Question

我正在尝试将 RestaurantReservationEventsTbl 中的 RestaurantId 与 RestaurantTbl 中的 RestaurantID 相关联以显示仅对当前登录的餐厅进行的预订。

我在代码中收到以下错误 operator ==无法应用于int类型的操作数和iqueryable int

以下是我在家庭控制器中所做的事情

var RestaurantIDRestaurantTbl = from r in db.Restaurants select r.RestaurantID;
//var listOfRestaurantsReservations = db.RestaurantReservationEvents.ToList();
var listOfRestaurantsReservations = db.RestaurantReservationEvents.Where(x => x.RestaurantID == RestaurantIDRestaurantTbl).ToList();
//return View(restaurants.Where(x => x.RestaurantEmailAddress == UserEmail).ToList());
//create partial view called _RestaurantReservation
return PartialView("_RestaurantReservations", listOfRestaurantsReservations);

Answer 1

您必须更改代码才能实现restaurantIds，如下所示：

var RestaurantIDRestaurantTbl = (from r in db.Restaurants
                                 select r.RestaurantID).ToList();

然后您可以更改下面的代码以进行比较：

 var listOfRestaurantsReservations = db.RestaurantReservationEvents.Where(x => RestaurantIDRestaurantTbl.Contains(x.RestaurantID)).ToList();

无论如何，这不是最好的解决方案。我会为你写另一个例子，试试这个例子是否有效，让我知道结果。

我会考虑更改下面的代码以提高效率：

var listOfRestaurantsReservations = (from r in db.Restaurants
                                    join e in  db.RestaurantReservationEvents 
                                    on r.RestaurantID equals e.RestaurantID
                                    //where r.RestaurantID == something //if where condition needed
                                    select e).ToList();

如果你的表没有与外键相关联，请考虑阅读本文档here以更好地构建表格，因为它们彼此相关。

如果您的表格与文档文章相关，那么您可能会有类似的内容：

var RestaurantIDRestaurantTbl = db.Restaurants.SingleOrDefault(x => x.RestaurantID == something);
if(RestaurantIDRestaurantTbl != null)
{
   var listOfRestaurantsReservations = RestaurantIDRestaurantTbl.RestaurantReservationEvents.ToList();
}

Answer 2

{
    // This will give you a list of IDs
    var RestaurantIDRestaurantTbl = db.Restaurants
        .Select(p => p.RestaurantID)
        .ToList();

    // Using .Any() is a better choice instead of .Contains()
    // .Contains is used to check if a list contains an item while .Any will look for an item in a list with a specific ID
    var listOfRestaurantsReservations = db.RestaurantReservationEvents
        .Where(p => RestaurantIDRestaurantTbl.Any(r => r.pRestaurantID == p))
        .ToList();
}

如何链接MVC5中不同类的两个ID以显示某些信息

2 个答案: