Xml序列化：无法在父元素和子元素中定义相同的名称空间

Question

i need to create a xml structure similar to this:

<?xml version="1.0" encoding="utf-8"?>
<ns0:RootElement xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:ns0="http://fuu.gub">
  <ns0:ChildElement xmlns:ns0="http://fuu.gub">
    <ns0:Data>Some-data</ns0:Data>
  </ns0:ChildElement>
</ns0:RootElement>

The namespace ns0 must be defined in the RootElement and in the ChildElement. I'm using Xml.Serialization to serialize my objects and i cant get this done. The serializer is ignoring the namespace on the child element because it's already defined in the parent. This means i end up with the following result:

<?xml version="1.0" encoding="utf-8"?>
<ns0:RootElement xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:ns0="http://fuu.gub">
  <ns0:ChildElement>
    <ns0:Data>Some-data</ns0:Data>
  </ns0:ChildElement>
</ns0:RootElement>

Here is my code

[XmlRoot("RootElement", Namespace = "http://fuu.gub")]
public class RootElement
{
    [XmlNamespaceDeclarations]
    public XmlSerializerNamespaces XmlNamespaces { get; set; }

    [XmlElement("ChildElement")]
    public ChildElement Child { get; set; }

    public RootElement() {
        XmlNamespaces = new XmlSerializerNamespaces();
        XmlNamespaces.Add("ns0", "http://fuu.gub");

        Child = new ChildElement();
    }

    public void ToXml(string path)
    {
        XmlSerializer x = new System.Xml.Serialization.XmlSerializer(this.GetType());

        TextWriter txtW = new StreamWriter(path);
        x.Serialize(txtW, this);
    }
}


[XmlRoot(Namespace = "http://fuu.gub")]
public class ChildElement
{
    [XmlNamespaceDeclarations]
    public XmlSerializerNamespaces XmlNamespaces { get; set; }

    [XmlElement]
    public string Data{ get; set; }

    public ChildElement()
    {
        XmlNamespaces = new XmlSerializerNamespaces();
        XmlNamespaces.Add("ns0", "http://fuu.gub");

        Data = "Some-data";
    }
}

Answer 1

Here http://www.w3schools.com/xml/xml_namespaces.asp I found this:

When a namespace is defined for an element, all child elements with the same prefix are associated with the same namespace.

Namespaces can be declared in the elements where they are used or in the XML root element

Note: The namespace URI is not used by the parser to look up information.

When you define a namespace, you can´t use the same prefix to define another/the same namespace again.

I believe you can use the same namespace with a different prefix though.