c# - 如何在 C# 中使用 XmlDocument 和 XmlNode 修改现有的 XML 文件

Question

我已经实现了在应用程序初始化时使用 XmlTextWriter 创建下面的 XML 文件。

并且知道我不知道如何使用 XmlDocument 和 XmlNode 更新 childNode id 值。

是否有一些属性可以更新 id 值？我尝试了 InnerText 但失败了。谢谢。

<?xml version="1.0" encoding="UTF-8"?>
<Equipment xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <License licenseId="" licensePath=""/>
  <DataCollections>
    <GroupAIDs>
      <AID id="100">
        <Variable id="200"/>
        <Variable id="201"/>
      </AID>
      <AID id="">
        <Variable id="205"/>
      </AID>
      <AID id="102"/>
    </GroupAIDs>
    <GroupBIDs>
      <BID id="2000">
        <AID id="100"/>
      </BID>
      <BID id="2001">
        <AID id="101"/>
        <AID id="102"/>
      </BID>
    </GroupBIDs>
    <GroupCIDs>
      <BID id="8"/>
      <BID id="9"/>
      <BID id="10"/>
    </GroupCIDs>
  </DataCollections>
</Equipment>

Answer 1

你需要做这样的事情:

// instantiate XmlDocument and load XML from file
XmlDocument doc = new XmlDocument();
doc.Load(@"D:\test.xml");

// get a list of nodes - in this case, I'm selecting all <AID> nodes under
// the <GroupAIDs> node - change to suit your needs
XmlNodeList aNodes = doc.SelectNodes("/Equipment/DataCollections/GroupAIDs/AID");

// loop through all AID nodes
foreach (XmlNode aNode in aNodes)
{
   // grab the "id" attribute
   XmlAttribute idAttribute = aNode.Attributes["id"];

   // check if that attribute even exists...
   if (idAttribute != null)
   {
      // if yes - read its current value
      string currentValue = idAttribute.Value;

      // here, you can now decide what to do - for demo purposes,
      // I just set the ID value to a fixed value if it was empty before
      if (string.IsNullOrEmpty(currentValue))
      {
         idAttribute.Value = "515";
      }
   }
}

// save the XmlDocument back to disk
doc.Save(@"D:\test2.xml");