c# - Linq-to-Xml prefix parse error

Question

I am currently trying to learn how to parse data, and its a bit confusing. can someone check out my code and see what I'm doing wrong or if im even heading in the right direction.

XML File:

<xml xmlns:a='BLAH'
     xmlns:b='BLAH'
     xmlns:c='BLAH'
     xmlns:d='BLAH'>
  <a:info>
   <b:cat Option1='blah' Option2='blah' Option3='blah' />
  </a:info>
</xml>

C# Code:

XmlDocument doc = new XmlDocument();
doc.Load(richTextBox2.Text);

XmlNamespaceManager man = new XmlNamespaceManager(doc.NameTable);
man.AddNamespace("a", "BLAH");
man.AddNamespace("b", "BLAH");
man.AddNamespace("c", "BLAH");
man.AddNamespace("d", "BLAH");

XmlNode temps = doc.SelectSingleNode("/a:info/b:cat/Option1/", man);

richTextBox1.Text = temps.InnerText;

I am new to C#, I cant find a good example explaining how to successfully use loops to find more then one:

<b:chat />

Answer 1

假设以下输入 XML 文档（请注意命名空间 URL）：

<xml xmlns:a='http://localhost/scheme_a'
     xmlns:b='http://localhost/scheme_b'
     xmlns:c='http://localhost/scheme_c'
     xmlns:d='http://localhost/scheme_d'>
    <a:info>
       <b:cat Option1='1' Option2='1' Option3='1' />
    </a:info>

    <a:info>
       <b:cat Option1='2' Option2='2' Option3='2' />
    </a:info>
</xml>

有获得所有<b:chat />元素的方法。

1. XmlDocument类：

   var xmlDocument = new XmlDocument();
   xmlDocument.Load(...);
   
   var xmlNamespaceManager = new XmlNamespaceManager(xmlDocument.NameTable);
   xmlNamespaceManager.AddNamespace("a", "http://localhost/scheme_a");
   xmlNamespaceManager.AddNamespace("b", "http://localhost/scheme_b");
   xmlNamespaceManager.AddNamespace("c", "http://localhost/scheme_c");
   xmlNamespaceManager.AddNamespace("d", "http://localhost/scheme_d");
   
   var bCatNodes = xmlDocument.SelectNodes("/xml/a:info/b:cat", xmlNamespaceManager);
   var option1Attributes = bCatNodes.Cast<XmlNode>().Select(node => node.Attributes["Option1"]);
   
   // Also, all Option1 attributes can be retrieved directly using XPath:
   // var option1Attributes = xmlDocument.SelectNodes("/xml/a:info/b:cat/@Option1", xmlNamespaceManager).Cast<XmlAttribute>();
   

2. LINQ to XML XDocument 类。XName可以通过命名空间传递给Descendants()和Element()方法。

   使用Descendants()获取所有<b:chat />元素。

   var xDocument = XDocument.Load(...);
   XNamespace xNamespace = "http://localhost/scheme_b";
   var xElements = xDocument.Descendants(xNamespace + "cat");
   
   // For example, get all the values of Option1 attribute for the b:chat elements:
   var options1 = xElements.Select(element => element.Attribute("Option1")).ToList();
   

Answer 2

如果您正在寻找 LINQ to XML，则您使用了错误的 API。请改用 XDocument 类。