fix(event-handler): handle single parameters correctly

Author: rubenfonseca

aws_lambda_powertools/event_handler/middlewares/openapi_validation.py

@@ -368,7 +368,10 @@ def _get_embed_body(
     return received_body, field_alias_omitted
 
 
-def _normalize_multi_query_string_with_param(query_string: Optional[Dict[str, str]], params: Sequence[ModelField]):
+def _normalize_multi_query_string_with_param(
+    query_string: Optional[Dict[str, List[str]]],
+    params: Sequence[ModelField],
+):
     """
     Extract and normalize resolved_query_string_parameters
 
@@ -383,15 +386,18 @@ def _normalize_multi_query_string_with_param(query_string: Optional[Dict[str, st
     -------
     A dictionary containing the processed multi_query_string_parameters.
     """
-    if query_string:
+    if not query_string:
+        return None
+    else:
+        resolved_query_string: Dict[str, Any] = query_string
         for param in filter(is_scalar_field, params):
             try:
                 # if the target parameter is a scalar, we keep the first value of the query string
                 # regardless if there are more in the payload
-                query_string[param.alias] = query_string[param.alias][0]
+                resolved_query_string[param.alias] = query_string[param.alias][0]
             except KeyError:
                 pass
-    return query_string
+        return resolved_query_string
 
 
 def _normalize_multi_header_values_with_param(headers: Optional[Dict[str, str]], params: Sequence[ModelField]):

aws_lambda_powertools/utilities/data_classes/alb_event.py

@@ -36,11 +36,15 @@ def multi_value_query_string_parameters(self) -> Optional[Dict[str, List[str]]]:
         return self.get("multiValueQueryStringParameters")
 
     @property
-    def resolved_query_string_parameters(self) -> Optional[Dict[str, Any]]:
+    def resolved_query_string_parameters(self) -> Optional[Dict[str, List[str]]]:
         if self.multi_value_query_string_parameters:
             return self.multi_value_query_string_parameters
 
-        return self.query_string_parameters
+        if self.query_string_parameters:
+            query_string = {key: value.split(",") for key, value in self.query_string_parameters.items()}
+            return query_string
+
+        return None
 
     @property
     def resolved_headers_field(self) -> Optional[Dict[str, Any]]:

aws_lambda_powertools/utilities/data_classes/api_gateway_proxy_event.py

@@ -119,11 +119,15 @@ def multi_value_query_string_parameters(self) -> Optional[Dict[str, List[str]]]:
         return self.get("multiValueQueryStringParameters")
 
     @property
-    def resolved_query_string_parameters(self) -> Optional[Dict[str, Any]]:
+    def resolved_query_string_parameters(self) -> Optional[Dict[str, List[str]]]:
         if self.multi_value_query_string_parameters:
             return self.multi_value_query_string_parameters
 
-        return self.query_string_parameters
+        if self.query_string_parameters:
+            query_string = {key: value.split(",") for key, value in self.query_string_parameters.items()}
+            return query_string
+
+        return None
 
     @property
     def resolved_headers_field(self) -> Optional[Dict[str, Any]]:
@@ -319,14 +323,12 @@ def header_serializer(self):
         return HttpApiHeadersSerializer()
 
     @property
-    def resolved_query_string_parameters(self) -> Optional[Dict[str, Any]]:
+    def resolved_query_string_parameters(self) -> Optional[Dict[str, List[str]]]:
         if self.query_string_parameters is not None:
-            query_string = {
-                key: value.split(",") if "," in value else value for key, value in self.query_string_parameters.items()
-            }
+            query_string = {key: value.split(",") for key, value in self.query_string_parameters.items()}
             return query_string
 
-        return {}
+        return None
 
     @property
     def resolved_headers_field(self) -> Optional[Dict[str, Any]]:

aws_lambda_powertools/utilities/data_classes/bedrock_agent_event.py

@@ -110,8 +110,12 @@ def query_string_parameters(self) -> Optional[Dict[str, str]]:
         return {x["name"]: x["value"] for x in self["parameters"]} if self.get("parameters") else None
 
     @property
-    def resolved_query_string_parameters(self) -> Optional[Dict[str, str]]:
-        return self.query_string_parameters
+    def resolved_query_string_parameters(self) -> Optional[Dict[str, List[str]]]:
+        if self.query_string_parameters is not None:
+            query_string = {key: value.split(",") for key, value in self.query_string_parameters.items()}
+            return query_string
+
+        return None
 
     @property
     def resolved_headers_field(self) -> Optional[Dict[str, Any]]:

aws_lambda_powertools/utilities/data_classes/common.py

@@ -104,15 +104,19 @@ def query_string_parameters(self) -> Optional[Dict[str, str]]:
         return self.get("queryStringParameters")
 
     @property
-    def resolved_query_string_parameters(self) -> Optional[Dict[str, str]]:
+    def resolved_query_string_parameters(self) -> Optional[Dict[str, List[str]]]:
         """
         This property determines the appropriate query string parameter to be used
         as a trusted source for validating OpenAPI.
 
         This is necessary because different resolvers use different formats to encode
         multi query string parameters.
         """
-        return self.query_string_parameters
+        if self.query_string_parameters is not None:
+            query_string = {key: value.split(",") for key, value in self.query_string_parameters.items()}
+            return query_string
+
+        return None
 
     @property
     def resolved_headers_field(self) -> Optional[Dict[str, Any]]:
@@ -186,17 +190,15 @@ def get_header_value(
         name: str,
         default_value: str,
         case_sensitive: Optional[bool] = False,
-    ) -> str:
-        ...
+    ) -> str: ...
 
     @overload
     def get_header_value(
         self,
         name: str,
         default_value: Optional[str] = None,
         case_sensitive: Optional[bool] = False,
-    ) -> Optional[str]:
-        ...
+    ) -> Optional[str]: ...
 
     def get_header_value(
         self,

aws_lambda_powertools/utilities/data_classes/vpc_lattice.py

@@ -1,5 +1,5 @@
 from functools import cached_property
-from typing import Any, Dict, Optional, overload
+from typing import Any, Dict, List, Optional, overload
 
 from aws_lambda_powertools.shared.headers_serializer import (
     BaseHeadersSerializer,
@@ -73,17 +73,15 @@ def get_header_value(
         name: str,
         default_value: str,
         case_sensitive: Optional[bool] = False,
-    ) -> str:
-        ...
+    ) -> str: ...
 
     @overload
     def get_header_value(
         self,
         name: str,
         default_value: Optional[str] = None,
         case_sensitive: Optional[bool] = False,
-    ) -> Optional[str]:
-        ...
+    ) -> Optional[str]: ...
 
     def get_header_value(
         self,
@@ -141,8 +139,11 @@ def query_string_parameters(self) -> Dict[str, str]:
         return self["query_string_parameters"]
 
     @property
-    def resolved_query_string_parameters(self) -> Optional[Dict[str, str]]:
-        return self.query_string_parameters
+    def resolved_query_string_parameters(self) -> Optional[Dict[str, List[str]]]:
+        if self.query_string_parameters is not None:
+            query_string = {key: value.split(",") for key, value in self.query_string_parameters.items()}
+            return query_string
+        return None
 
     @property
     def resolved_headers_field(self) -> Optional[Dict[str, Any]]:
@@ -264,8 +265,14 @@ def query_string_parameters(self) -> Optional[Dict[str, str]]:
         return self.get("queryStringParameters")
 
     @property
-    def resolved_query_string_parameters(self) -> Optional[Dict[str, str]]:
-        return self.query_string_parameters
+    def resolved_query_string_parameters(self) -> Optional[Dict[str, List[str]]]:
+        if self.query_string_parameters is not None:
+            query_string = {
+                key: value.split(",") if not isinstance(value, list) else value
+                for key, value in self.query_string_parameters.items()
+            }
+            return query_string
+        return None
 
     @property
     def resolved_headers_field(self) -> Optional[Dict[str, str]]: