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ViewsUnity Scriptable Object change field's type to new type based on another fields value
Is it possible for a Scriptable Object to have a field of a specific type, and have that type be determined based on the type of another field? For example:
public class ItemObject : ScriptableObject
{
public ItemType type;
public Item data = new Item();
}
ItemType is an enum
public enum ItemType
{
Physical,
Magical
}
Item is a basic class, with 2 other classes inheriting from it, MagicalItem and PhysicalItem.
[System.Serializable]
public class MagicalItem : Item {
public string passive;
public MagicalItem() {
passive = "";
}
}
ect.
I'd like ItemObject to be able to choose in the editor from either of these options, or many more as I add new item types to my game. I haven't been able to figure out a solution but my thought is to have the data type be set on Awake() based on the type, but I haven't been able to get that to work. IE something like this:
private void Awake() {
if(type == ItemType.Magical) {
data = new MagicalItem();
} else {
data = new PhysicalItem();
}
}
Is there a better way to solve this problem?
Thanks!
2 answers
Answer question0
Had fun solving this one.
The trick to this that I found is actually a new thing, [SerializeReference], which does a few things, one of which lets you do polymorphic serialization, which this question requires.
The major steps to solving this:
- Add
[SerializeReference]to thedatafield. - Add a static method that creates a new instance depending on the desired type
- Add a custom editor that checks the
typefield for changes, and if it changes, create a new instance with the above method and assign it to thedatafield
Altogether, this gives you this kind of result:
[CreateAssetMenu(fileName = "Data", menuName = "Inventory/Item", order = 1)]
public class ItemObject : ScriptableObject
{
[CustomEditor(typeof(ItemObject))]
public class ItemObjectInspector : Editor
{
SerializedProperty m_type;
SerializedProperty m_data;
private void OnEnable()
{
m_type = serializedObject.FindProperty("type");
m_data = serializedObject.FindProperty("data");
}
public override void OnInspectorGUI()
{
serializedObject.Update();
EditorGUI.BeginChangeCheck();
EditorGUILayout.PropertyField(m_type);
if (EditorGUI.EndChangeCheck())
{
m_data.managedReferenceValue =
ItemObject.CreateBlankData((ItemType)m_type.intValue);
}
// avoid drawing type a second time
// avoid drawing annoying Script field
DrawPropertiesExcluding(serializedObject, new string[] { "type", "m_Script" });
serializedObject.ApplyModifiedProperties();
}
}
[System.Serializable]
public enum ItemType
{
Physical,
Magical
}
// Determines how to create an Item from each ItemType
public static Item CreateBlankData(ItemType type)
{
switch (type)
{
default:
case ItemType.Physical:
return new PhysicalItem();
case ItemType.Magical:
return new MagicalItem();
}
}
[System.Serializable]
public class Item
{
[SerializeField] public string typeDescription;
}
[System.Serializable]
public class MagicalItem : Item
{
[SerializeField] string elementName;
public MagicalItem() { typeDescription = "Magical"; elementName = "fire"; }
}
[System.Serializable]
public class PhysicalItem : Item
{
[SerializeField] float materialHardness;
public PhysicalItem() { typeDescription = "Physical"; materialHardness = 1f; }
}
public ItemType type;
[SerializeReference] public Item data;
}
Note: all the above classes are only inner classes for the sake of brevity. They can be separate classes or inner classes with no issues.
0
Just as an addition to Ruzihm's good answer.
For this kind of stuff you could actually skip the overhead of implementing a custom editor and simply use OnValidate
This function is called when the script is loaded or a value is changed in the Inspector (Called in the editor only).
So simply e.g.
private void OnValidate()
{
switch(type)
{
case ItemType.Magical:
// To avoid losing already filled in data
// simply check if the current data already has the correct type
if(data != null && data.GetType != typeof(MagicalItem))
{
data = new MagicalItem();
}
break;
case ItemType.Physical:
default:
if(data != null && data.GetType != typeof(PhysicalItem))
{
data = new PhysicalItem();
}
break;
}
}