Couldn't call method inside method controller in route Nodejs Express Typescript

Question

I got two classes; authenticationRoutes.ts and authenticationController.ts. In authenticationRoutes I'm calling 'authenticationController.test', the 'authenticationController.test' method calls 'authenticationController.generateAccessAuthToken' method. Whenever I do this I get the following Error: Unhandled rejection TypeError: Cannot read property 'generateAccessAuthToken' of undefined

authenticationRoutes.ts
import { authenticationController } from '../controllers/authenticationController';

        //TEST ROUTE
        this.router.get('/users',  authenticationController.test);

authenticationController.ts


public test(req: Request, res: Response) {
        dbSequelize().User.findAll({
            where: {
                id: '0'
            },
            attributes: ['id']
        }).then((user: UserInstance[]) => {
            this.generateAccessAuthToken('0').then((response: any) => {
                console.log(response);
                res.send(response);
            });
        })
    }


generateAccessAuthToken(_id: any) {
        return new Promise(async (resolve, reject) => {
            await jwt.sign({ id: _id }, SECRET_KEY as string, function (err: Error, token: any) {
                if (err) {
                    reject(err);
                } else {
                    resolve(token);
                }
            })
        })
    }

I want to be able to do what I described without receiving an error.

Sergeon · Accepted Answer · 2019-05-13 13:32:01Z

4

I think this will do the trick:

this.router.get('/users', authenticationController.test.bind(AuthenticationController));

Basically, when you have a class A with a method b, if you pass around A.b like:

const a = new A();
const b = a.b;
b(); // now 'this' is lost, any reference to `this` in b() code would be undefined

You are passing only the function. It has nothing to do with the A class now, it is just a function.

So, among other things, you can use bind to explicitly set the this context for a function:

const a = new A();
const b = a.b.bind(a);
b(); // so now b() is forced to use a as this context

I bet there are tons of duplicates about your issue, but I couldn't find anyone fast because the search is tricky (this binding in js has A LOT of issues).

Hope this helps.

edited May 13, 2019 at 13:32

answered May 13, 2019 at 13:25

Sergeon

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1 Comment

vikrant Over a year ago

when i instantiate the controller class, it says that the class is not a constructor

Zehava · Accepted Answer · 2020-12-15 21:33:05Z

1

I faced the same issue and solved it :

public test = (req: Request, res: Response) => {
        dbSequelize().User.findAll({
            where: {
                id: '0'
            },
            attributes: ['id']
        }).then((user: UserInstance[]) => {
            this.generateAccessAuthToken('0').then((response: any) => {
                console.log(response);
                res.send(response);
            });
        })
    }

answered Dec 15, 2020 at 21:33

Zehava

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