DDB Stream

from __future__ import unicode_literals
import sys
import logging
import os
import json
import decimal

log = logging.getLogger()
log.setLevel(logging.DEBUG)

sys.path.insert(0, './vendored')
import boto3

client = boto3.client('comprehend')

region = os.environ["AWS_REGION"]

dynamodb = boto3.resource('dynamodb', region_name=region)
table = dynamodb.Table('dynamo_serverless')


def remove_key(d, key):
    r = dict(d)
    del r[key]
    return r


def replace_decimals(obj):
    if isinstance(obj, list):
        for i in xrange(len(obj)):
            obj[i] = replace_decimals(obj[i])
        return obj
    elif isinstance(obj, dict):
        for k in obj.iterkeys():
            obj[k] = replace_decimals(obj[k])
        return obj
    elif isinstance(obj, float):
        return decimal.Decimal(obj)
    else:
        return obj


def update_to_dynamo(feedback_id, sentiment):
    response = table.update_item(
        Key={
            'feedback_id': feedback_id
        },
        UpdateExpression='set sentiment = :vall',
        ExpressionAttributeValues={
            ':vall': sentiment,
        }
    )
    return response, feedback_id


def handler(event, context):
    feedback_id = ""
    for record in event['Records']:
        if record['eventName'] == "INSERT":
            feedback_id = record['dynamodb']['NewImage']['feedback_id']['S']
    if feedback_id is not "":
        sentiment = client.detect_sentiment(
            Text=record['dynamodb']['NewImage']['session_comment']['S'],
            LanguageCode='en'
        )
        sent = replace_decimals(remove_key(sentiment, 'ResponseMetadata'))
        resp = update_to_dynamo(feedback_id, sent)
        return True
    else:
        return False