Textualize
Invalid tag crashes app even when escaping
The string [/ is escaped using textual.markup.escape, but the app still crashes:
from textual.app import App, ComposeResult
from textual.widgets import Header, Static
from textual.markup import escape
class BugSample(App):
BINDINGS = [("q", "quit", "Quit")]
def __init__(self):
super().__init__()
def compose(self) -> ComposeResult:
yield Header(show_clock=True)
yield Static(id="main-text")
def on_mount(self) -> None:
to_show = "[/"
self.query_one("#main-text").update(escape(to_show))
BugSample().run()
Exception:
╭────────────────────────────────────────────────────────────────────────────────────── Traceback (most recent call last) ──────────────────────────────────────────────────────────────────────────────────────╮
│ test.py:18 in on_mount │
│ │
│ 15 │ ╭───────────────────────────────────────────── locals ─────────────────────────────────────────────╮ │
│ 16 │ def on_mount(self) -> None: │ self = BugSample(title='BugSample', classes={'-dark-mode'}, pseudo_classes={'focus', 'dark'}) │ │
│ 17 │ │ to_show = "[/" │ to_show = '[/' │ │
│ ❱ 18 │ │ self.query_one("#main-text").update(escape(to_show)) ╰──────────────────────────────────────────────────────────────────────────────────────────────────╯ │
│ 19 │
│ 20 │
│ 21 BugSample().run() │
│ │
│ /home/kwl/.local/lib/python3.10/site-packages/textual/widgets/_static.py:94 in update │
│ │
│ 91 │ │ """ ╭───────────── locals ─────────────╮ │
│ 92 │ │ │ content = '[/' │ │
│ 93 │ │ self.__content = content │ layout = True │ │
│ ❱ 94 │ │ self.__visual = visualize(self, content, markup=self._render_markup) │ self = Static(id='main-text') │ │
│ 95 │ │ self.refresh(layout=layout) ╰──────────────────────────────────╯ │
│ 96 │
╰───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯
MarkupError: auto closing tag ('[/]') has nothing to close
In addition, the string '[/b' throws MarkupError: closing tag '[/b]' does not match any open tag.
Textual Diagnostics
Versions
| Name | Value |
|---|---|
| Textual | 6.2.1 |
| Rich | 13.7.0 |
Python
| Name | Value |
|---|---|
| Version | 3.10.12 |
| Implementation | CPython |
| Compiler | GCC 11.4.0 |
| Executable | /usr/bin/python3 |
Operating System
| Name | Value |
|---|---|
| System | Linux |
| Release | 6.6.87.2-microsoft-standard-WSL2 |
| Version | #1 SMP PREEMPT_DYNAMIC Thu Jun 5 18:30:46 UTC 2025 |
Terminal
| Name | Value |
|---|---|
| Terminal Application | Windows Terminal |
| TERM | xterm-256color |
| COLORTERM | Not set |
| FORCE_COLOR | Not set |
| NO_COLOR | Not set |
Rich Console options
| Name | Value |
|---|---|
| size | width=209, height=52 |
| legacy_windows | False |
| min_width | 1 |
| max_width | 209 |
| is_terminal | True |
| encoding | utf-8 |
| max_height | 52 |
| justify | None |
| overflow | None |
| no_wrap | False |
| highlight | None |
| markup | None |
| height | None |
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This is an automated reply, generated by FAQtory
![github-actions[bot] avatar](https://avatars.githubusercontent.com/in/15368?v=4 "Published by a pub.dev verified publisher"){kind=small}
This seems to be the problem:
>>> from textual.content import Content
>>> Content.from_markup("[r")
Content('[r')
>>> Content.from_markup("[/")
Traceback (most recent call last):
Cell In[9], line 1
Content.from_markup("[/")
File ~/work/software/playground-textual/.venv/lib/python3.13/site-packages/textual/content.py:253 in from_markup
content = to_content(markup, template_variables=variables or None)
File ~/work/software/playground-textual/.venv/lib/python3.13/site-packages/textual/markup.py:320 in to_content
raise MarkupError(str(error)) from None
MarkupError: auto closing tag ('[/]') has nothing to close
So [r is recognised as text, not markup. But [/ is interpreted exactly the same as [/], which is an autoclosing tag. But there's nothing to close, so it crashes. It shouldn't recognise [/ as a tag.
