How do you find python package metadata information given a module

Question

I'm trying to retrieve metadata information for a python package given the name of the module.

I can use importlib-metadata to retrieve the information, but in some cases the top-level module name is not the same as the package name.

example:

>>> importlib_metadata.metadata('zmq')['License'] Traceback (most recent call last): File "<stdin>", line 1, in <module> File "c:\Users\xxxxx\AppData\Local\Programs\Python\Python37\Lib\site-packages\importlib_metadata\__init__.py", line 499, in metadata return Distribution.from_name(distribution_name).metadata File "c:\Users\xxxxx\AppData\Local\Programs\Python\Python37\Lib\site-packages\importlib_metadata\__init__.py", line 187, in from_name raise PackageNotFoundError(name) importlib_metadata.PackageNotFoundError: zmq >>> importlib_metadata.metadata('pyzmq')['License'] 'LGPL+BSD'

Some ideas: stackoverflow.com/a/60363617/11138259 -- stackoverflow.com/a/60351412/11138259 — sinoroc
– sinoroc, Commented Apr 1, 2020 at 16:14
For others who come past here (via Google etc.) check out [this other discussion][1] for more ideas based on @sinoroc's suggestion. [1]: stackoverflow.com/questions/63847850/… — sarlacii
– sarlacii, Commented Sep 14, 2020 at 15:45

sinoroc · Accepted Answer · 2021-02-24 18:47:41Z

I believe something like the following should work:

#!/usr/bin/env python3 import importlib.util import pathlib import importlib_metadata def get_distribution(file_name): result = None for distribution in importlib_metadata.distributions(): try: relative = ( pathlib.Path(file_name) .relative_to(distribution.locate_file('')) ) except ValueError: pass else: if relative in distribution.files: result = distribution return result def alpha(): file_name = importlib.util.find_spec('easy_install').origin distribution = get_distribution(file_name) print("alpha", distribution.metadata['Name']) def bravo(): file_name = importlib_metadata.__file__ distribution = get_distribution(file_name) print("bravo", distribution.metadata['Name']) if __name__ == '__main__': alpha() bravo()

Update (February 2021):

Looks like this could become easier thanks to the newly added packages_distributions() function in importlib_metadata:

This assumes the path of the toplevel modules are subdirectories of the package. zmq and pyzmq-<version>.dist-info are both subdirectories of site-packages.
@nsk I do not understand the issue. As a test I just installed pyzmq and the above code seems to work perfectly fine.
@nsk Did that answer your question or is there still some clarification needed?
Nice solution. The only thing I would add is there is a is_relative_to method that can slightly simplify things.
I spoke too soon: unfortunately, because so many packages are just eggs in e.g. /usr/local/lib/python3.9/site-packages/, this fails.

Noldorin · Accepted Answer · 2021-03-09 17:50:24Z

Here is a function that does what you want, I believe. It's not terribly efficient, in that it has to enumerate all the installed package distributions and read the list of top-level modules for each — however, I believe it's the best one can do. (Of course, you can also cache a dict mapping from top-level module names to package names.)

from importlib.metadata import Distribution, distributions from pathlib import Path from typing import * def get_pkg_distribution(top_level_module: str) -> Optional[Distribution]: pkg_path = Path(__file__).parent for dist in distributions(): package_namespaces = (dist.read_text("top_level.txt") or "").splitlines() if top_level_module in package_namespaces: return dist return None # Get the package metadata for the current package. Note, `__package__` is actually the name of the top-level module! pkg_metadata = dict(get_pkg_distribution(__package__).metadata.items()) __version__ = pkg_metadata["Version"]

This solution seems to have the same shortcomings as mine. In that it relies on filenames. It would be better to rely on fully qualified module name, get the top level package/module name and then compare with importlib-metadata.readthedocs.io/en/stable/…
Actually, my solution is very similar to the implementation of packages_distributions, having just looked at the source code for that lib! I believe __package should get the full-qualified name of the top-level module? Not 100% sure though. Does the trick for me.
Does it work for code that is installed as egg, or something like that?
It seemed to when I last tried... but I can investigate properly later, maybe.
Yes, please let me know if you manage to test. I really wonder how to get a valid __file__ out of an egg.

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