event-normalizer

Middleware for iterating through an AWS event records, parsing and normalizing nested events.

AWS Events Transformations: https://docs.aws.amazon.com/lambda/latest/dg/lambda-services.html

Event Source	Included	Comments
Alexa	No	Normalization not required
API Gateway (HTTP)	No *	See middleware prefixed with @middy/http-
API Gateway (REST)	No *	See middleware prefixed with @middy/http-
API Gateway (WS)	No *	See middleware @middy/ws-json-body-parser
Application LB	No *	See middleware prefixed with @middy/http-
CloudFormation	No	Normalization not required
CloudFront	No	Normalization not required
CloudTrail	No	Normalization not required
CloudWatch Alarm	No	Normalization not required
CloudWatch Logs	Yes	Base64 decode and JSON parse data
CodeCommit	No	Normalization not required
CodePipeline	Yes	JSON parse UserParameters
Cognito	No	Normalization not required
Config	Yes	JSON parse invokingEvent and ruleParameters
Connect	No	Normalization not required
DocumentDB	No	Normalization not required
DynamoDB	Yes	Unmarshall Keys, OldImage, and NewImage
EC2	No	Normalization not required
EventBridge	No	Normalization not required
IoT	No	Normalization not required
IoT Event	No	Normalization not required
Kafka	Yes	Base64 decode and JSON parse value
Kafka (MSK)	Yes	Base64 decode and JSON parse value
Kinesis Firehose	Yes	Base64 decode and JSON parse data
Kinesis Stream	Yes	Base64 decode and JSON parse data
Lex	No	Normalization not required
MQ	Yes	Base64 decode and JSON parse data
RDS	No	Normalization not required
S3	Yes	URI decode key
S3 Batch	Yes	URI decode s3Key
S3 Object Lambda	No *	See middleware @middy/s3-object-response
Secrets Manager	No	Normalization not required
SES	No	Normalization not required
SNS	Yes	JSON parse Message
SQS	Yes	JSON parse body
VPC Lattice	No *	See middleware prefixed with @middy/http-

* Handled in another dedicated middleware(s)

Test Events Some events send test events after set, you will need to handle these.

// S3 Test Event
{
  Service: 'Amazon S3',
  Event: 's3:TestEvent',
  Time: '2020-01-01T00:00:00.000Z',
  Bucket: 'bucket-name',
  RequestId: '***********',
  HostId: '***/***/***='
}

Install

To install this middleware you can use NPM:

npm

npm install --save @middy/event-normalizer

Yarn

yarn add @middy/event-normalizer

pnpm

pnpm add @middy/event-normalizer

Options

• wrapNumbers (boolean) (default undefined): Whether to return numbers as a string instead of converting them to native JavaScript numbers. This allows for the safe round-trip transport of numbers of arbitrary size. For DynamoDB Events only.

Sample usage

import middy from '@middy/core'
import eventNormalizer from '@middy/event-normalizer'

const lambdaHandler = (event, context) => {
  const { Records } = event
  for (const record of Records) {
    // ...
  }
}

export const handler = middy().use(eventNormalizer()).handler(lambdaHandler)