Model Predictions for incomplete Intents

[dariowho]

AS A chatbot user
I WANT developers to have visibility and control over the slot filling process
SO THAT I can have more sophisticated interactions

Details

An Intent can be predicted without all of its required parameters. In this case Dialogflow and Alexa will enter slot filling, returning incomplete predictions and prompts for missing parameters.

At the moment, this will cause intent=None in the Prediction object, with no signal that slot filling is in progress. We want to model this case by

• Provide explicit information about slot filling being in progress (e.g. Prediction.slot_filling=True)
• Return the set of partially matched parameters (could be an Intent objects with a sentinel MISSING value on missing parameters)
• Adding a separate fulfillment procedure for slot filling