（转）自制AutoMapper实现DTO到持久层Entity的转换

原文地址：http://www.cnblogs.com/qidian10/p/3173907.html

项目中经常涉及到页面DTO更新，保存到数据库的操作，这就必然牵扯到DTO和持久层对象的转换，常见的第三方库有：

java：dozer

.net: AutoMapper

看到AutoMapper已经许久没更新了，而且项目中没必要用这么大的东西，于是自己实现了一个简易DTO到Entity的转换器。

实现的功能

自定义的AutoMapper主要实现了如下几点功能：

1.DTO字段忽略转换

[AutoMapping(Ignore=true)]
public DateTime CreateTime { get; set; }

2.DTO字段和Entity的强制映射

[AutoMapping(EntityColumn="Sex")]
public string XingBie { get; set; }

3.默认DTO和Entity字段相同的，自动转换

核心代码:

using System;
using System.Collections.Generic;
using System.Reflection;
using System.Text;
using System.Linq;

namespace ElegantWM.AutoMapper
{
    public class AutoMapper<T1,T2> where T1:new() where T2:new()
    {
        /// <summary>
        /// DTO 转换为 Entity
        /// </summary>
        /// <typeparam name="T1">DTO</typeparam>
        /// <typeparam name="T2">Entity</typeparam>
        /// <param name="t1">Dto</param>
        /// <param name="t2">Entity</param>
        /// <returns></returns>
        public static T2 Convert(T1 t1, T2 t2)
        {
            var dtoProperList = t1.GetType().GetProperties().Where(p => p.PropertyType.IsPublic == true).ToList();
            var entityProperList = t2.GetType().GetProperties().Where(p => p.PropertyType.IsPublic == true).ToList();
            foreach (System.Reflection.PropertyInfo pi in dtoProperList)
            {
                string realName=pi.Name;
                //首先判断列是否ignore？,是否含有Column
                object[] cusAttrs = pi.GetCustomAttributes(typeof(AutoMappingAttribute), true);
                if (cusAttrs.Length > 0)
                {
                    AutoMappingAttribute attr = cusAttrs[0] as AutoMappingAttribute;
                    if (attr.Ignore)
                        continue;
                    if (!string.IsNullOrEmpty(attr.EntityColumn))
                        realName = attr.EntityColumn;
                }
                var entityPi = entityProperList.Single(p => p.Name == realName);
                if (entityPi == null)
                    continue;
                object value = pi.GetValue(t1, null);
                if (value == null)
                    continue;
                entityPi.SetValue(t2, value, null);                
            }
            return t2;
        }
    }
}

案例

持久层Entity的定义如下：

public class Entity:IEntity
    {
        public Guid Id { get; set; }
        public string CreateUser { get; set; }
        public DateTime CreateTime { get; set; }
        public string ModifyUser { get; set; }
        public DateTime? ModifyTime { get; set; }
        [Timestamp]
        public Byte[] RowVersion { get; set; }
    }   
 public class WMS_User : Entity
    {
        public WMS_User() { }

        public string UserName { get; set; }
        public string NickName { get; set; }
        public string UserPwd { get; set; }
        public string Sex { get; set; }
        public string Phone { get; set; }
        public string Email { get; set; }
        public string QQ { get; set; }
        public string Address { get; set; }
        public string Remark { get; set; }
        public bool Disable { get; set; }
        public virtual ICollection<WMS_OrgUser> UserOrgIds { get; set; }
    }

页面DTO定义如下：

public class UserDto
    {
        public UserDto() { }
        public Guid Id { get; set; }
        public string UserName { get; set; }
        public string NickName { get; set; }       
        public string UserPwd { get; set; }
        //强制字段映射
        [AutoMapping(EntityColumn="Sex")]
        public string XingBie { get; set; }

        public string Phone { get; set; }
        public string Email { get; set; }
        public string QQ { get; set; }
        public string Address { get; set; }
        public string Remark { get; set; }
        public bool Disable { get; set; }
        //忽略字段映射
        [AutoMapping(Ignore=true)]
        public DateTime CreateTime { get; set; }
    }    

使用AutoMapper，做转换：

　　　　 [Action]
        [Description("更新用户")]
        [HttpPut]
        public JsonResult Update(UserDto user)
        {
            WMS_User userEntity = WMFactory.WMSUser.GetById(user.Id.ToString());
//*******看这里哦********
            userEntity = AutoMapper<UserDto, WMS_User>.Convert(user, userEntity);
            if (WMFactory.WMSUser.Update(userEntity))
                return Json(ResultMsg.Success("用户信息更新成功！"));
            else
                return Json(ResultMsg.Failure("用户信息更新失败，请您重试！"));
        }

写在后面

自己实现，相对来说，自由度高了很多，你可以自己扩展方法，实现客制化的DTO转Entity，让AutoMapper更加适合自己的项目。