address more gemini comments

Author: derrickaw

sdks/python/apache_beam/yaml/yaml_mapping.py

@@ -16,6 +16,8 @@
 #
 
 """This module defines the basic MapToFields operation."""
+import datetime
+from decimal import Decimal
 import itertools
 import json
 import re
@@ -219,6 +221,12 @@ def py_value_to_js_dict(py_value):
     py_value = py_value._asdict()
   if isinstance(py_value, dict):
     return {key: py_value_to_js_dict(value) for key, value in py_value.items()}
+  elif isinstance(py_value, bytes):
+    return py_value.decode('utf-8', errors='replace')
+  elif isinstance(py_value, (datetime.datetime, datetime.date, datetime.time)):
+    return py_value.isoformat()
+  elif isinstance(py_value, Decimal):
+    return float(py_value)
   elif not isinstance(py_value, str) and isinstance(py_value, abc.Iterable):
     return [py_value_to_js_dict(value) for value in list(py_value)]
   else:
@@ -237,8 +245,8 @@ def _expand_javascript_mapping_func(
 
   if expression:
     unpacking_code = '\n'.join([
-        f'  var {name} = __row__.{name};' for name in original_fields
-        if name in expression
+        f"  var {name} = __row__['{name}'];" for name in original_fields
+        if name in expression and name.isidentifier()
     ])
     source_code = f"""
     const udf = function(__row__) {{

sdks/python/apache_beam/yaml/yaml_udf_test.py

@@ -14,6 +14,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
+import datetime
+from decimal import Decimal
 import logging
 import os
 import shutil
@@ -374,6 +376,40 @@ def g(x):
                   row=beam.Row(rank=2, values=[7, 8, 9])),
           ]))
 
+  @unittest.skipIf(quickjs is None, 'quickjs-ng not installed.')
+  def test_map_to_fields_js_non_serializable_types(self):
+    with beam.Pipeline(options=beam.options.pipeline_options.PipelineOptions(
+        pickle_library='cloudpickle', yaml_experimental_features=['javascript'
+                                                                  ])) as p:
+      data = [
+          beam.Row(
+              b=b'hello',
+              dt=datetime.datetime(2026, 5, 14, 12, 0, 0),
+              dec=Decimal('10.5'))
+      ]
+      elements = p | beam.Create(data)
+      result = elements | YamlTransform(
+          '''
+      type: MapToFields
+      config:
+        language: javascript
+        fields:
+          b_out:
+            expression: "b + '_world'"
+          dt_out:
+            expression: "dt"
+          dec_out:
+            expression: "dec * 2"
+      ''')
+      assert_that(
+          result,
+          equal_to([
+              beam.Row(
+                  b_out='hello_world',
+                  dt_out='2026-05-14T12:00:00',
+                  dec_out=21.0),
+          ]))
+
 
 if __name__ == '__main__':
   logging.getLogger().setLevel(logging.INFO)