Fix issue when getting the field type (#44)

* Fix issue when getting the field type

* Updated history log

* Updated version

Author: dfurtado

HISTORY.md

@@ -67,3 +67,11 @@
 * Added type hinting to external API
 * Documentation updates
 * Bug fixes
+
+## 1.3.0 (2021-04-10)
+
+* Included stub files
+* check if the CSV file has duplicated header values
+* Fixed issues #22 and #33
+* code cleanup
+

dataclass_csv/dataclass_reader.py

@@ -5,6 +5,8 @@
 from distutils.util import strtobool
 from typing import Union, Type, Optional, Sequence, Dict, Any, List
 
+import typing
+
 from .field_mapper import FieldMapper
 from .exceptions import CsvValueError
 
@@ -29,6 +31,20 @@ def _verify_duplicate_header_items(header):
         )
 
 
+def is_union_type(t):
+    if hasattr(t, "__origin__") and t.__origin__ is Union:
+        return True
+
+    return False
+
+
+def get_args(t):
+    if hasattr(t, "__args__"):
+        return t.__args__
+
+    return tuple()
+
+
 class DataclassReader:
     def __init__(
         self,
@@ -61,6 +77,8 @@ def __init__(
         if validate_header:
             _verify_duplicate_header_items(self._reader.fieldnames)
 
+        self.type_hints = typing.get_type_hints(cls)
+
     def _get_optional_fields(self):
         return [
             field.name
@@ -175,20 +193,12 @@ def _process_row(self, row):
                 values.append(None)
                 continue
 
-            field_type = field.type
-            # Special handling for Optional (Union of a single real type and None)
-            if (
-                # The first part of the condition is for Python < 3.8
-                type(field_type).__name__ == "_Union"
-                # The second part of the condition is for Python >= 3.8
-                or "__origin__" in field_type.__dict__
-                and field_type.__origin__ is Union
-            ):
-                real_types = [
-                    t for t in field_type.__args__ if t is not type(None)  # noqa: E721
-                ]
-                if len(real_types) == 1:
-                    field_type = real_types[0]
+            field_type = self.type_hints[field.name]
+
+            if is_union_type(field_type):
+                type_args = [x for x in get_args(field_type) if x is not type(None)]
+                if len(type_args) == 1:
+                    field_type = type_args[0]
 
             if field_type is datetime:
                 try:

setup.cfg

@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 1.2.0
+current_version = 1.3.0
 commit = True
 tag = True
 

setup.py

@@ -51,6 +51,6 @@
     test_suite="tests",
     tests_require=test_requirements,
     url="https://github.com/dfurtado/dataclass-csv",
-    version="1.2.0",
+    version="1.3.0",
     zip_safe=False,
 )