Can I reload a TreeControl's list of items? #151

MasterKale · 2021-10-19T15:45:44Z

MasterKale
Oct 19, 2021

I've been tinkering with Textual to build with a TUI that can be used to view details about hardware devices connected to my computer. On the left is the list of devices in TreeControl and the right is info about an item in the tree. So far I've managed to get things working to the point that selecting an item in the tree populates the details pane to the right of it:

Screen.Recording.2021-10-15.at.8.44.05.AM.mov

What's stumped me now is, how can I display a new list of items in the tree? I want to offer a "Reload" command that will rescan for hardware devices and then display the new list in place of the old. Unfortunately all I've been able to manage is adding additional items, with the unfortunate side effect of the app crashing with an Exception: Wrong channel if you happen to click an item that existed in the tree prior to adding more:

Screen.Recording.2021-10-19.at.8.37.55.AM.mov

I'm attempting to reload the items like this, with a method on my subclass of TreeControl that the app can pass new devices to:

async def on_reload_authenticators(
    self, new_authenticators: List[AuthenticatorViewModel]
) -> None:
    self.authenticators = new_authenticators
    for auth_view_model in self.authenticators:
        tree_data = AuthenticatorListData(authenticator=auth_view_model)
        await self.add(self.root.id, auth_view_model.aaguid, tree_data.dict())
    self.refresh(layout=True)

But this clearly isn't the complete formula.

What I think I want is the ability to specify async render() methods so that I can declare self.authenticators as a Reactive() and hopefully the tree list Just Updates when I specify a new value for self.authenticators. However the issue with that is that render() seems to want to be synchronous, and I can't reconcile that with the fact that I need to await calls to TreeControl.add().

Has anyone tackled this before? Will said he was inspired by VueJS for some of Textual's inner workings, and I'm coming at this from a predominantly web dev background; I was hoping Textual might emulate some of the magic of the "one-way data flow" of front end SPA frameworks with automatic re-renderings. In this case TreeControl seems to need a bit more manual manipulation...