jsonschema.py

def create_validator():
    default_class = jsonschema.Draft4Validator
    validate_properties = default_class.VALIDATORS['properties']

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

        for key in list(instance.keys()):
            if key not in properties:
                del instance[key]

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

    return jsonschema.validators.extend(
        default_class, {'properties': handle_props})


Validator = create_validator()


def validate_and_normalize(schema, data):
    """Validates data and modifies it in place."""
    Validator(schema).validate(data)
    return data


def get_validated_json(schema):
    """Applies the request input JSON to the schema."""
    return validate_and_normalize(schema, request.get_json() or {})