AssetDatabase.TryGetGUIDAndLocalFileIdentifier

Parameters

Returns

bool True if the guid and file id were successfully found, false if not.

Description

Get the GUID and local file id from an object instance id.

Warning: Avoid the obsolete versions of this function, which use int for the localId parameter instead of long. Local Ids can be longer than 32 bits in some cases, such as for Prefabs. When Unity serializes an asset reference it points to two things: the GUID and file ID. GUID is a unique hash, and file ID is a value relative to the asset. Both of these values are used when a serialized asset references another asset.

If working with a text serialized project (see Editor Settings) it is possible to manually modify this information. A common use is moving C# script files from a project to a DLL while keeping any GameObjects using these scripts intact. As an example, suppose your project contains a C# MonoBehaviour, a Scene, and a GameObject with this script attached. When serialized the Unity Scene file will contain something that looks like this (reduced to the relevant parts):

/* example .unity Scene contents:

--- !u!1 &65078845
GameObject:
  m_Component:
  -component: {fileID : 65078850}
--- !u!114 &65078850
MonoBehaviour:
  m_Script: {fileID : 11500000, guid : 9cbd8cdf99d44b58972fbc7f6f38088f, type : 3}

*/

using System.Text;
using UnityEngine;
using UnityEditor;

class ShowAssetIds
{
    [MenuItem("Assets/Show Asset Ids")]
    static void MenuShowIds()
    {
        var stringBuilder = new StringBuilder();

        foreach (var obj in AssetDatabase.LoadAllAssetsAtPath(AssetDatabase.GetAssetPath(Selection.activeObject)))
        {
            string guid;
            long file;

            if (AssetDatabase.TryGetGUIDAndLocalFileIdentifier(obj, out guid, out file))
            {
                stringBuilder.AppendFormat("Asset: " + obj.name +
                    "\n  Instance ID: " + obj.GetInstanceID() +
                    "\n  GUID: " + guid +
                    "\n  File ID: " + file);
            }
        }

        Debug.Log(stringBuilder.ToString());
    }
}

Additional resources: GlobalObjectId