XPO ORM 實戰入門：一對多關聯、CRUD 與 Session 管理

為什麼選擇 XPO？

• DevExpress 出品，Visual Studio 深度集成
• 無 XML 映射文件，特性驅動映射
• 自動建表、遷移、連接池管理
• LINQ 查詢原生支持，Criteria API 強大

領域模型定義

[Persistent("Users")]
public class User : XPObject {
    public User(Session session) : base(session) { }
    
    string _accountName, _realName, _userPwd = "U";
    [Size(50)] public string AccountName { get => _accountName; set => SetPropertyValue(nameof(AccountName), ref _accountName, value); }
    [Size(50)] public string RealName { get => _realName; set => SetPropertyValue(nameof(RealName), ref _realName, value); }
    [Size(100)] public string UserPwd { get => _userPwd; set => SetPropertyValue(nameof(UserPwd), ref _userPwd, value); }
    
    [Association("User-Details")]
    public XPCollection Details => GetCollection(nameof(Details));
}

[Persistent("UserDetails")]
public class UserDetail : XPObject {
    public UserDetail(Session session) : base(session) { }
    
    string _accountName, _address;
    [Size(50)] public string AccountName { get => _accountName; set => SetPropertyValue(nameof(AccountName), ref _accountName, value); }
    [Size(200)] public string Address { get => _address; set => SetPropertyValue(nameof(Address), ref _address, value); }
    
    [Association("User-Details")]
    public User User { get; set; } // 反向導航
}

核心操作模式

新增（含關聯）

using (var uow = new UnitOfWork()) {
    var user = new User(uow) { AccountName = "zhangsan", RealName = "張三" };
    user.Details.Add(new UserDetail(uow) { Address = "北京市朝陽區" });
    user.Details.Add(new UserDetail(uow) { Address = "上海市浦東區" });
    uow.CommitChanges(); // 事務提交
}

查詢（LINQ + Criteria）

// LINQ
var users = from u in session.Query() 
            where u.AccountName.StartsWith("zhang") 
            select u;

// Criteria 複雜條件
var criteria = CriteriaOperator.Parse("AccountName LIKE 'zhang%' AND Details[].Address CONTAINS '北京'");
var users = session.GetObjects(criteria);

修改與刪除

// 修改
user.RealName = "李四"; uow.CommitChanges();

// 刪除（級聯由 Association 控制）
uow.Delete(user); uow.CommitChanges();

Session/UnitOfWork 最佳實踐

• Web 請求範圍：HttpContext.Current.Items["XpoSession"] 單例
• 後台任務：using (var uow = new UnitOfWork()) 短生命周期
• 避免長 Session 持有鎖，及時 CommitChanges() 或 Rollback()