如何在訂購後減去我的產品數量 - laravel 5.2

Question

我有一個產品表，我在那裏跟蹤產品數量。我在前端的用戶可以選擇他們想要添加到購物車的數量，然後購買。一旦他們購買產品，我想從該產品的產品表數量中減去他們購買的數量。

EX）所以他們買了2個iPhone，在Products表中有5個iPhone，我想在插入訂單後在Products表中有3個iPhone。

這裏是我的產品表（注意「product_qty」字段）

我order_product表（注意是「數量」這是買了該產品）

而我的後序功能：

public function postOrder(Request $request) { 

     // Validate each form field 
     $validator = Validator::make($request->all(), [ 
      'first_name' => 'required|max:30|min:2', 
      'last_name' => 'required|max:30|min:2', 
      'address' => 'required|max:50|min:4', 
      'address_2' => 'max:50|min:4', 
      'city'  => 'required|max:50|min:3', 
      'state'  => 'required|', 
      'zip'  => 'required|max:11|min:4', 
      'full_name' => 'required|max:30|min:2', 
     ]); 


     // If error occurs, display it 
     if ($validator->fails()) { 
      return redirect('/checkout') 
       ->withErrors($validator) 
       ->withInput(); 
     } 


     // Set Inputs to the the form fields so we can store them in DB 
     $first_name = Input::get('first_name'); 
     $last_name = Input::get('last_name'); 
     $address = Input::get('address'); 
     $address_2 = Input::get('address_2'); 
     $city = Input::get('city'); 
     $state = Input::get('state'); 
     $zip = Input::get('zip'); 
     $full_name = Input::get('full_name'); 

     // Set $user_id to the currently authenticated user 
     $user_id = Auth::user()->id; 

     // Set $cart_products to the Cart Model with its products where 
     // the user_id = to the current signed in user ID 
     $cart_products = Cart::with('products')->where('user_id', '=', $user_id)->get(); 

     // Set $cart_total to the Cart Model alond with all its products, and 
     // where the user_id = the current signed in user ID, and 
     // also get the sum of the total field. 
     $cart_total = Cart::with('products')->where('user_id', '=', $user_id)->sum('total'); 

     // Get the total, and set the charge amount 
     $charge_amount = number_format($cart_total, 2) * 100; 

     // Create the order in DB, and assign each variable to the correct form fields 
     $order = Order::create (
      array(
       'user_id' => $user_id, 
       'first_name' => $first_name, 
       'last_name' => $last_name, 
       'address' => $address, 
       'address_2' => $address_2, 
       'city'  => $city, 
       'state'  => $state, 
       'zip'  => $zip, 
       'total'  => $cart_total, 
       'full_name' => $full_name, 
      )); 

     // Attach all cart items to the pivot table with their fields 
     foreach ($cart_products as $order_products) { 
      $order->orderItems()->attach($order_products->product_id, array(
       'qty' => $order_products->qty, 
       'price' => $order_products->products->price, 
       'reduced_price' => $order_products->products->reduced_price, 
       'total' => $order_products->products->price * $order_products->qty, 
       'total_reduced' => $order_products->products->reduced_price * $order_products->qty, 
      )); 
     } 


     // Insert Quantity count here???? 


     // Delete all the items in the cart after transaction successful 
     Cart::where('user_id', '=', $user_id)->delete(); 

     // Then return redirect back with success message 
     flash()->success('Success', 'Your order was processed successfully.'); 

     return redirect()->route('cart'); 

    } 

如何獲得我剛購買的產品數量，然後從「產品」表格數量字段中減去它？

Answer 1

由於金槍魚說tuna在評論中說。

DB::table('products')->decrement('product_qty', $order_products->qty);