Rails活动记录未按预期保存

Question

我有一个更新方法，它没有按预期方式保存数据库记录。

基本上，正在发生的是排列_id没有保存到时隙表中，正如我期望的那样，使用以下方法。

从我变量的输出之后save! 的我会认为，Transactions_id将保存在时隙表中。

谁能告诉我为什么不是这样，我在做什么错呢？

# PUT /arrangements/1
  def update
    success = false

    @arrangement = Arrangement.find(params[:id])

    # Remove arrangement id from old timeslot
        old_timeslot = Timeslot.find(@arrangement.timeslot_id)
        old_timeslot.arrangement_id = nil

        # Save arrangement id to new timeslot
        new_timeslot = Timeslot.find(@arrangement.timeslot_id)
        new_timeslot.arrangement_id = @arrangement.id

        p "old_timeslot = #{old_timeslot.inspect}"
        p "new_timeslot = #{new_timeslot.inspect}"

        old_timeslot.save!
        new_timeslot.save!

        p "after save old_timeslot = #{old_timeslot.inspect}"
        p "after save new_timeslot = #{new_timeslot.inspect}"

        @arrangement.update_attributes!(params[:arrangement])
        success = true

    respond_to do |format|
      if success
        format.html { redirect_to @arrangement, notice: 'Arrangement was successfully updated.' }
      else
        format.html { render action: "edit" }
      end
    end
  end

这是控制台输出：

# These are before the old_timeslot and new_timeslot variables are saved
"old_timeslot = #<Timeslot id: 17306, location_id: 3, arrangement_id: nil, timeslot: \"2014-01-10 17:00:00\", created_at: \"2013-05-20 04:03:30\", updated_at: \"2014-01-11 01:35:55\">"
"new_timeslot = #<Timeslot id: 17306, location_id: 3, arrangement_id: 839, timeslot: \"2014-01-10 17:00:00\", created_at: \"2013-05-20 04:03:30\", updated_at: \"2014-01-11 01:35:55\">"

# These are after the old_timeslot and new_timeslot variables are saved
"after save old_timeslot = #<Timeslot id: 17306, location_id: 3, arrangement_id: nil, timeslot: \"2014-01-10 17:00:00\", created_at: \"2013-05-20 04:03:30\", updated_at: \"2014-01-11 01:37:09\">"
"after save new_timeslot = #<Timeslot id: 17306, location_id: 3, arrangement_id: 839, timeslot: \"2014-01-10 17:00:00\", created_at: \"2013-05-20 04:03:30\", updated_at: \"2014-01-11 01:35:55\">"


Started PUT "/arrangements/839" for 127.0.0.1 at 2014-01-10 19:37:09 -0600
Processing by ArrangementsController#update as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"REBgw/kRwlclqS670aIcIZ1Ug6kgxr/itEevwMQO2w8=", "arrangement"=>{"family_name"=>"smith", "location_id"=>"3", "date"=>"01/10/2014", "timeslot_id"=>"17306", "need"=>"myNeed", "notes"=>"mynotes", "user_id"=>"66"}, "button"=>"", "id"=>"839"}
  User Load (0.4ms)  SELECT `users`.* FROM `users` WHERE `users`.`id` = 2 LIMIT 1
  Setting Load (0.4ms)  SELECT `settings`.* FROM `settings` 
  Arrangement Load (0.4ms)  SELECT `arrangements`.* FROM `arrangements` WHERE `arrangements`.`id` = 839 LIMIT 1
  Timeslot Load (0.2ms)  SELECT `timeslots`.* FROM `timeslots` WHERE `timeslots`.`id` = 17306 LIMIT 1
  CACHE (0.0ms)  SELECT `timeslots`.* FROM `timeslots` WHERE `timeslots`.`id` = 17306 LIMIT 1
   (0.1ms)  BEGIN
   (0.3ms)  UPDATE `timeslots` SET `arrangement_id` = NULL, `updated_at` = '2014-01-11 01:37:09' WHERE `timeslots`.`id` = 17306
   (53.5ms)  COMMIT
   (0.1ms)  BEGIN
   (0.2ms)  COMMIT
Redirected to http://localhost:3000/arrangements/839
Completed 302 Found in 168ms (ActiveRecord: 55.5ms)

Answer 1

首先，奇怪的是您尝试连续保存两次相同的记录。 只要这些记录的ID相同，第二个保存就应该覆盖第一个。

另一方面，由于Rails 2.0左右，Rails具有“脏”对象和属性的概念。 所以很可能是分配

new_timeslot.arrangement_id = @arrangement.id

如果arrangement_id属性已经具有@arrangement.id的值，则实际上不会更改任何内容。 因此， new_timeslot对象不会被标记为“脏”，并且rails可以跳过save! 作为一种优化措施。 即使您预先更新了数据库中的同new_timeslot记录， new_timeslot仍然不会被标记为“脏”，因为您是在不同的实例中进行的。

因此，或者您要保存两个不同的记录，然后应该将至少一个的id更改为nil （或创建一个新记录并使用相同的属性对其进行初始化），或者只想使用new_timeslot属性来更新记录，然后没有理由致电save! 在old_timeslot 。