src/dataclasses_config/__init__.py

@@ -8,7 +8,7 @@ __title__ = 'dataclasses-config'
 __author__ = 'Peter Zaitcev / USSX Hares'
 __license__ = 'BSD 2-clause'
 __copyright__ = 'Copyright 2019 Peter Zaitcev'
-__version__ = '0.1.2'
+__version__ = '0.1.3'
 
 VersionInfo = namedtuple('VersionInfo', 'major minor micro releaselevel serial')
 version_info = VersionInfo(*__version__.split('.'), releaselevel='alpha', serial=0)

src/dataclasses_config/_classes.py

 import os
 import warnings
-from dataclasses import field
 from importlib import import_module
 from types import ModuleType
 from typing import *
 
+from dataclasses import field
 from typing_inspect import get_origin, get_args
 
 from ._decorations import *
@@ -59,6 +59,9 @@ class DynamicClass(Generic[T]):
         expected_parent = type_args[0]
         if (not issubclass(self.cls, expected_parent)):
             raise TypeError(f"{self.cls!r} is not a subclass of {expected_parent!r} (from {tp!r}).")
+    
+    def __repr__(self):
+        return f'{type(self).__name__}({self.cls!r})'
 del T
 
 @deserialize_with(ConstructorDataType.String)

src/dataclasses_config/_config.py

 import os
 from abc import ABC
 from copy import deepcopy
-from dataclasses import fields, dataclass, Field, field, replace
 from logging import getLogger
 from typing import *
 
 import pkg_resources
+from dataclasses import fields, dataclass, Field, field, replace
 from dataclasses_json import DataClassJsonMixin
 from dataclasses_json.core import Json
 from functional import Option
 from pyhocon import ConfigTree, ConfigFactory, ConfigException
-from typing_inspect import is_generic_type, get_origin, is_optional_type, get_args
+from typing_inspect import is_generic_type, get_origin, is_optional_type, get_last_args
 
 from ._classes import Path, RelPath
 from ._decorations import *
@@ -112,7 +112,7 @@ class Config(DataClassJsonMixin, ABC):
         for f in fields(cls): # type: Field
             tp = f.type
             if (is_optional_type(tp)):
-                tp = get_args(tp)[0]
+                tp = get_last_args(tp)[0]
             if (is_generic_type(tp)):
                 tp = get_origin(tp)
             if (isinstance(tp, type) and issubclass(tp, Config)):
@@ -128,6 +128,12 @@ class Config(DataClassJsonMixin, ABC):
         # # noinspection PyDataclass
         for f in fields(self): # type: Field
             tp = f.type
+            if (is_optional_type(tp)):
+                tp = get_last_args(tp)[0]
+                is_optional = True
+            else:
+                is_optional = False
+            
             if (is_generic_type(tp)):
                 tp = get_origin(tp)
             if (hasattr(tp, _FIELD_CONSTRUCTOR_ARGUMENT_TYPE)):
@@ -135,6 +141,9 @@ class Config(DataClassJsonMixin, ABC):
                 post: PostInitFunctionType = getattr(tp, _FIELD_CONSTRUCTOR_POST_INIT)
                 
                 v = getattr(self, f.name)
+                if (is_optional and v is None):
+                    continue
+                
                 v = tp(v)
                 if (post is not None):
                     x = post(v, f.type, parent=self)
@@ -437,7 +446,7 @@ class ConfigWithRoot(Config, ABC):
         for f in fields(self): # type: Field
             tp = f.type
             if (is_optional_type(tp)):
-                tp = get_args(tp)[0]
+                tp = get_last_args(tp)[0]
             if (is_generic_type(tp)):
                 tp = get_origin(tp)
             if (isinstance(tp, type) and issubclass(tp, RelPath)):