说说底层架构之实体类的设计

 

首先，那要和真实数据表一一对应，必要的话，可以对类型抽象化，可以引入枚举，泛型列表等类型；其次，对实体要集成它的数据有效性的验证功能；再次，为了数据操作方便，有必要去引入数据表字段的列举集合；综上所述，我们来设计一个用户表实体;

本例中的知识点为：部分类，接口规范，Flag属性的枚举，迭代器等

     /// <summary>
    /// 数据实体统一接口
    /// </summary>
    public interface IDataEntity
    {
    }
     /// <summary>
    /// 用户实体
    /// </summary>
    partial class UserBase : IDataEntity
    {
        public string UserName { get; set; }
        public int Age { get; set; }
    }
     /// <summary>
    /// 实体验证类
    /// </summary>
    public class RuleViolation
    {
        /// <summary>
        /// 错误属性
        /// </summary>
        public string ErrProperty { get; private set; }
        /// <summary>
        /// 错误信息
        /// </summary>
        public string ErrMessage { get; private set; }
        public RuleViolation(string errProperty, string errMessage)
        {
            this.ErrProperty = errProperty;
            this.ErrMessage = errMessage;
        }
        public RuleViolation(string errMessage)
            : this(errMessage, null)
        {

        }
    }
    /// <summary>
    /// 实体验证统一接口
    /// </summary>
    public interface IEntity
    {
        /// <summary>
        /// 验证是否通过
        /// </summary>
        bool IsValid { get; }
        /// <summary>
        /// 以迭代的形式返回验证列表
        /// </summary>
        /// <returns></returns>
        IEnumerable<RuleViolation> GetRuleViolations();
    }
     /// <summary>
    /// 用户实体验证
    /// </summary>
    public partial class UserBase : IEntity
    {

        #region IEntity Members

        public bool IsValid
        {
            get { return this.GetRuleViolations().Count() == 0; }
        }

        public IEnumerable<RuleViolation> GetRuleViolations()
        {
            if (string.IsNullOrEmpty(this.UserName))
                yield return new RuleViolation("UserName", "用户名为能为空");
            if (this.Age == 0)
                yield return new RuleViolation("Age", "没有年龄为０的数据,至少为１");
        }

        #endregion
    }
     /// <summary>
    /// 表字段列举
    /// </summary>
    [Flags]
    public enum UserBaseColumns
    {
        UserName = 1,
        Age = 2,
    }