如何使用LINQ to XML按正确数字顺序向XML添加新元素？

当前代码会将新的<PublicTalk>元素直接追加到eng节点末尾，需要修改为按Number属性的数字顺序插入到对应位置。

现有代码 #

foreach(var talkNumber in listNumbers)
{
       var newElem = new XElement("PublicTalk",
                               new XAttribute("Number", talkNumber),
                               new XAttribute("Excluded", false),
                               new XAttribute("ExcludedFromDate", "1900-01-01"),
                               new XAttribute("Note", ""),
                               new XAttribute("TimesHeard", 0),
                               new XAttribute("LastHeard", "1900-01-01")
                              );
       ptLangInfo.Add(newElem);
}

目标XML结构 #

<?xml version="1.0" encoding="utf-8"?>
<PublicTalkTitles>
  <!-- English -->
  <eng>
    <PublicTalk Number="21" Excluded="false" ExcludedFromDate="1900-01-01" Note="" TimesHeard="1" LastHeard="2023-10-15" />
    <PublicTalk Number="1" Excluded="false" ExcludedFromDate="1900-01-01" Note="" TimesHeard="0" LastHeard="1900-01-01" />
    <PublicTalk Number="2" Excluded="false" ExcludedFromDate="1900-01-01" Note="" TimesHeard="0" LastHeard="1900-01-01" />
    <PublicTalk Number="3" Excluded="false" ExcludedFromDate="1900-01-01" Note="" TimesHeard="0" LastHeard="1900-01-01" />
  </eng>
</PublicTalkTitles>

解决方案 #

方案1：逐个插入到对应位置 #

对每个新元素，找到第一个Number值大于当前元素的节点，将新元素插入到它前面；若所有现有节点的Number都更小，则追加到末尾。修改后的代码如下：

foreach(var talkNumber in listNumbers)
{
    var newElem = new XElement("PublicTalk",
                            new XAttribute("Number", talkNumber),
                            new XAttribute("Excluded", false),
                            new XAttribute("ExcludedFromDate", "1900-01-01"),
                            new XAttribute("Note", ""),
                            new XAttribute("TimesHeard", 0),
                            new XAttribute("LastHeard", "1900-01-01")
                           );

    // 找到第一个Number数值大于当前talkNumber的元素
    var targetElem = ptLangInfo.Elements("PublicTalk")
        .FirstOrDefault(elem => int.Parse(elem.Attribute("Number").Value) > talkNumber);

    if (targetElem != null)
    {
        targetElem.AddBeforeSelf(newElem);
    }
    else
    {
        ptLangInfo.Add(newElem);
    }
}

方案2：合并后整体排序（适合大量新元素） #

先批量创建所有新元素，与现有元素合并后按Number排序，再重新替换eng节点下的内容：

// 批量创建新元素
var newElements = listNumbers.Select(talkNumber => new XElement("PublicTalk",
    new XAttribute("Number", talkNumber),
    new XAttribute("Excluded", false),
    new XAttribute("ExcludedFromDate", "1900-01-01"),
    new XAttribute("Note", ""),
    new XAttribute("TimesHeard", 0),
    new XAttribute("LastHeard", "1900-01-01")
));

// 合并现有元素与新元素，按Number数值排序
var sortedElements = ptLangInfo.Elements("PublicTalk")
    .Concat(newElements)
    .OrderBy(elem => int.Parse(elem.Attribute("Number").Value));

// 清空原有内容，添加排序后的元素
ptLangInfo.RemoveAll();
ptLangInfo.Add(sortedElements);

注意：如果Number属性可能存在非数字值，需要增加解析异常处理逻辑。

内容的提问来源于stack exchange，提问作者Andrew Truckle