Associate my custom asset with a custom EditorWindow

Questions & Answers
1

Hello,

In the Project pane, when I right-click on an Animation Controller and select Open, it opens the Animator window.

I have a custom asset in the Project pane. When I right-click on it, I see the Open menu item but it doesn’t do anything. I’d like to have it open my custom EditorWindow. Does anyone know how to do this?

(Please note, this is not the same as having a custom Editor in the Inspector pane - which is working fine!)

EDIT - Feb 20th.

I have two “almost” solutions. I’m posting them here in the hope that someone can turn one of them into a proper solution. Failing that, they might be useful to someone else…

Half-solution 1

The following code will get a callback with the user tries to open an asset. Unfortunately, this is only for assets which are going to be opened in external tools - like .cs files. It doesn’t fire for my custom asset (Scriptable object). This feature was introduced in Unity 4.2

public class OpenAssetCallback
{
	[UnityEditor.Callbacks.OnOpenAsset(1)]
	public static bool OnOpenAsset(int instanceID, int line)
	{
		Debug.Log(string.Format("Going to open asset {0} at line {1}", instanceID, line));
		return false;
	}
}

Half-solution 2
The following code will create a new Asset>Open menu item. But of course, you lose all the existing functionality. So even if you re-implemented all the existing functionality, this approach wouldn’t scale to support 2 or more custom extensions that didn’t know about each other.

public class OpenAssetCallback
{
	[MenuItem("Assets/Open")]
	public static void Execute()
	{
		Debug.Log("User wants to open the selected asset...");
	}
}
3

I think this is a necropost but I just found a good answer for this …
Using “OnOpenAsset” callback, you can try to cast the selected active object to your type.
Ie:

[UnityEditor.Callbacks.OnOpenAsset(1)]
  public static bool OnOpenAsset(int instanceID, int line)
  {
    if (Selection.activeObject as YourScriptableObject != null) {
      OpenYourScriptableObjectEditorWindow();
      return true; //catch open file
    }        
    
    return false; // let unity open the file
  }
2

I found a bit of an hackish solution:

Write a custom Editor (inspector) for your asset and inside its OnEnable() method open your EditorWindow.

[CustomEditor(typeof(YourAsset))]
public class YourAssetEditor : Editor {

    void OnEnable() {
        YourAssetEditorWindow window = 
            EditorWindow.GetWindow<YourAssetEditorWindow>();
        window.yourAsset = (YourAsset) target;
    }
}

When you click on your asset the window is immediately shown. If you don’t want that you could use a button in your custom inspector. Both solutions aren’t perfect but it works.

4

Necro so people googling can find the right answer. Selection.activeObject is not always updated when OnOpenAsset is called. This means Selection.activeObject may be some random object. For example, when you click a build error in the console, OnOpenAsset will be called but Selection.activeObject will be the last selected object, not the build error, and the last editor window will open rather than the code editor. Here’s the more correct way of doing it:

 public static bool OnOpenAsset(int instanceID, int line)
    {
        string assetPath = AssetDatabase.GetAssetPath(instanceID);
        YourScriptableObjectType scriptableObject = AssetDatabase.LoadAssetAtPath<YourScriptableObjectType>(assetPath);
         if (scriptableObject != null)
         {
            YourWindow window = (GameObjectDataEditorWindow)GetWindow(typeof(YourWindow ));
            window.SetScriptableObject(scriptableObject);
            window.Show();
            return true;
        }
        return false; //let unity open it.
    }