如何从一个XmlNode实例获取的XPath [英] How to get xpath from an XmlNode instance

问题描述

有人可以提供一些code，它会得到一个System.Xml.XmlNode实例的XPath的？

Could someone supply some code that would get the xpath of a System.Xml.XmlNode instance?

谢谢！

推荐答案

好吧，我忍不住有一展身手吧。这将仅适用于属性和元素的工作，但嘿......你能在15分钟内期待:)同样也很可能是这样做的一个更清洁的方式。

Okay, I couldn't resist having a go at it. It'll only work for attributes and elements, but hey... what can you expect in 15 minutes :) Likewise there may very well be a cleaner way of doing it.

这是多余的，包括每一个元素的索引（尤其是根之一！），但它不是试图找出是否有任何含糊之处，否则容易。

It is superfluous to include the index on every element (particularly the root one!) but it's easier than trying to work out whether there's any ambiguity otherwise.

using System;
using System.Text;
using System.Xml;

class Test
{
    static void Main()
    {
        string xml = @"
<root>
  <foo />
  <foo>
     <bar attr='value'/>
     <bar other='va' />
  </foo>
  <foo><bar /></foo>
</root>";
        XmlDocument doc = new XmlDocument();
        doc.LoadXml(xml);
        XmlNode node = doc.SelectSingleNode("//@attr");
        Console.WriteLine(FindXPath(node));
        Console.WriteLine(doc.SelectSingleNode(FindXPath(node)) == node);
    }

    static string FindXPath(XmlNode node)
    {
        StringBuilder builder = new StringBuilder();
        while (node != null)
        {
            switch (node.NodeType)
            {
                case XmlNodeType.Attribute:
                    builder.Insert(0, "/@" + node.Name);
                    node = ((XmlAttribute) node).OwnerElement;
                    break;
                case XmlNodeType.Element:
                    int index = FindElementIndex((XmlElement) node);
                    builder.Insert(0, "/" + node.Name + "[" + index + "]");
                    node = node.ParentNode;
                    break;
                case XmlNodeType.Document:
                    return builder.ToString();
                default:
                    throw new ArgumentException("Only elements and attributes are supported");
            }
        }
        throw new ArgumentException("Node was not in a document");
    }

    static int FindElementIndex(XmlElement element)
    {
        XmlNode parentNode = element.ParentNode;
        if (parentNode is XmlDocument)
        {
            return 1;
        }
        XmlElement parent = (XmlElement) parentNode;
        int index = 1;
        foreach (XmlNode candidate in parent.ChildNodes)
        {
            if (candidate is XmlElement && candidate.Name == element.Name)
            {
                if (candidate == element)
                {
                    return index;
                }
                index++;
            }
        }
        throw new ArgumentException("Couldn't find element within parent");
    }
}

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