public void Save()
    {
        UserInventorySaveData dataToSave = new UserInventorySaveData();

        dataToSave.currenciesDataList = currenciesDataList;
        dataToSave.productDataList    = productDataList;

        string userInventoryString = JsonUtility.ToJson(dataToSave, true);

        SaveDataManager.Instance.WriteToFile(filename, userInventoryString);
    }
    public void Load()
    {
        UserInventorySaveData dataToSave = new UserInventorySaveData();
        string json = SaveDataManager.Instance.ReadFromFile(filename);

        if (json == "")
        {
            Save();
            return;
        }
        JsonUtility.FromJsonOverwrite(json, dataToSave);
        if (dataToSave == null)
        {
            return;
        }
        if (dataToSave.currenciesDataList != null)
        {
            currenciesDataList = dataToSave.currenciesDataList;
        }
        if (dataToSave.productDataList != null)
        {
            productDataList = dataToSave.productDataList;
        }
    }