MyPy error: Expected type in class pattern; found "Any"

Want to add MyPy checker to my html scraper. I manage to fix all errors except this one Expected type in class pattern.

Source code:

from bs4 import BeautifulSoup

from bs4.element import Tag, NavigableString

soup = BeautifulSoup("""
    <!DOCTYPE html>
    <html>
        <body>
            EXTRA TEXT
            <p>
            first <b>paragraph</b>
            <br>
            <br>
            second paragraph
            </p>
        </body>
    </html>
    """, "lxml")

tag = soup.select_one('body')

for el in tag.children:
    match el:
        case NavigableString():
            ...
        case Tag(name="p"):
            ...
        case Tag():
            ...

mypy example.py

Errors:

example.py:24: error: Expected type in class pattern; found "Any"
example.py:26: error: Expected type in class pattern; found "Any"
example.py:28: error: Expected type in class pattern; found "Any"
Found 3 errors in 1 file (checked 1 source file)

So, what does this error mean? And how can I fix it?

Solution

You can use TYPE_CHECKING to load classes that have the typing

from typing import TYPE_CHECKING

if TYPE_CHECKING:

    class NavigableString:
        ...

    class Tag:
        children: list[NavigableString | Tag]
        name: str

    class BeautifulSoup:
        def __init__(self, markup: str, features: str | None) -> None:
            ...

        def select_one(self, text: str) -> Tag:
            ...

else:
    from bs4 import BeautifulSoup
    from bs4.element import Tag, NavigableString

soup = BeautifulSoup(
    """
    <!DOCTYPE html>
    <html>
        <body>
            EXTRA TEXT
            <p>
            first <b>paragraph</b>
            <br>
            <br>
            second paragraph
            </p>
        </body>
    </html>
    """,
    "lxml",
)

tag = soup.select_one("body")

for el in tag.children:
    match el:
        case NavigableString():
            ...
        case Tag(name="p"):
            ...
        case Tag():
            ...