laravel 5 - Eloquent relation query with some column -

i'm running query give me result.query given below

model file

public function units()     {         return $this->hasmany('app\powerconsumption','device_id','device_id');     } 

controller file

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

result of query is:

[{ 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" } ] 

but want run query

device::with('units')->groupby('hour')                 ->selectraw('round(sum(unit),4) yaxis,hour xaxis')                 ->where('user_id',2)->get();         } 

and query generate error like

queryexception in connection.php line 713: sqlstate[42s22]: column not found: 1054 unknown column 'unit' in 'field list' (sql: select round(sum(unit),4) yaxis,hour xaxis `devices` `user_id` = 2 group `hour`) 

so please me in query.

try 1

$devices = device::with(['units' => function($query){         $query->selectraw('device_id,round(sum(unit),4) yaxis,hour xaxis');     }])     ->where('user_id',2)     ->get()     ->each(function ($item, $key) {         return $item->units->groupby('xaxis');     });