additionalItems can blow up when rendering a message for a non-homogeneous array

[michaelmior]

The extras_msg function sometimes throws an exception when everything in extras is not the same type because sorting fails.

Assuming the specific sort order is not terribly important, changing from

        return ", ".join(repr(extra) for extra in sorted(extras)), verb

to

        return ", ".join(extra for extra in sorted(map(repr, extras))), verb

should solve the problem.

[Julian]

Hi. Thanks. Can you include a full reproducing example?

[michaelmior]

Unfortunately this was part of a larger job that failed and I didn't catch the specific input. I do however have a stack trace.

Traceback (most recent call last):
  File "/home/mmior/apps/json-fetcher/download.py", line 57, in <module>
    jsonschema.validate(instance=doc_obj, schema=schema)
  File "/home/mmior/.local/share/virtualenvs/json-fetcher-ZSn11VnQ/lib/python3.9/site-packages/jsonschema/validators.py", line 1305, in validate
    error = exceptions.best_match(validator.iter_errors(instance))
  File "/home/mmior/.local/share/virtualenvs/json-fetcher-ZSn11VnQ/lib/python3.9/site-packages/jsonschema/exceptions.py", line 444, in best_match
    best = next(errors, None)
  File "/home/mmior/.local/share/virtualenvs/json-fetcher-ZSn11VnQ/lib/python3.9/site-packages/jsonschema/validators.py", line 368, in iter_errors
    for error in errors:
  File "/home/mmior/.local/share/virtualenvs/json-fetcher-ZSn11VnQ/lib/python3.9/site-packages/jsonschema/_validators.py", line 57, in additionalProperties
    yield ValidationError(error % extras_msg(extras))
  File "/home/mmior/.local/share/virtualenvs/json-fetcher-ZSn11VnQ/lib/python3.9/site-packages/jsonschema/_utils.py", line 94, in extras_msg
    return ", ".join(repr(extra) for extra in sorted(extras)), verb
TypeError: '<' not supported between instances of 'str' and 'bool'

[davidrios]

I have the same issue.

Here's a minimal schema for reproduction:

{
  "$schema": "https://json-schema.org/draft/2019-09/schema",
  "type": "object",
  "properties": {
    "array_multiple_types": {
      "oneOf": [
        {
          "type": "array",
          "items": [
            {
              "const": "test1"
            }
          ],
          "additionalItems": false,
          "minItems": 1
        },
        {
          "type": "array",
          "items": [
            {
              "const": "test2"
            },
            {
              "type": "string"
            },
            {
              "type": "number"
            }
          ],
          "additionalItems": false,
          "minItems": 3
        }
      ]
    }
  }
}

and an instance to be validated:

{
  "array_multiple_types": [
    "test2",
    "aaa",
    99
  ]
}

Although the proposed solution does fix the problem, my first instinct would be to not sort a list if I'm not sure it's homogenous. Sorting also makes the error message slightly more confusing as it shows elements in a different ordering from the validated instance. I would just remove it.

return ", ".join(repr(extra) for extra in extras), verb

Thanks for the project BTW!

[Julian]

Thanks, that helps!