type: string format: regex does not fail on invalid regular expressions

[thomasborgen]

Hi, I'd like to validate regular expression strings, but it does not seem to give me an error on for example missing closing brackets etc.

tested with python 3.8.2, josnschema 3.2

from jsonschema import Draft7Validator

schema = {
    '$schema': 'http://json-schema.org/draft-07/schema#',
    '$id': 'testid',
    'title': 'regex test schema',
    '$ref': '#/definitions/regexp',
    'definitions': {
        'regexp': {
            'description': 'Regex search string',
            'type': 'object',
            'properties': {
                'search': {
                    'type': 'string',
                    'format': 'regex',
                },
            },
            'required': ['search'],
        },
    },
}


validator = Draft7Validator(schema)

print(validator.check_schema(schema))

print(validator.is_valid({'search': 'test'}))
# True
print(validator.is_valid({'search': '[0-9'}))
# True, but i expect False because of missing bracket.

[Julian]

Hi. Please review the docs on validating format:

https://python-jsonschema.readthedocs.io/en/stable/validate/#validating-formats

[thomasborgen]

Sry i missed that and its clear from the docs.

Because type is enforced it didn't even cross my mind that format wouldn't be.
If its about performance I would argue that having it enabled/enforced by default would make more sense as one would expect that the rules you set in your schema is executed and checked.

Is there any specific reason why it's not enabled by default?

[Julian]

That is what the specification requires.

format is indeed not like type. By default, it's informational only. Validation is opt-in behavior in implementations.

Have a look at the format spec for some more notes on why.

[thomasborgen]

I see, I'll read up about it.
Thanks for the replies, and thanks for the awesome library.