鑒于我的模型Person和Student. 現在，我的一個控制器正在這樣做：$person_id = \App\Models\Person::insertGetId(['name' => $request->name, ...]);\App\Models\Student::create(['person_id' => $person_id, ...]);$student = \App\Models\Student::where('person_id', $person_id)->first();dd($student);在執行期間，一切都已保存，但我的問題是為什么我在死亡和轉儲時收到空值？順便說一下，我的student表primary和foreign鍵是person_id列。編輯class Student extends Model{    protected $fillable = ['section', 'current_year'];//there are other attribute here which I didn't show because I am using mobile    public function person(){       return $this->belongsTo('App\Models\Person', 'person_id', 'id');    }    ...}