构造时的 Automapper 异常

Question

我最近将一个项目从 .net5 更新到 .net6，现在我在尝试从 DI 解析 automapper(11.0.1)（或实例化它）时遇到错误。

注册：

services.AddAutoMapper(typeof(MatchProfile).Assembly);

实例化：

var mapper = services.GetService<IMapper>();

堆栈跟踪：

System.InvalidOperationException: Sequence contains no matching element
   at System.Linq.ThrowHelper.ThrowNoMatchException()
   at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source, Func`2 predicate)
   at AutoMapper.Configuration.MemberConfigurationExpression`3.Configure(TypeMap typeMap)
   at AutoMapper.Configuration.MappingExpressionBase.Configure(TypeMap typeMap)
   at AutoMapper.ProfileMap.BuildTypeMap(IGlobalConfiguration configurationProvider, ITypeMapConfiguration config)
   at AutoMapper.ProfileMap.Register(IGlobalConfiguration configurationProvider)
   at AutoMapper.MapperConfiguration.Seal()
   at AutoMapper.MapperConfiguration..ctor(MapperConfigurationExpression configurationExpression)
   at Microsoft.Extensions.DependencyInjection.ServiceCollectionExtensions.<>c.<AddAutoMapperClasses>b__12_2(IServiceProvider sp)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSiteMain(ServiceCallSite callSite, TArgument argument)

有没有办法找出错误所在的配置文件？我可以通过某种方式调试它吗？

at AutoMapper.Configuration.MemberConfigurationExpression`3.Configure(TypeMap typeMap)

上面的错误并不是找到错误的有用提示，因为项目非常大，我真的不想为 fow 注释掉行。

为此创建了一个单元测试，它引发了完全相同的错误：

[TestClass]
public class MapperTests
{
    [TestMethod]
    public void AssertConfigIsValid()
    {
        var configuration = new MapperConfiguration(cfg =>
        {
            cfg.AddMaps(typeof(ReportsProfile).Assembly);
        });

        configuration.AssertConfigurationIsValid();
    }
}

编辑：

视图模型：

public class AnswerModel
{
    public ICollection<AnswerFieldModel> Fields { get; set; }
}

public abstract class AnswerFieldModel
{
    public Guid FieldId { get; set; }

    public abstract object GetValue();

}

public sealed class AnswerFieldModel<TValue> : AnswerFieldModel
{
    public TValue Value { get; set; }

    public override object GetValue() => Value;

}

映射配置文件：

CreateMap<Domain.Entities.Reports.ValueObjects.Answer, AnswerModel>()
    .ForMember(dest => dest.Fields, opt => opt.MapFrom(src => src.Fields))
    .ReverseMap();

CreateMap<Domain.Entities.Reports.ValueObjects.AnswerField, AnswerFieldModel>()
    .ForMember(dest => dest.FieldId, opt => opt.MapFrom(src => src.FieldId))
    .Include(typeof(Domain.Entities.Reports.ValueObjects.AnswerField<>), typeof(AnswerFieldModel<>))
.ReverseMap();

CreateMap(typeof(Domain.Entities.Reports.ValueObjects.AnswerField<>), typeof(AnswerFieldModel<>))
    .ForMember("Value", opt => opt.MapFrom("Value"))
    .ReverseMap();

Answer 1

由于错误起源于MemberConfigurationExpression.Configure()，我在以下映射表达式中发现了问题：

CreateMap(typeof(Domain.Entities.Reports.ValueObjects.AnswerField<>), typeof(AnswerFieldModel<>))
    //.ForMember("Value", opt => opt.MapFrom("Value"))
    .ReverseMap();

当这个 .ForMember("Value", opt => opt.MapFrom("Value")) 被注释掉时，一切都按预期工作。在 AM 10.1.1 中，这并没有引发错误。

这里是documentation如何映射开放泛型。

构造时的 Automapper 异常

Automapper Exception on construction

c#

exception

automapper

.net-6.0