Laravel 5.1用（）和max（）使用多重關係多數人關係

Question

我試圖用Eloquent在多重關係的最後一個表上找到列的最大值。

給出下面的表格結構。

建築

+----+---------------+ 
| id | building_name | 
+----+---------------+ 
| 1 | Building 1 | 
| 2 | Building 2 | 
+----+---------------+ 

客房

+----+-----------+-------------+ 
| id | room_name | building_id | 
+----+-----------+-------------+ 
| 1 | Room 1 |   1 | 
| 2 | Room 2 |   1 | 
| 3 | Room 3 |   2 | 
+----+-----------+-------------+ 

maintenancelog

+----+-------------------+---------+---------------------+ 
| id | maintenance_value | room_id |  timestamp  | 
+----+-------------------+---------+---------------------+ 
| 1 | Cleaned   |  1 | 2015-09-06 00:54:59 | 
| 2 | Cleaned   |  1 | 2015-09-06 01:55:59 | 
| 3 | Cleaned   |  2 | 2015-09-06 02:56:59 | 
| 4 | Cleaned   |  2 | 2015-09-06 03:57:59 | 
| 5 | Cleaned   |  3 | 2015-09-06 04:58:59 | 
| 6 | Cleaned   |  3 | 2015-09-06 05:59:59 | 
+----+-------------------+---------+---------------------+ 

我想看看是否有可能生成將檢索建築物名稱的雄辯的發言，房間名稱和僅最後一個維護日誌日期值。

下面的工作給我一個所有值的集合。

$buildings = Building::with('rooms.maintenancelog')->get(); 

但這樣的錯誤了，它看起來像它試圖在建築物表調用MAX（maintenancelog.timestamp）..

$buildings = Building::with('rooms.maintenancelog')->max('maintenancelog.timestamp')->get(); 

返回錯誤：

.....(SQL: select max(`maintenancelog`.`timestamp`) as aggregate from `buildings`) 

上午我只是從雄辯中提出太多問題，應該只使用基本查詢構建器

Answer 1

將以下關係onship的房間模型...

public function latestMaintenance() 
{ 
    return $this->hasOne('App\Maintenancelog')->latest(); 
} 

，改變雄辯的發言，以..

$buildings = Building::with('rooms.latestMaintenance')->get(); 

引用Getting just the latest value on a joined table with Eloquent