Updated code for updateProductQuantity controller and route changed to POST

controllers/productControllers.js

@@ -356,37 +356,37 @@ exports.updateProductQuantity = async (req, res) => {
   try {
     const { productId, quantity } = req.body;
 
-      // Find the user
-      const user = await User.findById(req.user.id);
-
-      if (!user.myCart) {
-        return res.status(400).json({ message: 'Cart is empty' });
-      }
-
-      const itemIndex = user.myCart.findIndex(item => item.productId === productId);
-
-      if (itemIndex === -1) {
-        return res.status(404).json({ message: 'Product not found in cart' });
-      }
-
     // Validate quantity (e.g., must be positive, not exceed available inventory)
     if (quantity <= 0) {
       return res.status(400).json({ message: 'Quantity must be greater than zero' });
     }
 
-      // Update quantity in the cart
-      user.myCart[itemIndex].quantity = quantity;
+    // Update quantity in the cart using findByIdAndUpdate
+    const updatedUser = await User.findByIdAndUpdate(
+      req.user.id,
+      { $set: { 'myCart.$[element].quantity': quantity } },
+      { 
+        new: true, // return the updated document
+        arrayFilters: [{ 'element.productId': productId }] // update the element where productId matches
+      }
+    );
 
-      await user.save(); // Save the updated cart
+    if (!updatedUser) {
+      return res.status(404).json({ message: 'User not found' });
+    }
 
-      res.json({ message: 'Product quantity updated successfully' });
-      console.log(user.myCart);
+    if (!updatedUser.myCart) {
+      return res.status(400).json({ message: 'Cart is empty' });
+    }
+
+    res.json({ message: 'Product quantity updated successfully', updatedCart: updatedUser.myCart });
   } catch (error) {
     console.error(error);
     res.status(500).json({ message: 'Error updating product quantity' });
   }
 };
 
+
 exports.removeProductFromCart = async (req, res) => {
   try {
     const productId = req.params.productId;

routes/productRoutes.js

@@ -44,7 +44,7 @@ router.post('/getProductName', productControllers.getProductName);
 // My Cart
 
 router.post('/add-to-cart', verify, verifyNonAdmin, productControllers.addProductToCart);
-router.put('/update-quantity', productControllers.updateProductQuantity);
+router.post('/update-quantity', verify, verifyNonAdmin, productControllers.updateProductQuantity);
 router.delete('/remove/:productId', verify, verifyNonAdmin, productControllers.removeProductFromCart);
 router.post('/view-my-cart', verify, verifyNonAdmin, productControllers.getCartDetails);