I'm doing an express app with typescript. The router code is:
let user = new User();
router.get("/", user.test);
the user class is
export class User {
test(req, res, next) {
// this === undefined
}
}
the problem is that the this object is undefined inside test method. Is there a better way to implement express routing?
You need to use the bind function to keep the scope of this when the method is invoked:
let user = new User();
router.get("/", user.test.bind(user));
Or you can do that in the User constructor:
export class User {
constructor() {
this.test = this.test.bind(this);
}
test(req, res, next) {
...
}
}
Another option is to use an arrow function:
let user = new User();
router.get("/", (req, res, next) => user.test(req, res, next));
You can use export default and instantiate the controller so it can be used without instantiation in whichever file you've imported the controller.
register.controller.ts
import { Router, Request, Response, NextFunction } from 'express';
class Register {
constructor() {
this.register = this.register.bind(this);
}
register(req: Request, res: Response, next: NextFunction) {
// ... removed for brevity
}
}
export default new Register();
server.ts or auth.routes.ts
import registerCtrl from '../controllers/auth/register.controller.js';
// ... removed for brevity
router.post('/register', registerCtrl.register);
With the new version of TS, you can create a static method with or without an accessor modifier, and call that method in the router without instantiating a class:
export class UserController {
// arrow function
public static test: RequestHandler = async (req, res, next) => {
// ...
}
// regular function
public static async getAll(req: Request, res: Response, next: NextFunction)
{
// ...
}
}
and in the router use it as:
import { Router } from "express";
import { UserController } from '/controllers/UserController';
const router = Router();
...
router.get('/test', UserController.test);
....
