json_util.py 文件源码

def get_type_cls(cls, jobj):
        """Get the registered class for ``jobj``."""
        if cls in six.itervalues(cls.TYPES):
            if cls.type_field_name not in jobj:
                raise errors.DeserializationError(
                    "Missing type field ({0})".format(cls.type_field_name))
            # cls is already registered type_cls, force to use it
            # so that, e.g Revocation.from_json(jobj) fails if
            # jobj["type"] != "revocation".
            return cls

        if not isinstance(jobj, dict):
            raise errors.DeserializationError(
                "{0} is not a dictionary object".format(jobj))
        try:
            typ = jobj[cls.type_field_name]
        except KeyError:
            raise errors.DeserializationError("missing type field")

        try:
            return cls.TYPES[typ]
        except KeyError:
            raise errors.UnrecognizedTypeError(typ, jobj)