Mapping Interfaces

There are three interfaces that enable the definition of mappings making;

1. IMapTo
2. IMapFrom
3. ICustomMap

IMapTo & IMapFrom

The IMapTo<T> and IMapFrom<T> interfaces enable the definition of simple mappings i.e. If you have a database entity and domain entity that may have the same properies eg.

A database entity that has two properties

public class DatabaseEntity
{
    public string Name {get;set;}
    public string Description {get;set;}
}

A domain object with the same 2 properties with the same names

public class DomainObject
{
    public string Name {get;set;}
    public string Description {get;set;}
}

You don’t necessarily want to write mapping logic to map between the two objects. You have simply make use of the IMapTo and IMapFrom interfaces to define the mappings

public class DatabaseEntity : IMapTo<DomainObject>
{
    public string Name {get;set;}
    public string Description {get;set;}
}

Once the interface has been implemented and the designated class name supplied there is nothing else you need to do to implement the mapping. The automapper libraries take care of all the mapping for you.

ICustomMap

The ICustomMap interface is required if your objects require more complex mapping logic. The interface requires the implementation of a mapping method

 public interface ICustomMap
{
    void CustomMap(IMapperConfigurationExpression configuration);
}

It is in the CustomMap method that you can use all the power and functionality of Automapper to implement your required mapping logic

 public class ComplexDomainObject  : ICustomMap
{
    public string Firstname { get; set; }
    public string LastName { get; set; }
    public string Summary { get; set; }
    public string Title { get; set; }
    public int Age { get; set; }

    public void CustomMap(IMapperConfigurationExpression configuration)
    {
        configuration.CreateMap<ComplexDomainObject, SimpleEntity>()
            .ForMember(dest => dest.Name, opt => opt.MapFrom(src => string.Concat( src.Firstname, " ", src.LastName )))
            .ForMember(dest => dest.Description, opt => opt.MapFrom(src => string.Concat( src.Title , " ", src.Summary)))
            .ForMember(dest => dest.Age, opt => opt.MapFrom(src => src.Age));

    }
}