Adapted to work with the most recent module versions

.gitignore

@@ -1,2 +1,2 @@
 node_modules
-.vscode/*
+config/.env

config/database.js

@@ -5,8 +5,6 @@ const connectDB = async () => {
     const conn = await mongoose.connect(process.env.DB_STRING, {
       useNewUrlParser: true,
       useUnifiedTopology: true,
-      useFindAndModify: false,
-      useCreateIndex: true
     })
 
     console.log(`MongoDB Connected: ${conn.connection.host}`)

config/passport.js

@@ -3,31 +3,43 @@ const mongoose = require('mongoose')
 const User = require('../models/User')
 
 module.exports = function (passport) {
-  passport.use(new LocalStrategy({ usernameField: 'email' }, (email, password, done) => {
-    User.findOne({ email: email.toLowerCase() }, (err, user) => {
-      if (err) { return done(err) }
-      if (!user) {
-        return done(null, false, { msg: `Email ${email} not found.` })
-      }
-      if (!user.password) {
-        return done(null, false, { msg: 'Your account was registered using a sign-in provider. To enable password login, sign in using a provider, and then set a password under your user profile.' })
-      }
-      user.comparePassword(password, (err, isMatch) => {
-        if (err) { return done(err) }
-        if (isMatch) {
-          return done(null, user)
+  passport.use(
+    new LocalStrategy({ usernameField: 'email' }, async (email, password, done) => {
+      try {
+        const user = await User.findOne({ email: email.toLowerCase() }).exec();
+
+        if (!user) {
+          return done(null, false, { msg: `Email ${email} not found.` });
+        }
+        if (!user.password) {
+          return done(null, false, {
+            msg: 'Your account was registered using a sign-in provider. To enable password login, sign in using a provider, and then set a password under your user profile.',
+          });
         }
-        return done(null, false, { msg: 'Invalid email or password.' })
-      })
+
+        user.comparePassword(password, (err, isMatch) => {
+          if (err) { return done(err) }
+          if (isMatch) {
+            return done(null, user)
+          }
+          return done(null, false, { msg: 'Invalid email or password.' })
+        })
+      } catch (err) {
+        return done(err);
+      }
     })
-  }))
-
+  )
 
   passport.serializeUser((user, done) => {
     done(null, user.id)
   })
 
-  passport.deserializeUser((id, done) => {
-    User.findById(id, (err, user) => done(err, user))
-  })
+  passport.deserializeUser(async (id, done) => {
+    try {
+      const user = await User.findById(id).exec();
+      done(null, user);
+    } catch (err) {
+      done(err, null);
+    }
+  });
 }

controllers/auth.js

@@ -37,15 +37,18 @@ const User = require('../models/User')
   }
 
   exports.logout = (req, res) => {
-    req.logout(() => {
-      console.log('User has logged out.')
-    })
-    req.session.destroy((err) => {
-      if (err) console.log('Error : Failed to destroy the session during logout.', err)
-      req.user = null
-      res.redirect('/')
-    })
-  }
+    req.logout(function (err) {
+      if (err) {
+        return next(err);
+      }
+      req.session.destroy((err) => {
+        if (err) console.log("Error : Failed to destroy the session during logout.", err);
+        req.user = null;
+        res.redirect("/");
+      });
+    });
+  };
+
 
   exports.getSignup = (req, res) => {
     if (req.user) {
@@ -56,41 +59,54 @@ const User = require('../models/User')
     })
   }
 
-  exports.postSignup = (req, res, next) => {
-    const validationErrors = []
-    if (!validator.isEmail(req.body.email)) validationErrors.push({ msg: 'Please enter a valid email address.' })
-    if (!validator.isLength(req.body.password, { min: 8 })) validationErrors.push({ msg: 'Password must be at least 8 characters long' })
-    if (req.body.password !== req.body.confirmPassword) validationErrors.push({ msg: 'Passwords do not match' })
+  exports.postSignup = async (req, res, next) => {
+    try {
+      const validationErrors = [];
+      if (!validator.isEmail(req.body.email))
+        validationErrors.push({ msg: 'Please enter a valid email address.' });
+      if (!validator.isLength(req.body.password, { min: 8 }))
+        validationErrors.push({ msg: 'Password must be at least 8 characters long' });
+      if (req.body.password !== req.body.confirmPassword)
+        validationErrors.push({ msg: 'Passwords do not match' });
 
-    if (validationErrors.length) {
-      req.flash('errors', validationErrors)
-      return res.redirect('../signup')
-    }
-    req.body.email = validator.normalizeEmail(req.body.email, { gmail_remove_dots: false })
+      if (validationErrors.length) {
+        req.flash('errors', validationErrors);
+        return res.redirect('../signup');
+      }
+      req.body.email = validator.normalizeEmail(req.body.email, {
+        gmail_remove_dots: false,
+      });
 
-    const user = new User({
-      userName: req.body.userName,
-      email: req.body.email,
-      password: req.body.password
-    })
+      const existingUser = await User.findOne({
+        $or: [
+          { email: req.body.email },
+          { userName: req.body.userName },
+        ],
+      }).exec();
 
-    User.findOne({$or: [
-      {email: req.body.email},
-      {userName: req.body.userName}
-    ]}, (err, existingUser) => {
-      if (err) { return next(err) }
       if (existingUser) {
-        req.flash('errors', { msg: 'Account with that email address or username already exists.' })
-        return res.redirect('../signup')
+        req.flash('errors', {
+          msg: 'Account with that email address or username already exists.',
+        });
+        return res.redirect('../signup');
       }
-      user.save((err) => {
-        if (err) { return next(err) }
-        req.logIn(user, (err) => {
-          if (err) {
-            return next(err)
-          }
-          res.redirect('/todos')
-        })
-      })
-    })
-  }
+
+      const user = new User({
+        userName: req.body.userName,
+        email: req.body.email,
+        password: req.body.password,
+      });
+
+      await user.save();
+
+      req.logIn(user, (err) => {
+        if (err) {
+          return next(err);
+        }
+        res.redirect('/todos');
+      });
+    } catch (err) {
+      return next(err);
+    }
+  };
+