S3 key normalizer middleware for the middy framework

Usage no npm install needed!

<script type="module">
  import middyS3KeyNormalizer from 'https://cdn.skypack.dev/@middy/s3-key-normalizer';


Middy s3-key-normalizer middleware

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S3 key normalizer middleware for the middy framework, the stylish Node.js middleware engine for AWS Lambda

Normalizes key names in s3 events.

S3 events like S3 PUT and S3 DELETE will contain in the event a list of the files that were affected by the change.

In this list the file keys are encoded in a very peculiar way (urlencoded and space characters replaced by a +). Very often you will use the key directly to perform operations on the file using the AWS S3 SDK, in which case it's very easy to forget to decode the key correctly.

This middleware, once attached, makes sure that every S3 event has the file keys properly normalized.


To install this middleware you can use NPM:

npm install --save @middy/s3-key-normalizer


This middleware does not have any option

Sample usage

import middy from '@middy/core'
import s3KeyNormalizer from '@middy/s3-key-normalizer'

const handler = middy((event, context) => {
  // use the event key directly without decoding it

  // return all the keys
  return event.Records.map(record => record.s3.object.key)


Middy documentation and examples

For more documentation and examples, refers to the main Middy monorepo on GitHub or Middy official website.


Everyone is very welcome to contribute to this repository. Feel free to raise issues or to submit Pull Requests.


Licensed under MIT License. Copyright (c) 2017-2021 Luciano Mammino, will Farrell, and the Middy team.

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