Question

对于Mongoid 3+，是否有各种回调的图表/描述？ http://mongoid.org/en/mongoid/v3/callbacks.html

例如，before_upsert与before_save之间的区别是什么。由save或insert电话引起的update不是吗？或save也会调用destroy？

另外，before_xxx和around_xxx之间有什么区别？

干杯，

Answer 1

使用before_xxx，代码在操作之前执行，使用around_xxx，您可以选择在操作本身之前和之后执行代码。

例如，假设您想在销毁用户项目后更新所有用户所有物（User has_many：proyects和Project belongs_to User）：

class ProjectsController < ApplicationController

  around_destroy :destroy_belongings

  def destroy_belongings
    old_user = self.user
    ...
    # Here the before_destroy ends.

    yield # Here the destroy is performed itself.

    # Here the after_destroy starts. It's needed to do this operation after destroy the project because, imagine, the update_belongings method calculates something related to the current number of proyects. And a simple after_destroy is not useful as we would have lost the project owner.

    old_user.update_belongings
  end
end

您还可以查看相关答案here和here。此外this other article可能对您有用。

Mongoid 3回调：before_upsert与before_save

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