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.

• Amazon Lex V2 replaces the currentIntent and alternativeIntents structures with the interpretations structure. Each interpretation contains an intent, the NLU confidence score for the intent, and an optional sentiment analysis.

• Amazon Lex V2 moves the activeContexts, sessionAttributes in Amazon Lex V1 to the unified sessionState structure. This structure provides information about the current state of the conversation, including the originating request ID.

• Amazon Lex V2 doesn't return the recentIntentSummaryView. Use the information in the sessionState structure instead.

• The Amazon Lex V2 input provides the botId and localeId in the bot attribute.

• The input structure contains an inputMode attribute that provides information on the type of input: text, speech, or DTMF.

These are the differences in the Lambda function output format:

• The activeContexts and sessionAttributes structures in Amazon Lex V1 are replaced by the sessionState structure in Amazon Lex V2.

• The recentIntentSummaryView isn't included in the output.

• The Amazon Lex V1 dialogAction structure is split into two structures, dialogAction that is part of the sessionState structure, and messages that is required when the dialogAction.type is ElicitIntent. Amazon Lex chooses messages from this structure to show to the user.

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.

V1 structure	V2 structure
activeContexts	sessionState.activeContexts
activeContexts[*].timeToLive	sessionState.activeContexts[*].timeToLive
activeContexts[*].timeToLive.timeToLiveInSeconds	sessionState.activeContexts[*].timeToLive.timeToLiveInSeconds
activeContexts[*].timeToLive.turnsToLive	sessionState.activeContexts[*].timeToLive.turnsToLive
activeContexts[*].name	sessionState.activeContexts[*].name
activeContexts[*].parameters	sessionState.activeContexts[*].contextAttributes

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.

V1 structure	V2 structure
alternativeIntents	interpretations[1:*]
recentIntentSummaryView	N/A

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.

V1 structure	V2 structure
bot	bot
bot.name	bot.name
N/A	bot.id
bot.alias	N/A
N/A	bot.aliasId
bot.version	bot.version
N/A	bot.localeId

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.

V1 structure	V2 structure
currentIntent	sessionState.intent OR interpretations[0].intent
currentIntent.name	sessionState.intent.name OR interpretations[0].intent.name
currentIntent.nluConfidenceScore	interpretations[0].nluConfidence.score

Dialog action

The confirmationStatus field is now part of the sessionState structure.

V1 structure	V2 structure
currentIntent.confirmationStatus	sessionState.intent.confirmationState OR interpretations[0].intent.confirmationState
N/A	sessionState.intent.state OR interpretations[*].intent.state

Amazon Kendra

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

V1 structure	V2 structure
kendraResponse	sessionState.intent.kendraResponse OR interpretations[0].intent.kendraResponse

Sentiment

The sentimentResponse structure is moved to the new interpretations structure.

V1 structure	V2 structure
sentimentResponse	interpretations[0].sentimentResponse
sentimentResponse.sentimentLabel	interpretations[0].sentimentResponse.sentiment
sentimentResponse.sentimentScore	interpretations[0].sentimentResponse.sentimentScore

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.

V1 structure	V2 structure
currentIntent.slots	sessionState.intent.slots OR interpretations[0].intent.slots
currentIntent.slots[*].value	sessionState.intent.slots[*].value.interpretedValue OR interpretations[0].intent.slots[*].value.interpretedValue
N/A	sessionState.intent.slots[*].value.shape OR interpretations[0].intent.slots[*].shape
N/A	sessionState.intent.slots[*].values OR interpretations[0].intent.slots[*].values
currentIntent.slotDetails	sessionState.intent.slots OR interpretations[0].intent.slots
currentIntent.slotDetails[*].resolutions	sessionState.intent.slots[*].resolvedValues OR interpretations[0].intent.slots[*].resolvedValues
currentIntent.slotDetails[*].originalValue	sessionState.intent.slots[*].originalValue OR interpretations[0].intent.slots[*].originalValue

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.

V1 structure	V2 structure
userId	sessionId
inputTranscript	inputTranscript
invocationSource	invocationSource
outputDialogMode	responseContentType
messageVersion	messageVersion
sessionAttributes	sessionState.sessionAttributes
requestAttributes	requestAttributes
N/A	inputMode
N/A	originatingRequestId

Response

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

Active contexts

The activeContexts structure moved to the sessionState structure.

V1 structure	V2 structure
activeContexts	sessionState.activeContexts
activeContexts[*].timeToLive	sessionState.activeContexts[*].timeToLive
activeContexts[*].timeToLive.timeToLiveInSeconds	sessionState.activeContexts[*].timeToLive.timeToLiveInSeconds
activeContexts[*].timeToLive.turnsToLive	sessionState.activeContexts[*].timeToLive.turnsToLive
activeContexts[*].name	sessionState.activeContexts[*].name
activeContexts[*].parameters	sessionState.activeContexts[*].contextAttributes

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.

V1 structure	V2 structure
dialogAction	sessionState.dialogAction
dialogAction.type	sessionState.dialogAction.type
dialogAction.slotToElicit	sessionState.intent.dialogAction.slotToElicit
dialogAction.type.fulfillmentState	sessionState.intent.state
dialogAction.message	messages
dialogAction.message.contentType	messages[*].contentType
dialogAction.message.content	messages[*].content
dialogAction.responseCard	messages[*].imageResponseCard
dialogAction.responseCard.version	N/A
dialogAction.responseCard.contentType	messages[*].contentType
dialogAction.responseCard.genericAttachments	N/A
dialogAction.responseCard.genericAttachments[*].title	messages[*].imageResponseCard.title
dialogAction.responseCard.genericAttachments[*].subTitle	messages[*].imageResponseCard.subtitle
dialogAction.responseCard.genericAttachments[*].imageUrl	messages[*].imageResponseCard.imageUrl
dialogAction.responseCard.genericAttachments[*].buttons	messages[*].imageResponseCard.buttons
dialogAction.responseCard.genericAttachments[*].buttons[*].value	messages[*].imageResponseCard.buttons[*].value
dialogAction.responseCard.genericAttachments[*].buttons[*].text	messages[*].imageResponseCard.buttons[*].text
dialogAction.kendraQueryRequestPayload	dialogAction.kendraQueryRequestPayload
dialogAction.kendraQueryFilterString	dialogAction.kendraQueryFilterString

Intents and slots

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

V1 structure	V2 structure
dialogAction.intentName	sessionState.intent.name
dialogAction.slots	sessionState.intent.slots
dialogAction.slots[*].key	sessionState.intent.slots[*].key
dialogAction.slots[*].value	sessionState.intent.slots[*].value.interpretedValue
N/A	sessionState.intent.slots[*].value.shape
N/A	sessionState.intent.slots[*].values

Others

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

V1 structure	V2 structure
sessionAttributes	sessionState.sessionAttributes
recentIntentSummaryView	N/A