如何使用AutoMapper映射单层对象到属性不匹配的嵌套结构

1. 前置准备 #

首先安装所需NuGet包：

• 核心基础包：AutoMapper
• 若为ASP.NET Core项目，可额外安装依赖注入扩展包：AutoMapper.Extensions.Microsoft.DependencyInjection

2. 核心映射配置 #

推荐通过AutoMapper的Profile类统一管理映射规则，由于源和目标的Employee类同名，建议通过命名空间区分两类避免冲突，配置示例如下：

using AutoMapper;
// 引入源实体所在命名空间
using Source = YourSourceNamespace;
// 引入目标实体所在命名空间
using Target = YourTargetNamespace;

public class CustomMappingProfile : Profile
{
    public CustomMappingProfile()
    {
        CreateMap<Source.Employee, Target.Employee>()
            // 映射姓名字段，AutoMapper默认忽略属性名大小写，此处显式配置更易维护
            .ForMember(dest => dest.Name, opt => opt.MapFrom(src => src.name))
            // 手动映射嵌套Location对象
            .ForMember(dest => dest.Location, opt => opt.MapFrom(src => new Target.Location
            {
                City = src.city_name,
                State = src.State_name
            }));
    }
}

3. 初始化与使用 #

非依赖注入场景（如控制台应用） #

// 加载映射配置
var mapperConfig = new MapperConfiguration(cfg =>
{
    cfg.AddProfile<CustomMappingProfile>();
});
// 验证配置正确性，开发阶段建议开启，可提前发现映射遗漏
mapperConfig.AssertConfigurationIsValid();
// 创建Mapper实例
var mapper = mapperConfig.CreateMapper();

// 测试映射
var sourceEmployee = new Source.Employee
{
    name = "张三",
    city_name = "杭州",
    State_name = "浙江"
};
var targetEmployee = mapper.Map<Target.Employee>(sourceEmployee);

ASP.NET Core依赖注入场景 #

在Program.cs中注册AutoMapper即可：

var builder = WebApplication.CreateBuilder(args);
// 注册AutoMapper，自动扫描所有Profile类
builder.Services.AddAutoMapper(typeof(CustomMappingProfile));
// 其他服务注册...

var app = builder.Build();
// 中间件配置...
app.Run();

后续使用时直接在构造函数注入IMapper接口调用即可。

4. 可选优化：复用Location映射规则 #

如果存在多个场景需要从源Employee映射到Location类型，可以单独抽离Location的映射规则，提高代码复用性：

public class CustomMappingProfile : Profile
{
    public CustomMappingProfile()
    {
        // 单独配置Employee到Location的映射
        CreateMap<Source.Employee, Target.Location>()
            .ForMember(dest => dest.City, opt => opt.MapFrom(src => src.city_name))
            .ForMember(dest => dest.State, opt => opt.MapFrom(src => src.State_name));

        // Employee之间的映射可简化为
        CreateMap<Source.Employee, Target.Employee>()
            .ForMember(dest => dest.Name, opt => opt.MapFrom(src => src.name))
            .ForMember(dest => dest.Location, opt => opt.MapFrom(src => src));
    }
}

内容的提问来源于stack exchange，提问作者user5979