Customizing serialization at the property/field level about fullserializer HOT 4 OPEN

Sure, here is roughly how I'd implement it. There are only a few required modifications.

Usage

class Model {
    [fsProperty(ShouldSerialize="CheckMember")]
    public int Member;
    bool CheckMember() { return member % 2 == 0; }
}

fsConfig.SerializeDefaultValues = false;

Implementation

For implementation, there are two primary areas that you should check: the reflected converter and AOT generated converters. Luckily it is simple in both scenarios:

For the reflected converter, see here.

For the AOT compiled converters, they all reference a common SerializeMember function. You should modify it so that it only emits data if it should, ie, it should read something like:

protected fsResult SerializeMember<T>(Dictionary<string, fsData> data, string name, T value) {
    // should we skip serialization?
    // TODO: is default(T) how we actually want to get the default value? What about arrays/lists/collections?
    // TODO: There should be no reflection in this method. For the ShouldSerialize method,
    //       the AOT generator should be modified so it will invoke the method before calling
    //       SerializeMember
    if (value == default(T)) return fsResult.Success; // skip serialization

    // below: the existing method
    fsData memberData;
    var result = Serializer.TrySerialize(typeof(T), value, out memberData);
    if (result.Succeeded) data[name] = memberData;
    return result;
}

The AOT generation is done here, and the conditional check should be emitted around here.

Then there is also the issue of serializing default values inside of collections - should the following list be serialized? [0, 0, 0, 0]. I think this is a scenario where default serialization will skip only the empty collection, ie, []. Anything beyond that can be handled by the ShouldSerialize user-defined method.

Make sure to cache the reflection computations inside of fsMetaType and/or fsMetaProperty.

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Thanks for the detailed insights. Good stuff!

My first choice would be an attribute based system that allowed custom converters at the property level since that is more declarative and reusable but maybe that just isn't feasible. I'm going to let this percolate a few days, maybe some of the other repo watchers will chime in. For now, I'm hung up on making sure the serialization process doesn't emit metadata when I don't expect it. I'll post some test cases in the existing issue.

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An additional scenario this system should handle is

public class Model {
    [fsProperty(DoNotEmitTypeMetadata = true)]
    public object Member;
}

(see some of the comments in #24)

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Link is broken, I need this...

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