[Question]: Nav does not update the SelectedKey before firing OnSelect

[ghurlman]

Describe the bug
When clicking on a nav item, the SelectedKey property is not being updated until after the event fires. So, it always seems to be a click "behind". SelectedKey is updated properly before OnChange is fired, however.

To Reproduce
Steps to reproduce the behavior:

1. Create an app, add the Nav control, configure the Items property
2. Add Notify("SelectedKey: " & Self.SelectedKey to the OnSelect behavior property
3. Run the app in preview mode, and click a nav item.
4. Click a different nav item.

Expected behavior
A notification pops up, properly reflecting the item clicked, and then again with the second click

Actual behavior
The first notification shows a blank SelectedKey, and the second notification shows the SelectedKey for the first item clicked.

[denise-msft]

Thanks for reporting this @ghurlman.

Nav has been implemented in a way that is intended to bind a variable in Power Apps to the Nav.SelectedKey property. This enables a way to set a default value to display on first load state (e.g., the first item in the Nav on app load, display the current page of the app).

This can be done by:

• Initializing varSelectedKey to the desired record (e.g., in App.OnStart): Set(varSelectedKey, First(NavItems).ItemKey);
• Setting Nav.SelectedKey to varSelectedKey
• Updating varSelectedKey in Nav.OnChange: Set(varSelectedKey, Self.Selected.ItemKey); Notify(varSelectedKey);

At this point, the notification should be showing you the current value of varSelectedKey.

Is this acceptable? I realize it might not reflect the way in-product components are implemented, however it is consistent with how Creator Kit controls have been implemented. If so, we can update documentation to make these steps clearer.