Inspector - editing array of polymorphic objects?

Questions & Answers
1

So I have a ScriptableObject with an array of polymorphic objects like this:

[System.Serializable]
public class CMyObject : ScriptableObject 
{
	public List<CElementBase> _Elements = new List<CElementBase>();
}

[System.Serializable]
public class CElementBase
{
	public string _Name;
}
[System.Serializable]
public class CElementInt : CElementBase
{
	public int _SomeInt;
}
[System.Serializable]
public class CElementString : CElementBase
{
	public string _SomeString;
}

Is there a good way to use the inspector to add and edit derived-class element to the array?

I was able to add the support for adding derived classes using CustomEditor for MyObject and

public override void OnInspectorGUI() 
{
	DrawDefaultInspector ();
    CMyObject myTarget = (CMyObject) target;

	if(GUILayout.Button("Add Int"))
	{
		myTarget._Elements.Add ( new CElementInt() );
	}
	if(GUILayout.Button("Add String"))
	{
		myTarget._Elements.Add ( new CElementString() );
	}

But even so, the elements that show up in the array only allow me to edit the base class properties (_Name), not the derived class ones (_SomeInt or _SomeString).

Is there a way to have Unity let me edit the actual derived class, or do I need to manually create edit fields for each property based on the type? Please advise!

2

So I just found out every time I recompile my scripts it somehow reverts the derived class back to its base class (thus losing the _SomeInt and _SomeString params). Blast - what am I doing wrong?

EDIT: found my answer: http://forum.unity3d.com/threads/155352-Serialization-Best-Practices-Megapost

3

It’s possible natively since 2019.3 release via [SerializeReference] attribute Unity - Scripting API: SerializeReference