使用 after_save 回调修改同一个对象而不再次触发回调(递归) [英] Using the after_save callback to modify the same object without triggering the callback again (recursion)
问题描述
如果我向 ActiveRecord 模型添加 after_save 回调，并且在该回调中我使用 update_attribute 更改对象，则会再次调用回调，因此会发生堆栈溢出"(呵呵，无法抗拒).
If I add an after_save callback to an ActiveRecord model, and on that callback I use update_attribute to change the object, the callback is called again, and so a 'stack overflow' occurs (hehe, couldn't resist).
是否可以避免这种行为，也许可以在执行期间禁用回调?或者还有其他方法吗?
Is it possible to avoid this behavior, maybe disabling the callback during it's execution? Or is there another approach?
谢谢！
推荐答案
一种解决方法是在类中设置一个变量，并在 after_save 中检查其值.
One workaround is to set a variable in the class, and check its value in the after_save.
- 先检查一下.(如果变量)
- 在调用 update_attribute 之前将其指定为false"值.
- 调用 update_attribute.
- 将其分配给真"值.
- 结束
这样，它只会尝试保存两次.这可能会两次访问您的数据库，这可能会也可能不会.
This way, it'll only attempt to save twice. This will likely hit your database twice, which may or may not be desirable.
我有一种模糊的感觉，即内置了一些东西，但这是一种相当万无一失的方法，可以防止几乎所有应用程序中的特定递归点.我还建议再次查看代码，因为很可能您在 after_save 中所做的任何事情都应该在 before_save 中完成.有时这不是真的，但这种情况相当罕见.
I have a vague feeling that there's something built in, but this is a fairly foolproof way to prevent a specific point of recursion in just about any application. I would also recommend looking at the code again, as it's likely that whatever you're doing in the after_save should be done in before_save. There are times that this isn't true, but they're fairly rare.
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