c# - 获取 XElement 的 XPath？

Question

我在文档深处有一个 XElement。给定 XElement(和 XDocument？)，是否有扩展方法来获取其完整(即绝对，例如 /root/item/element/child)XPath？

例如myXElement.GetXPath()?

编辑:好吧，看来我忽略了一些非常重要的事情。哎呀!需要考虑元素的索引。有关建议的更正解决方案，请参阅我的最后一个答案。

Answer 1

扩展方法:

public static class XExtensions
{
    /// <summary>
    /// Get the absolute XPath to a given XElement
    /// (e.g. "/people/person[6]/name[1]/last[1]").
    /// </summary>
    public static string GetAbsoluteXPath(this XElement element)
    {
        if (element == null)
        {
            throw new ArgumentNullException("element");
        }

        Func<XElement, string> relativeXPath = e =>
        {
            int index = e.IndexPosition();
            string name = e.Name.LocalName;

            // If the element is the root, no index is required

            return (index == -1) ? "/" + name : string.Format
            (
                "/{0}[{1}]",
                name, 
                index.ToString()
            );
        };

        var ancestors = from e in element.Ancestors()
                        select relativeXPath(e);

        return string.Concat(ancestors.Reverse().ToArray()) + 
               relativeXPath(element);
    }

    /// <summary>
    /// Get the index of the given XElement relative to its
    /// siblings with identical names. If the given element is
    /// the root, -1 is returned.
    /// </summary>
    /// <param name="element">
    /// The element to get the index of.
    /// </param>
    public static int IndexPosition(this XElement element)
    {
        if (element == null)
        {
            throw new ArgumentNullException("element");
        }

        if (element.Parent == null)
        {
            return -1;
        }

        int i = 1; // Indexes for nodes start at 1, not 0

        foreach (var sibling in element.Parent.Elements(element.Name))
        {
            if (sibling == element)
            {
                return i;
            }

            i++;
        }

        throw new InvalidOperationException
            ("element has been removed from its parent.");
    }
}

和测试:

class Program
{
    static void Main(string[] args)
    {
        Program.Process(XDocument.Load(@"C:\test.xml").Root);
        Console.Read();
    }

    static void Process(XElement element)
    {
        if (!element.HasElements)
        {
            Console.WriteLine(element.GetAbsoluteXPath());
        }
        else
        {
            foreach (XElement child in element.Elements())
            {
                Process(child);
            }
        }
    }
}

和示例输出:

/tests/test[1]/date[1]
/tests/test[1]/time[1]/start[1]
/tests/test[1]/time[1]/end[1]
/tests/test[1]/facility[1]/name[1]
/tests/test[1]/facility[1]/website[1]
/tests/test[1]/facility[1]/street[1]
/tests/test[1]/facility[1]/state[1]
/tests/test[1]/facility[1]/city[1]
/tests/test[1]/facility[1]/zip[1]
/tests/test[1]/facility[1]/phone[1]
/tests/test[1]/info[1]
/tests/test[2]/date[1]
/tests/test[2]/time[1]/start[1]
/tests/test[2]/time[1]/end[1]
/tests/test[2]/facility[1]/name[1]
/tests/test[2]/facility[1]/website[1]
/tests/test[2]/facility[1]/street[1]
/tests/test[2]/facility[1]/state[1]
/tests/test[2]/facility[1]/city[1]
/tests/test[2]/facility[1]/zip[1]
/tests/test[2]/facility[1]/phone[1]
/tests/test[2]/info[1]

这应该可以解决这个问题。不？