Button Action Parameter Not Detecting In Correct Namespace

[ddkasa]

So it says this here

Textual will look for action methods in the class where they are defined (App, Screen, or Widget). If we were to create a custom widget it can have its own set of actions.

But after running the provided MRE no action gets detected for the buttons. Although if I set the namespace explicitly the action still works.

https://github.com/Textualize/textual/blob/3f3259246f4cb8956d1818b1c516c23e7777f606/src/textual/widgets/_button.py#L287-L289

My suspicion is that the above default_namespace parameter is the culprit, as its pointing to the incorrect parent Screen(id="_default"), which doesn't contain the method. For example when I change it to self.app, as a band aid fix it works correctly. In my opinion it should search up the DOM to the active screen, until an action actually matches or if no explicit screen is set it should check the main app class last instead of a screen.

MRE

from textual.app import App
from textual.widgets import Button


class BugReportApp(App):
    BINDINGS = [("n", "notify_test")]

    def compose(self):
        yield Button("Broken", action="notify_test")
        yield Button("Works", action="app.notify_test")

    def _action_notify_test(self):
        self.notify("It works")


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

Textual Diagnostics

Versions

Name	Value
Textual	1.0.0
Rich	13.9.4

Python

Name	Value
Version	3.12.3
Implementation	CPython
Compiler	GCC 13.2.1 20240316 (Red Hat 13.2.1-7)
Executable	/home/dk/dev/tmp/t-button-action/.venv/bin/python

Operating System

Name	Value
System	Linux
Release	6.11.11-200.fc40.x86_64
Version	#1 SMP PREEMPT_DYNAMIC Thu Dec 5 18:38:39 UTC 2024

Terminal

Name	Value
Terminal Application	Kitty
TERM	xterm-kitty
COLORTERM	truecolor
FORCE_COLOR	Not set
NO_COLOR	Not set

Rich Console options

Name	Value
size	width=137, height=54
legacy_windows	False
min_width	1
max_width	137
is_terminal	True
encoding	utf-8
max_height	54
justify	None
overflow	None
no_wrap	False
highlight	None
markup	None
height	None

[github-actions[bot]]

We found the following entry in the FAQ which you may find helpful:

• How do I pass arguments to an app?

Feel free to close this issue if you found an answer in the FAQ. Otherwise, please give us a little time to review.

This is an automated reply, generated by FAQtory

[darrenburns]

This was changed way back in https://github.com/Textualize/textual/releases/tag/v0.61.0 to make it a requirement that the namespace is specified. I think that's just some outdated documentation.

Changed in PR: https://github.com/Textualize/textual/pull/4516

[ddkasa]

I can create a PR adding a sentence specifying that a namespace is required if using the action parameter.

[anschweitzer]

The MRE for this example doesn't seem quite (See #5422). I wonder if that is relevant to this issue.