C# 基于XML中给定的子id获取根节点id

以下是我的XML结构：

<DirectoryNode Id="297fe1ac-ff9b-4c40-ada4-86dc713a9537" Title="Root">
   <DirectoryNode Id="80e01248-1170-4393-a327-b97409d51159" Title="A">
      <DirectoryNode Id="e6db6d3f-be30-4cdf-b79e-864cc9b52c5f" Title="A1">
         <DirectoryNode Id="4368d898-6fb0-4e2f-ba56-edbaf4bd0077" Title="A11" />
      </DirectoryNode>
      <DirectoryNode Id="11c5336b-462e-45dc-b4d3-92032ebc3ae3" Title="A2" />
   </DirectoryNode>
   <DirectoryNode Id="b983fd39-fc2e-43e0-80e6-3808fb47f995" Title="B">
      <DirectoryNode Id="433851d6-9935-4adb-9acb-7055c26e85cb" Title="B1">
         <DirectoryNode Id="f2602aed-6d97-4e46-9e8a-fb181b28f0c8" Title="B11" />
      </DirectoryNode>
   </DirectoryNode>
   <DirectoryNode Id="9144d8cf-93c0-4de6-9109-448d396a9e17" Title="C" />
   <DirectoryNode Id="182491af-452e-40bc-b51e-59f078db3ad3" Title="D" />
</DirectoryNode>

我试图做的是在给定目录节点id的情况下获取根节点（而不是主根节点）id。以下是一些示例：

有了A11的身份证，我要A的身份证

给定A2的Id，我要A的Id

给A的身份证，我要A的身份证

给定B1的Id，我要B的Id

---

当涉及到解析xml和提取值时，我很糟糕——有人知道一种快速的方法吗？

听起来您可以使用以下方法：

XDocument doc = XDocument.Parse("nodes.xml");
XElement node = doc.Descendants("DirectoryNode")
                   .Where(n => (string) n.Attribute("Id") == id)
                   .Single();

// Now go up until we find the highest node beneatht the document root node
while (node.Parent != doc.Root)
{
    node = node.Parent;
}

请注意，如果可以有多个具有相同ID的节点，或者如果该ID可能根本不存在，则必须更改查询。例如，如果您只关心第一个匹配，但可能没有匹配，则可以将

Single

更改为

FirstOrDefault（）

，然后使用（在

while

循环之前）：

---

这里有一个小的递归方法

using System;
using System.Linq;
using System.Xml.Linq;

namespace Test
{
    class Program
    {
        static void Main(string[] args)
        {
            string sampleXml =  @"<DirectoryNode Id=""297fe1ac-ff9b-4c40-ada4-86dc713a9537"" Title=""Root"">" + Environment.NewLine +
                                @"   <DirectoryNode Id=""80e01248-1170-4393-a327-b97409d51159"" Title=""A"">" + Environment.NewLine +
                                @"      <DirectoryNode Id=""e6db6d3f-be30-4cdf-b79e-864cc9b52c5f"" Title=""A1"">" + Environment.NewLine +
                                @"         <DirectoryNode Id=""4368d898-6fb0-4e2f-ba56-edbaf4bd0077"" Title=""A11"" />" + Environment.NewLine +
                                @"      </DirectoryNode>" + Environment.NewLine +
                                @"      <DirectoryNode Id=""11c5336b-462e-45dc-b4d3-92032ebc3ae3"" Title=""A2"" />" + Environment.NewLine +
                                @"   </DirectoryNode>" + Environment.NewLine +
                                @"   <DirectoryNode Id=""b983fd39-fc2e-43e0-80e6-3808fb47f995"" Title=""B"">" + Environment.NewLine +
                                @"      <DirectoryNode Id=""433851d6-9935-4adb-9acb-7055c26e85cb"" Title=""B1"">" + Environment.NewLine +
                                @"         <DirectoryNode Id=""f2602aed-6d97-4e46-9e8a-fb181b28f0c8"" Title=""B11"" />" + Environment.NewLine +
                                @"      </DirectoryNode>" + Environment.NewLine +
                                @"   </DirectoryNode>" + Environment.NewLine +
                                @"   <DirectoryNode Id=""9144d8cf-93c0-4de6-9109-448d396a9e17"" Title=""C"" />" + Environment.NewLine +
                                @"   <DirectoryNode Id=""182491af-452e-40bc-b51e-59f078db3ad3"" Title=""D"" />" + Environment.NewLine +
                                @"</DirectoryNode>" + Environment.NewLine +
                                @"";

            XDocument document = XDocument.Parse(sampleXml);

            //    Given A11's Id, I want A's Id
            XElement parentDirectory = GetParentDirectory(document.Descendants("DirectoryNode").Single(element => (string) element.Attribute("Title") == "A11"));
            Console.WriteLine(parentDirectory.Attribute("Title").Value);

            //    Given A2's Id, I want A's Id
            parentDirectory = GetParentDirectory(document.Descendants("DirectoryNode").Single(element => (string)element.Attribute("Title") == "A2"));
            Console.WriteLine(parentDirectory.Attribute("Title").Value);

            //    Given A's Id, I want A's Id
            parentDirectory = GetParentDirectory(document.Descendants("DirectoryNode").Single(element => (string)element.Attribute("Title") == "A"));
            Console.WriteLine(parentDirectory.Attribute("Title").Value);

            //    Given B1's Id, I want B's Id
            parentDirectory = GetParentDirectory(document.Descendants("DirectoryNode").Single(element => (string)element.Attribute("Title") == "B1"));
            Console.WriteLine(parentDirectory.Attribute("Title").Value);

            Console.ReadLine();
        }

        public static XElement GetParentDirectory(XElement element)
        {
            if (element.Parent == element.Document.Root)
                return element;

            return GetParentDirectory(element.Parent);
        }
    }
}

使用系统；
使用System.Linq；
使用System.Xml.Linq；
名称空间测试
{
班级计划
{
静态void Main（字符串[]参数）
{
字符串sampleXml=@“+Environment.NewLine+
@“”+Environment.NewLine+
@“”+Environment.NewLine+
@“”+Environment.NewLine+
@“”+Environment.NewLine+
@“”+Environment.NewLine+
@“”+Environment.NewLine+
@“”+Environment.NewLine+
@“”+Environment.NewLine+
@“”+Environment.NewLine+
@“”+Environment.NewLine+
@“”+Environment.NewLine+
@“”+Environment.NewLine+
@“”+Environment.NewLine+
@“”+Environment.NewLine+
@"";
XDocument document=XDocument.Parse（sampleXml）；
//有了A11的身份证，我要A的身份证
XElement parentDirectory=GetParentDirectory（document.substands（“DirectoryNode”）.Single（element=>（string）element.Attribute（“Title”）==“A11”）；
Console.WriteLine（parentDirectory.Attribute（“Title”）.Value）；
//给定A2的Id，我要A的Id
parentDirectory=GetParentDirectory（document.subscriptions（“DirectoryNode”）.Single（element=>（string）element.Attribute（“Title”）==“A2”）；
Console.WriteLine（parentDirectory.Attribute（“Title”）.Value）；
//给A的身份证，我要A的身份证
parentDirectory=GetParentDirectory（document.subscriptions（“DirectoryNode”）.Single（element=>（string）element.Attribute（“Title”）==“A”）；
Console.WriteLine（parentDirectory.Attribute（“Title”）.Value）；
//给定B1的Id，我要B的Id
parentDirectory=GetParentDirectory（document.subscriptions（“DirectoryNode”）.Single（element=>（string）element.Attribute（“Title”）==“B1”）；
Console.WriteLine（parentDirectory.Attribute（“Title”）.Value）；
Console.ReadLine（）；
}
公共静态XElement GetParentDirectory（XElement元素）
{
if（element.Parent==element.Document.Root）
返回元素；
返回GetParentDirectory（element.Parent）；
}
}
}

using System;
using System.Linq;
using System.Xml.Linq;

namespace Test
{
    class Program
    {
        static void Main(string[] args)
        {
            string sampleXml =  @"<DirectoryNode Id=""297fe1ac-ff9b-4c40-ada4-86dc713a9537"" Title=""Root"">" + Environment.NewLine +
                                @"   <DirectoryNode Id=""80e01248-1170-4393-a327-b97409d51159"" Title=""A"">" + Environment.NewLine +
                                @"      <DirectoryNode Id=""e6db6d3f-be30-4cdf-b79e-864cc9b52c5f"" Title=""A1"">" + Environment.NewLine +
                                @"         <DirectoryNode Id=""4368d898-6fb0-4e2f-ba56-edbaf4bd0077"" Title=""A11"" />" + Environment.NewLine +
                                @"      </DirectoryNode>" + Environment.NewLine +
                                @"      <DirectoryNode Id=""11c5336b-462e-45dc-b4d3-92032ebc3ae3"" Title=""A2"" />" + Environment.NewLine +
                                @"   </DirectoryNode>" + Environment.NewLine +
                                @"   <DirectoryNode Id=""b983fd39-fc2e-43e0-80e6-3808fb47f995"" Title=""B"">" + Environment.NewLine +
                                @"      <DirectoryNode Id=""433851d6-9935-4adb-9acb-7055c26e85cb"" Title=""B1"">" + Environment.NewLine +
                                @"         <DirectoryNode Id=""f2602aed-6d97-4e46-9e8a-fb181b28f0c8"" Title=""B11"" />" + Environment.NewLine +
                                @"      </DirectoryNode>" + Environment.NewLine +
                                @"   </DirectoryNode>" + Environment.NewLine +
                                @"   <DirectoryNode Id=""9144d8cf-93c0-4de6-9109-448d396a9e17"" Title=""C"" />" + Environment.NewLine +
                                @"   <DirectoryNode Id=""182491af-452e-40bc-b51e-59f078db3ad3"" Title=""D"" />" + Environment.NewLine +
                                @"</DirectoryNode>" + Environment.NewLine +
                                @"";

            XDocument document = XDocument.Parse(sampleXml);

            //    Given A11's Id, I want A's Id
            XElement parentDirectory = GetParentDirectory(document.Descendants("DirectoryNode").Single(element => (string) element.Attribute("Title") == "A11"));
            Console.WriteLine(parentDirectory.Attribute("Title").Value);

            //    Given A2's Id, I want A's Id
            parentDirectory = GetParentDirectory(document.Descendants("DirectoryNode").Single(element => (string)element.Attribute("Title") == "A2"));
            Console.WriteLine(parentDirectory.Attribute("Title").Value);

            //    Given A's Id, I want A's Id
            parentDirectory = GetParentDirectory(document.Descendants("DirectoryNode").Single(element => (string)element.Attribute("Title") == "A"));
            Console.WriteLine(parentDirectory.Attribute("Title").Value);

            //    Given B1's Id, I want B's Id
            parentDirectory = GetParentDirectory(document.Descendants("DirectoryNode").Single(element => (string)element.Attribute("Title") == "B1"));
            Console.WriteLine(parentDirectory.Attribute("Title").Value);

            Console.ReadLine();
        }

        public static XElement GetParentDirectory(XElement element)
        {
            if (element.Parent == element.Document.Root)
                return element;

            return GetParentDirectory(element.Parent);
        }
    }
}