Nordstrom/dynamo-stream-diff

Provides diff of new and old images of dynamo stream record

Dynamo Stream Diff

Allows comparing of new and old images from dynamo stream records. Note, this only works on Dynamo Streams with a StreamViewType of NEW_AND_OLD_IMAGES

Installation

npm install dynamo-stream-diff --save

Usage

const dynamoStreamDiff = require('dynamo-stream-diff')

module.exports.handler = function(event, context, callback) {
  event.Records.forEach( (streamRecord) => {
    let diff = dynamoStreamDiff(streamRecord)
    // .... do something with the difference
  
  })
  callback(null, "Successfully handled all the differences")
}

Example Input & Output

Input

{
  "awsRegion": "us-west-2",
  "dynamodb": {
    "ApproximateCreationDateTime": 123456789,
    "Keys": {
      "id" : {
        "S": "abc"
      }
    },
    "NewImage": {
      "id" : {
        "S": "abc"
      },
      "name" : {
        "S": "new-name"
      },
      "size" : {
        "N": 456
      },
      "enabled" : {
        "BOOL": true
      }
    },
    "OldImage": {
      "id" : {
        "S": "abc"
      },
      "name" : {
        "S": "old-name"
      },
      "size" : {
        "N": 123
      },
      "enabled" : {
        "BOOL": false
      }
    },
    "SequenceNumber": "seq-num",
    "SizeBytes": 1245,
    "StreamViewType": "NEW_AND_OLD_IMAGES"
  },
  "eventID": "event-id",
  "eventName": "MODIFY",
  "eventSource": "event-source",
  "eventVersion": "event-version"
}

Output

{
  "diffMap": {
    "id": {
      "type": "unchanged",
      "oldVal": "abc",
      "newVal": "abc"
    },
    "name": {
      "type": "updated",
      "oldVal": "old-name",
      "newVal": "new-name"
    },
    "size": {
      "type": "updated",
      "oldVal": 123,
      "newVal": 456
    },
    "enabled": {
      "type": "updated",
      "oldVal": false,
      "newVal": true
    }
  },
  "diffList": [
    {
      "path": "name",
      "diff": "updated",
      "oldVal": "old-name",
      "newVal": "new-name"
    },
    {
      "path": "size",
      "diff": "updated",
      "oldVal": 123,
      "newVal": 456
    },
    {
      "path": "enabled",
      "diff": "updated",
      "oldVal": false,
      "newVal": true
    }
  ]
}