单个订单只能添加一个特价商品

app/Service/ShopCarService.php

@@ -27,6 +27,20 @@ class ShopCarService implements ShopCarServiceInterface
             ];
             return $error;
         }
+		//一个订单只能添加一个特价商品
+		if($params['money'] == 0.01){
+			$goods_exists = ShopCar::where([
+				['money','=',0.01],
+				['user_id','=',$params['user_id']]
+			])
+			->exists();
+			if($goods_exists){
+				$error = [
+					'error' => '一个订单只能添加一个特价商品'
+				];
+				return $error;
+			}
+		}
         //获取主表商品表信息
         $goods = Goods::where([
                 ['id','=',$params['good_id']],