minor tweaks for datetime and gemini comments

Author: derrickaw

sdks/python/apache_beam/yaml/yaml_mapping.py

@@ -19,7 +19,6 @@
 
 import datetime
 import itertools
-import json
 import re
 import threading
 import uuid
@@ -225,8 +224,13 @@ def js_to_py(obj):
     return obj
   elif isinstance(obj, Mapping):
     return {k: js_to_py(v) for k, v in obj.items()}
-  elif not isinstance(obj, str) and isinstance(obj, Iterable):
+  elif not isinstance(obj, (str, bytes)) and isinstance(obj, Iterable):
     return [js_to_py(v) for v in obj]
+  elif isinstance(obj, str):
+    try:
+      return datetime.datetime.fromisoformat(obj)
+    except ValueError:
+      return obj
   else:
     return obj
 

sdks/python/apache_beam/yaml/yaml_udf_test.py

@@ -394,12 +394,10 @@ def test_map_to_fields_js_date(self):
               }
       ''')
 
-      expected_date = '2026-04-17T18:00:00.000Z'
+      expected_date = datetime.datetime(
+          2026, 4, 17, 18, tzinfo=datetime.timezone.utc)
 
-      assert_that(
-          result | as_rows(), equal_to([
-              beam.Row(date=expected_date),
-          ]))
+      assert_that(result | as_rows(), equal_to([beam.Row(date=expected_date)]))
 
 
 if __name__ == '__main__':