.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 = , firstname = "fan", lastname = "qi", uname = "fanqisoft", pwd = "admin", enabled =
             };
             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} \n用户姓名：{this.fullname}\n用户名：{this.username} \n用户密码：{this.password} \n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 >=  && s.age <= ));
             });

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[],
                 lastname = names[]
             };
         }
     }
 }

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