ruby-on-rails - Rails - 依赖 => destroy 遵循什么顺序？

Question

鉴于这个例子:

class Server < ActiveRecord::Base
  has_many :clients,:dependent => :destroy 
  after_destroy: delete_server_directory
end

class Client < ActiveRecord::Base
  belongs_to :server

  before_destroy :copy_some_important_stuff_from_the_server_directory_before_its_too_late
end

这会是我打电话时的破坏顺序 server.destroy吗？ ?

Server#clients ，以及 Client的 before/after_destroy回调

Server将被摧毁

其次是 Server的 after_destroy回调

Answer 1

您可以非常轻松地进行测试。我接受了您的代码，并通过对 puts 的简单调用实现了回调。 .然后推出script/console并将 ActiveRecord 日志记录到控制台:

>> ActiveRecord::Base.logger = Logger.new(STDOUT)
=> #<Logger:0x0000000308d2f0 ...>

设置一些基本环境:

>> a = Client.create :name => 'Client 1'
  Client Create (0.4ms)   INSERT INTO "clients" ("name", "server_id") VALUES('Client 1', NULL)
=> #<Client id: 1, name: "Client 1", server_id: nil>
>> b = Client.create :name => 'Client 2'
  Client Create (0.5ms)   INSERT INTO "clients" ("name", "server_id") VALUES('Client 2', NULL)
=> #<Client id: 2, name: "Client 2", server_id: nil>
>> server = Server.create :name => 'The Server'
  Server Create (0.3ms)   INSERT INTO "servers" ("name") VALUES('The Server')
=> #<Server id: 1, name: "The Server">
>> server.clients = [a, b]
  Client Load (0.4ms)   SELECT * FROM "clients" WHERE ("clients".server_id = 1) 
  Client Update (0.4ms)   UPDATE "clients" SET "server_id" = 1 WHERE "id" = 1
  Client Update (0.2ms)   UPDATE "clients" SET "server_id" = 1 WHERE "id" = 2
=> [#<Client id: 1, name: "Client 1", server_id: 1>, #<Client id: 2, name: "Client 2", server_id: 1>]

这是它的要点:

>> server.destroy
>>> copy_some_important_stuff_from_the_server_directory_before_its_too_late called!
  Client Destroy (0.5ms)   DELETE FROM "clients" WHERE "id" = 1
>>> copy_some_important_stuff_from_the_server_directory_before_its_too_late called!
  Client Destroy (0.2ms)   DELETE FROM "clients" WHERE "id" = 2
  Server Destroy (0.2ms)   DELETE FROM "servers" WHERE "id" = 1
>>> delete_server_directory called!
=> #<Server id: 1, name: "The Server">

所以看起来你已经瞄准了目标。 :)

附言

服务器模型的 after_destroy 中有一个小的语法错误.

我假设在第 1 步中您的意思是 before_destroy ，如您的示例所示。