Sum of product prices in the shopping cart

this not work I want to add prices together by deducting the discount price

one cart with multiple products

Ok so I dont know the full context here and its kind of confusing with caregories and coupons looping before you loop over the products. but maybe you should be doing something like this

				$cartTotal = 0;
                foreach ($this->carts as  $cartProduct) {
                    $cartProduct->coupon_id = $coupons[0]->id;
					$cartTotal += $total 
                }
				$this->carts->final_price = $cartTotal ;
				$this->carts->save();  

Ideally you should loop over the cart's product first .. On each iteration apply the discount to product. and add to total .

Sorry, this did not work😢

if you are just copy-pasting then it wont. I am just giving you ideas now . You clearly need to refactor this method.

I refracted your code but it does not give the desired result This is my shopping cart collection

Illuminate\Support\Collection {#1829 ▼
  #items: array:3 [▼
    0 => App\Course {#1853 ▶}
    1 => App\Course {#1852 ▶}
    2 => App\Course {#1851 ▶}
  ]
}

not working

paste your updated code here, let's see

    public function getPriceAfterApplyCoupon()
    {
        foreach ($this->categories as $category) {
            $coupons = $category->validCoupons();
            if ($coupons->isNotEmpty()) {
                $amount = $this->price;
                $discount = ($amount * $coupons[0]->percent) / 100;
                $total = $amount - $discount;
                foreach ($this->carts as  $cart) {
                    $cart->coupon_id = $coupons[0]->id;
                    //this code should working
                    $cart->final_price = $total;
                    $cart->save();
                }
                return number_format($cart->final_price);
            }
        }

        return $this->price;
    }

in your table, i take it that final price is the price for an item yes or is it the total price?

This is how my card table is structured

        Schema::create('carts', function (Blueprint $table) {
            $table->id();
            $table->foreignId('user_id')->constrained('users')->cascadeOnDelete();
            $table->foreignId('coupon_id')->nullable()->constrained('coupons')->cascadeOnDelete();
            $table->string('status');
            $table->integer('price')->default(0);
            $table->integer('final_price')->default(0);
            $table->dateTime('expired_at');
            $table->timestamps();
        });

        Schema::create('cart_course', function (Blueprint $table) {

            $table->foreignId('cart_id')->constrained('carts')->cascadeOnDelete();
            $table->foreignId('course_id')->constrained('courses')->cascadeOnDelete();
        });

if you're trying to get the total price, use this

I have a collection of courses on my card Some of these courses are discounted Some others do not have a discount Now I want to add the prices of these courses together and save them in the final price field on the card

so thats why i recommended that you start with a foreach loop on cart

	foreach($this->cart as $cartItem) { 
		$cartTotal = 0;
		
		// check if this cart Item has discount 

		// check for discount coupons
		// if yes . Apply the discount 
		
		// $cartItem->price = $cartItem->price() - $discount;
		
		// Add total to $cartTotal 
		// $cartTotal += $cartItem->price

	} 
	// outside the loop
	return $cartTotal ;