Updated add to cart controller

controllers/productControllers.js

@@ -307,43 +307,50 @@ async function updateProductInventory(cartItems) {
 // My Cart
 
 exports.addProductToCart = async (req, res) => {
-   try {
-      const { productId, quantity } = req.body;
+  try {
+    const { productId, quantity } = req.body;
 
-      // Find the user
-      const user = await User.findById(req.user.id);
+    // Find the user
+    const user = await User.findById(req.user.id);
 
-      // Check if the cart array exists
-      if (!user.myCart) {
-        user.myCart = [];
-      }
+    // Check if the cart array exists
+    if (!user.myCart) {
+      user.myCart = [];
+    }
 
-      const existingItemIndex = user.myCart.findIndex(item => item.productId === productId);
+    // 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;
-      } else {
-        if (quantity <= 0) {
-          return res.json({ message: 'Provide valid quantity' });
-        }
-        // Add new item to cart
-        const product = await Product.findById(productId);
-        user.myCart.push({
-          productId,
-          name: product.name,
-          quantity
-        });
+    if (existingItemIndex !== -1) {
+      // Update quantity of existing item
+      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' });
       }
-
+      // Add new item to cart
+      const product = await Product.findById(productId);
+      user.myCart.push({
+        productId,
+        name: product.name,
+        quantity
+      });
       await user.save(); // Save the updated user with cart items
-
-      res.json({ message: 'Product added to cart successfully' });
-    } catch (error) {
-      console.error(error);
-      res.status(500).json({ message: 'Error adding product to cart' });
     }
-  };
+
+    res.json({ message: 'Product added to cart successfully' });
+  } catch (error) {
+    console.error(error);
+    res.status(500).json({ message: 'Error adding product to cart' });
+  }
+};
+
 
 exports.updateProductQuantity = async (req, res) => {
   try {