Updated add to cart controller

controllers/productControllers.js

@@ -318,11 +318,18 @@ exports.addProductToCart = async (req, res) => {
       user.myCart = [];
     }
 
+    // Check if the product already exists in the cart
     const existingItemIndex = user.myCart.findIndex(item => item.productId === productId);
 
     if (existingItemIndex !== -1) {
       // Update quantity of existing item
-        user.myCart[existingItemIndex].quantity += quantity;
+      await User.findByIdAndUpdate(
+        req.user.id,
+        {
+          $inc: { [`myCart.${existingItemIndex}.quantity`]: quantity } // Increment the quantity field
+        },
+        { new: true } // Return the updated user after the operation
+      );
     } else {
       if (quantity <= 0) {
         return res.json({ message: 'Provide valid quantity' });
@@ -334,9 +341,8 @@ exports.addProductToCart = async (req, res) => {
         name: product.name,
         quantity
       });
-      }
-
       await user.save(); // Save the updated user with cart items
+    }
 
     res.json({ message: 'Product added to cart successfully' });
   } catch (error) {
@@ -345,6 +351,7 @@ exports.addProductToCart = async (req, res) => {
   }
 };
 
+
 exports.updateProductQuantity = async (req, res) => {
   try {
       const { productId, quantity } = req.body;