ネームスペースでもNULLを選択します

Question

私はこの質問が前に同様の方法で尋ねられたことを知っていますが、私はこの作業を受けているようには思えません。

いくつかのXMLを持っています：

<?xml version="1.0" encoding="ISO-8859-1" ?> 
    <Research xmlns="http://www.rixml.org/2005/3/RIXML" xmlns:xalan="http://xml.apache.org/xalan" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" createDateTime="2011-03-29T15:41:48Z" language="eng" researchID="MusiJvs3008">
    <Product productID="MusiJvs3008">
    <StatusInfo currentStatusIndicator="Yes" statusDateTime="2011-03-29T15:41:48Z" statusType="Published" />
    <Source>
    <Organization type="SellSideFirm" primaryIndicator="Yes">
    <OrganizationID idType="Reuters">9999</OrganizationID> 

.

そしてXPathを使って値を読み込もうとしています：

XPathDocument xmldoc = new XPathDocument(xmlFile); 
XPathNavigator nav = xmldoc.CreateNavigator(); 
XmlNamespaceManager nsMgr = new XmlNamespaceManager(nav.NameTable);
nsMgr.AddNamespace(string.Empty, "http://www.rixml.org/2005/3/RIXML"); 
XPathNavigator result = nav.SelectSingleNode("/Research", nsMgr); // <-- Returns null!

.

しかしルートノードの単純な選択でさえNULLを返します。私は名前空間に何か問題があると確信しています。誰かが助けてくれる？

理想的には、XMLファイルから値を選択する単純な行に、すなわち。

String a = xmlDoc.SelectSingleNode(@"/Research/Product/Content/Title").Value;

.

btw、私はXMLファイルの内容を介した（直接）制御されています。

Answer 1

I don't believe you can use an empty namespace alias and have it used automatically by the XPath expression. As soon as you use an actual alias, it should work though. This test is fine, for example:

using System;
using System.Xml;
using System.Xml.XPath;

class Test
{
    static void Main() 
    {
        string xmlFile = "test.xml";
        XPathDocument xmldoc = new XPathDocument(xmlFile); 
        XPathNavigator nav = xmldoc.CreateNavigator(); 
        XmlNamespaceManager nsMgr = new XmlNamespaceManager(nav.NameTable);
        nsMgr.AddNamespace("x", "http://www.rixml.org/2005/3/RIXML"); 
        XPathNavigator result = nav.SelectSingleNode("/x:Research", nsMgr);
        Console.WriteLine(result);
    }
}

Do you have to use XPath and XPathDocument, by the way? I tend to find that LINQ to XML is a much more pleasant API, particularly when it comes to namespaces. If you're using .NET 3.5 and you have no particular requirement to use XPath, I'd suggest you check it out.

Answer 2

Make the following changes

nsMgr.AddNamespace("x", "http://www.rixml.org/2005/3/RIXML"); 
XPathNavigator result = nav.SelectSingleNode("/x:Research", nsMgr);

Answer 3

i could post, and answer my own question, for the native equivalent of this code. Instead i'll just add it as an answer to the end.

When using the native IXMLDOMDocument (version 6) object:

//Give the default namespace as alias of "x"
document.setProperty("SelectionNamespaces","xmlns:x='http://www.rixml.org/2005/3/RIXML'");

//Query for the nodes we want
document.selectSingleNode("/x:Research");

Bonus Question: Why, oh why, does no Xml Document object model query the default namespace when no namespace is specified... sigh