AutoMapper ForMember Ignore not working

Question

Doing a copy of the same entity type in an MVC app, but looking to ignore copying the primary key (doing an update to an existing entity). But setting the Id column to ignore in the map below is not working and the Id is being overwritten.

cfg.CreateMap<VendorContact, VendorContact>()
    .ForMember(dest => dest.Id, option => option.Ignore())
    .ForMember(dest => dest.CreatedById, option => option.Ignore())
    .ForMember(dest => dest.CreatedOn, option => option.Ignore())
    ; 

Executing the Map:

existingStratusVendorContact = Mapper.Map<VendorContact>(vendorContact);

Saw this other answer, but it appears I am doing that already.

UPDATE:

Fyi, I am creating my maps in the Global.asax like so:

Mapper.Initialize(cfg =>
{
    cfg.CreateMap<VendorContact, VendorContact>()
        .ForMember(dest => dest.Id, option => option.Ignore())
        .ForMember(dest => dest.CreatedById, option => option.Ignore())
        .ForMember(dest => dest.CreatedOn, option => option.Ignore())
        ;  

});

Answer 1

Your issue is that you're not giving automapper the existing object. Automapper can absolutely do this.

Mapper.Map<VendorContact>(vendorContact, existingStratusVendorContact);

Should do what you want. You current code is creating a brand new object, and replacing existingStratusVendorContact with the entirely new object. The above code will take the existing object and update values, as you expected.