相关疑难解决方法(0)

这似乎不应该是困难的,但我现在卡住了.我正在尝试从与给定XPath查询字符串匹配的节点获取特定属性的属性值.这是我到目前为止所拥有的:

    public static IEnumerable<string> GetAttributes(this XmlDocument xml,
        string xpathQuery, string attributeName)
    {
        var doc = new XPathDocument(new XmlNodeReader(xml));
        XPathNavigator nav = doc.CreateNavigator();
        XPathExpression expr = nav.Compile(xpathQuery);
        XPathNodeIterator iterator = nav.Select(expr);
        while (iterator.MoveNext())
        {
            XPathNavigator curNav = iterator.Current;
            if (curNav.HasAttributes)
            {
                XmlNode curNode = ((IHasXmlNode)curNav).GetNode();
                if (null != curNode)
                {
                    XmlAttribute attrib = curNode.Attributes[attributeName];
                    if (null != attrib)
                    {
                        yield return attrib.Value;
                    }
                }
            }
        }
    }

这目前抛出异常:

System.InvalidCastException:无法将类型为"MS.Internal.Xml.Cache.XPathDocumentNavigator"的对象强制转换为"System.Xml.IHasXmlNode".

我错了吗？是否有更简单的方法从匹配节点获取属性值？