get type hints if a forward reference is used

Signed-off-by: Zen <[email protected]>

Author: desultory

src/zenlib/types/validated_dataclass.py

@@ -1,11 +1,11 @@
 from dataclasses import dataclass
+from typing import ForwardRef, Union, get_args, get_origin, get_type_hints
 
 
 def validatedDataclass(cls):
     from zenlib.logging import loggify
     from zenlib.util import merge_class
 
-
     cls = loggify(dataclass(cls))
     base_annotations = {}
     for base in cls.__mro__:
@@ -28,6 +28,9 @@ def _validate_attribute(self, attribute, value):
             expected_type = self.__class__.__annotations__.get(attribute)
             if not expected_type:
                 return value  # No type hint, so we can't validate it
+            if get_origin(expected_type) is Union and isinstance(get_args(expected_type)[0], ForwardRef):
+                expected_type = get_type_hints(self.__class__)[attribute]
+
             if not isinstance(value, expected_type):
                 try:
                     value = expected_type(value)