Serializating a base class array to a prefab

Questions & Answers
1

I have been dealing with this issue for the whole week and I am kind of stuck and out of ideas.

I am working in a quick item editor. Each item may have one or more properties. These properties have all a common parent since they have common properties. Each child may also have particular properties.

I want to use the editor to show the properties array, edit it, and when finished, save the created gameobject to a prefab.

I almost have it working but I am facing a problem:

  • If I make MyBaseClass not to inherit from ScriptableObject (see comments on code below), everything works almost like a charm, but the child objects are casted to the parent class and they will remain like that forever. This problem was already stated [here][1] and was supposed to be solved with the next option, which is:

  • If I make MyBaseClass to inherit from ScriptableObject everything works fine before prefab creation, but then after creating the prefab, the array seems to be in a corrupted state. It seems that the CustomEditor is no longer correctly executed for that prefab.

This is my code, simplified for a better understanding. Just create each script separately (it should run as it is) and drag the SerializeMe.cs to a gameobject to reproduce the scenery. Remember to store SerializeMeInspector.cs into the Editor folder.

SerializeMe.cs

using System;
using System.Collections.Generic;
using UnityEngine;
using UnityEditor;

[Serializable]
public class SerializeMe : MonoBehaviour
{
	[SerializeField]
	public List<MyBaseClass> m_Instances;

	public void OnEnable ()
	{
		if (m_Instances == null)
			m_Instances = new List<MyBaseClass>();

		hideFlags = HideFlags.HideAndDontSave;
	}
}

MyBaseClass.cs

using UnityEngine;
using System;

[Serializable]
public class MyBaseClass : ScriptableObject
//public class MyBaseClass
{
	[SerializeField]
	public int m_IntField;
	
	public void OnEnable()
	{
		hideFlags = HideFlags.HideAndDontSave;
	}
}

ChildClass.cs

using UnityEngine;
using System;

[Serializable]
public class ChildClass : MyBaseClass
{
	[SerializeField]
	public float m_FloatField;
}

SerializeMeInspector.cs (stored in the Editor folder)

using UnityEngine;
using System.Collections.Generic;
using System;

[CustomEditor(typeof(SerializeMe))]
public class SerializeMeInspector : Editor
{
	SerializedProperty SP_m_Instances;
	
	public void OnEnable()
	{
		SP_m_Instances = serializedObject.FindProperty ("m_Instances");
	}
	
	public override void OnInspectorGUI() 
	{
		serializedObject.Update ();
		
		if (GUILayout.Button ("Add Base"))
		{
			//(target as SerializeMe).m_Instances.Add(new MyBaseClass());
			(target as SerializeMe).m_Instances.Add(
				(MyBaseClass) ScriptableObject.CreateInstance("MyBaseClass"));
		}
		
		if (GUILayout.Button ("Add Child"))
		{
			//(target as SerializeMe).m_Instances.Add(new ChildClass());
			(target as SerializeMe).m_Instances.Add(
				(MyBaseClass) ScriptableObject.CreateInstance("ChildClass"));
		}
		
		for (int i = 0; i < SP_m_Instances.arraySize; i++)
		{	
			EditorGUILayout.Foldout(false,"Element #"+i);
			
			MyBaseClass parent = (target as SerializeMe).m_Instances*;*

  •  	// Base common display*

  •  	parent.m_IntField = EditorGUILayout.IntField(*

  •  		"Base prop", parent.m_IntField);*

  •  	// Child display if casting is a success*

  •  	ChildClass child;*

  •  	try* 

  •  	{	*

  •  		child = (ChildClass) parent;*

  •  	}*

  •  	catch (InvalidCastException)*

  •  	{*

  •  		child = null;*

  •  	}*

  •  	if (child != null)*

  •  	{*

  •  		child.m_FloatField = EditorGUILayout.FloatField(*

  •  			"Child prop", child.m_FloatField);*

  •  	}*

  •  }*

  •  serializedObject.ApplyModifiedProperties ();*

  • }*
    }
    I’d really appreciate any ideas or help with this.
    Thank you very much in advance.
    EDITED: Some code added as suggested by Bunny83, but still not working
    [1]: Unity Serialization | Unity Blog

2

You simply forgot to set the hideflags in OnEnable of your MyBaseClass.

3

I have found this great post about this exact issue. It seems that Unity does not serialize polymorphic types properly. In this post, a kind of workaround is offered. I will try it and let you know the results.

I am still willing to hear any other idea to get rid of this issue.

Additionally, you can vote for an idea to solve this issue right here.