How can I tell whether an object is a prefab asset or an instance of that prefab?

Question

How can I determine whether a game object is a prefab asset or is an instance of a prefab within my scene?

I tried making a custom editor and doing

public override void OnInspectorGUI()
{
   if (EditorUtility.IsPersistent(this.target))
   {
      Debug.Log("is persisent");
   }
   else
   {
      Debug.Log("is not persistent");
   }
}

But whether I select the prefab asset in the Project view or I select the prefab instance in my scene, both scenarios print "is not persistent"

The reason I'm doing this is that I want to have a MonoBehaviour with a Guid field, and the MonoBehaviour should generate a unique GUID for itself if it's part of a game object within a scene, but it should leave its Guid field blank if its part of a prefab asset (so that each instance of the same prefab gets a unique GUID).

sounds more like you need a factory or prefab manager, but technically they are all prefab instances in your scene, there only assets in there folder. — Technivorous
PrinceOfRavens is right, scenes don't contain assets (including prefabs). Unity instead creates prototypes that it clones when you call Instantiate. But maybe there is a way to distinguish those prototypes. — Nikaas
You maybe able to tell with docs.unity3d.com/ScriptReference/… - it sounds a bit like a long shot — BugFinder
Be aware that some of the functions being used here are Editor methods that won't work when you build your game. I can't tell if you already know that or not. — Draco18s no longer trusts SE

Ben Rubin Ben Rubin · Accepted Answer · 2019-02-23T01:26:17

I found a solution, although I don't think it's an ideal one.

public override void OnInspectorGUI()
{
   var component = this.target as MyScript;

   if (component.gameObject.scene.name.Equals(UnityEngine.SceneManagement.SceneManager.GetActiveScene().name))
   {
      Debug.Log("editing the prefab instance in the scene");          
   }
   else
   {
      Debug.Log("editing the prefab asset");       
   }
}

How can I tell whether an object is a prefab asset or an instance of that prefab?

2 Answers