fix: reduce complexity of dynamo envelope

Author: Ran Isenberg

aws_lambda_powertools/utilities/advanced_parser/envelopes/base.py

@@ -9,6 +9,8 @@
 
 class BaseEnvelope(ABC):
     def _parse_user_dict_schema(self, user_event: Dict[str, Any], schema: BaseModel) -> Any:
+        if user_event is None:
+            return None
         logger.debug("parsing user dictionary schema")
         try:
             return schema(**user_event)
@@ -17,6 +19,8 @@ def _parse_user_dict_schema(self, user_event: Dict[str, Any], schema: BaseModel)
             raise
 
     def _parse_user_json_string_schema(self, user_event: str, schema: BaseModel) -> Any:
+        if user_event is None:
+            return None
         logger.debug("parsing user dictionary schema")
         if schema == str:
             logger.debug("input is string, returning")

aws_lambda_powertools/utilities/advanced_parser/envelopes/dynamodb.py

@@ -18,11 +18,10 @@ def parse(self, event: Dict[str, Any], schema: BaseModel) -> Any:
             raise
         output = []
         for record in parsed_envelope.Records:
-            parsed_new_image = (
-                None if not record.dynamodb.NewImage else self._parse_user_dict_schema(record.dynamodb.NewImage, schema)
-            )  # noqa: E501
-            parsed_old_image = (
-                None if not record.dynamodb.OldImage else self._parse_user_dict_schema(record.dynamodb.OldImage, schema)
-            )  # noqa: E501
-            output.append({"NewImage": parsed_new_image, "OldImage": parsed_old_image})
+            output.append(
+                {
+                    "NewImage": self._parse_user_dict_schema(record.dynamodb.NewImage, schema),
+                    "OldImage": self._parse_user_dict_schema(record.dynamodb.OldImage, schema),
+                }
+            )
         return output

aws_lambda_powertools/utilities/advanced_parser/schemas/dynamodb.py

@@ -2,7 +2,6 @@
 from typing import Any, Dict, List, Optional
 
 from pydantic import BaseModel, root_validator
-
 from typing_extensions import Literal
 
 

aws_lambda_powertools/utilities/advanced_parser/schemas/sqs.py

@@ -3,7 +3,6 @@
 from typing import Dict, List, Optional
 
 from pydantic import BaseModel, root_validator, validator
-
 from typing_extensions import Literal
 
 

tests/functional/parser/schemas.py

@@ -1,6 +1,7 @@
 from typing import Dict, List, Optional
 
 from pydantic import BaseModel
+from typing_extensions import Literal
 
 from aws_lambda_powertools.utilities.advanced_parser.schemas import (
     DynamoDBSchema,
@@ -10,7 +11,6 @@
     SqsRecordSchema,
     SqsSchema,
 )
-from typing_extensions import Literal
 
 
 class MyDynamoBusiness(BaseModel):