c# - Protobuf-net serialization without annotation

Question

I looked at this answer and I am in a situation where I don't need to maintain backward compatibility and I have to have a solution that works without having to decorate dozens of classes with the attributes needed for protobuf-net. So I tried using RuntimeTypeModel.Default.InferTagFromNameDefault = true; but I may be not using it correctly because the Serializer.Serialize call still throws an exception asking for a contract. Here is my quick test, what am I doing wrong?

public enum CompanyTypes
{
    None, Small, Big, Enterprise, Startup
}

public class BaseUser
{
    public string SSN { get; set; }    
}

public class User : BaseUser
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public int Age { get; set; }
    public DateTime BirthDate { get; set; }
    public List<string> Friends { get; set; }
    public Company Company { get; set; }
}

public class Company
{
    public string Name { get; set; }
    public string Address { get; set; }
    public CompanyTypes Type { get; set; }
    public List<Product> Products { get; set; }
}

public class Product
{
    public string Name { get; set; }
    public string Sku { get; set; }
}

[TestClass]
public class SerializationTest
{
    [TestMethod]
    public void SerializeDeserializeTest()
    {
        var user = new User
                       {
                           Age = 10,
                           BirthDate = DateTime.Now.AddYears(-10),
                           FirstName = "Test First",
                           LastName = "Test Last",
                           Friends = new List<string> { "Bob", "John" },
                           Company = new Company
                                         {
                                             Name = "Test Company",
                                             Address = "Timbuktu",
                                             Type = CompanyTypes.Startup,
                                             Products = new List<Product>
                                             {
                                                new Product{Name="Nerf Rocket", Sku="12324AC"},
                                                new Product{Name="Nerf Dart", Sku="DHSN123"}
                                             }
                                         }
                       };

        RuntimeTypeModel.Default.InferTagFromNameDefault = true;
        using (var memoryStream = new MemoryStream())
        {
            Serializer.Serialize(memoryStream, user);
            var serialized = Convert.ToBase64String(memoryStream.GetBuffer(), 0, (int)memoryStream.Length);
        }
    }
}

Answer 1

InferTagFromName (and it's twin, InferTagFromNameDefault) only take a hand when it is necessary to resolve a tag number for a member; they don't influence which members need to be serialized (so currently the answer to that would be: none, even if the system knew about them). The option you might have chosen would be ImplicitFields, but that is currently only available as a [ProtoContract(...)] marker. If you don't mind a little annotation, a pragmatic fix may be:

[ProtoContract(ImplicitFields = ImplicitFields.AllPublic)]

on User, Company and Product, and something a bit more complex for BaseUser (because of the inheritance):

[ProtoContract(ImplicitFields = ImplicitFields.AllPublic, ImplicitFirstTag = 10)]
[ProtoInclude(1, typeof(User))]

Note we haven't had to add lots of per-member annotation. If you are really really anti-attributes, then it is also possible to configure the entire model through code, via:

RuntimeTypeModel.Default.Add(typeof(Product), false).Add("Name", "Sku");
RuntimeTypeModel.Default.Add(typeof(Company), false).Add("Name", "Address",
         "Type", "Products");
RuntimeTypeModel.Default.Add(typeof(User), false).Add("FirstName", "LastName",
         "Age", "BirthDate", "Friends", "Company");
RuntimeTypeModel.Default.Add(typeof(BaseUser), false).Add(10, "SSN")
         .AddSubType(1, typeof(User));