Unity_Utils/JohnsonUtils/Utilities/SerializableDictionary.cs

using System;
using System.Collections.Generic;
using UnityEngine;

namespace JohnsonUtils.Utilities
{
    [Serializable]
    public class SerializableDictionary<TKey, TValue> : Dictionary<TKey, TValue>, ISerializationCallbackReceiver
    {
        [SerializeField] private List<TKey> keys = new ();
        [SerializeField] private List<TValue> values = new ();
    
        public void OnBeforeSerialize()
        {
            keys.Clear();
            values.Clear();

            foreach (KeyValuePair<TKey,TValue> pair in this)
            {
                keys.Add(pair.Key);
                values.Add(pair.Value);
            }
        }

        public void OnAfterDeserialize()
        {
            Clear();

            if (keys.Count != values.Count)
            {
                throw new Exception(
                    $"There are {keys.Count} keys and {values.Count} values after deserialization." +
                    " Make sure that both key and value types are serializable.");
            }

            for (int i = 0; i < keys.Count; ++i)
            {
                Add(keys[i], values[i]);
            }
        }
    }
}