Question CreateInstance<VisualTreeAsset>() and Save it as an Asset at path?

Hi

I am having trouble saving an instance of VisualTreeAsset to 'Assets/'

I had an error: CreateAsset() should not be used to create a file of type '' - consider using AssetDatabase.ImportAsset() to import an existing '' file instead or change the file type to '*.asset'. This error will in a future release be changed to an exception.

When I fix that error by doing AssetDatabase.CreateAsset(visualTree, $"{path}/{name}.asset"); asset gets created successfully, BUT when I try to open the Uxml the UI Builder throw errors:

No1.
Exception thrown while invoking [OnOpenAssetAttribute] method 'Unity.UI.Builder.Builder:OnOpenAsset (int,int)' : ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index

No2.
ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index

How can I CreateInstance<VisualTreeAsset>() and Save it as an Asset at path? Because the CreateInstance<VisualTreeAsset>() way, doesn't work for this type.

Code (CSharp):

1.             var path = Path.GetDirectoryName(AssetDatabase.GetAssetPath(this));
2.             var assemblyName = System.Reflection.Assembly.GetExecutingAssembly().GetName().Name;
3.  
4.             if (visualTree == null)
5.             {
6.                 var visualTree = CreateInstance<VisualTreeAsset>();
7.                 visualTree.name = name;
8.  
9.                 AssetDatabase.CreateAsset(visualTree, $"{path}/{name}");
10.              
11.                 this.visualTree = visualTree;
12.             }

 

Bump. How can we create instance and save a VisualTreeAsset properly? Because the way shown above creates half of a VisualTreeAsset.

 

I think you would probably need to just write out a uxml instead of trying to save it as a Unity asset.