XPath的：如何选择其属性的节点？ [英] XPath: How to select a node by its attribute?

问题描述

我有一个是这样的XML：

I have an XML that goes like this:

<?xml version="1.0" encoding="utf-8" ?>
<colors>
  <color index = "0">#FF0000</color>
  <color index = "1">#FF0200</color>
  <color index = "2">#FF0300</color>
  <color index = "3">#FF0500</color>
  [..]

我想选择由它的索引节点：

I'm trying to select a node by its index:

XmlDocument ColorTable = new XmlDocument();
ColorTable.Load(HttpContext.Current.Server.MapPath("~/App_Data/ColorTable.xml"));
int percentage = 2;
string xpath = string.Format(@"//color[index={0}]", percentage.ToString());
//string xpath = string.Format(@"//color[index=""{0}""]", percentage.ToString());
//string xpath = string.Format(@"//color[index='{0}']", percentage.ToString());
var r = ColorTable.SelectSingleNode(xpath).Value;

我也试过了评论的版本，但它不返回任何结果。
任何建议？

I tried also the commented versions, but it does not return any result. Any suggestion?

推荐答案

使用 //颜色[@index ={0} '] 来代替。 。@符号的意思是属性

Use //color[@index='{0}'] instead. The @ sign means "attribute".

我注意到，您使用的是逐字字符串的方式字面 - 在的启动字符串。有没有在这种情况下，没有必要 - 你不必在字符串中的反斜杠，这不是多行。你也不需要显式调用的ToString 在百分比 - 它会自动转换

I note that you're using a verbatim string literal by the way - the @ sign at the start of the string. There's no need in this case - you don't have any backslashes in the string, and it's not multi-line. You also don't need to explicitly call ToString on percentage - it will be converted automatically.

string xpath = string.Format("//color[@index='{0}']", percentage);

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