How to save and load a ScriptableObject from a Firebase Realtime Database?

[XoetziX]

Hello everyone,

so far I have a very simple PlayerDataSO which I use to easily transport player data from scene to scene.

public class PlayerDataSO : ScriptableObject
{
    [Header("Variable Values")]
    [SerializeField] private string playerName;
    [SerializeField] private string playerDBUserId;

    [Header("Fixed Values")]
    [SerializeField] private float _baseSidewayForce;

Now I try to save it to my realtime database (Firebase) and load it again.
My test methods look like this:

public void SavePlayerData(PlayerDataSO playerData)
    {
        string jsonNet = JsonConvert.SerializeObject(playerData);
        Debug.Log("SavePlayerData - jsonNet - " + jsonNet);
        DBreference.Child("PlayerData").SetRawJsonValueAsync(jsonNet);
        LoadPlayerDataTest();        
    }
    private void LoadPlayerDataTest()
    {
        PlayerDataSO tmpPlayerSO = null;
        DBreference.Child("PlayerData").GetValueAsync().ContinueWith(task =>
        {
            if (task.IsFaulted)
                Debug.Log("OH OH, ERROR");
            else if (task.IsCompleted)
            {
                DataSnapshot snapshot = task.Result;
                Debug.Log("LoadPlayerDataTest - snapshot - to string " + snapshot.Child("PlayerName").Value.ToString());
                Debug.Log("LoadPlayerDataTest - snapshot - JSON --> " + snapshot.GetRawJsonValue());
                // evil line of code coming:
                tmpPlayerSO = JsonConvert.DeserializeObject<PlayerDataSO>(snapshot.GetRawJsonValue()); 
                string tmpJson = JsonConvert.SerializeObject(tmpPlayerSO);
                Debug.Log("LoadPlayerDataTest - snapshot - JSON --> " + tmpJson);
            }
        });
    }

The debug output is this:

SavePlayerData - jsonNet - {“PlayerName”:“oetzi”,"PlayerDBUserId…[shortened]

LoadPlayerDataTest - snapshot - to string oetzi

LoadPlayerDataTest - snapshot - JSON → {“BaseSidewayForce”:50,"Player…[shortened]

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As you can see the last debug output is missing and with some testing I found out that the following line causes a wierd behaviour.

tmpPlayerSO = JsonConvert.DeserializeObject<PlayerDataSO>(snapshot.GetRawJsonValue());

The execution of the code simply stops. No exception is thrown, nothing.

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So I have 2 questions:

First: How can I reach my actual goal, to load my data from the database back into my scriptable object?

Second: Why does Unity behave that strange?

[Llama_w_2Ls]

Are you sure no exception is thrown? If you put the line tmpPlayerSO = JsonConvert.DeserializeObject<PlayerDataSO>(snapshot.GetRawJsonValue()); into a try-catch block, does it output any messages?

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I believe that because you’re using GetValueAsync() your code runs in a task that isn’t the main Unity thread. Therefore, scriptable objects and Monobehaviour methods work unexpectedly, such as GameObject.Find, which doesn’t work outside the main Unity thread.

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I think if you use the namespace Firebase.Extensions, you have access to the ContinueWithOnMainThread method, which runs on the main Unity thread, so creating scriptable objects should work as expected, hopefully. @XoetziX

[XoetziX]

@Llama_w_2Ls You are absolutly right with your assumption regarding the parallel thread!

“I believe that because you’re using GetValueAsync() your code runs in a task that isn’t the main Unity thread. Therefore, scriptable objects and Monobehaviour methods work unexpectedly, such as GameObject.Find, which doesn’t work outside the main Unity thread.”

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Using the try catch block helped indeed to get the hidden exception:

ScriptableObject.ctor can only be called from the main thread.
Constructors and field initializers will be executed from the loading thread when loading a scene.
Don't use this function in the constructor or field initializers, instead move initialization code to the Awake or Start function.

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How ironic: By not supporting the use of threads Unity not only causes the problem that I cannot call the constructor but it also causes that I do not get the information that it cannot use it…

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Now, the question of all questions:

Is there an elegant way to solve this issue?

The first thing which comes into my mind is that I can use a reference to a class within my ScriptableObject and then store this class in the database and the other way round. Would work probably but I would have to live with another tier within my ScriptableObjects which makes it more complicate to work with it.