feat(event-source): add function to get multi-value query string params by name (#3846)

Co-authored-by: Heitor Lessa <lessa@amazon.nl>
Co-authored-by: heitorlessa <lessa@amazon.co.uk>

Author: TonySherman

aws_lambda_powertools/utilities/data_classes/alb_event.py

@@ -32,8 +32,8 @@ def request_context(self) -> ALBEventRequestContext:
         return ALBEventRequestContext(self._data)
 
     @property
-    def multi_value_query_string_parameters(self) -> Optional[Dict[str, List[str]]]:
-        return self.get("multiValueQueryStringParameters")
+    def multi_value_query_string_parameters(self) -> Dict[str, List[str]]:
+        return self.get("multiValueQueryStringParameters") or {}
 
     @property
     def resolved_query_string_parameters(self) -> Dict[str, List[str]]:

aws_lambda_powertools/utilities/data_classes/common.py

@@ -7,6 +7,7 @@
 from aws_lambda_powertools.shared.headers_serializer import BaseHeadersSerializer
 from aws_lambda_powertools.utilities.data_classes.shared_functions import (
     get_header_value,
+    get_multi_value_query_string_values,
     get_query_string_value,
 )
 
@@ -103,6 +104,10 @@ def headers(self) -> Dict[str, str]:
     def query_string_parameters(self) -> Optional[Dict[str, str]]:
         return self.get("queryStringParameters")
 
+    @property
+    def multi_value_query_string_parameters(self) -> Dict[str, List[str]]:
+        return self.get("multiValueQueryStringParameters") or {}
+
     @property
     def resolved_query_string_parameters(self) -> Dict[str, List[str]]:
         """
@@ -184,6 +189,31 @@ def get_query_string_value(self, name: str, default_value: Optional[str] = None)
             default_value=default_value,
         )
 
+    def get_multi_value_query_string_values(
+        self,
+        name: str,
+        default_values: Optional[List[str]] = None,
+    ) ->List[str]:
+        """Get multi-value query string parameter values by name
+
+        Parameters
+        ----------
+        name: str
+            Multi-Value query string parameter name
+        default_values: List[str], optional
+            Default values is no values are found by name
+        Returns
+        -------
+        List[str], optional
+            List of query string values
+
+        """
+        return get_multi_value_query_string_values(
+            multi_value_query_string_parameters=self.multi_value_query_string_parameters,
+            name=name,
+            default_values=default_values,
+        )
+
     @overload
     def get_header_value(
         self,

aws_lambda_powertools/utilities/data_classes/shared_functions.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import base64
-from typing import Any
+from typing import Any, Dict
 
 
 def base64_decode(value: str) -> str:
@@ -63,7 +63,7 @@ def get_header_value(
 
 
 def get_query_string_value(
-    query_string_parameters: dict[str, str] | None,
+    query_string_parameters: Dict[str, str] | None,
     name: str,
     default_value: str | None = None,
 ) -> str | None:
@@ -84,3 +84,30 @@ def get_query_string_value(
     """
     params = query_string_parameters
     return default_value if params is None else params.get(name, default_value)
+
+
+def get_multi_value_query_string_values(
+    multi_value_query_string_parameters: Dict[str, list[str]] | None,
+    name: str,
+    default_values: list[str] | None = None,
+) -> list[str]:
+    """
+    Retrieves the values of a multi-value string parameters specified by the given name.
+
+    Parameters
+    ----------
+    name: str
+        The name of the query string parameter to retrieve.
+    default_value: list[str], optional
+        The default value to return if the parameter is not found. Defaults to None.
+
+    Returns
+    -------
+    List[str]. optional
+        The values of the query string parameter if found, or the default values if not found.
+    """
+
+    default = default_values or []
+    params = multi_value_query_string_parameters or {}
+
+    return params.get(name) or default

examples/event_handler_rest/src/accessing_request_details.py

@@ -1,4 +1,4 @@
-from typing import Optional
+from typing import List, Optional
 
 import requests
 from requests import Response
@@ -20,6 +20,9 @@ def get_todos():
     # alternatively
     _: Optional[str] = app.current_event.query_string_parameters.get("id")
 
+    # or multi-value query string parameters; ?category="red"&?category="blue"
+    _: List[str] = app.current_event.get_multi_value_query_string_values(name="category")
+
     # Payload
     _: Optional[str] = app.current_event.body  # raw str | None
 

tests/unit/data_classes/test_alb_event.py

@@ -11,7 +11,9 @@ def test_alb_event():
     assert parsed_event.path == raw_event["path"]
     assert parsed_event.query_string_parameters == raw_event["queryStringParameters"]
     assert parsed_event.headers == raw_event["headers"]
-    assert parsed_event.multi_value_query_string_parameters == raw_event.get("multiValueQueryStringParameters")
+
+    assert parsed_event.multi_value_query_string_parameters == raw_event.get("multiValueQueryStringParameters", {})
+
     assert parsed_event.multi_value_headers == raw_event.get("multiValueHeaders")
     assert parsed_event.body == raw_event["body"]
     assert parsed_event.is_base64_encoded == raw_event["isBase64Encoded"]

tests/unit/test_data_classes.py

@@ -259,6 +259,25 @@ def test_base_proxy_event_get_query_string_value():
     assert value is None
 
 
+def test_base_proxy_event_get_multi_value_query_string_values():
+    default_values = ["default_1", "default_2"]
+    set_values = ["value_1", "value_2"]
+
+    event = BaseProxyEvent({})
+    values = event.get_multi_value_query_string_values("test", default_values)
+    assert values == default_values
+
+    event._data["multiValueQueryStringParameters"] = {"test": set_values}
+    values = event.get_multi_value_query_string_values("test", default_values)
+    assert values == set_values
+
+    values = event.get_multi_value_query_string_values("unknown", default_values)
+    assert values == default_values
+
+    values = event.get_multi_value_query_string_values("unknown")
+    assert values == []
+
+
 def test_base_proxy_event_get_header_value():
     default_value = "default"
     set_value = "value"