C# of）为什么作出IEnumerable声明。我认为这个变量是多余的。您只需将两个LINQ一起Concat（）并返回结果IMHO_C#_Linq_Linq To Sql

C# of）为什么作出IEnumerable声明。我认为这个变量是多余的。您只需将两个LINQ一起Concat（）并返回结果IMHO

c# linq linq-to-sql

C# of）为什么作出IEnumerable声明。我认为这个变量是多余的。您只需将两个LINQ一起Concat（）并返回结果IMHO,c#,linq,linq-to-sql,C#,Linq,Linq To Sql,有点像这样： public static IEnumerable<TradeContribution> GetTradeContributions(uint portfolioId, List<uint> portfolioIdList, IEnumerable<DateTime> nodeDateList, int? whatIfBatchNumber = null) { var originalItems = (from tc in xml.XPa

有点像这样：

public static IEnumerable<TradeContribution> GetTradeContributions(uint portfolioId, List<uint> portfolioIdList, IEnumerable<DateTime> nodeDateList, int? whatIfBatchNumber = null)
{
    var originalItems = (from tc in xml.XPathSelectElement("body/portfolios/portfolio/contributions").Elements("tradeContribution")
    select new TradeContribution
    {
      SysId = tc.Attribute("sysId") == null ? 0 : int.Parse(tc.Attribute("sysId").Value),
      TradeContextId = tc.Attribute("contextId") == null ? 0 : int.Parse(tc.Attribute("contextId").Value),
      TradeId = tc.Attribute("tradeId") == null ? "" : tc.Attribute("tradeId").Value,
      ProductType = tc.Attribute("desc").Value,
      ProductDescription = tc.Attribute("desc").Value, // TODO: In future could lookup the description in a reference data cache
      Contribution = decimal.Parse(tc.Attribute("contribution").Value)
  })
  .OrderByDescending(x => x.Contribution);



// ... code omitted for brevity

// THIS IS MY NEW CODE TO HANDLE THE NEW REQUIREMENTS
    var additionalItems = xml.XPathSelectElements("body/portfolios/portfolio")
        .SelectMany(pfElem => 
        {
            (from tc in pfElem.XPathSelectElement("contributions").Elements("tradeContribution")
          select new TradeContribution
          {
          SysId = tc.Attribute("sysId") == null ? 0 : int.Parse(tc.Attribute("sysId").Value),
          TradeContextId = tc.Attribute("contextId") == null ? 0 : int.Parse(tc.Attribute("contextId").Value),
          TradeId = tc.Attribute("tradeId") == null ? "" : tc.Attribute("tradeId").Value,
          ProductType = tc.Attribute("desc").Value,
          ProductDescription = tc.Attribute("desc").Value,
          Contribution = decimal.Parse(tc.Attribute("contribution").Value)
          }
        });

    return originalItems.Concat(additionalItems);
}

public static IEnumerable GetTradeContributions（uint portfolioId，List portfolioIdList，IEnumerable nodeDateList，int？whatIfBatchNumber=null）
{
var originalItems=（来自xml.XPathSelectElement（“主体/组合/组合/贡献”）中的tc.Elements（“交易贡献”）
选择新的贸易贡献
{
SysId=tc.Attribute（“SysId”）==null？0:int.Parse（tc.Attribute（“SysId”）.Value），
TradeContextId=tc.Attribute（“contextId”）==null？0:int.Parse（tc.Attribute（“contextId”）.Value），
TradeId=tc.Attribute（“TradeId”）==null？”：tc.Attribute（“TradeId”）.Value，
ProductType=tc.属性（“描述”）值，
ProductDescription=tc.Attribute（“desc”）.Value，//TODO:将来可以在引用数据缓存中查找描述
贡献=decimal.Parse（tc.Attribute（“贡献”）.Value）
})
.OrderByDescending（x=>x.Contribution）；
//…为简洁起见，省略了代码
//这是我处理新需求的新代码
var additionalItems=xml.XPathSelectElements（“主体/组合/组合”）
.SelectMany（pfElem=>
{
（来自pfElem.XPathSelectElement（“贡献”）.Elements（“交易贡献”）中的tc）
选择新的贸易贡献
{
SysId=tc.Attribute（“SysId”）==null？0:int.Parse（tc.Attribute（“SysId”）.Value），
TradeContextId=tc.Attribute（“contextId”）==null？0:int.Parse（tc.Attribute（“contextId”）.Value），
TradeId=tc.Attribute（“TradeId”）==null？”：tc.Attribute（“TradeId”）.Value，
ProductType=tc.属性（“描述”）值，
ProductDescription=tc.属性（“描述”）值，
贡献=decimal.Parse（tc.Attribute（“贡献”）.Value）
}
});
返回原始目录（附加项）；
}

tradeContributions为什么是

IEnumerable

？tradeContributions为什么是

IEnumerable

？是的，我也不明白以前的开发人员为什么创建

tradeContributions

作为IEnumerable。所以我把我的原始帖子更新到显示在添加新的

foreach

节之前我正在处理的代码块。此外，如果我尝试将原始tradeContributions对象更改为

new List{}

，那么顶部的原始

选择新部分将导致某种异常。这让我有点困惑，所以我将为您给我的列表想法使用一个新的变量。谢谢。对，我也不明白为什么以前的开发人员将tradeContributions
创建为IEnumerable。所以我更新了我的原始版本post显示我在添加新的foreach
节之前处理的代码块。此外，如果我尝试将原始tradeContributions对象更改为new List{}
，则顶部原始的选择新的部分将导致某种异常。这对我来说有点混乱，因此我将为您给我的列表想法使用一个新的变量。谢谢。
List<TradeContribution> tradeContributions = new List<TradeContribution> { };

foreach (XElement pfElem in xml.XPathSelectElements("body/portfolios/portfolio"))
{
    var temp = (from tc in pfElem.XPathSelectElement("contributions").Elements("tradeContribution")
      select new TradeContribution
      {
          SysId = tc.Attribute("sysId") == null ? 0 : int.Parse(tc.Attribute("sysId").Value),
          TradeContextId = tc.Attribute("contextId") == null ? 0 : int.Parse(tc.Attribute("contextId").Value),
          TradeId = tc.Attribute("tradeId") == null ? "" : tc.Attribute("tradeId").Value,
          ProductType = tc.Attribute("desc").Value,
          ProductDescription = tc.Attribute("desc").Value,
          Contribution = decimal.Parse(tc.Attribute("contribution").Value)
      }
    );
    tradeContributions.AddRange(temp.ToArray()); //then add the results to the List
}

foreach (XElement pfElem in xml.XPathSelectElements("body/portfolios/portfolio"))
{
    var temp = (from tc in pfElem.XPathSelectElement("contributions").Elements("tradeContribution")
      select new TradeContribution
      {
          SysId = tc.Attribute("sysId") == null ? 0 : int.Parse(tc.Attribute("sysId").Value),
          TradeContextId = tc.Attribute("contextId") == null ? 0 : int.Parse(tc.Attribute("contextId").Value),
          TradeId = tc.Attribute("tradeId") == null ? "" : tc.Attribute("tradeId").Value,
          ProductType = tc.Attribute("desc").Value,
          ProductDescription = tc.Attribute("desc").Value,
          Contribution = decimal.Parse(tc.Attribute("contribution").Value)
      }
    );
    tradeContributions = tradeContributions.Concat(temp);
}

IEnumerable<TradeContribution> tradeContributions = new List<TradeContribution> { };

var  tradeContributions = new List<TradeContribution> { };

tradeContributions.AddRange((from tc in pfElem.XPathSelectElement("contributions").Elements("tradeContribution")
  select new TradeContribution
  {
      SysId = tc.Attribute("sysId") == null ? 0 : int.Parse(tc.Attribute("sysId").Value),
      TradeContextId = tc.Attribute("contextId") == null ? 0 : int.Parse(tc.Attribute("contextId").Value),
      TradeId = tc.Attribute("tradeId") == null ? "" : tc.Attribute("tradeId").Value,
      ProductType = tc.Attribute("desc").Value,
      ProductDescription = tc.Attribute("desc").Value,
      Contribution = decimal.Parse(tc.Attribute("contribution").Value)
  }));

public static IEnumerable<TradeContribution> GetTradeContributions(uint portfolioId, List<uint> portfolioIdList, IEnumerable<DateTime> nodeDateList, int? whatIfBatchNumber = null)
{
    var originalItems = (from tc in xml.XPathSelectElement("body/portfolios/portfolio/contributions").Elements("tradeContribution")
    select new TradeContribution
    {
      SysId = tc.Attribute("sysId") == null ? 0 : int.Parse(tc.Attribute("sysId").Value),
      TradeContextId = tc.Attribute("contextId") == null ? 0 : int.Parse(tc.Attribute("contextId").Value),
      TradeId = tc.Attribute("tradeId") == null ? "" : tc.Attribute("tradeId").Value,
      ProductType = tc.Attribute("desc").Value,
      ProductDescription = tc.Attribute("desc").Value, // TODO: In future could lookup the description in a reference data cache
      Contribution = decimal.Parse(tc.Attribute("contribution").Value)
  })
  .OrderByDescending(x => x.Contribution);



// ... code omitted for brevity

// THIS IS MY NEW CODE TO HANDLE THE NEW REQUIREMENTS
    var additionalItems = xml.XPathSelectElements("body/portfolios/portfolio")
        .SelectMany(pfElem => 
        {
            (from tc in pfElem.XPathSelectElement("contributions").Elements("tradeContribution")
          select new TradeContribution
          {
          SysId = tc.Attribute("sysId") == null ? 0 : int.Parse(tc.Attribute("sysId").Value),
          TradeContextId = tc.Attribute("contextId") == null ? 0 : int.Parse(tc.Attribute("contextId").Value),
          TradeId = tc.Attribute("tradeId") == null ? "" : tc.Attribute("tradeId").Value,
          ProductType = tc.Attribute("desc").Value,
          ProductDescription = tc.Attribute("desc").Value,
          Contribution = decimal.Parse(tc.Attribute("contribution").Value)
          }
        });

    return originalItems.Concat(additionalItems);
}