`ValueError`: "Empty strings are not supported"

[ndonkoHenri]

Inside the docstring of a class, i have [width][(c).] which points to property of this class. Cross ref works normally (as expected).
But when i have the same [width][(c).] inside the docstring of a prop inside this same class, it fails with the below error:

Traceback (most recent call last):
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/mkdocs_autorefs/_internal/plugin.py", line 484, in _get_urls
    return self._primary_url_map[identifier], "primary"
           ~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^
KeyError: '(c).'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/mkdocs_autorefs/_internal/plugin.py", line 496, in _get_item_url
    urls, qualifier = self._get_urls(identifier)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/mkdocs_autorefs/_internal/plugin.py", line 486, in _get_urls
    return self._secondary_url_map[identifier], "secondary"
           ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^
KeyError: '(c).'
During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/mkdocs/livereload/__init__.py", line 211, in _build_loop
    self.builder()
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/mkdocs/commands/serve.py", line 67, in builder
    build(config, serve_url=None if is_clean else serve_url, dirty=is_dirty)
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/mkdocs/commands/build.py", line 319, in build
    env = config.plugins.on_env(env, config=config, files=files)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/mkdocs/plugins.py", line 599, in on_env
    return self.run_event('env', env, config=config, files=files)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/mkdocs/plugins.py", line 566, in run_event
    result = method(item, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/mkdocs_autorefs/_internal/plugin.py", line 281, in on_env
    file.page.content, unmapped = fix_refs(
                                  ^^^^^^^^^
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/mkdocs_autorefs/_internal/references.py", line 564, in fix_refs
    html = AUTOREF_RE.sub(
           ^^^^^^^^^^^^^^^
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/mkdocs_autorefs/_internal/references.py", line 499, in inner
    url, original_title = _find_url(identifiers, url_mapper)
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/mkdocs_autorefs/_internal/references.py", line 586, in _find_url
    return url_mapper(identifier)
           ^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/mkdocs_autorefs/_internal/plugin.py", line 539, in get_item_url
    url = self._get_item_url(identifier, from_url, fallback)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/mkdocs_autorefs/_internal/plugin.py", line 502, in _get_item_url
    new_identifiers = fallback(identifier)
                      ^^^^^^^^^^^^^^^^^^^^
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/mkdocstrings/_internal/handlers/base.py", line 632, in get_anchors
    aliases = handler.get_aliases(identifier)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/mkdocstrings_handlers/python/_internal/handler.py", line 349, in get_aliases
    data = self._modules_collection[identifier]
           ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/_griffe/mixins.py", line 59, in __getitem__
    parts = _get_parts(key)
            ^^^^^^^^^^^^^^^
  File "/Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/.venv/lib/python3.12/site-packages/_griffe/mixins.py", line 25, in _get_parts
    raise ValueError("Empty strings are not supported")
ValueError: Empty strings are not supported
ERROR   -  [21:18:39] An error happened during the rebuild. The server will appear stuck until build errors are resolved.

[analog-cbarber]

Can you include an actual example? By prop do you mean a method with a @property decorator or a class attribute declaration?

Also report versions of this package, python, mkdocstrings-python and griffe.

[ndonkoHenri]

Thanks for your response.

Here is my (data)class:

@control("AnimatedSwitcher")
class AnimatedSwitcher(ConstrainedControl):
    """
    Used to switch between controls with an animation.

    mkdocstrings-python-xref example: [`content`][(c).]
    """

    content: Control
    """
    The content to display. When the `content` changes, the AnimatedSwitcher will
    animate the transition from the old `content` to the new one.
    """

    duration: DurationValue = field(default_factory=lambda: Duration(seconds=1))
    """
    The duration, in milliseconds, of the transition from the old `content` value
    to the new one.

     mkdocstrings-python-xref example: [`content`][(c).]
    """

The goal here is to display a cross ref to the content property using [´content´][(c).].

To better show the error, I added it to my code in two steps:

• first, in the class's docstring, then deployed it with github action and it got rendered as expected
• next, I added it to the duration property, but in this case the mkdocs build failed

Also report versions of this package, python, mkdocstrings-python and griffe.

Here are my deps. (I use the latest versions)

[analog-cbarber]

Not sure what is going on here. I might not have time to replicate this for a day or two, but as a workaround, you can always fallback on using the full path, or you can try using [..] in place of [(c).].

[analog-cbarber]

I cannot replicate this behavior with local examples. I think I might have to just try it on that project.....

[ndonkoHenri]

but as a workaround, you can always fallback on using the full path

Yeah, but I like the shorthands proposed by your package :)

Is it possible that autorefs and mkdocstrings-python-xref are kind of conflicting on who should handle the cross referencing there? 🤔

[ndonkoHenri]

When I use [content][..] I get the below:

WARNING -  mkdocs_autorefs:
           controls/animatedswitcher.md: from
           /Users/ndonkohenri/PycharmProjects/flet-dev/flet/sdk/python/packages/flet/src/flet/controls/core/animated_switcher.py:34:
           (flet.AnimatedSwitcher.duration) Could not
           find cross-reference target '..'

And it gets displayed like this: