LINQ Group具有多个级别的对象
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; } } 你可以看到它有几个级别。 我已经声明了一个这样的变量：
UserSpend[] allSpend;
我填充，所以我有几个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;
以便userData包含以下内容：
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UserName，我想按描述进行分组并对金额求和。 我正在尝试学习LINQ并且一直在尝试使用GroupBy来实现这一点，但我没有得到任何结果。 请有人提供一个如何实现这一目标的例子。 非常感谢，科林。
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）进行分组。 它是在group ... by {spend, spendDetail.Description}使用匿名类型完成的group ... by {spend, spendDetail.Description} 。 请参阅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;