Protobuf-net how to copy a RuntimeTypeModel into another?

user_10470101 0
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Context of the question: I need to modify a RuntimeTypeModel instance to add new subtypes, but after a serializer has been created and used already. I read from other questions that the model cannot be changed once a serializer is already created, so I thought I would just create a new model, copy over the information from the old one, and then modify the new one. But I am not sure how to do the copying properly...any help would be appreciated!

protobuf-net
1 Answers

From the comments, it seems that you're talking about cloning the sub-type definitions; one way to do this would be something like:

// given "RuntimeTypeModel oldModel", "MetaType newMetaType" and "Type dataType"
if (oldModel.IsDefined(dataType))
{
    var oldSubTypes = oldModel[dataType].GetSubtypes();
    foreach (var subType in oldSubTypes)
    {
        newMetaType.AddSubType(subType.FieldNumber, subType.DerivedType.Type);
    }
    // TODO: add the new sub-types here
}

Note that in your case it may make more sense to store these definitions somewhere external to protobuf-net when needed, and fetch them from there rather than having to retain the old model. In either case, I recommend using the AfterApplyDefaultBehaviour callback, which will make it easier to avoid timing complications (this allows you to hook into the code that happens inside the library when types are discovered):

newModel.AfterApplyDefaultBehaviour += (sender, args) =>
{
    var dataType = args.Type;
    var newMetaType = args.MetaType;
    // your code to apply the sub-types here, perhaps from the above
};

I should emphasise, however, that "knowing the sub-types earlier" is a much simpler solution to this scenario, even if it means loading assemblies earlier. If you're going to load them anyway, deferring them seems to be complicating the code.

Marc_Gravell_233540
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