Swift Vapor add additional info to custom response - swift

Question

I've two Models, Trip and Location. I would return a custom response with some field of trip and the number of Location that has the tripID equal to id of Trip. There is my code(not working). The field locationCount is always empty.
func getList(_ request: Request)throws -> Future<Response> {
let deviceIdReq = request.parameters.values[0].value
let queryTrips = Trip.query(on: request).filter(\.deviceId == deviceIdReq).all()
var tripsR = [TripCustomContent]()
var trips = [Trip]()
return queryTrips.flatMap { (result) -> (Future<Response>) in
trips = result
var count = 0
for t in trips {
let tripIdString = String(t.id!)
let v = Location.query(on: request).filter(\.tripID == tripIdString).count().map({ (res) -> Int in
return res
})/*.map{ (result) -> (Int) in
count = result
return result
}*/
let tripCustomContent = TripCustomContent.init(startTimestamp: t.startTimestamp, endTimestamp: t.endTimestamp, deviceId: t.deviceId, locationCount: v)
tripsR.append(tripCustomContent)
}
let jsonEncoder = JSONEncoder()
let data = try jsonEncoder.encode(tripsR)
let response = HTTPResponse.init(status: .ok, version: HTTPVersion.init(major: x, minor: y), headers: HTTPHeaders.init(), body: data)
let finalResponse = Response.init(http: response, using: request)
return try g.encode(for: request)
}
}
and this is my custom content struct:
struct TripCustomContent: Encodable {
var startTimestamp: String?
var endTimestamp: String?
var deviceId: String
var locationCount: Future<Int>
}
any suggestions?

Answer 1

You're trying to use a value which isn't available yet. When you're returning a Future, you aren't returning the value inside it.
So you want your TripCustomContent to be like this (use in vapor Content instead of Codable:
struct TripCustomContent: Content {
var startTimestamp: String?
var endTimestamp: String?
var deviceId: String
var locationCount: Int
}
You queried the Trip correctly, but not the Location. You could maybe try something like this:
return queryTrips.flatMap { trips -> Future<[TripCustomContent]> in
let tripIds = trips.map({ String($0.id!) })
return Location.query(on: request).filter(\.tripID ~~ tripIds).all().map { locations in
return trips.map { trip in
let locationCount = locations.filter({ $0.tripId == String(trip.id!) }).count
return TripCustomContent(... locationCount: locationCount)
}
}
}
What did I do here?
Map the trips to their tripIds to get an array of tripIds
Get all locations with a tripId of one of the tripIds in the above array
Map each of the trips to an instance of TripCustomContent, using the locations of the database filtered by tripId
Finally, you don't need to encode the JSON yourself, just return objects conforming Content:
func getList(_ request: Request) throws -> Future<[TripCustomContent]>
The above could be a solution to your strategy. But maybe you take a look at relations if they can be a more efficient, easier and faster way.