Recently I was playing around with Passport.js in an Express application. I created a login route that logged like that:

passport.authenticate('local', {
    successRedirect: '/app',
    failureRedirect: '/login',
    failureFlash: false
});

Everything worked fine and I could login to my application but I also wanted to show a message when the login fails. So I changed my route to:

passport.authenticate('local', {
    successRedirect: '/app',
    failureRedirect: '/login',
    failureFlash: true
});

Instead of redirect back to the login page I got this exception:

Object #<IncomingMessage> has no method 'flash' undefined TypeError: Object #<IncomingMessage> has no method 'flash' at allFailed

The solution for this is simple. I forgot to include the connect-flash module that provides the flash method. So I changed my startup code:

var flash = require('connect-flash');
app.use(cookieParser());
app.use(flash());

Even so the solution is quite simple and somehow obvious. It doesn’t seem right that changing a property to true introduces the need for a new middleware.