Loop through an Array in Vapor and handle future correctly

Question

I have an array of customers which follow the following model:

struct GuestListPeople: Codable {
    var fName: String
    var lName: String
    var dob: Date
    var waiver: Bool
} 

I want to loop through the array each time checking a MongoDB collection, using Mongokitten, to see if the waiver is signed then update the bool to true or false as needed. I have created this function to check the waiver status.

func checkGuestListWaiver(req: Request, col: Collection, firstName: String, lastName: String, dob: Date, orgId: String)throws->Future<Bool>{
        col.findOne(["firstName":firstName, "lastName":lastName, "dob": dob ,"orgId":orgId, "waiver":true]).flatMap{ custDoc in
            if let cd = custDoc {
                //found one so waiver must be true
                return req.future().map{
                    return true
                }
            }else {
                //not found return false. 
                return req.future().map{
                    return false
                }
            }
        }
    }

My issue is the function returns a Future Bool, and I am not sure how I should handle the future in the for loop.

 for var c in guestList {
     let w = try CustomerController().checkGuestListWaiver(req: req, col: customerCol, firstName: c.fName, lastName: c.lName, dob: c.dob, orgId: b.orgId)
     c.waiver = w 
 }

I get an error can't assign EventLoopFurture to type Bool. I have tried a few options, but always come back to the same issue of getting a Future back from the database.

Answer 1

You could iterate using flatten

func processGuestList(_ guestList: [Guest], on req: Request) throws -> Future<[Guest]> {
    var newList: [Guest] = []
    return try guestList.map { guest in
         return try CustomerController().checkGuestListWaiver(req: req, col: customerCol, firstName: c.fName, lastName: c.lName, dob: c.dob, orgId: b.orgId).map { w in
            var newGuest = guest
            newGuest.waiver = w
            newList.append(newGuest)
        }
    }.flatten(on: req).transform(to: newList)
}