Version: 2022.3
  • C#


struct in UnityEditor

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Struct providing an API for stable, project-global object identifiers.

Provides a project-scoped object identifier, which can be serialized and resolved back to the original object at a later time. It supports referencing objects inside scenes and in other types of assets (Prefabs, ScriptableObjects, etc).

The ID is persistent and unique for a given Unity Object.

The format of the string representation of the ID is "GlobalObjectId_V1-{i}-{a}-{l}-{p}" where:
{i} is the identifier type represented by an integer (0 = Null, 1 = Imported Asset, 2 = Scene Object, 3 = Source Asset).
{a} is the asset GUID.
{l} is the local file ID of the object. For objects inside a prefab instance this is the local file ID of the source object in the prefab.
{p} is the local file ID of the prefab instance of the object (or 0 when the object is not part of a prefab instance).

The default null ID is "GlobalObjectId_V1-0-00000000000000000000000000000000-0-0".

- The ID changes when the object is moved to a new scene, because the scene ID (assetGUID) is part of the GlobalObjectId.
- A GlobalObjectId referring to an object inside a scene can only be resolved back to an InstanceID or Object when that scene is already loaded.
- GlobalObjectIds cannot be requested for objects in the current scene until the scene has been saved at least once, otherwise the assetGUID value will be null.
- When converting multiple objects to or from GlobalObjectIds it is always faster to make a single call using the batch methods rather than making individual calls. For example a single call to GlobalObjectIdentifiersToObjectsSlow is much faster then making multiple calls to GlobalObjectIdentifierToObjectSlow.

Additional resources: Object.GetInstanceID, AssetDatabase.AssetPathToGUID, AssetDatabase.TryGetGUIDAndLocalFileIdentifier

using UnityEngine;
using UnityEditor;
using UnityEditor.SceneManagement;

public class GlobalObjectIdExample { [MenuItem("Example/GlobalObjectId")] static void MenuCallback() { const string testScenePath = "Assets/MyTestScene.unity";

var stringIds = CreateSceneWithTwoObjects(testScenePath);

// These string formatted ids could be saved to a file, then retrieved in a later session of Unity Debug.Log("Ids of new objects " + stringIds[0] + " and " + stringIds[1]);

ReloadSceneAndResolveObjects(testScenePath, stringIds); }

static string[] CreateSceneWithTwoObjects(string testScenePath) { var scene = EditorSceneManager.NewScene(NewSceneSetup.EmptyScene, NewSceneMode.Single);

// Scene must have been serialized at least once prior to generating GlobalObjectIds, so that the asset guid is available EditorSceneManager.SaveScene(scene, testScenePath);

var objects = new Object[2]; objects[0] = GameObject.CreatePrimitive(PrimitiveType.Plane); objects[0].name = "MyPlane"; objects[1] = GameObject.CreatePrimitive(PrimitiveType.Cube); objects[1].name = "MyCube";

var ids = new GlobalObjectId[2]; GlobalObjectId.GetGlobalObjectIdsSlow(objects, ids);

EditorSceneManager.SaveScene(scene, testScenePath);

// Close the scene EditorSceneManager.NewScene(NewSceneSetup.EmptyScene, NewSceneMode.Single);

var idsStringFormat = new string[2]; idsStringFormat[0] = ids[0].ToString(); idsStringFormat[1] = ids[1].ToString();

return idsStringFormat; }

static void ReloadSceneAndResolveObjects(string testScenePath, string[] objectIdsAsStrings) { var ids = new GlobalObjectId[2]; GlobalObjectId.TryParse(objectIdsAsStrings[0], out ids[0]); GlobalObjectId.TryParse(objectIdsAsStrings[1], out ids[1]);

// The scene must be loaded before the ids to objects it contains can be resolved EditorSceneManager.OpenScene(testScenePath);

var objects = new Object[2]; GlobalObjectId.GlobalObjectIdentifiersToObjectsSlow(ids, objects);

// Found MyPlane and MyCube Debug.Log("Found " + objects[0].name + " and " + objects[1].name); } }


assetGUIDThe GUID for the asset to which this object belongs.
identifierTypeThe identifier type represented as an integer.
targetObjectIdThe local file ID of the object.
targetPrefabIdThe prefab instance id of the object.

Public Methods

EqualsCheck equality between two GlobalObjectIds.
ToStringGet the string representation of the GlobalObjectId.

Static Methods

GetGlobalObjectIdSlowConverts an Object reference or InstanceID to a GlobalObjectId.
GetGlobalObjectIdsSlowCreates an array of GlobalObjectIds based on an array of Objects or InstanceIDs.
GlobalObjectIdentifiersToInstanceIDsSlowCreates an array of InstanceIDs based on an array of GlobalObjectIds.
GlobalObjectIdentifiersToObjectsSlowCreates an array of Objects based on an array of GlobalObjectIds.
GlobalObjectIdentifierToInstanceIDSlowConverts a GlobalObjectId to an InstanceID.
GlobalObjectIdentifierToObjectSlowConverts a GlobalObjectId to an Object reference.
TryParseParses the string representation of a GlobalObjectId into a GlobalObjectId struct.