How to serialize objects of type dictionary and dictionary using MessagePack with il2cpp

Questions & Answers
1

So I seem to have hit this roadblock in building my app where an attempt to serialize these two objects of called “Dictionary stat” and “Dictionary properties” just seem impossible. my code is sequential of course and an exception is returned at the point of serializing “stat” which comes before the serialization of"properties", meaning the code never even reaches the point of serializing properties dictionary, thus my first challenge is getting past serializing the stat dictionary. I’m asking both questions so I won’t have to come back to type another question.

Error Message: (UnityFramework)[8340] : FormatterNotRegisteredException: System.Collections.Generic.Dictionary`2[[System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],[System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]] is not registered in resolver: MessagePack.Resolvers.StaticCompositeResolver

Things I’ve tried:
Initialized messagePack composite resolvers before attempting to serialize or deserialize anything.:

//initialize messagepack
            StaticCompositeResolver.Instance.Register(
                 MessagePack.Resolvers.GeneratedResolver.Instance,
                 MessagePack.Resolvers.StandardResolver.Instance,
                 MessagePack.Resolvers.BuiltinResolver.Instance
                
            );

            var option = MessagePackSerializerOptions.Standard.WithResolver(StaticCompositeResolver.Instance);

            MessagePackSerializer.DefaultOptions = option;

The generated resolver does seem to cover the Property class, however, the code never reaches there and it throws an error when serializing the “stat” dictionary which comes before the “properties” dictionary. Neither the standard resolver nor the built-in resolver solves the challenge of serializing the “stat” dictionary.

static GeneratedResolverGetFormatterHelper()
        {
            lookup = new global::System.Collections.Generic.Dictionary<Type, int>(3)
            {
                { typeof(global::AchievementManager.Property_ActivationRules), 0 },
                { typeof(global::AchievementManager.Property_UpdateRules), 1 },
                { typeof(global::AchievementManager.Property), 2 },
            };
        }

What in the world am I supposed to do to get message pack to serialize the two dictionaries. Any help in the right direction would be much appreciated.
Unity Version:2019.4.17f1
ScriptingBackend: IL2CPP
Api Compatibility Level: .Net 4.x
Strip Engine Code: False
Build Platform: IOS and Android

2

I know this is an old post, but I just used MessagePack for my Unity project. I don’t know if it will work for your dictionary too, but to get my setup to work, I followed this great article:

To support android and iOS build targets, your project needs to be able to build to the IL2CPP backend which might require the resolvers for your custom types to be ahead-of-time generated by the code generator tool of MessagePack for C#

I also found a relevant thread for issues with serializing dictionaries, some posts also mention IL2CPP issues:
https://forum.unity.com/threads/how-to-serialize-dictionary-string-string-and-dictionary-string-customclass-in-messagepack.1107488/