A source member can map to multiple destination members

[Xriuk]

Source/destination types

class Order{
  public int ProductId {get; set;}
  public Product? Product {get; set;}
}

class OrderDto{
  public int ProductId {get; set;}
}

Mapping configuration

// ASP Net Core Dependency Injection - Global configuration
builder.Services.AddAutoMapper((serviceProvider, config) => {
  var postfixes = new[] { "Id", "Code" };
  config.RecognizePostfixes(postfixes);
  config.RecognizeDestinationPostfixes(postfixes);
  
  config.AllowNullCollections = true;
  config.AddCollectionMappers();
}, Assembly.GetExecutingAssembly());

// Actual map inside a profile
CreateMap<OrderDto, Order>();

Version: 11.0.1

Expected behavior

I'd expect Automapper to match members with the same un-altered name first before proceeding to exclude pre/postfixes, so that ProductId of OrderDto gets mapped correctly to ProductId of Order.

Actual behavior

I get an error saying missing mapping for int -> Product, because automapper tries to map Product(Id) to Product instead by removing the postfix.

[lbargaoanu]

Check the execution plan. You configured AM to map ProductId to both ProductId and Product and, as the validation says, it cannot do that. It seems that kind of config is not exactly a good idea :)

[Xriuk]

Yeah, that's kinda the point, the execution plan shouldn't be like that imo.
I think that AM should pick the first (and best) member if not explicitly configured (why would it map automatically to two members anyway?). I don't know how it's picking the members now in the code, so I don't know if it would be a big deal to change its behaviour or not.