Rails活動記錄沒有按預期保存

Question

我有一個更新方法沒有按預期保存數據庫記錄。

基本上，發生的情況是，arrange_id沒有保存到時隙表中，因爲我期望使用下面的方法。

從save!之後我的變量的輸出中，我認爲arrange_id會保存在時間表中。

任何人都可以告訴我爲什麼這不是，我在這裏做錯了什麼？

# 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 

這裏是控制檯輸出：

所有真奇怪，你嘗試做兩個

# 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

第一繼承人相同的記錄的保存。只要這些記錄的ID相同，第二次保存就應該覆蓋第一次。

另一方面，因爲Rails 2.0左右的Rails有「髒」對象和屬性的概念。因此，它很可能是分配

new_timeslot.arrangement_id = @arrangement.id 

實際上並沒有改變什麼，如果arrangement_id屬性已有的@arrangement.id值。因此new_timeslot對象不會被標記爲「髒」，並且rails可以跳過save!作爲優化措施。即使您事先更新了數據庫中的相同記錄，但new_timeslot仍不會被標記爲「髒」，因爲您在不同的實例中執行了該操作。

因此，要麼保存兩個不同的記錄，那麼您應該將至少一個ID更改爲nil（或者創建一個新記錄並使用相同的屬性對其進行初始化），或者您只想更新記錄new_timeslot屬性，那麼沒有理由在old_timeslot上調用save!。