Request+Promise extension for Vapor 3. May be handy if you often create promises in your controllers

Request+PromiseWrapper.swift

import Foundation
import Vapor

extension Request {
    func promise<T>(_ asyncCode: @escaping (() throws ->(T))) -> Future<T> where T: ResponseEncodable {
        let promise = eventLoop.newPromise(T.self)
        
        DispatchQueue.global().async {
            do {
                promise.succeed(result: try asyncCode())
            } catch {
                promise.fail(error: error)
            }
        }
        
        return promise.futureResult
    }
}

//How to use

final class LoginController {
  
    struct LoginResponse: Codable, Content {
        var token: String
    }

    func login(_ req: Request) throws -> Future<LoginResponse> {
        struct Content: Codable {
            var email: String
            var password: String
        }
        return req.promise { () -> (LoginResponse) in
            let requestContent = try req.content.decode(Content.self).wait()
            let email = requestContent.email.lowercased()
            if !email.doesEmailValid() {
                throw Abort(.badRequest, reason: "Invalid email")
            }
            let user = try User.get(on: req, email: email, password: requestContent.password).wait()
            let session = try Session(user: user)//create some session
            return LoginResponse(token: session.id)
        }
    }
}