How do I "Apply" a prefab if I have access to one of its instances via code?

Questions & Answers
1

If I modify something in an instance of my prefab, how can I “Apply” the changes to the prefab? (Just like clicking “Apply” from the editor)

Thanks!

2

If you want to recreate the behaviour of the Apply button in an editor script, this works (assuming instance is your disconnected scene instance)

PrefabUtility.ReplacePrefab(instance, PrefabUtility.GetPrefabParent(instance), ReplacePrefabOptions.ConnectToPrefab);

3

One caveat to the above answer: If ‘instance’ is actually a child object inside the prefab, that one line of code will do the wrong thing. You want this instead:

                    var instanceRoot = PrefabUtility.FindRootGameObjectWithSameParentPrefab(target.gameObject);
                    var targetPrefab = UnityEditor.PrefabUtility.GetPrefabParent(instanceRoot);

                    PrefabUtility.ReplacePrefab(
                            instanceRoot,
                            targetPrefab,
                            ReplacePrefabOptions.ConnectToPrefab
                            );
4

From Unity source:

UnityEngine.Object prefabParent = PrefabUtility.GetPrefabParent(target);
GameObject gameObject = PrefabUtility.FindValidUploadPrefabInstanceRoot(target);
PrefabUtility.ReplacePrefab(gameObject, prefabParent, ReplacePrefabOptions.ConnectToPrefab);