XmlSerializer: Serialized Syntax and How to Override It 

Recently I needed to specify exactly how I would like a specific class serialized. Suppose we have the following simple schema:

<xs:schema targetNamespace="http://my.favourite.ns/person.xsd"
  <xs:complexType name="Person">
      <xs:element name="Name" type="xs:string" />
      <xs:element name="Surname" type="xs:string" />
      <xs:element name="Age" type="xs:int" minOccurs="0" />

Let's call this schema President.xsd.

A valid XML instance against this schema would be, for example:

<Person xmlns="http://my.favourite.ns/person.xsd">

Since we are serializing against a specific XML schema (XSD), we have an option of schema compilation:

xsd /c President.xsd

This, obviously, yields a programmatic type system result in a form of a C# class. All well and done.


If we serialize the filled up class instance back to XML, we get a valid XML instance. It's valid against President.xsd.

There is a case where your schema changes ever so slightly - read, the namespaces change, and you don't want to recompile the entire solution to support this, but you still want to use XML serialization. Who doesn't - what do you do?

Suppose we want to get the following back, when serializing:

<PresidentPerson xmlns="http://schemas.gama-system.com/

There is an option to override the default serialization technique of XmlSerializer. Enter  the world of XmlAttributes and XmlAttributeOverrides:

private XmlSerializer GetOverridedSerializer()
   // set overrides for person element
   XmlAttributes attrsPerson = new XmlAttributes();
   XmlRootAttribute rootPerson =
      new XmlRootAttribute("PresidentPerson");
   rootPerson.Namespace = "
   attrsPerson.XmlRoot = rootPerson;

   // create overrider
   XmlAttributeOverrides xOver = new XmlAttributeOverrides();
   xOver.Add(typeof(Person), attrsPerson);

   XmlSerializer xSer = new XmlSerializer(typeof(Person), xOver);
   return xSer;

Now serialize normally:

Stream ms = new MemoryStream();
XmlTextWriter tw = new XmlTextWriter(ms, null);
xSer.Serialize(tw, person);

This will work even if you only have a compiled version of your object graph, and you don't have any sources. System.Xml.Serialization.XmlAttributeOverrides class allows you to adorn any XML serializable class with your own XML syntax - element names, attribute names, namespaces and types.

Remember - you can override them all and still serialize your angle brackets.

Categories:  XML
Friday, 29 August 2008 19:38:07 (Central Europe Standard Time, UTC+01:00)  #    Comments


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