Why do I get exception for AutoMapper int to int[] array

问题

I'm using the AutoMapper object mapper, but am getting the exception "Custom configuration for members is only supported for top-level individual members on a type."

Basically I have

public class Obj1 
{ 
    public int Id {get;set;} 
} 

and

public class Obj2 
{ 
    public int[] Ids { get; set; } 
} 

Th exception occurs when I try to create the mapping like;

Mapper
    .CreateMap<Obj1, Obj2>()
    .ForMember(d => d.Ids[0], o => o.MapFrom(s => s.Id)
);

Why is this happening ? What I'm wanting to achieve is when the objects are mapping that the single int Id in the source is mapped to the first element in the destination int array e.g [0]. The complete exception is

type="AutoMapper.AutoMapperConfigurationException" message="Custom configuration for members is only supported for top-level individual members on a type." source="AutoMapper"
detail="AutoMapper.AutoMapperConfigurationException: Custom configuration for members is only supported for top-level individual members on a type. at AutoMapper.Impl.ReflectionHelper.FindProperty(LambdaExpression lambdaExpression) at AutoMapper.MappingExpression2.ForMember(Expression1 destinationMember, Action`1 memberOptions) at ...

回答1:

You are close - just need to make the array instead of setting a individual member

Mapper.CreateMap<Obj1, Obj2>().ForMember(d => d.Ids, o => o.MapFrom(s => new[]{s.Id}));

来源：https://stackoverflow.com/questions/23088796/why-do-i-get-exception-for-automapper-int-to-int-array