Alexa skill, how to deal with missing slot

When we create an alexa skill, we have to specify intent, utterance, and slot(optional).These are called interaction model in alexa skill interface. For example, if we create a skill that provides information of repair center, we can define the interaction model like this:

{
   "intents":[
           "name" : GetRepairCenter,
            "samples":  where is the repair center in New York
            "slots": [
                             {
                                 "name": "location",
                                  "type":  "AMAZON.US_CITY"
                              }
                 ]
    ]


}


Apparently, our intent is GetRepairCenter,  utterance is where is the repair center in New York, and  slot is location


Sometime our skill has to ask another question, when user doesn't provide slot value like "where is the repaor center". In this case, we can specify a dialog in the interaction model and respond dialog delegate to alexa for the missing slot.


Step 1.Enable Slot filling

Step 2.Specify prompt message you want




Step 3. Build a dialog delegate request

generateResponseForMissingSlots = (sessionAttributes) => { return { version: "1.0", sessionAttributes: sessionAttributes, response: { "outputSpeech": null, "card": null, "directives": [{ "type": "Dialog.Delegate" }], "reprompt": null, "shouldEndSession": false } } }

Step 4. Handle missing slots in your Lambda function

if (event.request.dialogState !== "COMPLETED") { //check if dialogState is COMPLETED,if not, respond dialog deleget to alexa context.succeed( generateResponseForMissingSlots( {} ) } else { //Do something... }