Node.js Web 应用：Passport.js failureRedirect display message in ejs

Question

I am using Passport.js to authenticate user login. This is my code at the moment:

app.post('/login', passport.authenticate('local', {
  failureRedirect: '/login',
  successRedirect: "/secrets",
  failureMessage: "Incorrect password"
}));

Basically, if authentication succeeds it will direct to the "secrets" page; if authentication fails it will redirect back to "login" page.

The authentication works well in this case; however, when the authentication fails and it redirects back to the login page, I also want the failureMessage to display in a ejs template I have for the login page. How can I do that?

I want something like this in ejs (but this code does not work, of course):

<a> <%= failureMessage %> </a>

Answer 1

Including failureMessage: 'message' as you have done above adds your message to the session, which can then be accessed via the request object in the route handler, assuming you have session authentication set up. In the route handler for GET requests to /login (where you are redirecting to in the event of authentication failure) you can pass the messages array on the session to your ejs template:

app.get('/login', (req, res) => {res.render('login', {messages: req.session.messages})});

You can then access messages in the login.ejs template with something like this:

<a> <%= messages[0] %> </a>

From the docs: This (the failureRedirect option) is often paired with the failureMessage option, which will add an informative message to the session about why authentication failed which can then be displayed to the user. https://www.passportjs.org/concepts/authentication/