A script replacing one prefab with another

Is there a updated script for 2019.1.3f1 that can replace one prefab with another in the editor view? Really need a script that can do this to make world building a whole lot easier. I was trying to use this one, but it isn't working. I'll paste the code at the bottom.

Code (CSharp):

1. using UnityEngine;
2. using UnityEditor;
3. public class ReplaceWithPrefab : EditorWindow
4. {
5. [SerializeField] private GameObject prefab;
6. [MenuItem("Tools/Replace With Prefab")]
7. static void CreateReplaceWithPrefab()
8. {
9. EditorWindow.GetWindow<ReplaceWithPrefab>();
10. }
11. private void OnGUI()
12. {
13. prefab = (GameObject)EditorGUILayout.ObjectField("Prefab", prefab, typeof(GameObject), false);
14. if (GUILayout.Button("Replace"))
15. {
16. var selection = Selection.gameObjects;
17. for (var i = selection.Length - 1; i >= 0; --i)
18. {
19. var selected = selection;
20. var prefabType = PrefabUtility.GetPrefabType(prefab);
21. GameObject newObject;
22. if (prefabType == PrefabType.Prefab)
23. {
24. newObject = (GameObject)PrefabUtility.InstantiatePrefab(prefab);
25. }
26. else
27. {
28. newObject = Instantiate(prefab);
29. newObject.name = prefab.name;
30. }
31. if (newObject == null)
32. {
33. Debug.LogError("Error instantiating prefab");
34. break;
35. }
36. Undo.RegisterCreatedObjectUndo(newObject, "Replace With Prefabs");
37. newObject.transform.parent = selected.transform.parent;
38. newObject.transform.localPosition = selected.transform.localPosition;
39. newObject.transform.localRotation = selected.transform.localRotation;
40. newObject.transform.localScale = selected.transform.localScale;
41. newObject.transform.SetSiblingIndex(selected.transform.GetSiblingIndex());
42. Undo.DestroyObjectImmediate(selected);
43. }
44. }
45. GUI.enabled = false;
46. EditorGUILayout.LabelField("Selection count: " + Selection.objects.Length);
47. }
48. }

 

Wrap the code above in code tags to preserve the formatting, please.

What error(s) are you getting in the console? What behavior are you getting?

Also, you should be able to find the key change to instantiating prefabs with 2018.3+ with a quick googling around. What have you found?

 

I recently updated my build to the newest one, which resulted in this script not working. I posted an image below with the errors I am getting. Here is the youtube video where I got the code from. The guy in the video demos the script.

.

I know nothing about C# or how to go about solving the issue.

 

Talked to some of my Engineer buddies, but they aren't familiar with Unity. I have no errors or warnings, but I just can't get it to work like the video above.

Code (CSharp):

1. using UnityEngine;
2. using UnityEditor;
3. public class ReplaceWithPrefab : EditorWindow
4. {
5.     [SerializeField] private GameObject prefab;
6.     [MenuItem("Tools/Replace With Prefab")]
7.     static void CreateReplaceWithPrefab()
8.     {
9.         EditorWindow.GetWindow<ReplaceWithPrefab>();
10.     }
11.     private void OnGUI()
12.     {
13.         prefab = (GameObject)EditorGUILayout.ObjectField("Prefab", prefab, typeof(GameObject), false);
14.         if (GUILayout.Button("Replace"))
15.         {
16.             var selection = Selection.gameObjects;
17.             for (var i = selection.Length - 1; i >= 0; --i)
18.             {
19.                 var selected = selection[i];
20.                 var prefabType = PrefabUtility.GetPrefabAssetType(prefab);
21.                 GameObject newObject;
22.                 if (prefabType == PrefabAssetType.Model)
23.                 {
24.                     newObject = (GameObject)PrefabUtility.InstantiatePrefab(prefab);
25.                 }
26.                 else
27.                 {
28.                     newObject = Instantiate(prefab);
29.                     newObject.name = prefab.name;
30.                 }
31.                 if (newObject == null)
32.                 {
33.                     Debug.LogError("Error instantiating prefab");
34.                     break;
35.                 }
36.                 Undo.RegisterCreatedObjectUndo(newObject, "Replace With Prefabs");
37.                 newObject.transform.parent = selected.transform.parent;
38.                 newObject.transform.localPosition = selected.transform.localPosition;
39.                 newObject.transform.localRotation = selected.transform.localRotation;
40.                 newObject.transform.localScale = selected.transform.localScale;
41.                 newObject.transform.SetSiblingIndex(selected.transform.GetSiblingIndex());
42.                 Undo.DestroyObjectImmediate(selected);
43.             }
44.         }
45.         GUI.enabled = false;
46.         EditorGUILayout.LabelField("Selection count: " + Selection.objects.Length);
47.     }
48. }

 

It works fine in 2019, I think it may be the way you are implementing it.

Here is how to do this.

Within the unity editor:
Create a new folder in the Assets folder called Editor
Now Create a new C# script in that folder and rename it to match the code (class), in this case ReplaceWithPrefab <---- this is your error me thinks
Next open the script you just made and erase every thing in it.
Now copy the script from his web page into the empty c# script you made
Save the script.
Go back to Unity and look under the Tools menu to run the script.

Hope that helps.

 

I've updated his code to work with later versions since some of those functions are obsolete. Also commented so you know what's going on. Hope this helps.

Code (CSharp):

1. using UnityEngine;
2. using UnityEditor;
3.  
4. public class ReplaceWithPrefab : EditorWindow
5. {
6.     // -- this is the box in the window where you drag your "new" prefab
7.     [SerializeField] private GameObject prefab;
8.  
9.     // -- this creates the menu to open the "Replace With Prefab" window
10.     [MenuItem("Tools/Replace With Prefab")]
11.     static void CreateReplaceWithPrefab()
12.     {
13.         EditorWindow.GetWindow<ReplaceWithPrefab>();
14.     }
15.  
16.     private void OnGUI()
17.     {
18.         // -- get a handle to the prefab you want to replace everything with
19.         prefab = (GameObject)EditorGUILayout.ObjectField("Prefab", prefab, typeof(GameObject), false);
20.  
21.         // -- if you've pressed the "Replace" button...
22.         if (GUILayout.Button("Replace"))
23.         {
24.             // -- get the list of objects you have selected
25.             var selection = Selection.gameObjects;
26.  
27.             // -- get the prefab type (I moved this out of the loop because it makes
28.             // -- no sense to check it every time)
29.             var prefabType = PrefabUtility.GetPrefabAssetType(prefab);
30.  
31.             // -- loop over all of the selected objects
32.             for (var i = selection.Length - 1; i >= 0; --i)
33.             {
34.                 // -- get the next selected object
35.                 var selected = selection[i];
36.                 GameObject newObject;
37.  
38.                 // -- if your "prefab" really is a prefab . . .
39.                 if (prefabType != PrefabAssetType.NotAPrefab)
40.                 {
41.                     // -- . . . then this part should always run.
42.                     // -- If you update the original prefab, the replaced items will
43.                     // -- update as well.
44.                     newObject = (GameObject)PrefabUtility.InstantiatePrefab(prefab);
45.                 }
46.                 else
47.                 {
48.                     // -- if this code is running, you didn't drag a prefab to your window.
49.                     // -- it will just Instantiate whatever you did drag over.
50.                     newObject = Instantiate(prefab);
51.                     newObject.name = prefab.name;
52.                 }
53.  
54.                 // -- if for some reason Unity couldn't perform your request, print an error
55.                 if (newObject == null)
56.                 {
57.                     Debug.LogError("Error instantiating prefab");
58.                     break;
59.                 }
60.  
61.                 // -- set up "undo" features for the new prefab, like setting up the old transform
62.                 Undo.RegisterCreatedObjectUndo(newObject, "Replace With Prefabs");
63.                 newObject.transform.parent = selected.transform.parent;
64.                 newObject.transform.localPosition = selected.transform.localPosition;
65.                 newObject.transform.localRotation = selected.transform.localRotation;
66.                 newObject.transform.localScale = selected.transform.localScale;
67.                 newObject.transform.SetSiblingIndex(selected.transform.GetSiblingIndex());
68.                 // -- now delete the old prefab
69.                 Undo.DestroyObjectImmediate(selected);
70.             }
71.         }
72.  
73.         // -- prevent the user from editing the window
74.         GUI.enabled = false;
75.  
76.         // -- update how many items you have selected (Note, it only updates when the mouse cursor is above the Replace window)
77.         EditorGUILayout.LabelField("Selection count: " + Selection.objects.Length);
78.     }
79. }

 

If it's still not working with the suggestions above, let us know specifically what it does or doesn't do.

 

Spaz_1 - Awesome that works and thank you for writing that code out!

thundercat71 - Thank you for breaking it down on how to set up the script.

 

Just a tiny change so this also works for replacing objects that are already inside other prefabs (e.g. inside imported meshes):

Change

Code (CSharp):

1. Undo.DestroyObjectImmediate(selected);

to

Code (CSharp):

1. try {
2.   Undo.DestroyObjectImmediate(selected);
3. }
4. catch {
5.   selected.SetActive(false);
6. }

 

@spaz_1 @fherbst This crashes my editor in 2019.2.17

 

The update wasn't working

My 2020 build gave me this warning...

"Parent of RectTransform is being set with parent property. Consider using the SetParent method instead, with the worldPositionStays argument set to false. This will retain local orientation and scale rather than world orientation and scale, which can prevent common UI scaling issues."

So I did

newObject.transform.parent = selected.transform.parent;
becomes
newObject.transform.SetParent(selected.transform.parent,false);


and it worked

 

Can someone link a completed version rather than having to track tiny updates on each post please?

 

Code Update of obsolete code
var prefabType = PrefabUtility.GetPrefabType(prefab);
to
var prefabType = PrefabUtility.GetPrefabAssetType(prefab);
and
prefabType == PrefabType.Prefab
to
prefabType == PrefabAssetType.Regular

Code (CSharp):

1.  
2. using UnityEngine;
3. using UnityEditor;
4.  
5. public class ReplaceWithPrefab : EditorWindow
6. {
7.     [SerializeField] private GameObject prefab;
8.  
9.     [MenuItem("Tools/Replace With Prefab")]
10.     static void CreateReplaceWithPrefab()
11.     {
12.         EditorWindow.GetWindow<ReplaceWithPrefab>();
13.     }
14.  
15.     private void OnGUI()
16.     {
17.         prefab = (GameObject)EditorGUILayout.ObjectField("Prefab", prefab, typeof(GameObject), false);
18.  
19.         if (GUILayout.Button("Replace"))
20.         {
21.             var selection = Selection.gameObjects;
22.  
23.             for (var i = selection.Length - 1; i >= 0; --i)
24.             {
25.                 var selected = selection[i];
26.                 var prefabType = PrefabUtility.GetPrefabAssetType(prefab);
27.                 GameObject newObject;
28.  
29.                 if (prefabType == PrefabAssetType.Regular)
30.                 {
31.                     newObject = (GameObject)PrefabUtility.InstantiatePrefab(prefab);
32.                 }
33.                 else
34.                 {
35.                     newObject = Instantiate(prefab);
36.                     newObject.name = prefab.name;
37.                 }
38.  
39.                 if (newObject == null)
40.                 {
41.                     Debug.LogError("Error instantiating prefab");
42.                     break;
43.                 }
44.  
45.                 Undo.RegisterCreatedObjectUndo(newObject, "Replace With Prefabs");
46.                 newObject.transform.parent = selected.transform.parent;
47.                 newObject.transform.localPosition = selected.transform.localPosition;
48.                 newObject.transform.localRotation = selected.transform.localRotation;
49.                 newObject.transform.localScale = selected.transform.localScale;
50.                 newObject.transform.SetSiblingIndex(selected.transform.GetSiblingIndex());
51.                 Undo.DestroyObjectImmediate(selected);
52.             }
53.         }
54.  
55.         GUI.enabled = false;
56.         EditorGUILayout.LabelField("Selection count: " + Selection.objects.Length);
57.     }
58. }

 

Edited to support prefab variants:

Code (CSharp):

1. using UnityEngine;
2. using UnityEditor;
3. public class ReplaceWithPrefab : EditorWindow
4. {
5.     [SerializeField] private GameObject prefab;
6.     [MenuItem("Tools/Replace With Prefab")]
7.     static void CreateReplaceWithPrefab()
8.     {
9.         EditorWindow.GetWindow<ReplaceWithPrefab>();
10.     }
11.     private void OnGUI()
12.     {
13.         prefab = (GameObject)EditorGUILayout.ObjectField("Prefab", prefab, typeof(GameObject), false);
14.         if (GUILayout.Button("Replace"))
15.         {
16.             var selection = Selection.gameObjects;
17.             for (var i = selection.Length - 1; i >= 0; --i)
18.             {
19.                 var selected = selection[i];
20.                 var prefabType = PrefabUtility.GetPrefabAssetType(prefab);
21.                 GameObject newObject;
22.                 if (prefabType == PrefabAssetType.Regular || prefabType == PrefabAssetType.Variant)
23.                 {
24.                     newObject = (GameObject)PrefabUtility.InstantiatePrefab(prefab);
25.                 }
26.                 else
27.                 {
28.                     newObject = Instantiate(prefab);
29.                     newObject.name = prefab.name;
30.                 }
31.                 if (newObject == null)
32.                 {
33.                     Debug.LogError("Error instantiating prefab");
34.                     break;
35.                 }
36.                 Undo.RegisterCreatedObjectUndo(newObject, "Replace With Prefabs");
37.                 newObject.transform.parent = selected.transform.parent;
38.                 newObject.transform.localPosition = selected.transform.localPosition;
39.                 newObject.transform.localRotation = selected.transform.localRotation;
40.                 newObject.transform.localScale = selected.transform.localScale;
41.                 newObject.transform.SetSiblingIndex(selected.transform.GetSiblingIndex());
42.                 Undo.DestroyObjectImmediate(selected);
43.             }
44.         }
45.         GUI.enabled = false;
46.         EditorGUILayout.LabelField("Selection count: " + Selection.objects.Length);
47.     }
48. }

 

I know this is over a year old, but in the most recent LTS (as of this comment) destroying game objects is apparently deprecated as it throws an error saying that the functionality is not allowed to be used in order to prevent data loss. Furthermore, the PrefabUtility.ReplacePrefab approach is also deprecated (and in this case has also been removed completely) so that's not an option either. Why such basic functionality would be completely removed or disallowed is beyond me, but it's not my decision to make this kind of thing so difficult to do.

 

That only means you're destroying the wrong thing. You have written a bug.

That's beyond you because no functionality has been removed.

Instead of necro-jacking a thread from 2019, if you have a new question, please make a new post. It's FREE!!

How to report your problem productively in the Unity3D forums:

http://plbm.com/?p=220

This is the bare minimum of information to report:

- what you want
- what you tried
- what you expected to happen
- what actually happened, log output, variable values, and especially any errors you see
- links to documentation you used to cross-check your work (CRITICAL!!!)

The purpose of YOU providing links is to make our job easier, while simultaneously showing us that you actually put effort into the process. If you haven't put effort into finding the documentation, why should we bother putting effort into replying?

If you post a code snippet, ALWAYS USE CODE TAGS:

How to use code tags: https://forum.unity.com/threads/using-code-tags-properly.143875/

- Do not TALK about code without posting it.
- Do NOT post unformatted code.
- Do NOT retype code. Use copy/paste properly using code tags.
- Do NOT post screenshots of code.
- Do NOT post photographs of code.
- ONLY post the relevant code, and then refer to it in your discussion.

 

Well, it sure didn't seem that way considering that I was trying to destroy the intended object when I ran into the problem. But thanks for the heads up.

I can explain further in a separate discussion if necessary, so I'll update accordingly if I don't find a solution to this. Although as a side note, I'm considering swapping the prefab's animation controllers as an alternative.