CODEWITHSUNDEEP
node.jstypescriptexpress
Jean-Luc Aubert
Jean-Luc Aubert

Reputation: 620

Node + Express router + Type Script : string arg is not assignable to requesthandlerparams type

I'm following a tuto to create a full rest api, then, i create a TS class that export a new express router :

import { Router, Request, Response, NextFunction } from 'express';


export class TourRouter {
public router: Router;

constructor() {
    this.router = Router();

    this.init();
}

public init(): void {
    this.router.get(
        '/',
        this.getTours
    );
}

private getTours(request: Request, response: Response, next: NextFunction) {
    // Some JSON
    const tours = {
        "now": "2018-09-09 18:40:00",
        "date": "2018-09-09",
        "tours": [
            {
                "time": "8",
                "places": 8,
                "isPast": false
            },
            {
                "time": "11",
                "places": 8,
                "isPast": false
            },
            {
                "time": "14",
                "places": 8,
                "isPast": false
            },
            {
                "time": "17",
                "places": 8,
                "isPast": false
            }             
        ]
    };

    response.send(tours);
}
}

const tourRoutes = new TourRouter();
tourRoutes.init();

export default tourRoutes.router;

When i want to use this new Router in my App.ts as follow, i'm getting a TS error and the build failed with the message :

Argument of type 'string' is not assignable to parameter of type 'RequestHandlerParams'

The use statement is :

    private _routes(): void {
    let router = express.Router();

    router.get('/', (request, response, next) => {
        response.json({
            message: 'Hello World'
        });
    });

    this.express.use('/', router);
    this.express.use('/api/v1/tours', TourRouter);
}

As if TourRouter, in my case was not a Router as i expect but something else, but don't know why. What i'm missing ?

Regards

Upvotes: 3

Views: 4070

Answers (2)

Matt McCutchen
Matt McCutchen

Reputation: 30919

It sounds like you are importing the TourRouter class instead of the actual router, which is the default export. Replace import { TourRouter } from './routes/TourRouter'; with import TourRouter from './routes/TourRouter';. You might want to import the router using a name other than TourRouter to avoid confusion.

TypeScript knows that the arguments you are passing to this.express.use do not match any of the valid overload signatures, but it doesn't know which overload signature you intended to use. It (incorrectly) guesses the (...handlers: RequestHandlerParams[]) => T signature, which explains the strange error that the string path is not assignable to RequestHandlerParams.

Upvotes: 1

xrobert35
xrobert35

Reputation: 2556

For me it's perhaps a strange problem with the "Request" "Response" "NextFunction" type. Can you try to simply import * from express and qualify each type with express. ?

Request --> express.Request

https://github.com/DefinitelyTyped/DefinitelyTyped/issues/16639

Upvotes: 0

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