3

我有一些这样声明的类：

public class UserSpend
{
    public string UserName{ get; set; }
    public MonthSpend[] Spend { get; set; }

}

public class MonthSpend
{
    public DateTime Month { get; set; }
    public SpendDetail[] Detail { get; set; }

}

public class SpendDetail
{
    public string Description { get; set; }
    public decimal Amount { get; set; }
}

如您所见，它有几个级别。我已经声明了一个这样的变量：

UserSpend[] allSpend;

我填充了几个 UserSpend，每个都有几个 MonthSpend，每个都有几个 SpendDetail。所以数据看起来像这样：

allSpend =
UserSpend (UserName = "Bob", Spend = [
        MonthSpend (Month = "01/09/12", Detail = [
            SpendDetail (Description = "Local", Amount = "12.00"),
            SpendDetail (Description = "National", Amount = "7.00") ]
        MonthSpend (Month = "01/10/12", Detail = [
            SpendDetail (Description = "Local", Amount = "8.00"),
            SpendDetail (Description = "Mobile", Amount = "3.00"),
            SpendDetail (Description = "National", Amount = "15.00") ]
        MonthSpend (Month = "01/11/12", Detail = [
            SpendDetail (Description = "Local", Amount = "16.00"),
            SpendDetail (Description = "National", Amount = "5.00") ] ]
UserSpend (UserName = "Jack", Spend = [
        MonthSpend (Month = "01/09/12", Detail = [
            SpendDetail (Description = "Local", Amount = "1.00"),
            SpendDetail (Description = "National", Amount = "4.00"),
            SpendDetail (Description = "International", Amount = "17.00") ]
        MonthSpend (Month = "01/10/12", Detail = [
            SpendDetail (Description = "Local", Amount = "2.00"),
            SpendDetail (Description = "Mobile", Amount = "7.00"),
            SpendDetail (Description = "International", Amount = "5.00") ]
        MonthSpend (Month = "01/11/12", Detail = [
            SpendDetail (Description = "Local", Amount = "6.00"),
            SpendDetail (Description = "National", Amount = "2.00") ] ]

我想做的是填充这个变量：

public class UserDataPoint
{
    public string User { get; set; }
    public string Category { get; set; }
    public int Spend { get; set; }
}

UserDataPoint[] userData;

因此 userData 包含如下内容：

userData = UserDataPoint (
[User = "Bob", Category = "Local", Spend = 36.00]
[User = "Bob", Category = "Mobile", Spend = 3.00]
[User = "Bob", Category = "National", Spend = 27.00]
[User = "Jack", Category = "Local", Spend = 9.00]
[User = "Jack", Category = "Mobile", Spend = 6.00]
[User = "Jack", Category = "National", Spend = 7.00]
[User = "Jack", Category = "International", Spend = 22.00]

因此，对于每个用户名，我想按描述分组并对金额求和。我正在尝试学习 LINQ 并一直在尝试使用 GroupBy 来实现这一点，但我没有得到任何结果。请有人提供如何实现这一目标的示例。非常感谢，科林。

4

1 回答 1

3

使用 LINQ 中的语法查询：

userData = from spend in allSpend
           from monthSpend in spend.Spend
           from spendDetail in monthSpend.Detail
           group spendDetail by new {spend, spendDetail.Description} into g
           select new UserDataPoint
           {
               User = g.Key.spend.UserName,
               Category = g.Key.Description,
               Spend = g.Sum(t => t.Amount)
           };

这里的困难是按多列（用户名和类别）分组。它是使用匿名类型在group ... by {spend, spendDetail.Description}. 见Stackoverflow

更新

这是一个更好的版本（不需要复杂的GroupBy）：

userData = from spend in allSpend
           from userDataPoint in
               (from monthSpend in spend.Spend
               from spendDetail in monthSpend.Detail
               group spendDetail by spendDetail.Description into g
               select new UserDataPoint
               {
                   User = spend.UserName,
                   Category = g.Key,
                   Spend = g.Sum(t => t.Amount)
               })
           select userDataPoint;
于 2013-07-24T12:02:37.363 回答