c# automapper 使用(一)

一、最简单的用法

有两个类User和UserDto

     public class User
     {
         public int Id { get; set; }
         public string Name { get; set; }
         public int Age { get; set; }
     }

     public class UserDto
     {
         public string Name { get; set; }
         public int Age { get; set; }
     }

将User转换成UserDto也和简单

     Mapper.Initialize(x => x.CreateMap<User, UserDto>());
     User user = new User()
     {
         Id = ,
         Name = "caoyc",
         Age =
     };
     var dto = Mapper.Map<UserDto>(user);

这是一种最简单的使用，AutoMapper会更加字段名称去自动对于，忽略大小写。

二、如果属性名称不同

将UserDto的Name属性改成Name2

     Mapper.Initialize(x =>
         x.CreateMap<User, UserDto>()
          .ForMember(d =>d.Name2, opt => {
             opt.MapFrom(s => s.Name);
             })
         );

     User user = new User()
     {
         Id = ,
         Name = "caoyc",
         Age =
     };

     var dto = Mapper.Map<UserDto>(user);

三、使用Profile配置

自定义一个UserProfile类继承Profile，并重写Configure方法

     public class UserProfile : Profile
     {
         protected override void Configure()
         {
             CreateMap<User, UserDto>()
                 .ForMember(d => d.Name2, opt =>
                 {
                     opt.MapFrom(s => s.Name);
                 });
         }
     }

使用时就这样

     Mapper.Initialize(x => x.AddProfile<UserProfile>());

     User user = new User()
     {
         Id = ,
         Name = "caoyc",
         Age =
     };

     var dto = Mapper.Map<UserDto>(user);

四、空值替换NullSubstitute

空值替换允许我们将Source对象中的空值在转换为Destination的值的时候，使用指定的值来替换空值。

     public class UserProfile : Profile
     {
         protected override void Configure()
         {
             CreateMap<User, UserDto>()
                 .ForMember(d => d.Name2, opt => opt.MapFrom(s => s.Name))
                 .ForMember(d => d.Name2, opt => opt.NullSubstitute("值为空"));

         }
     }

     Mapper.Initialize(x => x.AddProfile<UserProfile>());

     User user = new User()
     {
         Id = ,
         Age =
     };

     var dto = Mapper.Map<UserDto>(user);

结果为：

五、忽略属性Ignore

     public class User
     {
         public int Id { get; set; }
         public string Name { get; set; }
         public int Age { get; set; }
     }

     public class UserDto
     {
         public string Name { get; set; }
         public int Age { get; set; }

     }

     public class UserProfile : Profile
     {
         protected override void Configure()
         {
             CreateMap<User, UserDto>().ForMember("Name", opt => opt.Ignore());
         }
     }

使用

     Mapper.Initialize(x => x.AddProfile<UserProfile>());

     User user = new User()
     {
         Id = ,
         Name="caoyc",
         Age =
     };

     var dto = Mapper.Map<UserDto>(user);

结果：

六、预设值

如果目标属性多于源属性，可以进行预设值

     public class User
     {
         public int Id { get; set; }
         public string Name { get; set; }
         public int Age { get; set; }
     }

     public class UserDto
     {
         public string Name { get; set; }
         public int Age { get; set; }
         public string Gender { get; set; }

     }

     public class UserProfile : Profile
     {
         protected override void Configure()
         {
             CreateMap<User, UserDto>();
         }
     }

使用

     Mapper.Initialize(x => x.AddProfile<UserProfile>());

     User user = new User()
     {
         Id = ,
         Name="caoyc",
         Age =
     };

     UserDto dto = new UserDto() {Gender = "男"};
     Mapper.Map(user, dto);

七、类型转换ITypeConverter

如果数据中Gender存储的int类型，而DTO中Gender是String类型

     public class User
     {
         public int Gender { get; set; }
     }

     public class UserDto
     {
         public string Gender { get; set; }
     }

类型转换类，需要实现接口ITypeConverter

     public class GenderTypeConvertert : ITypeConverter<int, string>
     {
         public string Convert(int source, string destination, ResolutionContext context)
         {
             switch (source)
             {
                 case :
                     destination = "男";
                     break;
                 case :
                     destination = "女";
                     break;
                 default:
                     destination = "未知";
                     break;
             }
             return destination;
         }
     }

配置规则

     public class UserProfile : Profile
     {
         protected override void Configure()
         {
             CreateMap<User, UserDto>();

             CreateMap<int, string>().ConvertUsing<GenderTypeConvertert>();
             //也可以写这样
             //CreateMap<int, string>().ConvertUsing(new GenderTypeConvertert());
         }
     }

使用

     Mapper.Initialize(x => x.AddProfile<UserProfile>());

     User user0 = new User() { Gender =  };
     User user1 = new User() { Gender =  };
     User user2 = new User() { Gender =  };
     var dto0= Mapper.Map<UserDto>(user0);
     var dto1 = Mapper.Map<UserDto>(user1);
     var dto2 = Mapper.Map<UserDto>(user2);

     Console.WriteLine("dto0:{0}", dto0.Gender);
     Console.WriteLine("dto1:{0}", dto1.Gender);
     Console.WriteLine("dto2:{0}", dto2.Gender);

结果

八、条件约束Condition

当满足条件时才进行映射字段，例如人类年龄，假设我们现在人类年龄范围为0-200岁（这只是假设），只有满足在这个条件才进行映射

DTO和Entity

     public class User
     {
         public int Age { get; set; }
     }

     public class UserDto
     {
         public int Age { get; set; }
     }

Profile

     public class UserProfile : Profile
     {
         protected override void Configure()
         {
             CreateMap<User, UserDto>().ForMember(dest=>dest.Age,opt=>opt.Condition(src=>src.Age>= && src.Age<=));
         }
     }

使用代码

     Mapper.Initialize(x => x.AddProfile<UserProfile>());

     User user0 = new User() { Age =  };
     User user1 = new User() { Age =  };
     User user2 = new User() { Age =  };
     var dto0= Mapper.Map<UserDto>(user0);
     var dto1 = Mapper.Map<UserDto>(user1);
     var dto2 = Mapper.Map<UserDto>(user2);

     Console.WriteLine("dto0:{0}", dto0.Age);
     Console.WriteLine("dto1:{0}", dto1.Age);
     Console.WriteLine("dto2:{0}", dto2.Age);

输出结果