如何使用ExecuteXmlReader正确输出XML数据

Question

I have an ASP.NET 4.0 Application and i try to use the function ExecuteXmlReader from the SQLCommand class to get a XML-result. The query don't produce any error. The query ends with FOR XML AUTO, ELEMENTS, ROOT('root') . But when i try this:

Dim XML As XElement = XElement.Load(query.ExecuteXmlReader)
XML.Save(HttpContext.Current.Server.MapPath("~/Result.xml"))

i get this errormessage:

The XmlReader must be on a node of type Element instead of a node of type None. (english translation)

Der XmlReader muss sich auf einem Knoten vom Typ 'Element' befinden, nicht auf einem Knoten vom Typ 'None'. (german translation)

It is strange that the error occures at the line with XElement.Load(query.ExecuteXmlReader) . But the code runs further! It also saves xml-data to disk! how can this happen and how can i read out the xml-result without an error?

Answer 1

I had similar issues with multiple FOR XML AUTO statements reading. Problem was solved passing XmlReader to System.Xml.XPath.XPathDocument:

 public static XDocument MultipleNodes(XmlReader reader, string RootName = "Root")
    {
        var doc = new XDocument(new XElement(RootName));

        var xn = new XPathDocument(reader).CreateNavigator();
        XPathNodeIterator iterator = xn.Select("/*");   // Level 1 multiple Elements
        foreach (XPathNavigator item in iterator)
        {
            doc.Root.Add(XElement.Load(item.ReadSubtree()));
        }

        return doc;
    }