Ensure optional type include None type

Author: kanghyojun

CHANGES.rst

@@ -6,13 +6,15 @@ Version 0.6.2
 
 To be released.
 
+- Added ``is_optional_type()`` to ensure optional type includes ``None`` type.
+
 
 Version 0.6.1
 -------------
 
 Released on December 9, 2017.
 
-- Made `nirum.datastructures.List` to copy the given value so that
+- Made ``nirum.datastructures.List`` to copy the given value so that
   it doesn't refer given value's state and is immutable.
 
 

nirum/_compat.py

@@ -1,7 +1,7 @@
 import datetime
 import typing
 
-__all__ = 'utc', 'is_union_type', 'get_union_types'
+__all__ = 'utc', 'is_optional_type', 'is_union_type', 'get_union_types'
 
 
 try:
@@ -43,6 +43,10 @@ def get_union_types(type_):
                 else type_.__args__
 
 
+def is_optional_type(type_):
+    return is_union_type(type_) and type(None) in get_union_types(type_)
+
+
 def get_abstract_param_types(type_):
     return type_.__parameters__ if type_.__parameters__ else type_.__args__
 

nirum/deserialize.py

@@ -13,7 +13,7 @@
 from iso8601 import iso8601, parse_date
 from six import text_type
 
-from ._compat import get_tuple_param_types, get_union_types, is_union_type
+from ._compat import get_tuple_param_types, get_union_types, is_optional_type
 from .datastructures import Map
 
 __all__ = (
@@ -175,9 +175,9 @@ def deserialize_primitive(cls, data):
 
 
 def deserialize_optional(cls, data):
+    if not is_optional_type(cls):
+        raise ValueError('{!r} is not optional type'.format(cls))
     union_types = get_union_types(cls)
-    if not any(isinstance(None, ut) for ut in union_types):
-        raise ValueError(cls)
     if data is None:
         return data
     for union_type in union_types:
@@ -206,7 +206,7 @@ def deserialize_meta(cls, data):
         d = deserialize_tuple_type(cls, data)
     elif is_support_abstract_type(cls):
         d = deserialize_abstract_type(cls, data)
-    elif is_union_type(cls):
+    elif is_optional_type(cls):
         d = deserialize_optional(cls, data)
     elif callable(cls) and cls in _NIRUM_PRIMITIVE_TYPE:
         d = deserialize_primitive(cls, data)