Passport.js - Custom unauthorized message

Question

Hello, I'm building the backend for my website when I reached the login part everything was ok until when I tried to put the false information to check what will happen. So when I tried it redirected me to another page and shows me "Unauthorized". So I tried fixing it and here is what I wrote.

app.post("/login", function (req, res) {
  // Other code...
  req.login(user, function (err) {
    if (err) {
      res.render("login", {
        alert: [{ field: "none", msg: "Username/password is incorrect!" }],
      });
    } else {
      passport.authenticate("local")(req, res, function () {
        if (res.statusCode == 401) {
          res.render("login", {
            alert: [{ field: "none", msg: "Username/password is incorrect!" }],
          });
        } else {
          res.redirect("/");
        }
      });
    }
  });
});

if anyone can help I will appreciate it! 🧡

Answer 1

I think you need to authenticate the user first and then render the page based on error or you can pass the error message to the express default error handler.

app.post('/login', (req, res, next) => {
  passport.authenticate('local',
  (err, user, info) => {
    if (err) {
      return next(err);  // default express error handler - unauthorized 
    }

    if (!user) {
      return res.redirect('/signup'); // you can redirect user to signup page if needed
    }

    req.logIn(user, function(err) {
      if (err) {
        return next(err);
      }
      return res.redirect('/dashboard');
    });

  })(req, res, next);
});