如何根据 C# 中的值创建子 XElement？答案

【问题标题】：How do I create child XElement based on values in C#?如何根据 C# 中的值创建子 XElement？
【发布时间】：2019-04-28 07:10:01
【问题描述】：

我的 XML 如下：

<?xml version="1.0" encoding="UTF-8"?>
<html xmlns:xml="http://www.w3.org/XML/1998/namespace" xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops" xmlns:ev="http://www.w3.org/2001/xml-events" xml:lang="de">
<head>
<title>Some Title</title>
<link rel="stylesheet" type="text/css" href="../Styles/9783748258957.css"/>
</head>
<body>
<div id="Inhalt">
<p class="toc-ch"><span class="bi">4 Main Value</span></p>
<p class="toc-h1">4.1 Child Value 1</p>
<p class="toc-h1">4.2 Child Value 2</p>
<p class="toc-h1">4.3 Child Value 3</p>
<p class="toc-h2">4.3.1 Grand-child Value</p>
<p class="toc-h2">4.3.2 Grand-child Value</p>
<p class="toc-h2">4.3.3 Grand-child Value</p>
<p class="toc-h2">4.3.4 Grand-child Value</p>
<p class="toc-h1">4.4 Child Value 4</p>
<p class="toc-h2">4.4.1 Grand-child Value</p>
<p class="toc-h2">4.4.2 Grand-child Value</p>
<p class="toc-h2">4.4.3 Grand-child Value</p>
<p class="toc-h2">4.4.4 Grand-child Value</p>
<p class="toc-h1">4.5 Child Value 5</p>
</div>
</body>
</html>

我想要以下结构的 XML：

<?xml version="1.0" encoding="UTF-8"?>
<ncx xmlns="http://www.daisy.org/z3986/2005/ncx/" version="2005-1" xml:lang="de">
<head>
<title>Some Title</title>
<link rel="stylesheet" type="text/css" href="../Styles/9783748258957.css"/>
</head>
<body>
<navMap>
<navPoint id="navPoint-01" playOrder="01"><navLabel><text>4 Main Value</text></navLabel>
    <navPoint id="navPoint-02" playOrder="02"><navLabel><text>4.1 Child Value 1</text></navLabel></navPoint>
    <navPoint id="navPoint-03" playOrder="03"><navLabel><text>4.2 Child Value 2</text></navLabel></navPoint>
    <navPoint id="navPoint-04" playOrder="04"><navLabel><text>4.3 Child Value 3</text></navLabel>
        <navPoint id="navPoint-05" playOrder="05"><navLabel><text>4.3.1 Grand-child Value</text></navLabel></navPoint>
        <navPoint id="navPoint-06" playOrder="06"><navLabel><text>4.3.2 Grand-child Value</text></navLabel></navPoint>
        <navPoint id="navPoint-07" playOrder="07"><navLabel><text>4.3.3 Grand-child Value</text></navLabel></navPoint>
        <navPoint id="navPoint-08" playOrder="08"><navLabel><text>4.3.4 Grand-child Value</text></navLabel></navPoint></navPoint>
    <navPoint id="navPoint-09" playOrder="09"><navLabel><text>4.4 Child Value 4</text></navLabel>
        <navPoint id="navPoint-10" playOrder="10"><navLabel><text>4.4.1 Grand-child Value</text></navLabel></navPoint>
        <navPoint id="navPoint-11" playOrder="11"><navLabel><text>4.4.2 Grand-child Value</text></navLabel></navPoint>
        <navPoint id="navPoint-12" playOrder="12"><navLabel><text>4.4.3 Grand-child Value</text></navLabel></navPoint>
        <navPoint id="navPoint-13" playOrder="13"><navLabel><text>4.4.4 Grand-child Value</text></navLabel></navPoint></navPoint>
    <navPoint id="navPoint-14" playOrder="14"><navLabel><text>4.5 Child Value 5</text></navLabel></navPoint></navPoint>
</navMap>
</body>
</ncx>

如何使用foreach 循环实现这一点？

我想嵌套基于class 属性的元素。所以，toc-ch 是主要元素，toc-h1 位于 toc-ch 之下，toc-h2 位于 toc-h1 之下

我无法使其嵌套。现在这只是一个<div id="inhalt">，而我有多个<div> 元素。每个类的结构保持不变。

这就是我所做的：

XDocument xtocdoc = XDocument.Load("epubv3TOC.xml");
XNamespace xtocNamespace = xtocdoc.Root.GetDefaultNamespace();
int navPointValue = 1;
int playOrdervalue = 1;

foreach (var value in breakslist)
{
    var valueElements = value.Descendants(htmlNamespace + "p").ToList();
    foreach (var values in valueElements)
        if (values.Attribute("class") != null)
        {
            if (values.Attribute("class") != null && values.Attribute("class").Value.Contains("ch"))
            {
                xtocdoc.Descendants(xtocNamespace + "navMap").FirstOrDefault(de => de != null)
                       .Add(new XElement(xtocNamespace + "navPoint", new XAttribute("id", "navPoint-" + navPointValue)
                                                            , new XAttribute("playOrder", playOrdervalue)
                                                            , new XElement(xtocNamespace + "navLabel"
                                                            , new XElement(xtocNamespace + "text", "ch"))));
                continue;
            }
            else if (values.Attribute("class") != null && values.Attribute("class").Value.Contains("h1"))
            {
                xtocdoc.Descendants(xtocNamespace + "navMap").FirstOrDefault(de => de != null)
                                                        .Elements(xtocNamespace + "navPoint")
                                                        .FirstOrDefault(el => el != null)
                                                        .Add(new XElement(xtocNamespace + "navPoint", new XAttribute("id", "navPoint-" + navPointValue)
                                                            , new XAttribute("playOrder", playOrdervalue)
                                                            , new XElement(xtocNamespace + "navLabel"
                                                            , new XElement(xtocNamespace + "text", "h1"))));
                continue;
            }
            else if (values.Attribute("class") != null && values.Attribute("class").Value.Contains("h2"))
            {
                xtocdoc.Descendants(xtocNamespace + "navMap").FirstOrDefault(de => de != null)
                                                        .Elements(xtocNamespace + "navPoint")
                                                        .FirstOrDefault(el => el != null)
                                                        .Add(new XElement(xtocNamespace + "navPoint", new XAttribute("id", "navPoint-" + navPointValue)
                                                            , new XAttribute("playOrder", playOrdervalue)
                                                            , new XElement(xtocNamespace + "navLabel"
                                                            , new XElement(xtocNamespace + "text", "h2"))));
                continue;
            }
        }
    }

【问题讨论】：

澄清一下，这是您当前的输入，是吗？您能否在问题中包含您想要的输出？是否打算使用每个文本值的“4.3.1”（等）部分来确定嵌套？每个输入元素末尾的尾随“3.1”（等）部分怎么样？
是的，这是我当前的输入，我已经用我想要的输出更新了问题。忽略playOrder 和id 属性。但是，如果您查看输出，则元素是嵌套的。基本上就是这样，所有的toc-h1 都在toc-ch 之下，而所有toc-h2 都在toc-h1 之下。
孙子值的处理方式与其他元素的处理方式不同（输出中添加了一个后缀，其他元素不存在）这一事实使这变得更加棘手。请您检查一下正是您所期望的输入和输出吗？
所以您想基于class 属性而不是文本值进行嵌套？如果您在问题中指定所有内容，而不仅仅是在 cmets 中，这将非常有帮助。
好的，有机会我会去看看，但很可能要到明天（英国时间）。（如果您可以展示您已经尝试过的内容，那也会改进问题。）希望其他人能够在更短的时间内提供答案。

标签： c# .net xml

【解决方案1】：

要处理嵌套，您需要跟踪当前顶级navPoint 和当前子navPoint（如果有）。然后，您可以根据p 元素的class 决定在何处添加新元素。

这里有一些示例代码可以做到这一点。它对标题等没有任何作用 - 我专注于嵌套：

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

class Program
{
    static void Main()
    {
        var input = XDocument.Load("test.xml");
        XNamespace ncx = "http://www.daisy.org/z3986/2005/ncx/";
        XNamespace xhtml = "http://www.w3.org/1999/xhtml";
        // Skipped creating all the rest of the structure: focusing on the
        // navMap
        var navMap = new XElement(ncx + "navMap");
        var inhalt = input.Descendants(xhtml + "div")
            .Single(div => (string) div.Attribute("id") == "Inhalt");

        XElement currentTop = null;
        XElement currentChild = null;

        int index = 1;
        foreach (var element in inhalt.Elements())
        {
            string id = $"navPoint-{index++:00}";
            var point = new XElement(ncx + "navPoint", new XAttribute("id", id));
            var navLabel = new XElement(ncx + "navLabel", element.Value);
            point.Add(navLabel);
            // TODO: playOrder attribute, text element etc. They're not important for nesting.
            switch (element.Attribute("class")?.Value)
            {
                case "toc-ch":
                    currentTop = point;
                    currentChild = null;
                    navMap.Add(point);
                    break;
                case "toc-h1":
                    if (currentTop == null)
                    {
                        throw new InvalidOperationException("toc-h1 with no toc-ch");
                    }
                    currentChild = point;
                    currentTop.Add(point);
                    break;
                case "toc-h2":
                    if (currentChild == null)
                    {
                        throw new InvalidOperationException("toc-h2 with no toc-h1");
                    }
                    currentChild.Add(point);
                    break;
                default:
                    throw new InvalidOperationException("Unknown class attribute");
            }
        }

        var output = new XDocument(new XElement(ncx + "ncx", navMap));
        var settings = new XmlWriterSettings { Indent = true };
        using (var writer = XmlWriter.Create(Console.Out, settings))
        {
            output.Save(writer);
        }
    }
}

输出是：

<?xml version="1.0" encoding="ibm850"?>
<ncx xmlns="http://www.daisy.org/z3986/2005/ncx/">
  <navMap>
    <navPoint id="navPoint-01">
      <navLabel>4 Main Value</navLabel>
      <navPoint id="navPoint-02">
        <navLabel>4.1 Child Value 1</navLabel>
      </navPoint>
      <navPoint id="navPoint-03">
        <navLabel>4.2 Child Value 2</navLabel>
      </navPoint>
      <navPoint id="navPoint-04">
        <navLabel>4.3 Child Value 3</navLabel>
        <navPoint id="navPoint-05">
          <navLabel>4.3.1 Grand-child Value</navLabel>
        </navPoint>
        <navPoint id="navPoint-06">
          <navLabel>4.3.2 Grand-child Value</navLabel>
        </navPoint>
        <navPoint id="navPoint-07">
          <navLabel>4.3.3 Grand-child Value</navLabel>
        </navPoint>
        <navPoint id="navPoint-08">
          <navLabel>4.3.4 Grand-child Value</navLabel>
        </navPoint>
      </navPoint>
      <navPoint id="navPoint-09">
        <navLabel>4.4 Child Value 4</navLabel>
        <navPoint id="navPoint-10">
          <navLabel>4.4.1 Grand-child Value</navLabel>
        </navPoint>
        <navPoint id="navPoint-11">
          <navLabel>4.4.2 Grand-child Value</navLabel>
        </navPoint>
        <navPoint id="navPoint-12">
          <navLabel>4.4.3 Grand-child Value</navLabel>
        </navPoint>
        <navPoint id="navPoint-13">
          <navLabel>4.4.4 Grand-child Value</navLabel>
        </navPoint>
      </navPoint>
      <navPoint id="navPoint-14">
        <navLabel>4.5 Child Value 5</navLabel>
      </navPoint>
    </navPoint>
  </navMap>
</ncx>

【讨论】：

【解决方案2】：

这是使用 Xml Linq 的解决方案。为什么有两个嵌套级别的 navPoint？：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using System.Xml.Linq;

namespace ConsoleApplication110
{
    class Program
    {
        const string INPUT_FILENAME = @"c:\temp\test.xml";
        const string OUTPUT_FILENAME = @"c:\temp\test1.xml";
        static void Main(string[] args)
        {
            XDocument doc = XDocument.Load(INPUT_FILENAME);
            XElement root = doc.Root;
            XNamespace ns = root.GetDefaultNamespace();
            XElement body = root.Element(ns + "body");

            string newBodyStr = "<body><navMap></navMap></body>";
            XElement newBodyX = XElement.Parse(newBodyStr);

            XElement navMap = newBodyX.Element("navMap");

            int count = 1;


            foreach (XElement p in body.Descendants(ns + "p"))
            {
                string innerText = (string)p;

                XElement newNavPoint = new XElement("navPoint", new object[] {
                    new XAttribute("id", "navPoint-" + count.ToString("d2")),
                    new XAttribute("playOrder", count.ToString("d2")),
                    new XElement("navLabel", new XElement("text", innerText))
                });
                navMap.Add(newNavPoint);
                count++;

            }

            body.ReplaceWith(newBodyX);
            doc.Save(OUTPUT_FILENAME);
        }
    }
}

【讨论】：