def test_get_origin(self):
self.assertEqual(list, get_origin(List[int]))
self.assertEqual(tuple, get_origin(Tuple[int, ...]))
self.assertEqual(dict, get_origin(Dict[str, int]))
self.assertEqual(set, get_origin(TypingSet))
self.assertEqual(deque, get_origin(Deque))
self.assertEqual(defaultdict, get_origin(DefaultDict))
self.assertEqual(type, get_origin(Type[int]))
self.assertEqual(Set, get_origin(AbstractSet))
self.assertIn('test_origin_and_alias', str(get_origin(Union)))
def is_optional_type(cls: type) -> bool:
"""
Return True if the given class is an optional type. A type is considered to
be optional if it allows ``None`` as value.
Example:
is_optional_type(Optional[str]) # True
is_optional_type(Union[str, int, None]) # True
is_optional_type(str) # False
is_optional_type(Union[str, int]) # False
:param cls: a type.
:return: True if cls is an optional type.
"""
origin = get_origin(cls)
args = get_args(cls)
return origin == typing.Union and NoneType in args
def default_mapping_deserializer(obj: dict, cls: type, **kwargs) -> Mapping:
"""
Deserialize a (JSON) dict into a mapping by deserializing all items of that
dict.
:param obj: the dict that needs deserializing.
:param cls: the type, optionally with a generic (e.g. Set[str]).
:param kwargs: any keyword arguments.
:return: a deserialized set instance.
"""
cls_ = Mapping
cls_args = get_args(cls)
if cls_args:
cls_ = MappingType[cls_args]
dict_ = default_dict_deserializer(obj, cls_, **kwargs)
result = dict_
# Strip any generics from cls to allow for an instance check.
if not isinstance(result, get_origin(cls)):
result = cls(dict_)
return result