Question

我是C＃和XML的新手，我需要以下代码的帮助，我已经通过C＃代码创建了一个Element，并希望在两个地方的XML文件中插入City Element并编码以下代码。但是C＃代码只在第4个节点中插入Element，而不是在第1个节点，我无法弄清楚我错过了什么。任何帮助都将不胜感激。如果我只保留一个INSERTAFTER，它工作正常。

 XmlElement childElement = doc.CreateElement("City"); // Creation of <City> ....... <City>
childElement.InnerText = "Hyderabad";// Adding Value <City> Hyderabad </City>


XmlNode SelectNode = doc.SelectSingleNode("Group/user"); //where to add XPATH expression 
SelectNode.InsertAfter(childElement, SelectNode.LastChild);//selects 1st "user" node lastchild and insert after

XmlNode refNode = doc.SelectSingleNode("Group/user[4]");// Indicating 4 Node in XML file
refNode.InsertAfter(childElement, refNode.LastChild); //selects 4th  "user" node lastchild and insert after

XML文件：

<?xml version="1.0" encoding="utf-8"?>
<Group>
  <user>
    <Name age="39">John Hay</Name>
    <RollNo>01</RollNo>
              === <City>Hyderabad</City> ===> is missing 
  </user>
  <user>
    <Name age="11">Ramsey</Name>
    <RollNo>02 </RollNo>
  </user>
  <user>
    <Name age="16">Roshan</Name>
    <RollNo>03</RollNo>
  </user>
  <user>
    <Name age="42">Rahiman</Name>
    <RollNo>04</RollNo>
<City>Hyderabad</City>    ==>   This is fine.      
    </user>
</Group>

我可以根据Text.value引用任何ELEMENT（例如RollNo）并再插入一个元素吗？

谢谢

Answer 1

您正在围绕xml文档移动城市节点的相同实例。你需要实例化另一个：

XmlElement childElement = doc.CreateElement("City"); // Creation of <City> ....... <City>
childElement.InnerText = "Hyderabad";// Adding Value <City> Hyderabad </City>

XmlNode SelectNode = doc.SelectSingleNode("Group/user"); //where to add XPATH expression 
SelectNode.InsertAfter(childElement, SelectNode.LastChild);//selects 1st "user" node lastchild and insert after

childElement = doc.CreateElement("City"); // Creation of <City> ....... <City>
childElement.InnerText = "Hyderabad";// Adding Value <City> Hyderabad </City>

XmlNode refNode = doc.SelectSingleNode("Group/user[4]");// Indicating 4 Node in XML file
refNode.InsertAfter(childElement, refNode.LastChild); //selects 4th  "user" node lastchild and insert after

/编辑：克隆你的城市节点可能更合适一些。 https://msdn.microsoft.com/de-de/library/system.xml.xmlelement.clonenode(v=vs.110).aspx

XmlElement childElement = doc.CreateElement("City"); // Creation of <City> ....... <City>
childElement.InnerText = "Hyderabad";// Adding Value <City> Hyderabad </City>

XmlNode SelectNode = doc.SelectSingleNode("Group/user"); //where to add XPATH expression 
SelectNode.InsertAfter(childElement, SelectNode.LastChild);//selects 1st "user" node lastchild and insert after

XmlNode refNode = doc.SelectSingleNode("Group/user[4]");// Indicating 4 Node in XML file
refNode.InsertAfter(childElement.CloneNode(true), refNode.LastChild); //selects 4th  "user" node lastchild and insert after

Answer 2

您可以使用XPath中的text()轻松访问特定的nodex ...

看一下这个例子：

//get roll node by it's text
var rollNode = doc.SelectSingleNode("//user/RollNo[text()='03']");
//user to whom roll is child
var parentUserNode = rollNode.ParentNode;
//add some nodex
parentUserNode.InsertAfter(childElement, parentUserNode.LastChild);

Answer 3

使用LINQ to XML API而不是旧的XmlDocument API会更容易。例如，要按顺序执行此操作：

var doc = XDocument.Parse(xml);

var hyderabad = new XElement("City", "Hyderabad");

doc.Descendants("user").First().Add(hyderabad);
doc.Descendants("user").Skip(3).First().Add(hyderabad);

或者按RollNo选择：

var doc = XDocument.Parse(xml);

var roll4 = doc.Descendants("user").Single(x => (int) x.Element("RollNo") == 4);

roll4.Add(new XElement("City", "Hyderabad"));

请参阅this fiddle了解演示。

XML与C＃奇怪的行为

3 个答案: