Dialogflow webhook set parameter value

Question

My intent sends a webhook as part of slot filling if a parameter is missing from the user query. My webhook then uses logic to estimate the value of the parameter. How can I return this parameter as part of the WebhookResponse object? I am using the C# client library in an ASP.NET Core app.

My code is:

string fulfillmentText;
WebhookRequest request = null;
using (var reader = new StreamReader(Request.Body))
{
    request = jsonParser.Parse<WebhookRequest>(reader);
}
//If Parameter-1 has no value
if (request.QueryResult.Fields["Parameter-1].StringValue.Length == 0)
{
    fulfillmentText = "I have guessed the value of Parameter-1";
    //I apply some logic that is unimportant to this question
    //For the sake of simplicity, say I estimate the value of Parameter-1 to be "foobar"
    //I want to be able to give the parameter this value like this:
    parameter["Parameter-1"] = "foobar"

}

UPDATE

So, I have pretty much got it all working using Prisoner's method. I will retry sid8491's at some point too. My intent is trying to obtain a user's address. I have required custom entities to retrieve the street number, street name, suburb and state.

Without creating any contexts myself, the following context is automatically generated by Dialogflow: projects/telebot-pianomoves-v1/agent/sessions/2b42cbc8-2418-4231-e4c0-bd3a175f2ea8/contexts/1320fe35-4329-4176-b136-9221dfaddd4e_id_dialog_context. I receive this context in my webhook, and can then CHANGE the value of a parameter. Let's assume $Suburb_Entity had no value in the webhook request and my code then returned the above context with the a new value for Suburb_Entity. My code successfully changes the Suburb_Entity from "" to aspendale as can be seen by the webhook response json:

Now the odd thing is, although I changed the Suburb_Entity to an actual value in the outputContext of my webhook response, the actual parameter $Suburb_Entity only changes to the new value of Suburb_Entity from the outputContext on the NEXT detect intent request. So, keeping in mind the fact that I returned the new Suburb_Entity in the outputContext of the webhook response, this is the detect intent response I get - noting that $Suburb_Entity is yet to be changed:

On the next detect intent request, the webhook request parameter Suburb_Entity is set to aspendale and $Suburb_Entity also equals aspendale. The important thing about this, is $Suburb_Entity only changed to the outputContext parameter value on the NEXT detect intent request, of which would have triggered another webhook. $Suburb_Entity did not change during the same detect intent request as when I modified the outputContext parameter Suburb_Entity, but in the next. This leads me to believe that somehow, $Suburb_Entity inherits parameter values from this automatically generated context. The issue here, is that when my webhook responds with the outputContext paramter Suburb_Entity equalling aspendale, $Suburb_Entity does not change to this value until the next request. This means that if all the other parameters have values set, but $Suburb_Entity is yet to have changed value, then allRequiredParamsSet == false. If I return the Suburb_Entity in the outputContext, I want it to immediately change the value of $Suburb_Entity without requiring another detect intent request so that allRequiredParamsSet == true in such a circumstance. I tried setting the default value by doing this (it didn't work):

An alternative of course would be a way for me to force allRequiredParamsSet = true. I save the parameter values from this the context parameter, not the actual response. So I don't need $Suburb_Entity, I just want the intent to think that it has a value.

Cheers

Answer 1

There are multiple steps for get it done:

1. First give an event in intent
2. Check your condition in webhook
3. If your condition is satisfied, invoke the intent by calling the event from webhook which you have defined in step 1
4. Pass the paylaod (in json format) along with event calling, give parameters in the payload
5. In the intent, give default value of parameter as #eventName.parameterName

Hope it helps.

Answer 2

When you use a webhook for "slot filling", the intention is that you return the prompts you want to ask the user for and continue to use the same Intent to handle the responses. You're not expected to create values yourself.

If you want to "fill in" some answers that are used in the static "response" section of the Dialogflow Intent, or if you just want to record the answers so you can use them later, you can set the parameters of a Context. In the response string, you can refer to this value as #context-name.parameter-name.

Update

I don't know the internal mechanics of slot filling, but it doesn't surprise me that setting a value in the internal context for the input parameters doesn't "register" until the next round of handling the Intent.

The webhook for slot filling isn't intended to create values - it is intended to handle values and create prompts for the user to respond to. Intents are generally about processing user inputs and webhooks about handling them.

My workaround suggested that if you want this for output, you use the context for output.