Json – How can I send custom object from my callable Firebase Cloud Function in TypeScript to my Unity app?

I’m trying to use Firebase and its callable Cloud Functions for my Unity project.

With the docs and different posts I found on the web I struggle to understand how returning data works. (I come from Azure Functions in C#)

I use TypeScript, and try to return a custom object CharactersResponse:

export class CharactersResponse //extends CustomResponse
{
    Code!: CharactersCode;
    CharacterID?: string;
}

export enum CharactersCode
{
    Success = 0,
    InvalidName = 2000,
    CharacterNameAlreadyExists = 2009,
    NoCharacterSlotAvailable = 3000,
    InvalidCharacterClass = 4000,
    EmptyResponse = 9000,
    UnknownError = 9999,
}

(Custom Response is a parent class with only an UnknownErrorMessage string property, that I use for adding extra message when needed, but only in Unity. I don’t need it in my functions.)

I have the same in my C# Unity Project:

public class CharactersResponse : CustomResponse
{
    public CharactersCode Code;
    public string CharacterID;
}

public enum CharactersCode
{
    Success = 0,
    InvalidName = 2000,
    CharacterNameAlreadyExists = 2009,
    NoCharacterSlotAvailable = 3000,
    InvalidCharacterClass = 4000,
    EmptyResponse = 9000,
    UnknownError = 9999,
}

I’m still learning but I found it useful to do this way for displaying correct messages in Unity (and also regarding localization).
When the Code is 0 (Success), I will usually need to get some data at the same time like in this example CharacterID, or CharacterLevel, CharacterName etc.. CharacterResponse will be used for all functions regarding Characters like "GetAllCharacters", "CreateNewCharacter" etc..

My Function (CreateNewCharacter) looks like this:

import * as functions from "firebase-functions";
import { initializeApp } from "firebase-admin/app";
import { getFirestore } from "firebase-admin/firestore";
import { CharactersResponse } from "./CharactersResponse";
import { CharactersCode } from "./CharactersResponse";
import { StringUtils } from "../Utils/StringUtils";

// DATABASE INITIALIZATION
initializeApp();
const db = getFirestore();

// CREATE NEW CHARACTER
export const CreateNewCharacter =
  functions.https.onCall((data, context) =>
  {
    // Checking that the user is authenticated.
    if (!context.auth)
    {
      // Throwing an HttpsError so that the client gets the error details.
      throw new functions.https.HttpsError('failed-precondition', 'The function must be called ' +
        'while authenticated.');
    }

    // TEST
    data.text = '';

    // Authentication / user information is automatically added to the request.
    const uid: string = context?.auth?.uid;
    const characterName: string = data.text;

    // Check if UserID is present
    if (StringUtils.isNullOrEmpty(uid))
    {
      // Throwing an HttpsError so that the client gets the error details.
      throw new functions.https.HttpsError('failed-precondition', 'Missing UserID in Auth Context.');
    }

    const response = new CharactersResponse();

    if (StringUtils.isNullOrEmpty(characterName))
    {
      response.Code = CharactersCode.InvalidName;
      console.log("character name null or empty return");
      return response; // PROBLEM IS HERE *****************
    }

    console.log("end return");
    return "Character created is named : " + characterName + ". UID = " + uid;
  });

In Unity, the function call looks like this:

private static FirebaseFunctions functions = FirebaseManager.Instance.Func;

    public static void CreateNewCharacter(string text, Action<CharactersResponse> successCallback, Action<CharactersResponse> failureCallback)
    {
        Debug.Log("Preparing Function");
        // Create the arguments to the callable function.
        var data = new Dictionary<string, object>();
        data["text"] = text;

        // Call the function and extract the operation from the result.
        HttpsCallableReference function = functions.GetHttpsCallable("CreateNewCharacter");
        function.CallAsync(data).ContinueWithOnMainThread((task) =>
        {
            if (task.IsFaulted)
            {
                foreach(var inner in task.Exception.InnerExceptions) 
                {
                    if (inner is FunctionsException)
                    {
                        var e = (FunctionsException)inner;
                        // Function error code, will be INTERNAL if the failure
                        // was not handled properly in the function call.
                        var code = e.ErrorCode;
                        var message = e.Message;

                        Debug.LogError($"Code: {code} // Message: {message}");

                        if (failureCallback != null)
                        {
                            failureCallback.Invoke(new CharactersResponse()
                            {
                                Code = CharacterCode.UnknownError,
                                UnknownErrorMessage = $"ERROR: {code} : {message?.ToString()}"
                            });
                        }
                    }
                }
            }
            else
            {
                Debug.Log("About to Deserialize response");
// PROBLEM IS HERE *********************
                CharactersResponse response = JsonConvert.DeserializeObject<CharactersResponse>(task.Result.Data.ToString());
                Debug.Log("Deserialized response");

                if (response == null)
                {
                    Debug.LogError("Response is NULL");
                }
                else
                {
                    Debug.Log("ELSE");
                    Debug.Log($"Response: {response}");
                    Debug.Log(response.Code.ToString());
                }
            }
        });
    }

The problem :
In my Unity C# code, task.Result.Data contains the CharactersCode I’ve set in my function, but I can’t find a way to convert it to CharactersResponse. (It worked in Azure Functions). Moreover, the line just after Deserialization Debug.Log("Deserialized response"); is not executed. The code seems stuck in the deserialization process.

I tried with and without extending my TypeScript class with CustomResponse(because I don’t need it in my Function so I didn’t extended it at first).
I also tried setting a CharacterID because I thought maybe it didn’t like the fact that this property was missing but the result is the same.

I don’t understand what is the problem here? If any of you can help.

Thanks.