如何使用Passport JS在登录逻辑中添加错误/成功消息？

npm install passport passport-local express-session connect-flash

const passport = require('passport');
const LocalStrategy = require('passport-local').Strategy;
const session = require('express-session');
const flash = require('connect-flash');

app.use(session({
  secret: 'your-secret-key',
  resave: false,
  saveUninitialized: false
}));
app.use(passport.initialize());
app.use(passport.session());
app.use(flash());

passport.use(new LocalStrategy({
  usernameField: 'email',
  passwordField: 'password',
  passReqToCallback: true
}, (req, email, password, done) => {
  // 在此处进行用户认证逻辑的实现
}));

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

app.post('/login', passport.authenticate('local', {
  successRedirect: '/dashboard',
  failureRedirect: '/login',
  failureFlash: true
}), (req, res) => {
  req.flash('success', '登录成功！');
  res.redirect('/dashboard');
});

<% if (messages.error) { %>
  <div class="alert alert-danger">
    <%= messages.error %>
  </div>
<% } %>

<% if (messages.success) { %>
  <div class="alert alert-success">
    <%= messages.success %>
  </div>
<% } %>