.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？

1             Mapper.Initialize(cfg => cfg.CreateMap<UsersInputDto, Users>());
2             UsersInputDto input = new UsersInputDto()
3             {
4                 id = 1, firstname = "fan", lastname = "qi", uname = "fanqisoft", pwd = "admin", enabled = 1
5             };
6             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

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Text;
 4
 5 namespace AutoMapperTest.Entities
 6 {
 7     public class Users
 8     {
 9         public int id { get; set; }
10         public string fullname { get; set; }
11         public int? age { get; set; }
12         public string username { get; set; }
13
14         public string password { get; set; }
15         public int? enabled { get; set; }
16
17         public override string ToString()
18         {
19             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‘)}";
20         }
21     }
22 }

　　InputDto

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Text;
 4
 5 namespace AutoMapperTest.Entities
 6 {
 7     public class UsersInputDto
 8     {
 9         public int id { get; set; }
10         public string firstname { get; set; }
11         public string lastname { get; set; }
12         public int? age { get; set; }
13         public string uname { get; set; }
14
15         public string pwd { get; set; }
16         public int? enabled { get; set; }
17     }
18 }

　　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

1             Mapper.Initialize(cfg =>
2             {
3                 cfg.CreateMap<UsersInputDto, Users>().BeforeMap((dto, ent) => ent.fullname = dto.firstname + "_" + dto.lastname);
4             });

⒊条件映射，必须必要的条件后才会映射属性。

1             Mapper.Initialize(cfg =>
2             {
3                 cfg.CreateMap<UsersInputDto, Users>().ForMember(d => d.age, u => u.Condition(s => s.age >= 0 && s.age <= 120));
4             });

⒋属性对应映射，Dto中属性名  ！= 数据表属性名

1             Mapper.Initialize(cfg =>
2             {
3                 cfg.CreateMap<UsersInputDto, Users>().ForMember(d => d.username, u => u.MapFrom(s => s.uname))
4                                                      .ForMember(d => d.password, u => u.MapFrom(s => s.pwd));
5             });

⒌使用配置文件？实现Profile类并在构造器中初始化你的配置。

 1 using AutoMapper;
 2 using AutoMapperTest.Entities;
 3 using System;
 4 using System.Collections.Generic;
 5 using System.Text;
 6
 7 namespace AutoMapperTest.AutoMapper
 8 {
 9     public class AutoMapperConfig:Profile
10     {
11         public AutoMapperConfig()
12         {
13             CreateMap<UsersInputDto, Users>();
14         }
15     }
16 }

1             Mapper.Initialize(cfg =>
2             {
3                 cfg.CreateMap<UsersInputDto, Users>().ForMember(d => d.username, u => u.MapFrom(s => s.uname))
4                                                      .ForMember(d => d.password, u => u.MapFrom(s => s.pwd));
5                 cfg.AddProfile<AutoMapperConfig>();   //添加一个配置文件
6             });

⒍Dto中数据类型和数据表不一致那就自定义转换器吧。

 1 using AutoMapper;
 2 using AutoMapperTest.Entities;
 3 using System;
 4 using System.Collections.Generic;
 5 using System.Text;
 6
 7 namespace AutoMapperTest.AutoMapper
 8 {
 9     public class UsersConverter:ITypeConverter<Users,UsersOutputDto>
10     {
11         public UsersOutputDto Convert(Users source, UsersOutputDto destination, ResolutionContext context)
12         {
13             string[] names = source.fullname.Split("_");
14             return new UsersOutputDto()
15             {
16                 id = source.id,
17                 firstname = names[0],
18                 lastname = names[1]
19             };
20         }
21     }
22 }

1             Mapper.Initialize(cfg =>
2             {
3                 cfg.CreateMap<Users, UsersOutputDto>().ConvertUsing<UsersConverter>();
4             });
5             Users users = new Users()
6             {
7                 id = 1, fullname = "fan_qi",age = 25,username = "fanqisoft",password ="admin",enabled = 1
8             };
9             UsersOutputDto output = Mapper.Map<UsersOutputDto>(users);

⒎附一个可用的静态工具类

 1 using AutoMapper;
 2 using System;
 3 using System.Collections;
 4 using System.Collections.Generic;
 5 using System.Data;
 6 using System.Text;
 7
 8 namespace AutoMapperTest.AutoMapper
 9 {
10     /// <summary>
11     /// AutoMapper扩展帮助类
12     /// </summary>
13     public static class AutoMapperHelper
14     {
15         /// <summary>
16         /// 类型映射
17         /// </summary>
18         /// <typeparam name="T"></typeparam>
19         /// <param name="obj"></param>
20         /// <returns></returns>
21         public static T MapTo<T>(this object obj)
22         {
23             if(obj == null)
24             {
25                 return default(T);
26             }
27             Mapper.Initialize(cfg =>
28             {
29                 cfg.CreateMap(obj.GetType(), typeof(T));
30             });
31             return Mapper.Map<T>(obj);
32         }
33
34         /// <summary>
35         /// 集合列表类型映射
36         /// </summary>
37         public static List<TDestination> MapToList<TDestination>(this IEnumerable source)
38         {
39             foreach (var first in source)
40             {
41                 var type = first.GetType();
42                 Mapper.Initialize(cfg =>
43                 {
44                     cfg.CreateMap(type, typeof(TDestination));
45                 });
46                 break;
47             }
48             return Mapper.Map<List<TDestination>>(source);
49         }
50         /// <summary>
51         /// 集合列表类型映射
52         /// </summary>
53         public static List<TDestination> MapToList<TSource, TDestination>(this IEnumerable<TSource> source)
54         {
55             //IEnumerable<T> 类型需要创建元素的映射
56             Mapper.Initialize(cfg =>
57             {
58                 cfg.CreateMap<TSource, TDestination>();
59             });
60             return Mapper.Map<List<TDestination>>(source);
61         }
62         /// <summary>
63         /// 类型映射
64         /// </summary>
65         public static TDestination MapTo<TSource, TDestination>(this TSource source, TDestination destination)
66                     where TSource : class
67                     where TDestination : class
68         {
69             if (source == null) return destination;
70             Mapper.Initialize(cfg =>
71             {
72                 cfg.CreateMap<TSource, TDestination>();
73             });
74             return Mapper.Map(source, destination);
75         }
76         /// <summary>
77         /// DataReader映射
78         /// </summary>
79         public static IEnumerable<T> DataReaderMapTo<T>(this IDataReader reader)
80         {
81             Mapper.Reset();
82             Mapper.Initialize(cfg =>
83             {
84                 cfg.CreateMap<IDataReader, IEnumerable<T>>();
85             });
86             return Mapper.Map<IDataReader, IEnumerable<T>>(reader);
87         }
88     }
89 }

原文地址：https://www.cnblogs.com/fanqisoft/p/10798007.html