customize validator to reject NaN, Infinity

[stealthrabbi]

I have a Draft7Validator I use to validate some messages. decode_schema calls json.loads() and then check_schema on the validator. I then use the validator to validate incoming messages. This works fine, except for handling NaNs and Inifity on number types. I'd like those to be rejected, but I am not sure how to do it with my current setup.

I have seen validators.extends(), but I am not sure how to use that method to to set the primary schema and ref schemas.

primary_schema_object = decode_schema(json_schema_text)
...
self.validator = Draft7Validator(primary_schema_object)
self.validator.resolver.store = reference_schema_objects

    def is_my_int(self, checker, instance):
       # example - change this
        return instance == 4 

When I attempt to use validators.extend() and validate it, I get an error as shown below:

        type_checker = (
            Draft7Validator.TYPE_CHECKER.redefine("number", self.is_my_int),
        )
        self.validator = validators.extend(Draft7Validator, type_checker=type_checker)
        self.validator(primary_schema_object)

    def validate(self, *args, **kwargs):
>       for error in self.iter_errors(*args, **kwargs):
E       AttributeError: 'dict' object has no attribute 'iter_errors'

[Julian]

There may be more than one problem, but there's certainly at least one simple one, which is you did:

type_checker = (
            Draft7Validator.TYPE_CHECKER.redefine("number", self.is_my_int),
        )

probably using the parentheses to break up the line, but that's a 1-element tuple, because you have a comma there.

So you've passed a tuple in as a type checker, when the right type for that argument is an instance of TypeChecker (which redefine returns).

You want just type_checker = Draft7Validator.TYPE_CHECKER.redefine("number", self.is_my_int) or if you want it on multiple lines remove the comma.

Beyond that it'd be helpful to see a bit more of a fully functioning example to offer advice, because yeah you're in the right spot, if you want to reject those you should redefine number (and/or integer) to return False for math.isnan and math.isinf, and then use ModifiedValidator = extend(Draft7Validator, type_checker=Draft7Validator.TYPE_CHECKER.redefine("number", self.is_my_int)); self.validator = ModifiedValidator(schema, store=reference_schema_objects) rather than using Draft7Validator as-is.

[stealthrabbi]

Thanks, the piece I was missing (figured out right before you posted) was that the return type of extend is returning a class, not an instance, so I had to init it as you've done. I ended up with the following. And yes, I missed the , at the end making it a tuple.

        type_checker = Draft7Validator.TYPE_CHECKER.redefine(
            "number", self._is_finite_number
        )
        extended = validators.extend(Draft7Validator, type_checker=type_checker)
        self.validator = extended(primary_schema_object)
        self.validator.resolver.store = reference_schema_objects

    def _is_finite_number(self, checker, instance):
        return Draft7Validator.TYPE_CHECKER.is_type(
            instance, "number"
        ) and math.isfinite(instance)