Sapper event for route change

Question

I need to redirect users to login page if they are not authenticated. I need something like route.beforeEach in Vue.js, ideally:

sapper.beforeRouteChange((to, from, next) => {

  const isAuth = "[some session or token check]";

  if (!isAuth) {
    next('/login')
  }

  next()
})

I found Sapper - protected routes (route guard) this question but I think it's not enough for my needs. What if token or auth changes in runtime? OR is it covered by reactivity?

Edit 1: I think that this issue on Sapper GitHub solves my problem.

Answer 1

So I placed this code to /src/routes/_layout.svelte:

  import AuthMiddleware from "../methods/authMiddleware.js";
  import { goto, stores } from '@sapper/app';
  const { page } = stores();

  if (typeof window !== "undefined" && typeof document !== "undefined") {
    page.subscribe(({ path, params, query }) => {
      const from = window.location.pathname;
      const redirect = (href) => { goto(href); }

      AuthMiddleware.beforeChange(from, path, redirect, params, query);
    })
  }

And this is authMiddleware.js file:

export default class AuthMiddleware {

  static beforeChange(from, to, redirect, params, query) {

    if (!AuthMiddleware._isUserAuthenticated()) {
      redirect("/login");
    }
  }

  // ~

  static _isUserAuthenticated() {
    return true; // TODO: Implement
  }
}

more information on route hooks can be found here

• https://github.com/sveltejs/sapper/issues/30
• https://sapper.svelte.dev/docs/#Stores

Answer 2

You can also use authenticationMiddleware.js inside server.js file

Here is authenticationMiddleware.js file

import { get, post } from "./../lib/api";
async function authenticationMiddleware(req, res, next) {
    let user = null
    const cookies = require('cookie-universal')(req, res);
    if (cookies.get('token')) {
        try {
            user = await get("users/me", null, cookies.get('token'));
        } catch (e) {
            console.log('err at users', e.toString());
        }
        req.user = user
        req.token = cookies.get('token')
    } else {
        req.user = {}
        req.token = null
        cookies.set('token', null)
    }
    next();
}
export { authenticationMiddleware }

e.g. https://github.com/itswadesh/sapper-ecommerce/blob/master/src/server.js