Flight booking

I am training a bot for flight booking. I have tried using entity role-based extraction to get the source and destination names, but there are many cities we can book. Is there any way we can use both role-based extraction and a lookup table? nlu look like:

  • intent: travel examples: |
    • i want to travel from [washington]{“entity”: “location”, “role”: “travel_from”} to [rajouri]{“entity”: “location”, “role”: “travel_to”}
    • i want to travel to [rajouri]{“entity”: “location”, “role”: “travel_to”} from [washington]{“entity”: “location”, “role”: “travel_from”}
    • i want to travel from [ghaziabad]{“entity”: “location”, “role”: “travel_from”} to [ramagundam]{“entity”: “location”, “role”: “travel_to”}
    • i want to travel to [ramagundam]{“entity”: “location”, “role”: “travel_to”} from [ghaziabad]{“entity”: “location”, “role”: “travel_from”}
  • lookup: location examples: |
    • delhi
    • katra
    • agra
    • agatti island
    • aizawl
    • akola
    • ahmedabad
    • amritsar
    • bhubaneswar
    • vadodara