Returning an XElement from a web service

Question

Is it possible to return an XElement from a webservice (in C#/asp.net)?

Try a simple web service that returns an XElement:

[WebMethod]
public XElement DoItXElement()
{
  XElement xe = new XElement("hello",
     new XElement("message", "Hello World")
     );

  return xe;
}

This compiles fine but if you try and run it you get

Cannot use wildcards at the top level of a schema.

I found this post implying that this is a bug in .net.

So... Can I return an XElement from a web service? If so, how?

Thanks.

Answer 1

There appears to be an issue with how an XElement is serialized, check here...

You can try outing the XElement as a string or as the article suggests you could just use a class wrapper and place your XElement inside. If the point is to output the data in a universal format you'll be stuck with returning a string.

Answer 2

I was trying to avoid the string!

I can return an XmlNode (created from the XElement), which gets me what I need - a slug of XML on the client. Thanks for that link - I shall investigate the XWrapper further...

Answer 3

Strangely enough, it seems that this only happens if you are trying to look at the "Discovery" part of the service - You can run the method without a problem...

Answer 4

Return an XmlElement type, and just use this extension method to convert from XElement to XmlElement:

[System.Runtime.CompilerServices.Extension()]
public XmlElement ToXmlElement(XElement value)
{
    var xmlDoc = new XmlDocument();
    xmlDoc.LoadXml(value.ToString());
    return xmlDoc.DocumentElement;
}

This seems to work well.