4.2.1 Bug - CreateMap(profileName) never initializes the NamedProfile instance.

I’m trying to confirm this is the issue I’m running into as I’m attempting to migrate from v3.3.1 to 4.2.1.

In doing so I came across what seems to be a decent size bug that breaks inheritance and ReverseMap. Possibly more but I’m unfamiliar with this code base.

Calling mapperConfiguration.CreateMap<>() may instantiate a new NamedProfile instance but never initialize it. See below:

    private Profile GetProfile(string profileName)
    {
      return this._profiles.GetOrAdd(profileName, (Func<string, Profile>) (name => (Profile) new MapperConfiguration.NamedProfile(profileName)));
    }

    private class NamedProfile : Profile
    {
      public NamedProfile(string profileName)
        : base(profileName)
      {
      }

      protected override void Configure()
      {
      }
    }

The profile instance never gets it’s Initialize() method called from CreateMap() and thus never has the private IConfiguration _configurator; private member set. From what I’ve found, this causes issues with ReverseMap() and IncludeBase<,>() functions. Possibly more if anything depends on the Profile instance using the _configurator field.

The code below caused me to get a NullReferenceException.

mapperConfiguration.CreateMap<File, FileDto>()
    .ForMember(dto => dto.CreatedByUserId, c => c.MapFrom(f => f.CreatedByUserId))
    .ForMember(dto => dto.CreatedOn, c => c.MapFrom(f => f.CreatedOn))
    .ForMember(dto => dto.Extension, c => c.MapFrom(f => f.Extension))
    .ForMember(dto => dto.Id, c => c.MapFrom(f => f.Id))
    .ForMember(dto => dto.Md5Hash, c => c.MapFrom(f => f.Md5Hash))
    .ForMember(dto => dto.Size, c => c.MapFrom(f => f.Size));

mapperConfiguration.CreateMap<DocumentRevisionFile, FileDto>()
    .IncludeBase<File, FileDto>(); // <<<< BREAKS! 

System.NullReferenceException: Object reference not set to an instance of an object. at AutoMapper.Profile.CreateMap(Type sourceType, Type destinationType) at AutoMapper.Internal.MappingExpression2.IncludeBase(Type sourceBase, Type destinationBase) at AutoMapper.Internal.MappingExpression2.IncludeBaseTSourceBase,TDestinationBase

It doesn’t matter how you register your mappings. I’ve tried both: Mapper.Initialize() & using new MapperConfiguration(c => { });

Temporary fix: Since I was moving from v3 to v4, CreateMap<,>() now takes a string parameter for profileName. For now I just created an extension method to fill this gap until I can confirm we may move to 4.2.1 without other breaking changes.

public static class AutoMapperExtensions
{
    public static IMappingExpression<TSource, TTarget> CreateMap<TSource, TTarget>(this IConfiguration configuration)
    {
        var profile = configuration.CreateProfile(string.Format("{0}|{1}", typeof (TSource).FullName, typeof (TTarget).FullName));
        return profile.CreateMap<TSource, TTarget>();
    }
}

The CreateProfile method correctly initializes the profile. Then just return the profile.CreateMap<,>();

[jbogard]

@Cephei I took that named profile stuff away because it was really hard to get the order of things right during config time. In 5.0 I gather all config, then apply it, but applying profile names willy-nilly really made my life difficult.

[TylerCarlson1]

Version 5.0 will most likely be the next release of Automapper. An update to 4.2.1 is probably not going to happen.