GCP DialogFlow CX - returning choice list / buttons in webhook response fulfillment_response or using parameters in custom payload to provide choices

Question

I have created a chatbot in DialogFlow CX. After a customer identifies themselves, a call is made to the webhook (written in Python) which finds the 3 closest retail stores to the customer, and returns those in the webhook response as parameters:

bot_response = {
    "fulfillment_response":
        {
            "messages": [
                {
                    "text": {
                        "text": [
                            f'Thanks {first_name}! I\'ve located your account.'
                        ]
                    }
                }
            ]
        },
    "session_info": {
        "session": session_name,
        "parameters": {
            "first_name": first_name,
            "email_address": email_address,
            "business_partner_id": business_partner_id,
            "address_line_1": c['response']['address_line_1'],
            "address_line_2": c['response']['address_line_2'],
            "suburb": c['response']['suburb'],
            "postcode": c['response']['postcode'],
            "region": c['response']['state'],
            "store_1": locations[0].store_name,
            "store_1_id": locations[0].store_id,
            "store_1_address": locations[0].address,
            "store_2": locations[1].store_name,
            "store_2_id": locations[1].store_id,
            "store_2_address": locations[1].address,
            "store_3": locations[2].store_name,
            "store_3_id": locations[2].store_id,
            "store_3_address": locations[2].address
        }
    }
}

My intention is to allow the customer to select 1 of these 3 store locations. In the above model, I've returned them as parameters, which are successfully recorded in dialogflow, however I am stuck on how to provide these values as a list of options to the customer. I am unsure whether I can

a) Provide a list of options back to the user as a Webhook Response (instead of parameters). All documentation I can find suggests only that text and parameters can be returned.

Or

b) Use the returned parameters to create a custom payload to present them as a list for the user to select from. Something like:

{
  "richContent": [
    [
      {
        "event": {
          "name": "Store1",
          "parameters": {},
          "languageCode": ""
        },
        "subtitle": "${store_1_id}",
        "title": "${store_1_address}",
        "type": "list"
      }
    ]
  ]
}

But I cannot find any documentation to suggest you can embed parameters into custom payloads.

Does anyone know of a way to solve this situation? Thank you!

Answer 1

As per usual, the mere act of posting a question on Stack Overflow somehow creates a higher statistical likelihood that I will in fact answer my own question. It's simple enough to add it to a custom payload to present in a list, simply using the syntax:

    {
  "richContent": [
    [
      {
        "event": {
          "name": "Store1",
          "parameters": {},
          "languageCode": ""
        },
        "subtitle": "$session.params.store_1_address",
        "title": "Store 1",
        "type": "list"
      }
    ]
  ]
}