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feat: Add a flag to ALBResolver to URL-decode query parameters#7940

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leandrodamascena merged 5 commits intoaws-powertools:developfrom
chriselion:chriselion/decode-alb-params
Jan 19, 2026
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feat: Add a flag to ALBResolver to URL-decode query parameters#7940
leandrodamascena merged 5 commits intoaws-powertools:developfrom
chriselion:chriselion/decode-alb-params

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@chriselion chriselion commented Jan 11, 2026

Issue number: closes #7621

Summary

From https://docs.aws.amazon.com/elasticloadbalancing/latest/application/lambda-functions.html, for ALB requests

If the query parameters are URL-encoded, the load balancer does not decode them. You must decode them in your Lambda function

This adds a flag to ALBResolver to decode the query parameters before they are validated.

Changes

  • Add a decode_query_parameters flag to ALBResolver initializer.
  • Add a decode_query_parameters to ALBEvent. This defaults to false.
    • I thought about adding a **kwargs argument to the BaseProxyEvent initializers, but didn't love that.
  • Add ALBResolver._to_proxy_event (overrides the parent method). This calls the parent method, and sets a decode_query_parameters flag on the resulting ALBEvent.
  • Added functional test to ensure that an encoded datetime string could be passed to a route that accepts a datetime parameter, and a unit test for the ALBEvent decoding.

User experience

No change to the user experience - default behavior is the same, and users have to opt-in to get the new behavior.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

Disclaimer: We value your time and bandwidth. As such, any pull requests created on non-triaged issues might not be successful.

@chriselion chriselion requested a review from a team as a code owner January 11, 2026 04:18
@chriselion chriselion requested a review from sdangol January 11, 2026 04:18
@pull-request-size pull-request-size bot added the size/L Denotes a PR that changes 100-499 lines, ignoring generated files. label Jan 11, 2026
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boring-cyborg bot commented Jan 11, 2026

Thanks a lot for your first contribution! Please check out our contributing guidelines and don't hesitate to ask whatever you need.
In the meantime, check out the #python channel on our Powertools for AWS Lambda Discord: Invite link

chriselion
chriselion commented Jan 11, 2026
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chriselion
chriselion commented Jan 11, 2026
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@chriselion chriselion mentioned this pull request Jan 11, 2026
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codecov bot commented Jan 11, 2026 •
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Codecov Report

❌ Patch coverage is 95.23810% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 96.72%. Comparing base (c9afa5d) to head (919cb4e).
⚠️ Report is 1 commits behind head on develop.

Files with missing lines Patch % Lines
aws_lambda_powertools/event_handler/api_gateway.py 85.71% 0 Missing and 1 partial ⚠️
Additional details and impacted files 
@@             Coverage Diff             @@
##           develop    #7940      +/-   ##
===========================================
- Coverage    96.72%   96.72%   -0.01%     
===========================================
  Files          278      278              
  Lines        13607    13626      +19     
  Branches      1080     1083       +3     
===========================================
+ Hits         13162    13180      +18     
  Misses         327      327              
- Partials       118      119       +1

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@leandrodamascena
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leandrodamascena commented Jan 13, 2026

Hey @chriselion I'm attending some internal training and will review this PR later this week. Thanks a lot for working on this.

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sonarqubecloud bot commented Jan 19, 2026

Quality Gate Passed Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

leandrodamascena
leandrodamascena approved these changes Jan 19, 2026
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Hey @chriselion thanks a lot for working on this! APPROVED!!!

@leandrodamascena leandrodamascena merged commit 8761fe7 into aws-powertools:develop Jan 19, 2026
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boring-cyborg bot commented Jan 19, 2026

Awesome work, congrats on your first merged pull request and thank you for helping improve everyone's experience!

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@hjgraca hjgraca hjgraca approved these changes

@leandrodamascena leandrodamascena leandrodamascena approved these changes

@sdangol sdangol Awaiting requested review from sdangol sdangol is a code owner automatically assigned from aws-powertools/lambda-python-core

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Feature request: Add a flag to ALBResolver to URL-decode query parameters

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@chriselion @leandrodamascena @hjgraca