How to show multiple selected data while editing in drop down using selectize in laravel?

I am imploding multiple id of subject table via selecting it and saving it in Users table , i am successully saving the data in users table but when i am trying to edit the the user by exploding it subject field is not showing in dropdown..

imploding it like:1,2,3 i want all selected subject of above id in dropdown

 Saving the data like this
      
      if(is_array($request->subject)){
                  $item->subject = implode(',', $request->subject);

Add function to show subject list

 public function editForm($id)
    {
            $item = Users::findOrFail($id);
 
      $subjects =  Subject::pluck('subject_title','id');
 $item->subject =   explode(',', $item->subject);

     return view('users.form',$data,compact('item','subjects'));
     }


                my form dropdown

                {!! Form::select('subject[]',  $subjects, !empty($item->subject) ? $item->subject : explode(',',old('subject'))  ,['class' =>'form-control ' ,'required'=>'true','multiple'=>'true']); !!}

     
                
                
                

                
                

via Chebli Mohamed