license metadata is checked but then discarded

[analog-cbarber]

You can put a license in your pyproject.toml and flit will check to make sure it has the correct form, but will then just throw it away rather than include it in the metadata.

flit/flit_core/flit_core/config.py

Lines 469 to 493 in 6982fae

	if 'license' in proj:
	_check_type(proj, 'license', dict)
	license_tbl = proj['license']
	unrec_keys = set(license_tbl.keys()) - {'text', 'file'}
	if unrec_keys:
	raise ConfigError(
	"Unrecognised keys in [project.license]: {}".format(unrec_keys)
	)
	# TODO: Do something with license info.
	# The 'License' field in packaging metadata is a brief description of
	# a license, not the full text or a file path. PEP 639 will improve on
	# how licenses are recorded.
	if 'file' in license_tbl:
	if 'text' in license_tbl:
	raise ConfigError(
	"[project.license] should specify file or text, not both"
	)
	lc.referenced_files.append(license_tbl['file'])
	elif 'text' in license_tbl:
	pass
	else:
	raise ConfigError(
	"file or text field required in [project.license] table"
	)

[takluyver]

I'm waiting for PEP 639 before reworking the options for license metadata. The TODO comment in that code explains why it doesn't put the license from pyproject.toml into the current package metadata format.

[pombredanne]

I am the taking-too-long-to-finish author of PEP639... IMHO you should not wait to include license metadata.

[WolfgangFahl]

I am also interested how this is supposed to work. I tried a work-around in my project like this:

# flit_core.config.ConfigError: license field should be <class 'dict'>, not <class 'str'>
license = { 
  file="LICENSE" 
}

and end up with a garbled result in pypi when using hatchling.

I can't find the "official" way how to do this properly and will need to revert to the plain string version of
e.g.

license=Apache-2.0

[takluyver]

I think Hatchling is doing the wrong thing there, though it's not entirely clear, because there isn't really a right thing. It has chosen to read the file and include the full contents as the License field in the package metadata. The metadata spec suggests that the License field is meant for a brief description to identify the license, not the full text.

Part of PEP 639 is to include a new License-File field for this case.

[takluyver]

Oh, and there's also an issue open on PyPI for how it displays really long license fields: pypi/warehouse#12392

[RossComputerGuy]

Is there a solution to this? I get the error described when building Hatchling v1.7.0 with Flit 3.9.0.

[mschoettle]

Maybe this could be revisited now that [PEP 639] has provisional status.

Some packages already use the license text field to specify the SPDX identifier of the license which results in PyPI returning this information in via the API in the license key. Although I am unsure whether this is documented behaviour.