项目属性值

Question

不确定这是否可行。我有 'MarketInventory' 个节点的子集：

<MARKET_INVENTORY _Type="TotalSales" _MonthRangeType="Prior7To12Months" _Count="18"/>
<MARKET_INVENTORY _Type="TotalSales" _MonthRangeType="Prior4To6Months" _Count="6"/>
<MARKET_INVENTORY _Type="TotalSales" _MonthRangeType="Last3Months" _Count="11"/>
<MARKET_INVENTORY _Type="TotalSales" _TrendType="Stable"/>

在 _Type="TotalSales" 节点上过滤。

我想知道是否可以将 _Count 值属性投影到此 class:

public class MarketInventoryListing
{
    public string Prior7To12Months { get; set; }
    public string Prior4To6Months { get; set; }
    public string LastThreeMonths { get; set; }
}

据我所知：

var marketInventoryTotalListings = from totalListings in xe.Descendants("MARKET_INVENTORY")
where (string) totalListings.Attribute("_Type") == "TotalSales"
select new MarketInventoryListing()
{
    Prior7To12Months = 
    (
        from thing in totalListings.Descendants()
        where (string)totalListings.Attribute("_MonthRangeType") == "Prior7To12Months"
        select thing.Attribute("_Count").Value
    )
};

Answer 1

如果您确定每个节点只有一个节点，那么您可以这样使用FirstOrDefault：-

var marketInventoryTotalListings = from totalListings in xe.Descendants("MARKET_INVENTORY")
  where (string)totalListings.Attribute("_Type") == "TotalSales"
  let prior712 = xe.Descendants("MARKET_INVENTORY")
        .FirstOrDefault(x => (string)x.Attribute("_MonthRangeType") == "Prior7To12Months")
  let prior46 = xe.Descendants("MARKET_INVENTORY")
        .FirstOrDefault(x => (string)x.Attribute("_MonthRangeType") == "Prior4To6Months")
  let last3 = xe.Descendants("MARKET_INVENTORY")
        .FirstOrDefault(x => (string)x.Attribute("_MonthRangeType") == "Last3Months")
  select new MarketInventoryListing
     {
         Prior7To12Months = prior712 != null ? (string)prior712.Attribute("_Count") : "",
         Prior4To6Months = prior712 != null ? (string)prior46.Attribute("_Count") : "",
         LastThreeMonths = last3 != null ? (string)last3.Attribute("_Count") : "",
     };

否则，如果它们是多个，那么您应该将 IEnumerable<string> 作为 MarketInventoryListing 属性中的数据类型，而不是 string。

Answer 2

它不工作有两个原因：

Select 在需要单个字符串的地方返回 IEnumerable
所有 MARKET_INVENTORY 元素都在同一级别，因此 "from thing in totalListings.Descendants()" 没有返回任何内容。所有这些元素此时都是兄弟姐妹。

我更改了您的代码以解决这些问题，它的工作原理如下：

var marketInventoryTotalListings = (from totalListings in xe.Descendants("MARKET_INVENTORY")
                                   where (string)totalListings.Attribute("_Type") == "TotalSales"
                                   select new MarketInventoryListing()
                                   {
                                      Prior7To12Months =
                                      (
                                           from thing in totalListings.Parent.Descendants()
                                           where (string)totalListings.Attribute("_MonthRangeType") == "Prior7To12Months"
                                           select thing.Attribute("_Count").Value
                                      ).FirstOrDefault(),
                                   }).FirstOrDefault();

项目属性值

Project attribute values

c#

linq

linq-to-xml