jsonschema

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Hi, I have a question regarding the change in 4.10.0 and the default filling custom validator suggested here.

Before this version, I could use this enhanced validator to fill in default values even across "$ref"s to different schema.

But 4.10.0 added support "for referencing schemas with $ref across different versions of the specification", which means that now the validator is determined dynamically based on the "$schema" and the custom one is not used for the referred schema.

Here is an example:

outer:

{
    "$schema": "http://json-schema.org/draft-04/schema#",
    "properties": {
        "count": {
            "default": 0,
            "type": "integer"
        },
        "nested": {
            "$ref": "file://nested.json"
        }
    }
}

nested:

{
    "$schema": "http://json-schema.org/draft-04/schema#",
    "properties": {
        "nestedcount": {
            "default": 0,
            "type": "integer"
        },
        "name": {
            "type": "string"
        }
    }
}

script:

import copy
import json
import jsonschema

def extend_with_default(validator_class):
    validate_properties = validator_class.VALIDATORS["properties"]

    def set_defaults(validator, properties, instance, schema):
        for property, subschema in properties.items():
            if "default" in subschema:
                instance.setdefault(property, subschema["default"])

        for error in validate_properties(
            validator, properties, instance, schema,
        ):
            yield error

    return jsonschema.validators.extend(
        validator_class, {"properties" : set_defaults},
    )

Draft4ValidatorWithDefaults = extend_with_default(jsonschema.Draft4Validator)


def load_schema(uri):
	with open(uri.removeprefix("file://")) as ifile:
		return json.load(ifile)

schema = load_schema("outer.json")

resolver = jsonschema.RefResolver(
    "outer.json", schema,
    handlers={"file": load_schema})

validator_with_defaults = Draft4ValidatorWithDefaults(schema, resolver=resolver)
validator = jsonschema.Draft4Validator(schema, resolver=resolver)

content = {
	"nested": {"name": "foo"}
}

print(jsonschema.__version__)
validator.validate(content)
print(content)
validator_with_defaults.validate(content)
print(content)

When I run this with jsonschema 4.9.1, I get:

4.9.1
{'nested': {'name': 'foo'}}
{'nested': {'name': 'foo', 'nestedcount': 0}, 'count': 0}

when I use 4.10.0, it looks like this:

4.10.0
{'nested': {'name': 'foo'}}
{'nested': {'name': 'foo'}, 'count': 0}

My question is, is there a way to revert to the previous behavior? I found out that when I delete the "$schema" key from the referred schema, it works as before, but that doesn't seem exactly nice (and I am not sure that won't cause other issues)...