mysql - undefined variable : mysql whereNotIn

Question

    public function show($id)
{
    $screening = Screnning::findOrFail($id);


    $seats = DB::table('seats')->whereNotIn('id',function($q){

        $q->select('seat_id')->from('reservations')
           ->where('screening_id',$screening) ;
          })->get();


    return view('reservation.show',compact('screening','seats'));

}

这是我获得 undefined variable 的代码:筛选。我想问题是 $screening 在另一个函数中。我该如何解决？

Answer 1

您可以使用 use 使变量在闭包中可用:

$seats = DB::table('seats')->whereNotIn('id', function($q) use ($screening) {
    $q->select('seat_id')->from('reservations')
       ->where('screening_id', $screening->id);
})->get();

关于匿名函数/闭包的更多信息:http://php.net/manual/en/functions.anonymous.php - 您特别感兴趣的是“示例 #3 从父作用域继承变量”