Utter with condition not working as expected

Rasa Open Source
1

Hello.

I’m working on a bot that answers when users ask for the definition of specific concepts. It searches for the concept within a file containing pairs of concepts and definitions and then provides the response.

I want:

  1. If there isn’t any ‘concept’ entity in the intent → The bot must utter “I’m sorry. I couldn’t understand the requested concept” or “I couldn’t realize what concept you are looking for.”
  2. If there is a ‘concept’ entity in the intent, but it wasn’t found in the definitions file → The bot must utter “There is no definition matching the concept {concept} in my database.” or “I couldn’t find {concept} in my database.”

The problem is that the bot always includes the concept in the utterance. The domain file fragment is below.

responses:

  utter_definition_not_found:
  # utterance for missing or not recognized entities
  - condition:
    - type: slot
      name: concept
      value:        # also tried with value: None or value: not_found (previously setting slot value within a custom action)
    text: |
      I'm sorry. I couldn't understand the requested concept.
  - condition:
    - type: slot
      name: concept
      value:        # also tried with value: None or value: not_found (previously setting slot value within a custom action)
    text: |
      I couldn't realize what concept you are looking for.
  - text: |
    There is no definition matching the concept {concept} in my database.
  - text: |
    I couldn't find {concept} in my database.

slots:
  concept:
    type: text
    influence_conversation: false
    mappings:
    - type: from_entity
      entity: concept

Thanks in advance!