id(category, declare_time):
try:
last_order = Order.objects.filter(declare_time=declare_time,
category=category).latest('daily_id')
return last_order.daily_id + 1
except Order.DoesNotExist:
# If no order has been registered in declare_time date.
return 1
问题是，当两个不同的用户同时注册同一类别的订单时，订单很可能存在重复的 <代码>daily_id 值。
我已经尝试过 DRF APIView 的 post 方法的 @transaction.atomic 装饰器，但它不起作用！
There is a race condition situation, when I want to create a new instance of model Order.
There is a daily_id field that everyday for any category starts from one. It means every category has its own daily id.
class Order(models.Model):
daily_id = models.SmallIntegerField(default=0)
category = models.ForeignKey(Categoty, on_delete=models.PROTECT, related_name="orders")
declare_time = models.DateField()
...
}
daily_id field of new record is being calculated using this method:
def get_daily_id(category, declare_time):
try:
last_order = Order.objects.filter(declare_time=declare_time,
category=category).latest('daily_id')
return last_order.daily_id + 1
except Order.DoesNotExist:
# If no order has been registered in declare_time date.
return 1
The problem is that when two different users are registering orders in the same category at the same time, it is highly likely that the orders have the repetitive daily_id values.
I have tried @transaction.atomic decorator for post method of DRF APIView and it didn't work!
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您必须使用自动增量并添加一个计算语义顺序的视图，例如：
You must use an auto increment and add a view that computes your semantic order like :