laravel one to many sync 一对多 attaceh 同步保存 有大用 有大大用

attach  增加(其实一对多当中是没有attach方法的),附加 见 /node-admin/9182

sync 同步保存见如下

一对多中 也是没有sync 方法 

It seems like there is no sync() function for morph tables on Laravel.

I have two tables avails and questions. questions is a morphMany table. I want to use the sync command, and this is what I did:

Avail::find($id)->questions()->sync($some_ids);

正确答案 

1)把原来的外键置为空 

$questionsOld = $avail->questions()->get();

$questionsOld->each(function ($question) {
  // appropriate fields here:
  // 1*
  $question->FOREIGN_ID = null;
  $question->FOREIGN_TYPE = null;
  $question->save();
});
//再取出所有副表的对象
$questionsNew = Question::whereIn('id', $someIds)->get();

2)进行保存 saveMany 
// *2
$avail->questions()->saveMany($questionsNew->getDictionary());

(2)我的方法是直接update副表的外键 先得到所有副表,然后再update)
Category::whereIn('category_id',$request->input('category_guanxi'))->update(['category_guanxi'=>$category->category_id]);