If you are using Amazon Lex V2, refer to the Amazon Lex V2 guide instead.

 

If you are using Amazon Lex V1, we recommend upgrading your bots to Amazon Lex V2. We are no longer adding new features to V1 and strongly recommend using V2 for all new bots.

Migrating a Lambda function from Amazon Lex V1 to Amazon Lex V2

Amazon Lex V2 allows only one Lambda function for each language in a bot. The Lambda function and its settings are configured for the bot alias that you use at runtime.

The Lambda function is invoked for all intents in that language if dialog and fulfillment code hooks are enabled for the intent.

Amazon Lex V2 Lambda functions have a different input and output message format from Amazon Lex V1. These are the differences in the Lambda function input format.

These are the differences in the Lambda function output format:

When you build a bot with the Amazon Lex V2 APIs, there is only one Lambda function per bot alias per language instead of a Lambda function for each intent. If you want to continue to use separate functions, you can create a router function that activates a separate function for each intent. The following is a router function that you can use or modify for your application.

import os
import json
import boto3

# reuse client connection as global
client = boto3.client('lambda') 

def router(event):
    intent_name = event['sessionState']['intent']['name']
    fn_name = os.environ.get(intent_name)
    print(f"Intent: {intent_name} -> Lambda: {fn_name}")
    if (fn_name):
        # invoke lambda and return result
        invoke_response = client.invoke(FunctionName=fn_name, Payload = json.dumps(event))
        print(invoke_response)
        payload = json.load(invoke_response['Payload'])
        return payload
    raise Exception('No environment variable for intent: ' + intent_name)
    
def lambda_handler(event, context):
    print(event)
    response = router(event)
    return response

List of updated fields

The following tables provide detailed information about the updated fields in the Amazon Lex V2 Lambda request and response. You can use these tables to map fields between the versions.

Request

The following fields have been updated in the Lambda function request format.

Active contexts

The activeContexts structure is now part of the sessionState structure.

Alternative intents

The interpretations list from index 1 to N contains the list of alternative intents predicted by Amazon Lex V2, along with their confidence scores. The recentIntentSummaryView is removed from the request structure in Amazon Lex V2. To see the details from the recentIntentSummaryView, use the GetSession operation.

Bot

In Amazon Lex V2, bots and aliases have identifiers. The bot ID is part of the codehook input. The alias ID is included, but not the alias name. Amazon Lex V2 supports multiple locales for the same bot so the locale ID is included.

Current intent

The sessionState.intent structure contains the details of the active intent. Amazon Lex V2 also returns a list of all of the intents, including alternative intents, in the interpretations structure. The first element in the interpretations list is always the same as sessionState.intent.

Dialog action

The confirmationStatus field is now part of the sessionState structure.

Amazon Kendra

The kendraResponse field is now part of the sessionState and interpretations structures.

Sentiment

The sentimentResponse structure is moved to the new interpretations structure.

Slots

Amazon Lex V2 provides a single slots object inside the sessionState.intent structure that contains the resolved values, interpreted value, and the original value of what the user said. Amazon Lex V2 also supports multi-valued slots by setting the slotShape as List and setting the values list. Single-value slots are supported by the value field, their shape is assumed to be Scalar.

Others

The Amazon Lex V2 sessionId field is the same as the userId field in Amazon Lex V1. Amazon Lex V2 also sends the inputMode of the caller: text, DTMF, or speech.

Response

The following fields have been changed in the Lambda function response message format.

Active contexts

The activeContexts structure moved to the sessionState structure.

Dialog action

The dialogAction structure moved to the sessionState structure. You can now specify multiple messages in a dialog action, and the genericAttachments structure is now the imageResponseCard structure.

Intents and slots

Intent and slot fields that were part of the dialogAction structure are now part of the sessionState structure.

Others

The sessionAttributes structure is now part of the sessionState structure. The recentIntentSummaryReview structure has been removed.