fix: Fix issue with non-CR routes showing up in nearby transit for stops that also serve distant CR #126
Conversation
The backend uses a different distance for nearby commuter rail vs every other mode, but when non-CR routes were also being served by those CR stations, they were also showing up in nearby transit. This was made worse by hoisting the subway routes up to the top, you could get weird results where it was showing stops that were actually quite far as one of the closest routes.
| @@ -13,6 +14,8 @@ data class UpcomingTripKey(val routeId: String, val headsign: String, val stopId | |||
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| typealias UpcomingTripsMap = Map<UpcomingTripKey, List<UpcomingTrip>> | |||
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| const val COMMUTER_NEARBY_THRESHOLD = 0.5 | |||
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This duplicates a value between the frontend and the backend, which seems inappropriate. How would you feel about a follow up where we remove 0.5 mile-ish threshold from the backend, and only make a single stops request with a 1 mile radius, then only have this distance threshold here. It's still weird to have the longer radius there and the shorter one here, but I think it's still better than this.
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I agree it seems a little weird to have a longer radius filter on the backend and a shorter one on the frontend.
What do you think of keeping the filtering entirely on the backend? We could filter cr_included_stops to be only CR stops based on Stop.vehicle_type, which is a field we aren't currently parsing.
That was one approach we discussed at refinement but didn't capture in detail in the ticket, sorry for the missing context there!
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Thanks! mbta/mobile_app_backend#116 I was initially going to implement it on the backend but couldn't see a clear path to doing so. I didn't realize that vehicle_type was a thing, that can maybe simplify some stuff on the frontend now that we have access to it.
Summary
Ticket: Nearby transit shows non-CR routes between 0.5 and 1 mile away
The nearby transit backend is separately fetching CR stops with a 1 mile radius, and any other stops with a 0.5 mile radius, but they're all passed to the frontend without any associated distance, so nearby transit is seeing subway or bus routes that are served by those more distant CR stops, and is displaying them even though they fall outside of 0.5 miles. This adds a filter to remove any routes over that threshold unless they're CR.
Testing
Added a test to make sure distant subway/bus routes are filtered out.