Laravel 5 带某列的雄辩关系查询

我正在运行查询，查询结果如下

模型文件

public function units()
    {
        return $this->hasMany('App\PowerConsumption','device_id','device_id');
    }

控制器文件

return Device::with('units')->where('user_id',2)->get();

此查询的结果是：

[{
device_id: 1,
user_id: 2,
device_name: "Bulb 1",
relay_num: 22,
sensor_num: 4,
status: 1,
created_at: "2016-07-11 02:11:32",
updated_at: "2016-07-19 08:25:30",
units: [
{
p_id: 1,
device_id: 1,
unit: 0.022121944444444,
month: "7",
hour: "1",
minute: "0",
created_at: "2016-07-18 00:00:00",
updated_at: "2016-07-18 00:00:00"
},
{
p_id: 2,
device_id: 1,
unit: 0.022121944444444,
month: "7",
hour: "1",
minute: "5",
created_at: "2016-07-18 00:00:00",
updated_at: "2016-07-18 00:00:00"
}
]

但是我想运行这个查询

Device::with('units')->groupBY('hour')
                ->selectRaw('round(sum(unit),4) as yAxis,hour as xAxis')
                ->where('user_id',2)->get();
        }

这个查询会产生如下错误

QueryException in Connection.php line 713:
SQLSTATE[42S22]: Column not found: 1054 Unknown column 'unit' in 'field list' (SQL: select round(sum(unit),4) as yAxis,hour as xAxis from `devices` where `user_id` = 2 group by `hour`)

所以请帮我查询。

试试这个

试试这个

---

此查询的结果[{设备id:1，用户id:2，设备名称：“灯泡1”，继电器编号：22，传感器编号：4，状态：1，创建地点：“2016-07-11 02:11:32”，更新地点：“2016-07-19 08:25:30”，单位：[]]请尝试我的更新答案，我已将设备id添加到该查询结果表的FK列列表中[{设备id:1，用户id:2，设备名称：“灯泡1”，继电器编号：22，传感器编号：4，状态：1，创建地点：“2016-07-11 02:11:32”，更新地点：“2016-07-19 08:25:30”，单位：[]]请尝试我的更新答案，我已将设备id添加到表格的FK列列表中

$devices = Device::with(['units' => function($query){
        $query->selectRaw('device_id,round(sum(unit),4) as yAxis,hour as xAxis');
    }])
    ->where('user_id',2)
    ->get()
    ->each(function ($item, $key) {
        return $item->units->groupBy('xAxis');
    });

$devices = Device::with(['units' => function($query){
        $query->selectRaw('device_id,round(sum(unit),4) as yAxis,hour as xAxis')->groupBy('xAxis);
    }])
    ->where('user_id',2)
    ->get();