Issue with JSON serialization in Unity

Question

I'm trying to serialize an array of custom Monobehaviours, using JSON. I know it can't be done directly, so I'm using a wrapper class and serializing that instead.

This is the wrapper object

[System.Serializable]  
public class WavesCollection {
    public Wave[] waves;
}

That's the object being wrapped (only the important bits of it)

[System.Serializable]
public class Wave : MonoBehaviour {
    [SerializeField]public float[] AppearTimes;//at that time should the n-th enemy appear;
    [SerializeField]public Vector2[] positions;//where should the n-th enemy appear;
    [SerializeField]public EnemyType[] EnemiesToAppear;//what enemies should appear
}

        wavesArray = new Wave[] {thisWave, thisWave, thisWave};
        WavesCollection collection = new WavesCollection();
        collection.waves = new Wave[10];
        wavesArray.CopyTo(collection.waves, 0);
        StreamWriter sw = File.CreateText(WritePath);
        string json = JsonUtility.ToJson(collection);
        sw.WriteLine(json);
        sw.Close();

And that's the code that does the serializing. Basically I've got an array of non-null Wave objects and I copy that to the wrapper object. I then try to write that in a file and the output is

{"waves":[{"instanceID":-99992},{"instanceID":-99992},{"instanceID":-99992},{"instanceID":0},{"instanceID":0},{"instanceID":0},{"instanceID":0},{"instanceID":0},{"instanceID":0},{"instanceID":0}]}

Could anyone give me a few directions on what I'm doing wrong?

No exceptions are thrown. The problem is that the wrong things are being serialized. — Mihai Stan
Why you inherited Wave class from MonoBehaviour? Please try without inheritance. — Barış Çırıka
I've already managed to serialize Wave objects directly, as in turning a single Wave object into a single JSON, and that works just fine. The problem comes when I try to serialize an array of Wave objects. Therefore, I believe that inheriting from MonoBehaviour shouldn't cause issues. — Mihai Stan

Life Alchemist Life Alchemist · Accepted Answer · 2018-04-28T20:25:49

I had the same issue while inheriting my base class (Wave in your case) with scriptable object and that gave me the same issue. I could put in a single object and pass that in just fine, but got problematic instance id's in a list. I removed all forms of inheritance on the base class and it worked.

Issue with JSON serialization in Unity

1 Answers