from __future__ import print_function

import boto3

import json

dynamo_ = boto3.resource('dynamodb')

def lambda_handler(event, context):

'''Provide an event that contains the following keys:

- operation: one of the operations in the operations dict below

- tableName: required for operations that interact with DynamoDB

- payload: a parameter to pass to the operation being performed

'''

#print("Received event: " + json.dumps(event, indent=2))

operation = event['operation']

if 'tableName' in event:

dynamo = dynamo_.Table(event['tableName'])

operations = {

'create': lambda x: dynamo.put_item(**x),

'read': lambda x: dynamo.get_item(**x),

'update': lambda x: dynamo.update_item(**x),

'delete': lambda x: dynamo.delete_item(**x),

'list': lambda x: dynamo.scan(**x),

'echo': lambda x: x,

'ping': lambda x: 'pong'

}

if operation in operations:

operations[operation](event.get('payload'))

else:

raise ValueError('Unrecognized operation "{}"'.format(operation))