Question

DealsThisMonthOpen = deals.Where(deal => deal.DateCreated.Month == date.Month && deal.DealStatus == "Open").Count(),
DealsThisMonthLost = deals.Where(deal => deal.DateCreated.Month == date.Month && deal.DealStatus == "Lost").Count(),
DealsThisMonthWon = deals.Where(deal => deal.DateCreated.Month == date.Month && deal.DealStatus == "Won").Count(),
DealsThisMonth = DealsThisMonthOpen + DealsThisMonthLost + DealsThisMonthWon;

最后一行语法不正确。是否可以这样做，或者我必须为此属性编写查询以计算总和？

由于

Answer 1

btw，Count()也支持predicate参数： http://msdn.microsoft.com/en-us/library/bb535181.aspx

所以你可以：

var a = deals.Count(deal => deal.DateCreated.Month == date.Month && deal.DealStatus == "Open"),
var b = deals.Count(deal => deal.DateCreated.Month == date.Month && deal.DealStatus == "Lost"),
var c = deals.Count(deal => deal.DateCreated.Month == date.Month && deal.DealStatus == "Won"),

new foobar
{
    DealsThisMonthOpen = a,
    DealsThisMonthLost = b,
    DealsThisMonthWon = c,
    DealsThisMonth = a + b + c
};

Answer 2

也许我错过了什么，但这肯定有用。

Count(）方法返回int，因此DealsThisMonthOpen，DealsThisMonthLost和DealsThisMonthWon都是整数值。 DealsThisMonth只是这三个整数值的总和。

你也可以让它更清洁一些（除非你以后需要三个不同的值：

var dealsThisMonth = deals
    .Count(d => d.DateCreated.Month == date.Month
        && (new string[] { "Open", "Lost", "Won" }).Contains(d.DealStatus));

Answer 3

您是否考虑过扩展方法？您提供总和功能的地方。

使用LINQ求和属性

3 个答案: