如何使用linqc#在字典中过滤嵌套集合

本文关键字：过滤 嵌套 集合 字典 何使用 linqc# | 更新日期: 2023-09-27 17:53:05

这是我的实体结构

Transaction Entity 
TransactionID, CompanyID  TransactionItems
  1             10           List<TransactionItems>
  2             10           List<TransactionItems>
  3             20           List<TransactionItems>
TransactionItems Entity
TransactionItemID TransactionID Value Postive Negative
1                  2            10    yes   
2                  2            20    yes
3                  2            30           yes   
4                  3            100          yes    
5                  3            200   yes   
I need to sum the values of Value based on positive or negative flag and then compute total like this
CompanyID Postive Negative
10          30     30
20          200    100

业务层的函数返回Dictionary<int, List<Transaction>>，它基本上是这样的

Key         Value
CompanyID, List<Transaction>

到目前为止我只完成了这个

 _Transaction.GetCompanyTransactions().
                Select(_Company => new
                {
                    Company = _Company.Key,
                    Positive = 
                    Negative =
                });

有谁能帮忙吗

如何使用linqc#在字典中过滤嵌套集合

您只需将列表中的值字段相加:

_Transaction.GetCompanyTransactions()
    .Select(g => new { 
        CompanyId = g.Key, 
        Positive = g.Value.SelectMany(t => t.TransactionItems).Where(t => t.Positive).Sum(t => t.Value), 
        Negative = g.Value.SelectMany(t => t.TransactionItems).Where(t => t.Negative).Sum(t => t.Value)})
        });

需要根据Positive/Negative标志对值进行Sum。

它分两步完成:首先需要Sum内部项，然后Sum内部和。

_Transaction.GetCompanyTransactions()
            .Select(g => new
            {
                Company = g.Key,
                Positive = g.Value.Sum(t => t.TransactionItems.Where(x => x.Positive).Sum(x => x.Value)),
                Negative = g.Value.Sum(t => t.TransactionItems.Where(x => x.Negative).Sum(x => x.Value)),
            });
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