Amazon Lex not prompting for missing variables when using CodeHook Validation

Question

I am building an agent in Amazon Lex with around 3 intents. All the 3 intents have a variable which has been ticked as \'required\', meaning the agent has to prompt for those va

Answer 1

This is happening because Lambda initialization and validation happens before Slot filling in Amazon Lex. You can still check that user have provided the "person" slot in DialogCodeHook i.e validation part. Something like below code will get your work done:

def build_validation_result(is_valid, violated_slot, message_content):
    if message_content == None:
        return {
            'isValid': is_valid,
            'violatedSlot': violated_slot
        }
    return {
        'isValid': is_valid,
        'violatedSlot': violated_slot,
        'message': {'contentType': 'PlainText', 'content': message_content}
    }


def validate_person(person):
    # apply validations here
    if person is None:
        return build_validation_result(False, 'person', 'Please enter the person name')
    return build_validation_result(True, None, None)


def get_notes(intent_request):
    source = intent_request['invocationSource']
    output_session_attributes = intent_request['sessionAttributes'] if intent_request['sessionAttributes'] is not None else {}
    slots = intent_request['currentIntent']['slots']
    person = slots['person']
    if source == 'DialogCodeHook':
        # check existence of "person" slot
        validation_result = validate_person(person)
        if not validation_result['isValid']:
            slots[ticket_validation_result['violatedSlot']] = None
            return elicit_slot(
                output_session_attributes,
                intent_request['currentIntent']['name'],
                slots,
                validation_result['violatedSlot'],
                validation_result['message']
            )
        return delegate(output_session_attributes, slots)

If the "person" slot is empty, user will be prompted the error message. This way you don't need to tick on "Required" on the slot. This was the only workaround I could think of when I faced this problem while using DialogCodeHook. Hope it helps.