仅在交易完成后才触发post_save信号 [英] Trigering post_save signal only after transaction has completed

问题描述

我已经编写了一些API，它们的相应功能在事务块内执行.我正在对一个或多个Model/s的实例调用save()方法(经过一些修改)，并且还在 Elasticsearch 中连续索引该实例的一些与JSON相关的信息.我希望数据库回滚，即使出于某些原因，其中一个实例的save()或索引到 Elasticsearch 的操作失败.

I have written some APIs, for which the respective functions executive inside a transaction block. I am calling the save() method (after some modifications) on instance/s of a/several Model/s, and also consecutively indexing some JSON related information of the instance/s in Elasticsearch. I want the database to rollback even if for some reason the save() for one of the instances or indexing to the Elasticsearch fails.

现在，出现的问题是，即使在事务块内部，也会调用post_save()信号，这是一个问题，因为从那些信号触发了一些通知.

Now, the problem is arising that even inside the transaction block, the post_save() signals gets called, and that is an issue because some notifications are being triggered from those signals.

是否只有在交易成功完成后才触发post_save()信号?

Is there a way to trigger post_save() signals only after the transactions have completed successful?

推荐答案

不是.该信号与db事务的成功或失败无关，但与save方法本身无关-在调用之前，您触发了pre_save信号，在调用之后，您触发了post_save信号.

Not really. The signals have nothing to do with the db transaction success or failure, but with the save method itself - before the call you have the pre_save signal fired and after the call you have the post_save signal fired.

这里有2种方法:

• 您将使用post_save方法检查实例，并确定模型是否成功保存；最简单的方法是:在save方法中，成功执行事务后，用一个标记instance.saved_successfully = True注释您的实例，您将在post_save处理程序中对其进行测试.
• 您将放弃post_save信号并为您自己创建一个自定义信号，您将在交易成功运行后触发该信号.

• you are going to inspect the instance in the post_save method and decide that the model was saved successfully or not; simplest way to do that: in the save method, after the transaction executed successfully, annotate your instance with a flag, say instance.saved_successfully = True, which you will test in the post_save handler.
• you are going to ditch the post_save signal and create a custom signal for yourself, which you will trigger after the transaction ran successfully.

有道理吗?

P.S.

如果您严格需要绑定到事务提交信号，请查看以下程序包:

If you strictly need to bind to the transaction commit signal, have a look over this package: https://django-transaction-hooks.readthedocs.org/en/latest/; it looks like the functionality is integrated in Django 1.9a.

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