fix(idempotency): resolve tech debt issues with falsy responses and Redis persistency

aws_lambda_powertools/utilities/idempotency/base.py

@@ -167,7 +167,7 @@ def _process_idempotency(self, is_replay: bool):
             # We give preference to ReturnValuesOnConditionCheckFailure because it is a faster and more cost-effective
             # way of retrieving the existing record after a failed conditional write operation.
             record = exc.old_data_record or self._get_idempotency_record()
-            if is_replay and record is not None and record.status == "INPROGRESS":
+            if is_replay and record is not None and record.status == STATUS_CONSTANTS["INPROGRESS"]:
                 return self._get_function_response()
             # If a record is found, handle it for status
             if record:
@@ -296,7 +296,7 @@ def _get_function_response(self):
 
         else:
             try:
-                serialized_response: dict = self.output_serializer.to_dict(response) if response else None
+                serialized_response: dict = self.output_serializer.to_dict(response) if response is not None else None
                 self.persistence_store.save_success(data=self.data, result=serialized_response)
             except Exception as save_exception:
                 raise IdempotencyPersistenceLayerError(

aws_lambda_powertools/utilities/idempotency/persistence/redis.py

@@ -332,8 +332,8 @@ def _item_to_data_record(self, idempotency_key: str, item: dict[str, Any]) -> Da
             idempotency_key=idempotency_key,
             status=item[self.status_attr],
             in_progress_expiry_timestamp=in_progress_expiry_timestamp,
-            response_data=str(item.get(self.data_attr)),
-            payload_hash=str(item.get(self.validation_key_attr)),
+            response_data=item.get(self.data_attr, ""),
+            payload_hash=item.get(self.validation_key_attr, ""),
             expiry_timestamp=item.get("expiration"),
         )
 

tests/functional/idempotency/_redis/test_redis_layer.py

@@ -330,6 +330,25 @@ def test_item_to_datarecord_conversion(valid_record):
     assert record.in_progress_expiry_timestamp == item[layer.in_progress_expiry_attr]
 
 
+def test_item_to_datarecord_conversion_missing_optional_attributes(persistence_store_standalone_redis):
+    """
+    When data_attr or validation_key_attr is missing from Redis,
+    response_data and payload_hash should be empty string, not the string "None".
+    Regression test for: https://github.com/aws-powertools/powertools-lambda-python/issues/8090
+    """
+    idempotency_key = "test-func#abc123"
+    item = {
+        persistence_store_standalone_redis.status_attr: "COMPLETED",
+        persistence_store_standalone_redis.expiry_attr: 9999999999,
+        # data_attr and validation_key_attr intentionally absent
+    }
+
+    record = persistence_store_standalone_redis._item_to_data_record(idempotency_key, item)
+
+    assert record.response_data == ""
+    assert record.payload_hash == ""
+
+
 def test_idempotent_function_and_lambda_handler_redis_basic(
     persistence_store_standalone_redis: RedisCachePersistenceLayer,
     lambda_context,