server/middlewares/async.ts

   1 import { eachSeries } from 'async'
   2 import { NextFunction, Request, RequestHandler, Response } from 'express'
   3 import { retryTransactionWrapper } from '../helpers/database-utils'
   4 import { ValidationChain } from 'express-validator'
   5
   6 // Syntactic sugar to avoid try/catch in express controllers
   7 // Thanks: https://medium.com/@Abazhenov/using-async-await-in-express-with-node-8-b8af872c0016
   8
   9 export type RequestPromiseHandler = ValidationChain | ((req: Request, res: Response, next: NextFunction) => Promise<any>)
  10
  11 function asyncMiddleware (fun: RequestPromiseHandler | RequestPromiseHandler[]) {
  12   return (req: Request, res: Response, next: NextFunction) => {
  13     if (Array.isArray(fun) === true) {
  14       return eachSeries(fun as RequestHandler[], (f, cb) => {
  15         Promise.resolve(f(req, res, cb))
  16           .catch(err => next(err))
  17       }, next)
  18     }
  19
  20     return Promise.resolve((fun as RequestHandler)(req, res, next))
  21       .catch(err => next(err))
  22   }
  23 }
  24
  25 function asyncRetryTransactionMiddleware (fun: (req: Request, res: Response, next: NextFunction) => Promise<any>) {
  26   return (req: Request, res: Response, next: NextFunction) => {
  27     return Promise.resolve(
  28       retryTransactionWrapper(fun, req, res, next)
  29     ).catch(err => next(err))
  30   }
  31 }
  32
  33 // ---------------------------------------------------------------------------
  34
  35 export {
  36   asyncMiddleware,
  37   asyncRetryTransactionMiddleware
  38 }