Bug: QueryString Parameters are not coming thru

[94Sip]

Expected Behaviour

I expect to be able to route to the appropriate method and the handling of querystrings to be available to me, depending on how I choose to do Validation, or not.

Current Behaviour

I've tried multiple ways to parse and handle querystring parameters, and neither is working.
The path of /rut/calendar will work (route), regardless of the below methods.
The path of /rut/calendar?yr=2023&mo=11 always fails and gets handled by the not found exception handler, regardless of the below methods

In the code snippet are the 2 separate ways I have tried.

Code snippet

app = APIGatewayRestResolver(cors=cors_config, enable_validation=False)

@app.get("/rut/calendar")
@tracer.capture_method
def get_rut_calendar():
   """Get rut calendar for specific year/month"""
   logger.info("Rut calendar requested")

#---------------------------- using Validation --------------------------------
app = APIGatewayRestResolver(cors=cors_config, enable_validation=True)

@app.get("/rut/calendar")
@tracer.capture_method
def get_rut_calendar(yr: Optional[int] = None, mo: Optional[int] = None):
   """Get rut calendar for specific year/month"""
   logger.info("Rut calendar requested")

Possible Solution

Obviously I think there is a bug with EnableValidation, but the documentation seems to be lacking clarity between the Validation of QueryStrings and the subsequent section on handling querystrings.

Steps to Reproduce

Call the 2 methods with the path I have provided, one with querystrings, and one without

Powertools for AWS Lambda (Python) version

latest

AWS Lambda function runtime

3.12

Packaging format used

Lambda Layers

Debugging logs

Here is the result from CloudWatch:
{
"level": "INFO",
"location": "handle_not_found_errors:333",
"message": "Not found route: /rut/calendar?yr=2023&mo=11",
"timestamp": "2025-06-30 13:02:48,993+0000",
"service": "rut-predictor-api",
"cold_start": true,
"function_name": "TexasRutPredictorProxy",
"function_memory_size": "1024",
"function_arn": "arn:aws:lambda:us-east-2:206693260617:function:TexasRutPredictorProxy",
"function_request_id": "7fcbddf5-f9bb-4d46-9f0b-ad2ef64260e8",
"xray_trace_id": "1-68628adf-01b87d1d2fef9f6b73865206"
}

[leandrodamascena]

Hey @94Sip thanks for opening this issue. I think this is what you're looking for: https://docs.powertools.aws.dev/lambda/python/latest/core/event_handler/api_gateway/#validating-query-strings.

You need to annotate the type with Annotated and Query model and then we can inject the querystring parameters into your function.

Pls let me know if this works.

[94Sip]

Hi, thank you for the reply.

Yes, I haven't tried that, because I was trying to do this: skipping validation

Which is what I was thinking would be "easier". But as I was showing in my bug filing, doesn't work, at least according to what I am seeing.

Also, if I set enable_validation=False, shouldn't I still be able to do this? enable_validation=False

[94Sip]

So I did what you

Hey @94Sip thanks for opening this issue. I think this is what you're looking for: https://docs.powertools.aws.dev/lambda/python/latest/core/event_handler/api_gateway/#validating-query-strings.

You need to annotate the type with Annotated and Query model and then we can inject the querystring parameters into your function.

Pls let me know if this works.

So I adjusted my code as follows, and I'm still getting the same error. Also, did you perhaps see my questions above?

When I call my function as /rut/calendar?yr=2023&mo=11 it always goes to the not found handler. If I leave off the query string, then it works.

I have also tested this with enable_validation=False and it still goes to the not found handler.

`

import json
import os
import boto3
from datetime import datetime, timedelta
from typing import Optional, Dict, List
from aws_lambda_powertools import Logger, Tracer, Metrics
from aws_lambda_powertools.event_handler import APIGatewayRestResolver, CORSConfig,Response, content_types
from aws_lambda_powertools.logging import correlation_paths
from aws_lambda_powertools.metrics import MetricUnit
from aws_lambda_powertools.utilities.typing import LambdaContext
from aws_lambda_powertools.utilities.parameters import get_app_config
from aws_lambda_powertools.event_handler.openapi.exceptions import RequestValidationError
from aws_lambda_powertools.event_handler.exceptions import NotFoundError
from aws_lambda_powertools.event_handler.openapi.params import Query
from rut_predictor import APITexasRutPredictor
from typing_extensions import Annotated

logger = Logger()
tracer = Tracer()
metrics = Metrics()

cors_config = CORSConfig(allow_origin="*")
app = APIGatewayRestResolver(cors=cors_config, enable_validation=True)

@app.get("/rut/calendar")
@tracer.capture_method
def get_rut_calendar(yr: Annotated[Optional[int], Query] = None, mo: Annotated[ Optional[int], Query] = None):
#this function is never called

@app.not_found
@tracer.capture_method
def handle_not_found_errors(exc: NotFoundError) -> Response:
logger.info(f"Not found route: {app.current_event.path}")
return Response(
status_code=418,
content_type=content_types.TEXT_PLAIN,
body="These are not the droids you're looking for."
)
`

[leandrodamascena]

Hey @94Sip thanks for providing more feedback. Lets break down your questions just to make sure we are not missing anything:

I expect to be able to route to the appropriate method and the handling of querystrings to be available to me, depending on how I choose to do Validation, or not.

The problem here is that since we rely on Pydantic to inject querystring/body and other fields into routes, we can only enable this when enable_validation is set, so the customer must bring Pydantic. We know that some customers don't need this, and forcing Pydantic in all situations may lead to them increase the Lambda bundle size for no reason.

One thing that we need to implementing is supporting injecting querystring parameter with Pydantic models, so, this can easy a lot the experience. I'll find some time to implement this.

So I adjusted my code as follows, and I'm still getting the same error. Also, did you perhaps see my questions above?

Can you please provide more information about your APIGW configuration? Are you using {proxy+} or specific routes? I'm super curious why this code is working in my environment (AWS and local machine) and not working in yours. I'm using a simpler version of your code:

from typing import Optional
from aws_lambda_powertools import Logger, Tracer, Metrics
from aws_lambda_powertools.event_handler import APIGatewayRestResolver, CORSConfig,Response, content_types
from aws_lambda_powertools.event_handler.exceptions import NotFoundError
from aws_lambda_powertools.event_handler.openapi.params import Query
from typing_extensions import Annotated

logger = Logger()
tracer = Tracer()
metrics = Metrics()

cors_config = CORSConfig(allow_origin="*")
app = APIGatewayRestResolver(cors=cors_config, enable_validation=True)


@app.get("/rut/calendar")
@tracer.capture_method
def get_rut_calendar(yr: Annotated[Optional[int], Query] = None, mo: Annotated[ Optional[int], Query] = None):
    return {"message": f"hello world {yr}{mo}"}

@app.not_found
@tracer.capture_method
def handle_not_found_errors(exc: NotFoundError) -> Response:
    logger.info(f"Not found route: {app.current_event.path}")
    return Response(
    status_code=418,
    content_type=content_types.TEXT_PLAIN,
    body="These are not the droids you're looking for."
)

def lambda_handler(event, context):
    return app.resolve(event, context)

➜ requests-python curl http://127.0.0.1:3000/rut/calendar\?yr\=2023\&mo\=11
{"message":"hello world 202311"}%

Invoking app.lambda_handler (python3.13)                                                                                                                                                                  
Requested to skip pulling images ...                                                                                                                                                                      
                                                                                                                                                                                                          
Mounting /private/tmp/querystring-problem/.aws-sam/build/HelloWorldFunction as /var/task:ro,delegated, inside runtime container                                                                           
START RequestId: 14443dee-58e2-436c-bedb-c08892117987 Version: $LATEST
END RequestId: 85de0735-29ce-4ca0-9c00-a91332a2864f
REPORT RequestId: 85de0735-29ce-4ca0-9c00-a91332a2864f	Init Duration: 0.42 ms	Duration: 653.05 ms	Billed Duration: 654 ms	Memory Size: 128 MB	Max Memory Used: 128 MB	

2025-07-03 11:01:35 127.0.0.1 - - [03/Jul/2025 11:01:35] "GET /rut/calendar?yr=2023&mo=11 HTTP/1.1" 200 -