Dynamically validate allowed entity values in Dialog Flow

Question

In my Dialog Flow agent, I have an entity @city. Possible values are New York, Berlin, ... But Amsterdam is not in that list.

Is there a way to dynamically validate an entity value against the values in my SQL database? For example, if the user writes Amsterdam, I want to give the user an hint that he should ask for another city. Can this be done via a webhook?

Or should I synchronize my database cities with the agent on a regular basis? If so, can this be done via an API?

I am not sure what the standard way of this is here.

Answer 1

You have a few options here, depending on what will work best for you.

In the most simple case you can set the parameter entity type to @sys.any and handle all the name resolution in your webhook. This is the worst possible scenario.

As you've done, you can create your own entity type, @city, and populate it with a few cities. If you want to populate it with the cities in your database, there is an API (hence the old name, API.AI) that lets you create and modify Entities. See the documentation at https://dialogflow.com/docs/reference/agent/entities for details.

Even best, however, might be a combination of the two. You have an Intent that uses @city, and another lower priority Intent that uses @sys.any (or a fallback intent) that handles the case of them saying something you don't understand.