Is there a way for a lambda function to execute it's custom error prompt for AWS Lex bot?

Question

I want to handle error messages dynamically and not rely on what we declared in the Lex dashboard. However when I tried to type a wrong message it will immediately trigger the default error message. When I check the lambda logs using Serverless the lambda function was not executed.

See logs:

There was no new entry when I typed in "can you do this". I was expecting that the lambda function would execute since I added some console.log to check out the event data.

Is it even possible?

Answer 1

You can handle these dynamically but for that you need to setup an API Gateway and Lambda function in between your chat-client and the lex.

Your chat-client will send request to API Gateway, then to Lambda function and then to Lex (Lex will have one more lambda function). While returning the response from Lex, you can check in the Lambda function if it's an error message and trigger some action.

In the Lambda function we can use something like this:

import logging
import boto3

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

client_run = boto3.client('lex-runtime')
client_model = boto3.client('lex-models')

def lambda_handler(event, context):
    response = client_run.post_text(
        botName='name_of_your_bot',
        botAlias='alias_of_your_bot',
        userId='some_id',
        sessionAttributes={
            'key1': 'value1'
        },
        inputText=event['user_query']
    )
    bot_details = client_model.get_bot(
    name='name_of_your_bot',
    versionOrAlias='$LATEST'
    )
    for content in bot_details['clarificationPrompt']['messages']:
        if response["message"] == content['content']:
            return error_handling_method(event)
    for content in bot_details['abortStatement']['messages']:
        if response["message"] == content['content']:
            return error_handling_method(event)
    return response["message"]

Hope it helps.