Add metadata validation

[bittner]

I'm trying to help fix the issue of broken package descriptions on PyPI (e.g. pypa/setuptools#1390).

Following a suggestion of @di in pypa/setuptools#1390 (comment), I would do the following:

1. Add a validation module to packaging that provides a class with a validate() method and an error list attribute (an interface that can be easily used in Web frameworks like Pyramid and Django).
2. Use this module in setuptools.dist.write_pkg_file to validate all incoming data against their specification. Setuptools, specifically, would then abort with an InvalidMetadataError if the specs are not met (instead of continuing silently generating a broken PKG-INFO file, as today).

Does that sound like something that makes sense?

Should I proceed and open a PR for a validation module?

[di]

Hi @bittner thanks for raising this issue. As I mentioned in pypa/setuptools#1390 (comment), this is something I'm currently working on, and planning to have a PR up for discussion soon.

[bittner]

I'm not sure if you have started already as there is no PR yet, but if it helps you can take over parts of my code in PR #732 (e.g. the Metadata class) -- if that looks somewhat the direction you want to go.

I'm curious about what the interface and and usage pattern will look like, to know whether the implementation in write_pkg_filewill have to look a lot different than in PR #732.

[bittner]

Any progress with this issue? Setuptools' issue #1390 is waiting for this to be implemented first.

[bittner]

Any progress on this? I had hoped I could help fix this easily and quickly. Anything I can do to help get up to speed?

Reference to my original PR: pypa/setuptools#1562

[bittner]

@di Any progress with metadata validation?

[brainwane]

We discussed this at the packaging mini-summit in May and I've created pypa/packaging-problems#264 as a tracking issue covering the various TODOs necessary to plumb this through the parts of the toolchain.

[bhrutledge]

Here's @di's work thus far, in case other folks are interested in picking it up:

https://github.com/di/packaging/tree/metadata-validation
Diff: master...di:metadata-validation

[brainwane]

master...crwilcox:metadata-validation @crwilcox also took a stab at this, I believe?

At this point I am guessing that both @di and @crwilcox have stepped away from this task; it would be very helpful for the pip resolver work (see pypa/packaging-problems#264 ) over the next few months.

[bittner]

As a feedback to our community: It pays off to encourage people to modify their contribution instead of bluntly dismissing it as "broken" or stating "my idea is the better one", in a certain sense. It's all about people. We Pythonistas should know better. We should do better.

</offtopic>

[merwok]

It’s not clear what you’re referring to: I don’t find any message saying broken or better in this thread.