即使没有任何变化，activeModel::dirty 记录也会发生变化

Question

我正在使用 ActiveModel::Dirty 库。我有以下代码：

def tasks_changed?
   @changed = false
   self.tasks.each do |task|
     if task.previous_changes.any?
       @changed = true
       puts 'task changed so no update'
       puts 'this task changed' + task.inspect.to_s
       puts 'here are the changes' + task.previous_changes.to_s
     end
   end
   return @changed
end

如果用户更改表单中的某些内容，此方法会更改控制器的行为。问题是其中一个字段是日期时间，并且由于某种原因，previous_changes 认为日期时间每次都会更改，无论它是否已更改。

控制台甚至告诉我没有任何变化。以下是上述 puts 语句在控制台中产生的内容：

task changed so no update
this task changed#<Task id: 19, title: "task 1", content: "task 2 content", created_at: "2014-03-11 17:33:26", updated_at: "2014-03-11 20:00:01", schedule_id: 1, amount: nil, time_frame: "2014-03-27 20:00:00", state: "incomplete", denied: 0, order_number: 0, finished_description: nil>
here are the changes{"time_frame"=>[Thu, 27 Mar 2014 16:00:00 EDT -04:00, Thu, 27 Mar 2014 16:00:00 EDT -04:00], "updated_at"=>[Tue, 11 Mar 2014 15:57:44 EDT -04:00, Tue, 11 Mar 2014 16:00:01 EDT -04:00]}
task changed so no update
this task changed#<Task id: 21, title: "task 2", content: "task 2 content", created_at: "2014-03-11 17:42:18", updated_at: "2014-03-11 20:00:01", schedule_id: 1, amount: nil, time_frame: "2014-03-29 20:00:00", state: "incomplete", denied: 0, order_number: 1, finished_description: nil>
here are the changes{"time_frame"=>[Sat, 29 Mar 2014 16:00:00 EDT -04:00, Sat, 29 Mar 2014 16:00:00 EDT -04:00], "updated_at"=>[Tue, 11 Mar 2014 15:57:44 EDT -04:00, Tue, 11 Mar 2014 16:00:01 EDT -04:00]}
task changed so no update
this task changed#<Task id: 22, title: "task 3 ", content: "change", created_at: "2014-03-11 18:43:23", updated_at: "2014-03-11 20:00:01", schedule_id: 1, amount: nil, time_frame: "2014-03-31 20:00:00", state: "incomplete", denied: 0, order_number: 2, finished_description: nil>
here are the changes{"time_frame"=>[Mon, 31 Mar 2014 16:00:00 EDT -04:00, Mon, 31 Mar 2014 16:00:00 EDT -04:00], "updated_at"=>[Tue, 11 Mar 2014 15:57:44 EDT -04:00, Tue, 11 Mar 2014 16:00:01 EDT -04:00]}

我的基本问题是为什么 previous_changes 每次都认为有变化，我该如何解决？

Answer 1

至少timeframe 和updated_at 发生了变化。请注意，时间对象不仅仅包含秒数，而且 inspect 方法不显示例如毫秒。

但是如果不提供执行此操作的代码，没有人能够告诉您为什么会发生这种情况。