diff --git a/utils/authOptions.js b/utils/authOptions.js
index 2e59c1b..aa96976 100644
--- a/utils/authOptions.js
+++ b/utils/authOptions.js
@@ -1,3 +1,6 @@
+import connectDB from '@/config/database';
+import User from '@/models/User';
+
 import GoogleProvider from 'next-auth/providers/google';
 
 export const authOptions = {
@@ -15,18 +18,34 @@ export const authOptions = {
     }),
   ],
   callbacks: {
-    // Invoked on successful sign in
+    // Invoked on successful signin
     async signIn({ profile }) {
       // 1. Connect to database
-      // 2. Check if user exists in database
-      // 3. If not, create user in database
-      // 4. return true to allow sign in
+      await connectDB();
+      // 2. Check if user exists
+      const userExists = await User.findOne({ email: profile.email });
+      // 3. If not, then add user to database
+      if (!userExists) {
+        // Truncate user name if too long
+        const username = profile.name.slice(0, 20);
+
+        await User.create({
+          email: profile.email,
+          username,
+          image: profile.picture,
+        });
+      }
+      // 4. Return true to allow sign in
+      return true;
     },
-    // Session callback function that modifies the session object
+    // Modifies the session object
     async session({ session }) {
       // 1. Get user from database
-      // 2. Assign user id from database to session
+      const user = await User.findOne({ email: session.user.email });
+      // 2. Assign the user id to the session
+      session.user.id = user._id.toString();
       // 3. return session
+      return session;
     },
   },
 };