使用接口类型定义的属性从动态映射到类型

Question

上下文是我想将dynamic dapper 结果映射到一个对象，并且该对象具有一个具有接口类型的属性：

public class TargetModel
{
    public int Id { get; set; }
    public IAddress AbstractAddress { get; set; }
}

动态到对象位是直截了当的，但我无法配置 AutoMapper 来告诉它如何处理接口。

dynamic sourceModel = new ExpandoObject();

// flat model - id should map to TargetModel, Address01 will map to a nested type Address on TargetModel
sourceModel.Id = 1;
sourceModel.Address01 = "address01";

// for debugging purposes address maps ok from dynamic
Address address = Mapper.Map<Address>(sourceModel);

// this maps, but AbstractAddress is null - I need to config AutoMapper to understand how to map IAddress to Address
TargetModel target = Mapper.Map<TargetModel>(sourceModel);

我试图告诉它如何处理该属性：

CreateMap<ExpandoObject, TargetModel>()
    .ForMember(y => y.AbstractAddress, opts => opts.MapFrom(f => f));

失败的原因是：

System.ArgumentException: 无法创建接口类型的实例

所以我试图暗示具体：

CreateMap<IAddress, Address>().As<Address>();

这不能解决问题并且异常仍然存在。

我查看了以下问题/概念并尝试了各种配置选项，但无法使地图正常工作：

• AutoMapper: Mapping objects with interface properties
• https://dotnetfiddle.net/fPQxWx

Answer 1

这是试图从ExpandoObject 中的string 映射到目标类型中的IAddress。显然它不能创建一个 IAddress 的实例来填充，所以你必须自己在映射中实现它。

如果您的模型如下所示：

public class TargetModel
{
    public int Id { get; set; }
    public IAddress AbstractAddress { get; set; }
}

public interface IAddress
{
    string Address01 { get; set; }
}

public class Address : IAddress
{
    public string Address01 { get; set; }
}

那么您的配置和设置可能如下所示：

public void MappingTests()
{
    dynamic sourceModel = new ExpandoObject();

    // flat model - id should map to TargetModel, Address01 will map to a nested type Address on TargetModel
    sourceModel.Id = 1;
    sourceModel.Address01 = "address01";

    Mapper.Initialize(cfg =>
    {
        cfg.CreateMap<ExpandoObject, TargetModel>()
        .ForMember(dest => dest.AbstractAddress, opt => opt.MapFrom(src => new Address() { Address01 = src.First(kvp => kvp.Key == "Address01").Value.ToString() }))
        .ForMember(destinationMember => destinationMember.Id, opt => opt.MapFrom(src => src.First(kvp => kvp.Key == "Id").Value));
    });

    TargetModel target = Mapper.Map<TargetModel>(sourceModel);
}

我只是将它用作IEnumerable<KeyValuePair<string, object>>，但您也可以通过强制转换将 expando 对象视为字典。

cfg.CreateMap<ExpandoObject, TargetModel>()
    .ForMember(dest => dest.AbstractAddress, opt => opt.MapFrom(src => new Address() { Address01 = ((IDictionary<string, object>)src)["Address01"].ToString() }))
    .ForMember(destinationMember => destinationMember.Id, opt => opt.MapFrom(src => ((IDictionary<string, object>)src)["Id"]));