如何更新 laravel 中的一對多關系？

Question

我在更新下表時遇到問題

數據來自如下視圖

這是我的代碼

 foreach ($request->input('class_teacher') as $key=>$value){
                $class_teacher =ClassTeacher::where('class_id',$id);
                $class_teacher->class_id = $classes->class_id;
                $class_teacher->teacher_id =$value;
                $class_teacher->save();
            }

更新后我希望它像這樣

Answer 1

首先刪除關系，然后重新創建它們。

 ClassTeacher::where('class_id',$id)->whereIn('teacher_id', $request->input('class_teacher'))->delete();
  
  foreach ($request->input('class_teacher') as $key=>$value){
    $class_teacher =new ClassTeacher;
    $class_teacher->class_id = $classes->class_id;
    $class_teacher->teacher_id =$value;
    $class_teacher->save();