How to select a tree node and expand it

[davetapley]

I have a populated a Tree and collected the NodeIDs in dictionary which maps the items to their nodes.

How can I select that node and expand the tree to show it exactly as if the user had manually expanded clicked on it?

I see a few methods like select_node, but they don't seem to do that 🤔

[TomJGooding]

You might find the code references in the docs for Tree and TreeNode helpful.

select_node will only "Move the cursor to the given node". You can change the expanded state of a TreeNode using the toggle or expand methods.

EDIT: It looks like you could also use action_toggle_node, but only after ensuring that the selected node has refreshed: tree.call_after_refresh(tree.action_toggle_node)

from textual.app import App, ComposeResult
from textual.widgets import Tree


class TreeApp(App):
    def compose(self) -> ComposeResult:
        tree: Tree[dict] = Tree("Dune")
        tree.root.expand()
        characters = tree.root.add("Characters")
        characters.add_leaf("Paul")
        characters.add_leaf("Jessica")
        characters.add_leaf("Chani")
        yield tree

        node_to_expand = tree.get_node_by_id(characters.id)
        tree.select_node(node_to_expand)
        node_to_expand.expand()


if __name__ == "__main__":
    app = TreeApp()
    app.run()

[TomJGooding]

For context as to why selecting a node is separate from expanding it, see this issue.