Silverlight MVVM 异步数据未载入完便返回空数据
Services\DataService.cs

        public List<User> GetAllUser()
        {
            List<User> userList = new List<User>();
            LoadOperation lo = pcs.Load<Web.User>(pcs.GetUsersQuery());
            pcs.Load<Web.User>(pcs.GetUsersQuery()).Completed += (s, a) =>
            {
                foreach (Web.User u in (s as LoadOperation<Web.User>).Entities)
                {
                    User user = new User();
                    user.Name = u.user_name;
                    user.Uid = u.user_id;
                    user.Uiid = u.user_iid;
                    userList.Add(user);
                }
            };
            MessageBox.Show("2");
            return userList;
        }

ViewModels\UserMgrViewModel.cs

void LoadUserList()
        {
            DataService ds = new DataService();
            this.UserList= new List<User>();
            MessageBox.Show("1");
            this.UserList= ds.GetAllUser();
            MessageBox.Show("3");
        }

弹出"1"后直接出"3",再出"2"...

请教大家用什么方法解决?
[解决办法]
异步本来就是这样的，跟同步编程是两回事。

程序的接口需要做出根本性的改变：

        public void GetAllUser(Action<List<User>> callback)
        {
            LoadOperation lo = pcs.Load<Web.User>(pcs.GetUsersQuery());
            pcs.Load<Web.User>(pcs.GetUsersQuery()).Completed += (s, a) =>
            {
                List<User> userList = new List<User>(); 
 
                foreach (Web.User u in (s as LoadOperation<Web.User>).Entities)
                {
                    User user = new User();
                    user.Name = u.user_name;
                    user.Uid = u.user_id;
                    user.Uiid = u.user_iid;
                    userList.Add(user);
                }
                callback(userList);
            };
        }