Question

Simple experiment: I created an entity model from Northwind, and find that the generated classes don’t work for protobuf-net v2 without adding the Order property. Is there a way to get the entity code generator to add Order, or is there a way to get protobuf-net to work without Order?

I have to change

[DataMemberAttribute()]

to

[DataMemberAttribute(Order=1)], etc.

NorthwindEntities e = new NorthwindEntities();

using(var file = File.Create("customers.bin"))
{
    Serializer.Serialize(file, e.Customers);
}

Answer 1

What is required is that it has a way to resolve members to numeric keys. This can take the form of inline attributes – for example, it allows [DataContract]/[DataMember(Order=key)], [XmlType]/[XmlElement(Order=key)], or [ProtoContract]/[ProtoMember(key)].

There are also options via [DataContract] to infer the contract alphabetically, but this is only safe if your contract type is not going to change in the future; to do this, add:

[ProtoContract(InferTagFromName = true)]

to the type (perhaps in a partial, see below). This applies directly to the scenario you present, where [DataMember] indicates the members, but there is no defined Order. Personally I prefer explicit layouts, for stability.

Another option doesn’t even need hints like [DataMember]; you can ask it to apply either BinaryFormatter rules (all fields, public or private), or XmlSerializer rules (public members, properties or fields); again, though, this is very unstable if your type changes!

[ProtoContract(ImplicitFields = ImplicitFields.AllPublic)]

But; another common scenario is that you have types coming from a generator, that you can’t conveniently edit, since any edits would get lost at re-generation; for that scenario, partial classes can be helpful. You can’t add attributes to members via attributes, but [ProtoPartialMember] can help here. For example, in a separate code file:

[ProtoContract]
[ProtoPartialMember(key, memberName)]
[ProtoPartialMember(anotherKey, anotherMemberName)]
...
public partial class Order {}

Sometimes, you have no access whatsoever to the type, so adding attributes of any kind is not an option. If your scenario is as you describe ([DataContract/[DataMember], noOrder`), then a lazy option is to enable this globally:

Serializer.GlobalOptions.InferTagFromName = true;

or in v2:

RuntimeTypeModel.Default.InferTagFromNameDefault = true;

For more complex scenarios, v2 has a new MetaType model devoted to this, where you can configure the layout at runtime:

RuntimeTypeModel.Default.Add(typeof(Order), false)
            .Add(key, memberName).Add(anotherKey, anotherMemberName);

or if your keys are 1, 2, 3, … then just:

   RuntimeTypeModel.Default.Add(typeof(Order), false)
            .Add(memberName, anotherMemberName, ...);

(there are a myriad of options on the MetaType to control all aspects of the serialization)

I think that covers most of the options here!