Polymorphism with AutoMapper

Question

I have these business classes:

class BaseNode
    {
        public string name;        
    }

    class CompositeNode : BaseNode
    {
        public List<BaseNode> childs = new List<BaseNode>();
    }   

And this flat dto:

class NodeDto
    {
        public string name;
        public List<NodeDto> childs;
    }

(note how all derived types are represented by one dto class)

I use auto mapper to do a conversion:

 Mapper.CreateMap<BaseNode, NodeDto>()
                .Include<CompositeNode, NodeDto>()
                .ForMember(s => s.childs, prop => prop.Ignore());

 Mapper.CreateMap<CompositeNode, NodeDto>();

 Mapper.AssertConfigurationIsValid();

 var root = new CompositeNode() { name = "root" };
 var child = new CompositeNode {name = "child"};
 var child2 = new CompositeNode { name = "child2" };            
 root.childs.Add(child);
 child.childs.Add(child2);

 var rootDto = Mapper.Map<CompositeNode, NodeDto>(root);

However the below is always null instead of having the child list:

rootDto.childs[0].childs

(ie only first level child is mapped correctly)

If I remove the prop.Ignore part I get an assert error that the childs property is not mapped.

What am I doing wrong?

Answer 1

This is old, but came across it looking for something else... You're telling it to ignore the childs field. AutoMapper is doing what it was told to do.

.ForMember(s => s.childs, prop => prop.Ignore());

Answer 2

You don't have properties in your classes public string Name {get;set;} , you have public Fields, I think that's the problem

also in order to map this classes you only need to create 2 simple maps

Mapper.CreateMap<CompositeNode, NodeDto>();
Mapper.CreateMap<BaseNode, NodeDto>()
         .ForMember(s => s.childs, prop => prop.Ignore());;