Mypy error: found module but no type hints or library stubs

[andreaslongo]

Python 3.9.5
mypy 0.910
sqlite-utils 3.17.1

While using sqlite-utils as a library, when I use mypy for static type checking, it throws an error:

mypy .
src/etl.py:5: error: Skipping analyzing "sqlite_utils": found module but no type hints or library stubs
    import sqlite_utils
    ^
src/etl.py:5: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
test/test_etl.py:4: error: Skipping analyzing "sqlite_utils": found module but no type hints or library stubs
    import sqlite_utils
    ^
Found 2 errors in 2 files (checked 7 source files)

When I add a py.typed file to the sqlite-utils package to mark it as PEP 561 compatible, the error goes away.

al@nbal ..b/python3.9/site-packages/sqlite_utils (git)-[main] % la
total 200
drwx------   3 al al   4096 Oct 14 22:00 .
drwx------ 117 al al   4096 Oct 12 21:12 ..
-rw-------   1 al al  64409 Oct 12 21:11 cli.py
-rw-------   1 al al 109092 Oct 12 21:11 db.py
-rw-------   1 al al      0 Oct 14 22:00 py.typed
-rw-------   1 al al    684 Oct 12 21:11 recipes.py
-rw-------   1 al al   7988 Oct 12 21:11 utils.py
-rw-------   1 al al    113 Oct 12 21:11 __init__.py

I would like to suggest adding a py.typed file to the repository.

See also the mypy docs on creating PEP 561 compatible packages:
https://mypy.readthedocs.io/en/stable/installed_packages.html#creating-pep-561-compatible-packages

[simonw]

Thanks - I didn't know this was needed!

[simonw]

Tested it like this, against a freshly built .tar.gz package from my development environment:

(w) w % mypy .                    
hello.py:1: error: Skipping analyzing "sqlite_utils": found module but no type hints or library stubs
hello.py:1: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
Found 1 error in 1 file (checked 1 source file)
(w) w % pip install ~/Dropbox/Development/sqlite-utils/dist/sqlite-utils-3.17.1.tar.gz
Processing /Users/simon/Dropbox/Development/sqlite-utils/dist/sqlite-utils-3.17.1.tar.gz
...
Successfully installed sqlite-utils-3.17.1
(w) w % mypy .                                                                        
Success: no issues found in 1 source file

I tested against the .whl too.

My hello.py script contained this:

import sqlite_utils
from typing import cast

if __name__ == "__main__":
    db = sqlite_utils.Database(memory=True)
    table = cast(sqlite_utils.db.Table, db["foo"])
    table.insert({"id": 5})
    print(list(db.query("select * from foo")))

That cast() is necessary because without it you get this error:

(w) w % mypy .
hello.py:7: error: Item "View" of "Union[Table, View]" has no attribute "insert"