Undefined property: App\Cart::$totalPrice - laravel

Question

Hello I am making a cart but when I click on add to cart link then it says:
Undefined property: App\Cart::$totalPrice
Error: https://ibb.co/ysB5CfG
model:
<?php
namespace App;
use Illuminate\Database\Eloquent\Model;
class Cart
{
private $contents;
private $totalQty;
private $contentsPrice;
public function __construct($oldCart){
if ($oldCart) {
$this->contents = $oldCart->contents;
$this->totalQty = $oldCart->totalQty;
$this->totalPrice = $oldCart->totalPrice;
}
}
public function addProduct($product, $qty){
$products = ['qty' => 0, 'price' => $product->price, 'product' => $product];
if ($this->contents) {
if (array_key_exists($product->slug, $this->contents)) {
$product = $this->contents[$product->slug];
}
}
$products['qty'] +=$qty;
$products['price'] +=$product->price * $product['qty'];
$this->contents[$product->slug] = $product;
$this->totalQty+=$qty;
$this->totalPrice += $product->price;
}
public function getContents()
{
return $this->contents;
}
public function getTotalQty()
{
return $this->totalQty;
}
public function getTotalPrice()
{
return $this->totalPrice;
}
}
controller:
public function cart()
{
if (!Session::has('cart')) {
return view('products.cart');
}
$cart = Session::has('cart');
return view('product.cart', compact('cart'));
}
public function addToCart(Product $product, Request $request, $qty= null)
{
if(empty(Auth::user()->email)){
$data['email'] = '';
}else{
$data['email'] = Auth::user()->email;
}
$oldCart = Session::has('cart') ? Session::get('cart') : null;
$qty = $request->qty ? $request->qty : 1;
$cart = new Cart($oldCart);
$cart->addProduct($product, $qty);
Session::put('cart', $cart);
return redirect()->back()->with('flash_message_success', 'Product $product->title has been successfully added to Cart');
}
routes:
Route::get('cart', 'Admin\ProductController#cart')->name('product.cart');
// Add to cart
Route::get('/addToCart/{product}/{qty?}', 'Admin\ProductController#addToCart')->name('addToCart');

Answer 1

You should use get() methods in cart() function in controller file.
public function cart()
{
if (!Session::has('cart')) {
return view('products.cart');
}
$cart = Session::get('cart');
return view('product.cart', compact('cart'));
}