decrease stock quantity at order placement in laravel

Question

I want to decrease quantity from products table when order is added to cart ,right now when I add something to cart, correct quantity is not decreasing. For example if a I place order of 6 items then a random amount gets decreased from my products table.

Here is my code in order controller of livewire:

public function IncrementQty($cartId)
{
    $carts=Cart::find($cartId);

    $carts->increment('product_qty',1);
    $updatePrice=$carts->product_qty * $carts->product->price;
    $carts->update(['product_price'=>$updatePrice]);

    $getProductStock=Product::where(['id'=>$carts['product_id']])->first()->toArray();
    $newStock=$getProductStock['quantity'] - $carts['product_qty'];
    Product::where(['id'=>$carts['product_id']])->update(['quantity'=>$newStock]);
    
    $this->mount();
}

Being a beginner I am unable to understand about what's wrong here. Should I be substracting it from orderDetails table instead of carts table? If yes then how?

Answer 1

A couple of things to note first,

1. You should not call $this->mount() or any other lifecycle hooks from Livewire. If there are code inside your mount-method you need to run again, then abstract it into a separate method, and call it from both your mount() method and your IncrementQty() method.

2. You can use model-route-binding to inject the correct model into the method

   public function IncrementQty(Cart $cart)
   

You can then simplify your code by using the product relation on the cart directly, and calling decrement() on that.

public function IncrementQty(Cart $cart)
{
    $product = $cart->product;
    $cart->increment('product_qty', 1);
    $cart->update(['product_price' => $cart->product_qty * $product->price]);

    $product->decrement('quantity', 1);
    
    $this->mount(); // Do not call mount manually, abstract the contents you need into a separate method instead
}

If you are still experiencing issues, then it cannot possibly be this piece of code, or you are misreading your data somehow - in any case, if you are still experiencing issues, you will need to provide additional information with your table-structure, models, how you call this method, and data before and after your actions.