DDD领域驱动设计之聚合、实体、值对象

关于具体需求，请看前面的博文：DDD领域驱动设计实践篇之如何提取模型，下面是具体的实体、聚合、值对象的代码，不想多说什么是实体、聚合等概念，相信理论的东西大家已经知晓了。本人对DDD表示好奇，没有在真正项目实践过，甚至也没有看过真正的DDD实践的项目源码，处于极度纠结状态，甚至无法自拔，所以告诫DDD爱好者们，如果要在项目里面实践DDD，除非你对实体建模和领域职责非常了解（很多时候会纠结一些逻辑放哪里好，属于设计问题）以及你的团队水平都比较高认同DDD，否则请慎重。。。勿喷！

代码在后，请先看DEMO结果图

1、聚合的基类，注意，几乎属性都是拼音首字母命名，勿喷哈，不要跑题！

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using DDD.Infrastructure;
using DDD.Infrastructure.Domain;

namespace DDD.Domain
{
    /// <summary>
    /// 项目基类
    /// </summary>
    public abstract class ProjectBase : EntityBase, IAggregateRoot
    {
        protected ProjectBase()
        {
            this.ND = DateTime.Now.Year;
            this.CJSJ = DateTime.Now;
            this.WH = new DocumentNumber();
        }

        /// <summary>
        /// 安排批次
        /// </summary>
        public int APPC { get; set; }
        /// <summary>
        /// 项目名称
        /// </summary>
        public string XMMC { get; set; }
        /// <summary>
        /// 项目编号
        /// </summary>
        public string XMBH { get; internal set; }
        /// <summary>
        /// 年度
        /// </summary>
        public int ND { get; set; }
        /// <summary>
        /// 文号
        /// </summary>
        public DocumentNumber WH { get; set; }
        /// <summary>
        /// 创建时间
        /// </summary>
        public DateTime CJSJ { get; set; }
        /// <summary>
        /// 下发行政区名称
        /// </summary>
        public string XFXZQMC { get; set; }
        /// <summary>
        /// 下发行政区代码
        /// </summary>
        public string XFXZQDM { get; set; }
        /// <summary>
        /// 行政区名称
        /// </summary>
        public string XZQMC { get; set; }
        /// <summary>
        /// 行政区代码
        /// </summary>
        public string XZQDM { get; set; }
        /// <summary>
        /// 备注
        /// </summary>
        public string BZ { get; set; }
        /// <summary>
        /// 指标级别
        /// </summary>
        public IndicatorGrade ZBJB { get; set; }
        /// <summary>
        /// 附件id
        /// </summary>
        public decimal ATTACHID { get; set; }
        /// <summary>
        /// 项目状态
        /// </summary>
        public ProjectStauts Status { get; set; }

        /// <summary>
        /// 业务代码
        /// </summary>
        protected abstract string BussinessCode { get; }

        /// <summary>
        /// 登记
        /// </summary>
        /// <param name="seq"></param>
        public virtual void Register()
        {
            this.XMBH = this.BussinessCode + SeqGeneratr.Generate();
        }

        /// <summary>
        /// 是否可以更新或者删除
        /// </summary>
        /// <returns></returns>
        public virtual bool CanUpdate()
        {
            return this.ZBJB == IndicatorGrade.Country || this.XFXZQDM == this.XZQDM || this.Status == ProjectStauts.Default;
        }

        public void Send()
        {
            this.Status = ProjectStauts.Sent;
        }
    }
}

2、聚合1

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using DDD.Infrastructure;
using DDD.Infrastructure.Domain;

namespace DDD.Domain.Indicator
{
    /// <summary>
    /// 计划指标
    /// </summary>
    public class PlanIndicator : ProjectBase
    {
        public PlanIndicator()
        {
            IndicatorArea = new IndicatorArea();
        }

        protected override string BussinessCode
        {
            get { return "103101"; }
        }

        /// <summary>
        /// 指标面积
        /// </summary>
        public IndicatorArea IndicatorArea
        {
            get;
            set;
        }

        public override IEnumerable<BusinessRule> Validate()
        {
            if (this.IndicatorArea.GD > this.IndicatorArea.NYD)
            {
                yield return new BusinessRule("IndicatorArea.GD", "耕地面积不能大于农用地面积");
            }
        }

        public override void Register()
        {
            if (this.ZBJB == IndicatorGrade.Country)
            {
                this.Send();
            }
            base.Register();
        }
    }
}

3、聚合2

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using DDD.Infrastructure;
using DDD.Infrastructure.Domain;

namespace DDD.Domain.Arrange
{
    /// <summary>
    /// 计划安排
    /// </summary>
    public class PlanArrange : ProjectBase
    {
        public PlanArrange()
        {
            JHSY = new IndicatorArea();
            SJSY = new IndicatorArea();
        }

        protected override string BussinessCode
        {
            get { return "103102"; }
        }

        /// <summary>
        /// 计划使用面积
        /// </summary>
        public IndicatorArea JHSY
        {
            get;
            set;
        }

        /// <summary>
        /// 实际使用面积
        /// </summary>
        public IndicatorArea SJSY
        {
            get;
            set;
        }

        /// <summary>
        /// 剩余面积
        /// </summary>
        public IndicatorArea SY
        {
            get
            {
                return JHSY - SJSY;
            }
        }

        /// <summary>
        /// 用地类别
        /// </summary>
        public string XMYDLB { get; set; }

        public override IEnumerable<BusinessRule> Validate()
        {
            if (this.JHSY.GD > this.JHSY.NYD)
            {
                yield return new BusinessRule("JHSY.GD", "计划使用中，耕地面积不能大于农用地面积");
            }
            if (this.SJSY.GD > this.SJSY.NYD)
            {
                yield return new BusinessRule("SJSY.GD", "实际使用中，耕地面积不能大于农用地面积");
            }
            if (string.IsNullOrEmpty(this.XMYDLB))
            {
                yield return new BusinessRule("XMYDLB", "项目用地类别不允许为空");
            }
        }
    }
}

4、值对象1

using System;
using DDD.Infrastructure.Domain;

namespace DDD.Domain
{
    /// <summary>
    /// 文号
    /// </summary>
    public class DocumentNumber : ValueObject<DocumentNumber>, ICloneable
    {
        public static readonly string LeftYearChar = "〔";
        public static readonly string RightYearChar = "〕";

        public DocumentNumber() 
        {
            
        }

        public DocumentNumber(string wh) 
        {
            try
            {
                this.Code = wh.Substring(0, wh.IndexOf(LeftYearChar));
                this.Year = wh.Substring(wh.IndexOf(LeftYearChar), wh.IndexOf(RightYearChar) - this.Code.Length + 1);
                this.Order = wh.Replace(this.Code + this.Year, "");
                this.Year = this.Year.Replace(LeftYearChar, "").Replace(RightYearChar, "");
            }
            catch(Exception ex)
            {
                throw new InvalidCastException("文号格式不正确", ex);
            }
        }

        /// <summary>
        /// 发文机关代字
        /// </summary>
        public string Code { get; set; }
        /// <summary>
        /// 年份
        /// </summary>
        public string Year { get; set; }
        private string order;
        /// <summary>
        /// 顺序号
        /// </summary>
        public string Order
        {
            get
            {
                if (!string.IsNullOrEmpty(order) && !order.Contains("号"))
                {
                    order += "号";
                }
                return order;
            }
            set
            {
                order = value;
            }
        }

        public override string ToString()
        {
            if (string.IsNullOrEmpty(Code) && string.IsNullOrEmpty(Year) && string.IsNullOrEmpty(order))
            {
                return string.Empty;
            }
            return this.Code + LeftYearChar + Year + RightYearChar + Order;
        }

        public static implicit operator DocumentNumber(string wh)
        {
            return new DocumentNumber(wh);
        }

        public object Clone()
        {
            return this.MemberwiseClone();
        }
    }
}

5、值对象2

using DDD.Infrastructure;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using DDD.Infrastructure.Domain;

namespace DDD.Domain
{
    /// <summary>
    /// 指标面积
    /// </summary>
    public class IndicatorArea : ValueObject<IndicatorArea>
    {
        /// <summary>
        /// 新增建设用地
        /// </summary>
        public decimal XZJSYD
        {
            get
            {
                return NYD + WLYD;
            }
        }
        /// <summary>
        /// 农用地
        /// </summary>
        public decimal NYD { get; set; }
        /// <summary>
        /// 耕地
        /// </summary>
        public decimal GD { get; set; }
        /// <summary>
        /// 未利用地
        /// </summary>
        public decimal WLYD { get; set; }

        /// <summary>
        /// 将公顷转换成亩
        /// </summary>
        /// <returns></returns>
        public IndicatorArea HectareToMu()
        {
            return new IndicatorArea
            {
                GD = this.GD * 15,
                NYD = this.NYD * 15,
                WLYD = this.WLYD * 15,
            };
        }

        /// <summary>
        /// 重载加法运算符
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <returns></returns>
        public static IndicatorArea operator +(IndicatorArea a, IndicatorArea b)
        {
            return new IndicatorArea
            {
                GD = a.GD + b.GD,
                NYD = a.NYD + b.NYD,
                WLYD = a.WLYD + b.WLYD,
            };
        }

        /// <summary>
        /// 重载减法运算符
        /// </summary>
        /// <param name="a"></param>
        /// <param name="b"></param>
        /// <returns></returns>
        public static IndicatorArea operator -(IndicatorArea a, IndicatorArea b)
        {
            return new IndicatorArea
            {
                GD = a.GD - b.GD,
                NYD = a.NYD - b.NYD,
                WLYD = a.WLYD - b.WLYD,
            };
        }

        public static IndicatorArea Sum(IEnumerable<IndicatorArea> query)
        {
            return new IndicatorArea
            {
                GD = query.Sum(t => t.GD),
                NYD = query.Sum(t => t.NYD),
                WLYD = query.Sum(t => t.WLYD),
            };
        }
    }
}

　　

6、枚举

using System.ComponentModel;

namespace DDD.Domain
{
    /// <summary>
    /// 指标级别
    /// </summary>
    public enum IndicatorGrade
    {
        /// <summary>
        /// 国家
        /// </summary>
        [Description("国家")]
        Country,
        /// <summary>
        /// 省级
        /// </summary>
        [Description("省级")]
        Province,
        /// <summary>
        /// 市级
        /// </summary>
        [Description("市级")]
        City,
        /// <summary>
        /// 县级
        /// </summary>
        [Description("县级")]
        County,
    }
}

using System.ComponentModel;

namespace DDD.Domain
{
    /// <summary>
    /// 项目状态
    /// </summary>
    public enum ProjectStauts
    {
        /// <summary>
        /// 默认状态，已登记
        /// </summary>
        Default,
        /// <summary>
        /// 已下发
        /// </summary>
        Sent,
    }
}