DynamoDB Stream - Lambda 处理公式

Question

I've got a DynamoDB Table that contains attributes similar to:

{
 "pk": "pk1",
 "values": {
  "v2": 5,
  "v1": 90
 },
 "formula": "(v1 + v2) / 100",
 "calc": 5.56
}

I've a Lambda that is triggered by DDB Stream. Is there any way to calculate the "calc" attribute based on the formula and values? Ideally I'd like to do it during update_item call which is updating this table every time Stream sends a message.

Answer 1

Your lambda function can trigger an event like this

def lambda_handler(event, context):
    records = event['Records']
    for record in records:
       new_record = record['dynamodb']['NewImage']
       calc = new_record.get('calc')
       # do your stuff here
       calc = some_functions()
    return event