Any gotchas when inheriting from ModalScreen

[grantm]

I have:

class ModalMessageScreen(ModalScreen):
    """Modal message screen with "OK" button to dismiss"""

    def __init__(self, title, message):
        self.title = title
        self.message = message
        super().__init__()

    def compose(self):
        with Grid(id="modal-message"):
            yield Static(self.title, classes="title")
            with ScrollableContainer():
                yield Static(self.message, classes="message")
            with Static(classes="button-bar"):
                yield Button("OK", variant="primary")

    def on_button_pressed(self, event: Button.Pressed):
        self.app.pop_screen()

Which I was using to pop up a modal message like this:

    self.push_screen(ModalMessageScreen("Login failed", message))

That used to work fine, but after installing the latest version of textual today (0.37.1), that code path now triggers an exception which ends with:

  File "/home/grant/.venvs/matrix-user-manager/lib/python3.8/site-packages/rich/pretty.py", line 648, in _traverse
    args = list(iter_rich_args(rich_repr_result))
  File "/home/grant/.venvs/matrix-user-manager/lib/python3.8/site-packages/rich/pretty.py", line 615, in iter_rich_args
    for arg in rich_args:
  File "/home/grant/.venvs/matrix-user-manager/lib/python3.8/site-packages/textual/widget.py", line 2644, in __rich_repr__
    yield "id", self.id, None
  File "/home/grant/.venvs/matrix-user-manager/lib/python3.8/site-packages/textual/dom.py", line 486, in id
    return self._id
AttributeError: 'ModalMessageScreen' object has no attribute '_id'

Am I doing something wrong when I subclass ModalScreen?

[davep]

v0.37.0 introduced a title property for screens. I would hazard a guess that there's a clash there that's causing an issue.

[davep]

To confirm this, if I try and make a small standalone example of the code you have, such that I get the same error, I can recreate it with this:

from textual import on
from textual.app import App, ComposeResult
from textual.containers import Grid
from textual.screen import ModalScreen
from textual.widgets import Button, Static

class ModalMessageScreen(ModalScreen):

    def __init__(self, title: str, message: str) -> None:
        self.title = title
        self.message = message
        super().__init__()

    def compose(self) -> ComposeResult:
        """Compose the child widgets."""
        with Grid():
            yield Static(self.title)
            yield Static(self.message)
            yield Button("Close")

    @on(Button.Pressed)
    def close_dialog(self) -> None:
        self.dismiss()


class ModalScreenErrorApp(App[None]):

    def compose(self) -> ComposeResult:
        yield Button("Show modal", id="test")

    @on(Button.Pressed, "#test")
    def show_modal(self) -> None:
        self.push_screen(ModalMessageScreen("Test", "This is a test of the error"))

if __name__ == "__main__":
    ModalScreenErrorApp().run()

if I rename self.title to self.dialog_title:

from textual import on
from textual.app import App, ComposeResult
from textual.containers import Grid
from textual.screen import ModalScreen
from textual.widgets import Button, Static

class ModalMessageScreen(ModalScreen):

    def __init__(self, title: str, message: str) -> None:
        self.dialog_title = title
        self.message = message
        super().__init__()

    def compose(self) -> ComposeResult:
        """Compose the child widgets."""
        with Grid():
            yield Static(self.dialog_title)
            yield Static(self.message)
            yield Button("Close")

    @on(Button.Pressed)
    def close_dialog(self) -> None:
        self.dismiss()


class ModalScreenErrorApp(App[None]):

    def compose(self) -> ComposeResult:
        yield Button("Show modal", id="test")

    @on(Button.Pressed, "#test")
    def show_modal(self) -> None:
        self.push_screen(ModalMessageScreen("Test", "This is a test of the error"))

if __name__ == "__main__":
    ModalScreenErrorApp().run()

it works fine.

[grantm]

Many thanks! I hadn't even given a thought to what properties I was inheriting/trampling over.