无法获取相关角色信息

app/Http/Resources/UserResource.php

    public function toArray($request)
    {
.
.
.
        $data['bound_phone'] = $this->resource->phone ? true : false;
        $data['bound_wechat'] = ($this->resource->weixin_unionid || $this->resource->weixin_openid) ? true : false;
        $data['roles'] = RoleResource::collection($this->whenloaded('roles'));

        return $data;
    }

中 RoleResource::collection($this->whenloaded('roles')); 没有获取相关角色