Automapper use destination properties and map single property

Question

I want to use automapper to map between 2 lists. One list contains a code and a string, the other contains the code and other fields. I want to use all the existing values/properties on the destination object, except for one. Is this possible with automapper? I don't want to specify all the properties with a UseDestinationValue(). Tried the following but instead of returning my destination list with the one property updated, it returns a new list with only matching items (in both lists) and all the fields are null:

public static IMappingExpression<TSource, TDest> UseAllDestinationValues<TSource, TDest>(this IMappingExpression<TSource, TDest> expression)
    {
        expression.ForAllMembers(opt => opt.UseDestinationValue());
        return expression;
    }

    Mapper.CreateMap<Perm, PermViewModel>()
            .UseAllDestinationValues()
            .ForMember(dest => dest.CanEdit, opt => opt.MapFrom(s => s.editable));

var items = Mapper.Map<List<Perm>, List<PermViewModel>>(list, model.Items.Items);

Answer 1

I had to do something sort of similar using nullable doubles from one application to another. You could set up a type converter. Without your specific classes I can't speak to exactly how to do this, but here is my example.

Mapper.CreateMap<double?, double>().ConvertUsing<NullableDoubleConverter>();

private class NullableDoubleConverter : TypeConverter<double?, double>
{
    protected override double ConvertCore(double? source)
    {
        if (source == null)
            return Constants.NullDouble;
        else
            return (double)source;
    }
}

You could obviously adapt this using something like.

Mapper.CreateMap<Perm, PermViewModel>().ConvertUsing<PermConverter>();

private class PermConverter : TypeConverter<Perm, PermViewModel>
{
    protected override PermViewModel ConvertCore(Perm source)
    {
        return new PermViewModel() 
        {
             //Set your parameters here. 
        };
    }
}