XmlSerializer in .NET with XmlSchemaForm.Unqualified

Question

Given the following piece of code:

using System;
using System.Xml.Schema;
using System.Xml.Serialization;

namespace XmlSerializationTest
{
    [XmlType(Namespace = "http://www.test.com")]
    public class Element
    {
        [XmlElement]
        public int X;
    }

    [XmlRoot(Namespace = "http://www.test.com")]
    public class Root
    {
        [XmlElement(Form = XmlSchemaForm.Unqualified)]
        public Element Element;
    }

    public static class Program
    {
        public static void Main(string[] args)
        {
            var root = new Root { Element = new Element { X = 1 } };
            var xmlSerializer = new XmlSerializer(typeof(Root));
            xmlSerializer.Serialize(Console.Out, root);
        }
    }
}

the output is:

<?xml version="1.0" encoding="ibm852"?>
<Root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.test.com">
  <Element xmlns="">
    <X xmlns="http://www.test.com">1</X>
  </Element>
</Root>

The question is why does setting the Form property to XmlSchemaForm.Unqualified cause the Element element's namespace being set to "" even if it has the XmlTypeAttribute attribute with the same namespace as the Root element?

This kind of code (the XmlSchemaForm.Unqualified part) is generated by the WSCF.blue tool and it's messing up with the namespaces.

"unqualified" indicates that attributes from the target namespace are not required to be qualified with the namespace prefix. So that's why you get the xmlns="" if set to qualified its all fine. As u said its from an automated tool. see if there are configurable options in the tool. — Aravind, Aug 02 '11 at 06:25
@Aravind: I think that unqualified means that the serializer is not forced to use the prefix (it may or may not). But I don't see why it would CHANGE the namespase of the Element element (from "http://www.test.com" to "")! Unfortunately WSCF.blue doesn't seem to have the right switch for fixing that. — Stefan, Aug 02 '11 at 07:18

score 0 · Answer 1 · answered Jul 05 '13 at 22:41

You can override namespace specified in the element type. E.g. you can have

[XmlElement(Namespace="http://foo.com")]
public Element Element;

And the output would be

<Root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.test.com">
  <Element xmlns="http://foo.com">
    <X xmlns="http://www.test.com">1</X>
  </Element>
</Root>

Microsoft's implementation of Form = XmlSchemaForm.Unqualified appears to be exactly equivalent to setting Namespace to "". In particular, it cannot be used if you explicitly specified any other namespace (MSDN reference). If you do, you will get this exception:

Unhandled Exception: System.InvalidOperationException: There was an error reflecting type 'XmlSerializationTest.Root'. ---> System.InvalidOperationException: There was an error reflecting field 'Element'. ---> System.InvalidOperationException: The Form property may not be 'Unqualified' when an explicit Namespace property is present.

XmlSerializer in .NET with XmlSchemaForm.Unqualified

1 Answers1