Prevent Reset() from clearing out serialized fields

Question

I have a component which stores a unique id, once it gets created. After it was once set, the id should never change.

However, when a designer selects the cog and "Reset" function on the component, all serialized values are cleared. I know I can implement my own Reset() call, but that doesn't help, because it gets called, after the fields were already cleared.

Is there any way I can prevent this or get a callback so that I can save and restore my unique id? I'm trying to prevent my level designes from accidentally corrupting references to said ids.

Answer 1

Best Answer

Answer by Bunny83 · Jul 24, 2017 at 10:27 AM

No, you can't prevent that fundamental editor feature. Just like you can't prevent the designer from removing the component and re-adding a new one which would result in the same problem.

Yout only options would be setting the hideflags and prevent interaction completely. Either set the "NotEditable" flag which would display the whole component "inactive" (just like the components on an imported fbx model). Or if the component doesn't even need to be seen you can completely hide it from the inspector by setting the "HideInInspector" flag as well.

However keep in mind that there are still ways to at least mess up your IDs. If the object gets duplicated or stored as prefab it would still have the same ID. So you would have multiple objects with the same ID.

However it depends on the actual usage of the component.

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Xarbrough · Jul 24, 2017 at 11:03 AM 0

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Thanks, those are some helpful pointers. I think the NotEditable flag might help. Still have to think about prefabs though. $$anonymous$$aybe I can retrieve the local file identifier from the scene asset and assign it as guid to my component when it is added to the scene, or something like that.

Answer 2

alt text
It is possible, and in a very intuitive way. First, copy this wrapper:

     [Serializable]
     public struct NonResetable<T> : ISerializationCallbackReceiver
     {
         public T value;
         private T _dump;
 
         [SerializeField] [HideInInspector] private bool valid;
 
         public static implicit operator T(NonResetable<T> nonResetable) => nonResetable.value;
         public static implicit operator NonResetable<T>(T value) => new NonResetable<T> { value = value };
 
         public void OnBeforeSerialize()
         {
             _dump = value;
         }
 
         public void OnAfterDeserialize()
         {
             if (!valid)
             {
                 value = _dump;
                 valid = true;
             }
         }
     }

You don't need to know how it works in order to use it. It automatically converts to and from the type it's wrapping, so you can use a NonResetable 'mostly' like you would a float.

 public NonResetable<float> f = 5f;
 float SomeMethod() => 10 * f; // Returns 50.

For styling, I would also suggest you copy this script inside an Editor folder:

     [CustomPropertyDrawer(typeof(NonResetable<>))]
     public class NonResetableDrawer : PropertyDrawer
     {
         public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
         {
             EditorGUI.BeginProperty(position, label, property);
             
             var valueProperty = property.FindPropertyRelative(nameof(NonResetable<bool>.value));
             EditorGUI.PropertyField(position, valueProperty, label);
 
             EditorGUI.EndProperty();
         }
     }

Prevent Reset() from clearing out serialized fields

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