验证器回调方法，错误消息加入消息集合，方便表单使用

public function checkAccountAndPhone(Request $request)
{
        $data = $request->all();
        $validator = $this->validator($data);
        //验证回调钩子方法，加入额外的验证
        $validator->after(function($validator)use($data){
            $user = User::where('account_name',$data['account_name'])->get();
            if ($user->isEmpty()){
                $validator->errors()->add('account_name', '用户名不存在');
            }
        })->validate();
        if ($validator->fails() == false) {
           …………
        }
}