laravel-错误 - 数据丢失

Question

我正在尝试编写代码。\ app \ Http \ Controllers \ DienController.php

public function store(Request $request)
{
     try
    {
    $dien=new Dien();
    $phong=Phong::find($request->p_id);
    $thang=date("m",strtotime($request->d_taoMoi));
    $nam=date("Y",strtotime($request->d_taoMoi));
    $dien->d_ma=$thang.$nam.($phong->p_ma);
    $dien->p_id=$request->p_id;
    $dien->d_chisoDau=$request->d_chisoDau;
    $dien->d_chisoCuoi=$request->d_chisoCuoi;
    $dien->d_slhienTai=$phong->p_soNguoi;
    $dien->dg_id=$request->dg_id;
    $id=Dongia::ALL()->max('dg_id'); //Lấy đơn giá id vừa cập nhật mới nhất
    $dongia=Dongia::find($id);
    $dien->d_tiendienPhong=($request->d_chisoCuoi-$request->d_chisoDau)*($dongia->dg_tienDien);
    $dien->d_tiendienSV=($request->d_chisoCuoi-$request->d_chisoDau)*($dongia->dg_tienDien)/($phong->p_soNguoi);
    $dien->d_taoMoi=$request->d_taoMoi;
    $dien->save();
//    $nuoc=new Nuoc();
    return redirect(route('dien.index'));
  }
  catch(QueryException $ex)
  {
    return response(['error'=> true ,'message'=> $ex->getMessage()],500);
  }
    //
}

我的模型（App \ Dien.php）是：

namespace App;

use Illuminate\Database\Eloquent\Model;
use App\Phong;
use App\Nuoc;
class Dien extends Model
{
    const CREATE_AT='d_taoMoi';
    const UPDATE_AT='d_capNhat';
    //
    protected $table='dien';
    protected $fillable=['d_ma','d_chisoDau','d_chisoCuoi','d_tiendienPhong','d_tiendienSV','d_slhienTai','dg_id','p_id'];
    protected $guarded=['d_id'];
    protected $primaryKey='d_id';
    protected $dates=['d_taoMoi','d_capNhat'];
    protected $dateFormat='Y-m-d H:i:s'; 
    public function dongia()
    {
        return $this->belongsTo('App\Dongia','dg_id','dg_id');
    }
     public function Phong()
    {
        return $this->belongsTo('App\Phong','p_id','p_id');
    }
    //
}

但是当我运行该程序时，我遇到了一个问题。“数据缺失”。我想知道我如何使用“$ thang”变量中的错误。

InvalidArgumentException
Data missing

请给我一个建议，非常感谢。