Amazon Lex fulfillment function - Lambda handler (Python)

lex.py

from lex_utils import elicit_slot, delegate, close, ElicitAction, DelegateAction
from utils import validate_dialog, init_or_load_session, finalize_session, actually_book_the_hotel

def lambda_handler(event, context):

    intent_name = event['currentIntent']['name']

    if intent_name == 'BookHotel':
        return book_hotel(event)
    # elif (add more intents here)
    else:
        raise Exception('Intent with name %s not supported' % intent_name)


def book_hotel(event):

    session_attributes = init_or_load_session(event)

    slots = event['currentIntent']['slots']
    name = event['currentIntent']['name']

    try:
        if event['invocationSource'] == 'DialogCodeHook':
            validate_dialog(slots, session_attributes)
    except ElicitAction as ea:
        # request a new value
        return elicit_slot(
            session_attributes,
            name,
            slots,
            ea.invalid_slot,  # elicit this invalid slot
            ea.message,       # with this custom message
        )
    except DelegateAction as da:
        # tell Lex to move on with the next slot
        return delegate(session_attributes, slots)

    # ok, we have all the slots and we can finally book the hotel!
    actually_book_the_hotel(session_attributes)
    finalize_session(session_attributes)

    return close(
        session_attributes,
        'Thanks, I have placed your hotel reservation. What shall we do next?',
    )