Howto set RadioSet selection programmatically

[UlrichGoebel]

Hi,

I try to set the actual choice of a RadioSet programmatically an struggle in understanding the RadioSet. To demonstrate my struggeling let's see the following code:

from textual.app import App
from textual.widgets import Button, Input, Label, RadioButton, RadioSet

class Main(App):
  
    def compose(self):
        with RadioSet():
            yield RadioButton('One',   id='one',    value=True)
            yield RadioButton('Two',   id='two')
            yield RadioButton('Three', id='three')
        yield Button('Action', id='action')
        yield Button('Show', id='show')
        yield Label('Actual Choice:')
        yield Input()
    
    def on_button_pressed(self, event):
        if event.button.id == 'action':
            self.query_one(RadioSet).action_next_button()   # may be commanded out
            self.query_one(RadioSet).action_toggle_button() # may be commanded out
        # In any case show which RadioButton is active
        self.query_one(Input).value = self.query_one(RadioSet).pressed_button.id
    
if __name__ == "__main__":
    app = Main()
    app.run()

It shows a RadioSet with three choices, then two Buttons, one for showing the actual choice, the other to trigger some action(s) on the RadioSet.

The on_button_pressed handler should start the action or even two actions, if the Action button is pressed. Independend which button was pressed it should update the value of the Input to show the actual/new choice.

That is what I expect. But...

1. Clicking the Action Button changes the choice (this can be seen in the terminal) but in the Input it shows the last choice, not the actual. Why?
2. Clicking the Show Button shows the actual choice as expected.
3. Commanding out the action_toggle_button, so just action_next_button is done: Well, the choice doesn' change. That's o.k. But what does it actually?
4. Commanding out the action_next_button, so just action_toggle_button should be done: Clicking the Action doesn't do anything but showing the actual choice. So it seems that it cant toggle the choice if it is alredy activated - which obviously makes sense in a RadioSetcontext because it can't know whichRadioButton` has to be the new choice. Does that mean that toggle in fact means set?
5. There seems to be a difference between selecting a RadioButton and choose it.
6. Is there a possibility to get the chosen RadioButton even if it is not the pressed one? Then I could step through the RadioButton using action_next_button until I found the right one which can then be toggled by action_toggle_button, which in fact means it would be the new choice.

Can someone help me to understand what's going on here?

Best regards
Ulrich

[TomJGooding]

This looks like a possible bug, rather than something you're doing wrong.

I don't yet fully understand the workings of the RadioSet, but my quick test also doesn't seem to work as expected. This might need some input from a maintainer...

from textual.app import App, ComposeResult
from textual.widgets import Footer, RadioButton, RadioSet


class ExampleApp(App):
    BINDINGS = [("n", "toggle_next_button", "Toggle Next Buttton")]

    def compose(self) -> ComposeResult:
        with RadioSet():
            yield RadioButton("One", id="one", value=True)
            yield RadioButton("Two", id="two")
            yield RadioButton("Three", id="three")

        yield Footer()

    def action_toggle_next_button(self) -> None:
        radio_set = self.query_one(RadioSet)
        assert radio_set._selected == 0

        radio_set.action_next_button()
        assert radio_set._selected == 1

        radio_set.action_toggle_button()
        assert radio_set._selected == 1
        assert radio_set.pressed_button is not None
        # The test below will fail, despite the toggle action seemingly using
        # `_selected` attribute as an index?
        assert radio_set.pressed_index == 1


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