Adding asyncMiddleware.

server/lib/middlewares/async.ts

@@ -0,0 +1,26 @@
+import { eachSeries } from 'async'
+import type { NextFunction, Request, RequestHandler, Response } from 'express'
+
+// Syntactic sugar to avoid try/catch in express controllers
+// Thanks: https://medium.com/@Abazhenov/using-async-await-in-express-with-node-8-b8af872c0016
+
+export type RequestPromiseHandler = ((req: Request, res: Response, next: NextFunction) => Promise<any>)
+
+function asyncMiddleware (fun: RequestPromiseHandler | RequestPromiseHandler[]): RequestHandler {
+  return (req: Request, res: Response, next: NextFunction) => {
+    if (Array.isArray(fun)) {
+      eachSeries(fun as RequestHandler[], (f, cb) => {
+        Promise.resolve(f(req, res, (err: any) => cb(err)))
+          .catch(err => next(err))
+      }, next)
+      return
+    }
+
+    Promise.resolve((fun as RequestHandler)(req, res, next))
+      .catch(err => next(err))
+  }
+}
+
+export {
+  asyncMiddleware
+}