.Net Core使用AutoMapper做对象关系映射

我想很多后端开发者，纠结于如何在Dto及表实体中做属性关系映射，因为真的太繁琐了。，

⒈如何使用？

            Mapper.Initialize(cfg => cfg.CreateMap<UsersInputDto, Users>());
            UsersInputDto input = new UsersInputDto()
            {
                id = 1, firstname = "fan", lastname = "qi", uname = "fanqisoft", pwd = "admin", enabled = 1
            };
            Users user = Mapper.Map<Users>(input);

⒉映射前或映射后进行操作

　　首先附上实体类

using System;
using System.Collections.Generic;
using System.Text;

namespace AutoMapperTest.Entities
{
    public class Users
    {
        public int id { get; set; }
        public string fullname { get; set; }
        public int? age { get; set; }
        public string username { get; set; }

        public string password { get; set; }
        public int? enabled { get; set; }

        public override string ToString()
        {
            return $"用户ID:{this.id} 
用户姓名：{this.fullname}
用户名：{this.username} 
用户密码：{this.password} 
用户是否启用：{(this.enabled==1?'是':'否')}";
        }
    }
}

　　InputDto

using System;
using System.Collections.Generic;
using System.Text;

namespace AutoMapperTest.Entities
{
    public class UsersInputDto
    {
        public int id { get; set; }
        public string firstname { get; set; }
        public string lastname { get; set; }
        public int? age { get; set; }
        public string uname { get; set; }

        public string pwd { get; set; }
        public int? enabled { get; set; }
    }
}

　　

　　当前端InputDto传到后端时，我需要将Dto中的firstname及lastname合并转换为数据表中的fullname

            Mapper.Initialize(cfg => 
            {
                cfg.CreateMap<UsersInputDto, Users>().BeforeMap((dto, ent) => ent.fullname = dto.firstname + "_" + dto.lastname);
            });

⒊条件映射，必须必要的条件后才会映射属性。

            Mapper.Initialize(cfg => 
            {
                cfg.CreateMap<UsersInputDto, Users>().ForMember(d => d.age, u => u.Condition(s => s.age >= 0 && s.age <= 120));
            });

⒋属性对应映射，Dto中属性名  ！= 数据表属性名

            Mapper.Initialize(cfg => 
            {
                cfg.CreateMap<UsersInputDto, Users>().ForMember(d => d.username, u => u.MapFrom(s => s.uname))
                                                     .ForMember(d => d.password, u => u.MapFrom(s => s.pwd)); 
            });

⒌使用配置文件？实现Profile类并在构造器中初始化你的配置。

using AutoMapper;
using AutoMapperTest.Entities;
using System;
using System.Collections.Generic;
using System.Text;

namespace AutoMapperTest.AutoMapper
{
    public class AutoMapperConfig:Profile
    {
        public AutoMapperConfig()
        {
            CreateMap<UsersInputDto, Users>();
        }
    }
}

            Mapper.Initialize(cfg => 
            {
                cfg.CreateMap<UsersInputDto, Users>().ForMember(d => d.username, u => u.MapFrom(s => s.uname))
                                                     .ForMember(d => d.password, u => u.MapFrom(s => s.pwd));
                cfg.AddProfile<AutoMapperConfig>();   //添加一个配置文件
            });

⒍Dto中数据类型和数据表不一致那就自定义转换器吧。

using AutoMapper;
using AutoMapperTest.Entities;
using System;
using System.Collections.Generic;
using System.Text;

namespace AutoMapperTest.AutoMapper
{
    public class UsersConverter:ITypeConverter<Users,UsersOutputDto>
    {
        public UsersOutputDto Convert(Users source, UsersOutputDto destination, ResolutionContext context)
        {
            string[] names = source.fullname.Split("_");
            return new UsersOutputDto()
            {
                id = source.id,
                firstname = names[0],
                lastname = names[1]
            };
        }
    }
}

            Mapper.Initialize(cfg =>
            {
                cfg.CreateMap<Users, UsersOutputDto>().ConvertUsing<UsersConverter>();
            });
            Users users = new Users()
            {
                id = 1, fullname = "fan_qi",age = 25,username = "fanqisoft",password ="admin",enabled = 1
            };
            UsersOutputDto output = Mapper.Map<UsersOutputDto>(users);

 ⒎附一个可用的静态工具类

using AutoMapper;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Text;

namespace AutoMapperTest.AutoMapper
{
    /// <summary>
    /// AutoMapper扩展帮助类
    /// </summary>
    public static class AutoMapperHelper
    {
        /// <summary>
        /// 类型映射
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="obj"></param>
        /// <returns></returns>
        public static T MapTo<T>(this object obj)
        {
            if(obj == null)
            {
                return default(T);
            }
            Mapper.Initialize(cfg =>
            {
                cfg.CreateMap(obj.GetType(), typeof(T));
            });
            return Mapper.Map<T>(obj);
        }

        /// <summary>
        /// 集合列表类型映射
        /// </summary>
        public static List<TDestination> MapToList<TDestination>(this IEnumerable source)
        {
            foreach (var first in source)
            {
                var type = first.GetType();
                Mapper.Initialize(cfg =>
                {
                    cfg.CreateMap(type, typeof(TDestination));
                });
                break;
            }
            return Mapper.Map<List<TDestination>>(source);
        }
        /// <summary>
        /// 集合列表类型映射
        /// </summary>
        public static List<TDestination> MapToList<TSource, TDestination>(this IEnumerable<TSource> source)
        {
            //IEnumerable<T> 类型需要创建元素的映射
            Mapper.Initialize(cfg =>
            {
                cfg.CreateMap<TSource, TDestination>();
            });
            return Mapper.Map<List<TDestination>>(source);
        }
        /// <summary>
        /// 类型映射
        /// </summary>
        public static TDestination MapTo<TSource, TDestination>(this TSource source, TDestination destination)
                    where TSource : class
                    where TDestination : class
        {
            if (source == null) return destination;
            Mapper.Initialize(cfg =>
            {
                cfg.CreateMap<TSource, TDestination>();
            });
            return Mapper.Map(source, destination);
        }
        /// <summary>
        /// DataReader映射
        /// </summary>
        public static IEnumerable<T> DataReaderMapTo<T>(this IDataReader reader)
        {
            Mapper.Reset();
            Mapper.Initialize(cfg =>
            {
                cfg.CreateMap<IDataReader, IEnumerable<T>>();
            });
            return Mapper.Map<IDataReader, IEnumerable<T>>(reader);
        }
    }
}