C# 具有多个级别的对象上的LINQ GroupBy

我有一些类声明如下：

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; }
}

UserSpend[] allSpend;

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") ] ]

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]

正如你所见，它有几个层次。我声明了一个如下的变量：

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; }
}

UserSpend[] allSpend;

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") ] ]

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]

我填充了几个UserSpend，每个都有几个MonthSpend，每个都有几个SpendDetail。因此，数据如下所示：

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; }
}

UserSpend[] allSpend;

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") ] ]

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]

我要做的是填充此变量：

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：

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; }
}

UserSpend[] allSpend;

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") ] ]

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，我想按描述进行分组，并计算总数。我正在努力学习LINQ，并一直在尝试使用GroupBy来实现这一点，但我没有取得任何进展。请有人提供一个如何实现这一点的例子。非常感谢，科林。

在LINQ中使用语法查询：

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)
           };

这里的困难在于按多个列（用户名和类别）分组。它是使用

组中的匿名类型完成的。。。通过{spend，spendDetail.Description}

。看

更新 下面是一个更好的版本（不需要复杂的

GroupBy

）：

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对于大收藏来说，它会有成效吗？你所说的大收藏是什么意思？1000? 100000? 10000000？我是说1000个用户，20个月，50个花费的细节。你确定交叉连接是这里最好的解决方案吗？非常感谢大家