JSON Schema string is inconsistent (no trailing #)

[henryiii]

In trying to support SchemaStore and validate-pyproject, I've run into a really annoying inconsistency. SchemaStore's JSON validator checks that the $schema property is a valid schema:

Valid schemas: [
    "https://json-schema.org/draft/2020-12/schema",
    "https://json-schema.org/draft/2019-09/schema",
    "http://json-schema.org/draft-07/schema#"
    "http://json-schema.org/draft-06/schema#",
    "http://json-schema.org/draft-04/schema#",
    "http://json-schema.org/draft-03/schema#"
]

But validate-pyproject requires "http://json-schema.org/draft-07/schema" (since fastjsonschema requires a subschema matches the parent schema exactly), so all plugins currently require the # not be present.

As far as I can tell, SchemaStore is correct - the correct spelling is with the trailing #, it was not removed until draft 2019-09 moved to https. And there are already 700+ schemas on SchemaStore there using it. :)

If you agree that the trailing # is correct, I think it would be easy to migrate, since validate-pyproject gets to pre-process schemas that go to fastjsonschema. The steps would be:

• Move all schemas stored in validate-pyproject to "http://json-schema.org/draft-07/schema#"
• Check all schemas loaded via the entry points to see if they have "http://json-schema.org/draft-07/schema". If they do, make a shallow copy and modify the $schema to have the trailing #.
• Eventually produce a warning if a plugin has the incorrect schema.

Doing it sooner rather than later would be ideal, so more plugins don't keep appearing with the missing #.

If we didn't change this, then we could still handle this in reverse when loading a plugin, we could strip the # instead, so it's not a blocker for SchemaStore support.

Thoughts?

[henryiii]

Ahh, finally found a fairly official reference: https://json-schema.org/understanding-json-schema/reference/schema#schema - which does include the # for the pre 2019 schemas.

[abravalheri]

Hi @henryiii, thank you very much for pointing this out. That was probably an oversight.
I agree with the suggestion. We should change the schemas we ship and modify any plugin that is not compatible, when loading them.

[henryiii]

Okay, I'll try to work on this soon, after #112.