AutoMapper 强制 null

Question

I use Automapper with EntityFramework Core, and have the following configuration for one of my objects ( Couche , having associated an Affaire and a Sol object)

CreateMap<Couche, CoucheDTO>()
    .ForMember(dto => dto.AffaireId, o => o.MapFrom(p => p.Affaire.Id))
    .ForMember(dto => dto.SolId, o => o.MapFrom(p => p.Sol.Id))
    .ForMember(dto => dto.SolNom, o => o.MapFrom(p => p.Sol.Nom))
    .ForMember(dto => dto.SolCode, o => o.MapFrom(p => p.Sol.Code))
    .ReverseMap()
    .ForPath(couche => couche.Affaire, o => o.MapFrom(p => {return null; })) // ???
    .ForPath(couche => couche.Sol, o => o.Ignore()); // ???

When I reverse map (from DTO to Business Object), I need only the correct AffaireId , the Affaire field should be set to null (I don't need to create invalid half-filled objects). How to do it with reverse map? Ignore seem do not put null....

PS. I tried

.ForPath(couche => couche.Affaire, o => o.MapFrom<AffaireDTO>(p => null))
.ForPath(couche => couche.Sol, o => o.MapFrom<AffaireDTO>(p => null));

but get then

InvalidOperationException: No coercion operator is defined between types 'MyApp.Core.Entities.Sol' and 'MyApp.Core.Entities.Affaire'. System.Linq.Expressions.Expression.GetUserDefinedCoercionOrThrow(ExpressionType coercionType, Expression expression, Type convertToType)

DependencyResolutionException: An exception was thrown while activating MyApp.Web.Services.SondageService -> λ:AutoMapper.IMapper -> λ:AutoMapper.IConfigurationProvider. Autofac.Core.Resolving.Middleware.ActivatorErrorHandlingMiddleware.Execute(ResolveRequestContext context, Action next)

Answer 1

There should be no need to use 'return'.

Try .ForPath(couche => couche.Affaire, o => o.MapFrom(p => null))

Answer 2

Finally, found solution to infere the type... (Affaire)null :

.ForPath(couche => couche.Affaire, o => o.MapFrom(p => (Affaire)null))
.ForPath(couche => couche.Sol, o => o.MapFrom(p => (Sol)null));