如何更新 laravel 中的一对多关系？

Question

我在更新下表时遇到问题

数据来自如下视图

这是我的代码

 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();
            }

更新后我希望它像这样

Answer 1

首先删除关系，然后重新创建它们。

 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();