using System;

using AutoMapper;

public class Program

{

    public static void Main()

    {

        var a = new A { Foo = 9, MyEnum = MyEnum.Alert};

        var b = new B();

        Mapper.CreateMap<A, B>().ForMember(dest => dest.Bar, opt => opt.MapFrom(src => src.Foo.HasValue ? src.Foo.Value.ToString() : string.Empty)).ForMember(dest => dest.MyEnumString, opt => opt.MapFrom(src => src.MyEnum.HasValue ? src.MyEnum.Value.ToString() : string.Empty));

        Mapper.AssertConfigurationIsValid();

        Mapper.Map(a, b);

        Console.WriteLine(b.Bar);

        Console.WriteLine(b.MyEnumString);

        a = new A { Foo = null, MyEnum = null };

        Mapper.Map(a, b);

        Console.WriteLine(b.Bar);

        Console.WriteLine(b.MyEnumString);

    }   

}

​

public class A 

{

    public int? Foo { get; set; }

    public MyEnum? MyEnum { get; set; }

}

​

public class B

{

    public string Bar { get; set; }

    public string MyEnumString { get; set; }

}

​

public enum MyEnum 

{

    Alert = 1,

    Other = 2,

    Etc = 3

}