AutoMapper ResolveUsing

gistfile1.txt

 public class Customer
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string SurName { get; set; }
        public DateTime DateOfBirth { get; set; }
        public string HighSchool { get; set; }
        public string University { get; set; }
    }

    public class CustomerDto
    {
        public string FullName { get; set; }
        public DateTime DateOfBirth { get; set; }

        public Dictionary<string, string> Schools;
    }
    class Program
    {
        static void Main(string[] args)
        {
            Mapper.Initialize(cfg =>
            {
                cfg.CreateMap<Customer, CustomerDto>()
                    .ForMember(d => d.FullName,
                        opts =>
                            opts.ResolveUsing(
                                (src, dest, destMember, resContext) =>
                                    resContext.Items["FullName"]))
                    .ForMember(d => d.Schools,
                        opts =>
                            opts.ResolveUsing(
                                (src, dest, destMember, resContext) =>
                                    (Dictionary<string, string>)resContext.Items["Schools"]))
                                    //resContext.Items["Schools"])) // Comment above line and Uncomment this line.

                    .ForMember(d => d.DateOfBirth, opts => opts.MapFrom(c => c.DateOfBirth));
            });

            var customer = new Customer { Name = "George", SurName = "Fanshaw", DateOfBirth = DateTime.Now.Subtract(TimeSpan.FromDays(365 * 30)), HighSchool = "The Salisbury School", University = "Harvard Business"};
            
            var customerDto = Mapper.Map<CustomerDto>(customer,
                opts =>
                {
                    opts.Items["FullName"] = null;
                    opts.Items["Schools"] = null;
                });
            // Missing type map configuration or unsupported mapping.

            Console.WriteLine($"Full Name: {customerDto.FullName}");
            Console.WriteLine($"Birth Date: {customerDto.DateOfBirth}");

            if (customerDto.Schools != null)
                foreach (var schools in customerDto.Schools)
                    Console.WriteLine($"{schools.Key}: {schools.Value}");
            Console.ReadKey(true);
        }
      }