How does deriving work in protobuf-net?

Question

Like I would do in C#:

class DerivedClass : BaseClass {}

is there a way to recreate this behaviour with messages in a proto-file? So that the DerivedClass is of type BaseClass and can inherit its properties.

I tried to extend my base message, but this yields a different result.

Answer 1

If we assume that this is:

[ProtoContract]
[ProtoInclude(7, typeof(DerivedClass))]
public class BaseClass {}

[ProtoContract]
public class DerivedClass : BaseClass {}

Then we can use:

string proto = Serializer.GetProto<BaseClass>();

to see how protobuf-net is interpreting it:

message BaseClass {
   // the following represent sub-types; at most 1 should have a value
   optional DerivedClass DerivedClass = 7;
}
message DerivedClass {
}

This would actually map fairly well to the new oneof - simply, GetProto hasn't been updated to use the new syntax (it wouldn't impact the output, though). But the following would also be equivalent:

message BaseClass {
    oneof subtypes {
        // the following represent sub-types; at most 1 should have a value
        DerivedClass DerivedClass = 7;
        AnotherDerivedClass AnotherDerivedClass = 8;
        AndOneMoreForLuck AndOneMoreForLuck = 9;
    }
}
message DerivedClass {
}
message AnotherDerivedClass {
}
message AndOneMoreForLuck {
}