计算总使用LINQ列在c＃

Question

我有这样

ID Description Principal Interest Total 
123 Paid  100   150  250 
    Balance  50   50   100 
    Total  ?   ?   ? 
124 Paid  100   150  250 
    Balance  50   50   100 
    Total  ?   ?   ? 

类的结构：

public class APIBillingHistory 
{ 
    public List<APIBillingHistoryDetails> BillingHistoryDetails; 
} 

public class APIBillingHistoryDetails 
{ 
    public string BillId; 
    public string Description; 
    public Decimal Principal; 
    public Decimal Interest; 
    public Decimal Total; 
} 

我想为每列总和值对于每个ID。因此，在上面的例子中，对于，ID 123的Total同样是150,Interest200。我在这里检查了这个解决方案How to create Total column and Total row using LINQ，但无法得到它。

代码：

responseObj = new APIBillingHistory 
{ 
    BillingHistoryDetails = billingHistory.BillingHistoryDetails 
      .GroupBy(detail => new { detail.BillId, detail.Description}) 
      .Select(group => new APIBillingHistoryDetails 
      { 
       BillId = group.Key.BillId, 
       Description = group.Key.Description, 
       Principal = group.Sum(t => t.Principal), 
       Interest = group.Sum(t => t.Interest), 
       Total = group.Sum(t => t.Principal) + group.Sum(t => t.Interest) 
      }).Concat(new APIBillingHistoryDetails 
      { 
       Description = "Total", 
       /* Not sure what to write over here */ 
      }) 
}; 

编辑：

为了澄清什么，我想实现：

• 我的源记录列表中不包含 “总计” 列& “总计” 行。我想手动添加它。
• 我能弄清楚如何添加将包含值的总和“总计”列。
• Principal & Interest将包含decimal格式的值。
• ID列是整数。我想正在通过聚合基于ID计算，即计算后，应该得到只显示Total行显示总计行每个ID
• 值Principal & Interest。

有什么建议吗？

Answer 1

由身份

BillId Description Principal Interest 
123 Paid  100   150  
123 Balance  50   50  
124 Paid  100   150  
124 Balance  50   50  

然后，只需组假设当前数据，通过总结分组属性设置描述为“总”创建总目标。

var totalsObj = new APIBillingHistory { 
    BillingHistoryDetails = billingHistory.BillingHistoryDetails 
      .GroupBy(detail => detail.BillId) 
      .Select(g => new APIBillingHistoryDetails { 
      BillId = g.Key, 
      Description = "Total", 
      Principal = g.Sum(detail => detail.Principal), 
      Interest = g.Sum(detail => detail.Interest), 
      Total = g.Sum(detail => detail.Principal) + g.Sum(detail => detail.Interest) 
      }).ToList() 
}; 

和totalsObj.BillingHistoryDetails本来期望了把

是经过计算，只有总计行应该得到显示。

BillId Description Principal Interest Total 
123 Total  150   200   350 
124 Total  150   200   350 

Answer 2

您不能使用Concat并参考以前的数据。您需要使用SelectMany：

BillingHistoryDetails = billingHistory.BillingHistoryDetails 
    .GroupBy(detail => detail.BillId) 
    .SelectMany(bg => bg.Concat(new[] { new APIBillingHistoryDetails { 
     BillId = bg.First().BillId, 
     Description = "Total", 
     Principal = bg.Sum(b => b.Principal), 
     Interest = bg.Sum(b => b.Interest), 
     Total = bg.Sum(b => b.Total) 
    } }));