In this article, I will explain how you can use slot filling to get a list of user inputs in Dialogflow ES.
Before we go further, a couple of things to note: I usually avoid slot filling in Dialogflow ES If are quite sure you need to use slot filling, it is best to go with Dialogflow CX
This will be one of the canonical slot filling examples: booking a flight ticket
We need the following pieces of information
- From
- To
- Departure date
- Return date
- Flight class
- Number of passengers
The appeal of slot filling is that the user might provide this information in any order and Dialogflow’s slot filling is smart enough to extract as much useful information as possible from the user utterance and prompt for the rest automatically.
When it works, slot filling makes for an amazing demo! And when it fails, it is equally spectacular.
Create an entity called flightclass
Create an intent called book.a.flight and add the following training phrases
Number of passengers will be a system entity of type sys.number-integer
The departure and return dates are system entities of type sys.date-time
The from and to cities are system entities of type sys.geo-city
The flight class slot is a user defined entity we declared earlier - flightclass
Here is the full list of training phrases
Open the Parameters section and mark ALL the parameters as required
Now click on the “Define prompts…” for flightclass
Add the following prompt for the flightclass
Add the following prompt for the city of departure
Follow the table below for the rest of the prompts
| Parameter | Prompt text |
|---|---|
| flightclass | What class are you flying? (Economy, Business or First) |
| fromcity | Where are you leaving from? |
| tocity | Where are you flying to? |
| departuredate | What date do you leave? |
| returndate | What date do you plan to return? |
| numpassengers | How many passengers? |
This is what your parameter table should look like after you add all the prompts
Now let us test this bot by trying different types of starting sentences
First, we start with just the intent phrase:
Next we start the number of passengers
Next we start by providing from and to locations
Next we start with the departure and return dates
But sometimes the bot can get into a loop. This is the biggest problem with slot filling, and usually the source of jokes online about how chatbots don’t work.
