AutoMapper中IValueResolver如何获取待映射目标属性名实现多属性复用

1. 修正映射配置 #

同一个<AlertLine, AlertLineDto>的映射规则不需要重复声明CreateMap，直接链式调用ForMember配置多个属性即可：

CreateMap<AlertLine, AlertLineDto>()
    .ForMember(dest => dest.BusinessArea, opt => opt.MapFrom<MyResolver>())
    .ForMember(dest => dest.Division, opt => opt.MapFrom<MyResolver>())
    .ForMember(dest => dest.SubDivision, opt => opt.MapFrom<MyResolver>());

2. 改造Resolver复用逻辑 #

IValueResolver的Resolve方法第三个入参destMember就是当前正在映射的目标属性名称，直接使用即可。你可以预先建立目标属性名和AddlInformation中对应ID字段、查询逻辑的匹配规则，即可实现同一份逻辑适配多个属性：

public class MyResolver : IValueResolver<AlertLine, AlertLineDto, string>
{
    private readonly ICatalogService _catalogService;
    // 修正构造函数名和类名保持一致，原代码此处为笔误
    public MyResolver(ICatalogService catalogService)
    {
        _catalogService = catalogService;
    }

    public string Resolve(AlertLine source, AlertLineDto destination, string destMember, ResolutionContext context)
    {
        var variant = JsonSerializer.Deserialize<AddlInformation>(source.AddlDimension);
        // 可根据实际业务调整匹配规则，这里示例不同属性对应不同的ID字段和查询接口
        var propertyMap = new Dictionary<string, (int Id, Func<int, object> Query)>
        {
            { 
                "BusinessArea", 
                (variant.BUSINESS_AREA_ID, _catalogService.GetCachedBusinessAreaById) 
            },
            { 
                "Division", 
                (variant.DIVISION_ID, _catalogService.GetCachedDivisionById) 
            },
            { 
                "SubDivision", 
                (variant.SUB_DIVISION_ID, _catalogService.GetCachedSubDivisionById) 
            }
        };

        if (!propertyMap.TryGetValue(destMember, out var config) || config.Id <= 0)
        {
            return string.Empty;
        }
        
        var data = config.Query(config.Id);
        // 所有查询结果统一取Description字段，符合你提到的处理逻辑完全一致的要求
        return data?.GetType().GetProperty("Description")?.GetValue(data)?.ToString() ?? string.Empty;
    }
}

可选优化 #

如果不想用反射读取Description属性，可以给所有目录实体添加统一的IHasDescription接口，所有实体实现该接口后即可强类型读取属性，性能更优。

内容的提问来源于stack exchange，提问作者pedrommuller