server/middlewares/async.ts

   1 import { eachSeries } from 'async'
   2 import { NextFunction, Request, RequestHandler, Response } from 'express'
   3 import { ValidationChain } from 'express-validator'
   4 import { ExpressPromiseHandler } from '@server/types/express'
   5 import { retryTransactionWrapper } from '../helpers/database-utils'
   6
   7 // Syntactic sugar to avoid try/catch in express controllers
   8 // Thanks: https://medium.com/@Abazhenov/using-async-await-in-express-with-node-8-b8af872c0016
   9
  10 export type RequestPromiseHandler = ValidationChain | ExpressPromiseHandler
  11
  12 function asyncMiddleware (fun: RequestPromiseHandler | RequestPromiseHandler[]) {
  13   return (req: Request, res: Response, next: NextFunction) => {
  14     if (Array.isArray(fun) === true) {
  15       return eachSeries(fun as RequestHandler[], (f, cb) => {
  16         Promise.resolve(f(req, res, err => cb(err)))
  17           .catch(err => next(err))
  18       }, next)
  19     }
  20
  21     return Promise.resolve((fun as RequestHandler)(req, res, next))
  22       .catch(err => next(err))
  23   }
  24 }
  25
  26 function asyncRetryTransactionMiddleware (fun: (req: Request, res: Response, next: NextFunction) => Promise<any>) {
  27   return (req: Request, res: Response, next: NextFunction) => {
  28     return Promise.resolve(
  29       retryTransactionWrapper(fun, req, res, next)
  30     ).catch(err => next(err))
  31   }
  32 }
  33
  34 // ---------------------------------------------------------------------------
  35
  36 export {
  37   asyncMiddleware,
  38   asyncRetryTransactionMiddleware
  39 }