Вы можете попробовать это:
_mapper.Map<DestType>(result, options => options.AfterMap((s, d) => ((DestType) d).Code = null));
Полный пример
void Main()
{
IConfigurationProvider conf = new MapperConfiguration(exp => exp.CreateMap<Src, Dest>());
IMapper mapper = new Mapper(conf);
var src = new Src(){
Id =1,
Name= "John Doe"
};
var result = mapper.Map<Dest>(src, options => options.AfterMap((s, d) => ((Dest) d).Name = null));
result.Dump();
var result2 = mapper.Map<List<Dest>>(srcList, options => options.AfterMap((s, d) => ((List<Dest>) d).ForEach(i => i.Name = null)));
result2.Dump();
}
public class Src
{
public int Id {get; set;}
public string Name {get; set;}
}
public class Dest
{
public int Id {get; set;}
public string Name {get; set;}
}
![enter image description here](https://i.stack.imgur.com/LmRPm.png)
В качестве альтернативы
void ConfigureMap(IMappingOperationOptions<Src, Dest> opt)
{
opt.ConfigureMap()
.ForMember(dest => dest.Name, m => m.Ignore());
};
var result3 = mapper.Map<List<Dest>>(srcList, ConfigureMap());
result3.Dump();