gistfile1.py

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

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

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

    def set_defaults_for_oneOf(validator, oneOf, instance, schema):
        subschemas = enumerate(oneOf)
        all_errors = []
        for index, subschema in subschemas:
            errs = list(validator.descend(instance, subschema, schema_path=index))
            if not errs:
                first_valid = subschema
                break
            all_errors.extend(errs)
        else:
            yield ValidationError(
                f"{instance!r} is not valid under any of the given schemas",
                context=all_errors,
            )

        more_valid = [
            each for _, each in subschemas
            if validator.evolve(schema=each).is_valid(instance)
        ]
        if more_valid:
            more_valid.append(first_valid)
            reprs = ", ".join(repr(schema) for schema in more_valid)
            yield ValidationError(f"{instance!r} is valid under each of {reprs}")

        set_defaults_here()

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