after_commit 属性 [英] after_commit for an attribute

问题描述

我在我的应用程序中使用了 after_commit.

I am using an after_commit in my application.

我希望它仅在我的模型中更新特定字段时触发.有人知道怎么做吗?

I would like it to trigger only when a particular field is updated in my model. Anyone know how to do that?

推荐答案

老问题，但这是我发现的一种方法，可能适用于 after_commit 回调(处理 paukul 的回答).至少，这些值都在 IRB 提交后保持不变.

Old question, but this is one method that I've found that might work with the after_commit callback (working off paukul's answer). At least, the values both persist post-commit in IRB.

after_commit :callback, 
  if: proc { |record| 
    record.previous_changes.key?(:attribute) &&
      record.previous_changes[:attribute].first != record.previous_changes[:attribute].last
  }

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