How to serialize an XPO object to XML

Description

Can XPO serialize objects to / from an XML file?

Solution

XPO 1.x does not include any means for serialization. You can serialize XPO objects using the same approach as you serialize any other objects:

[C#]





    XmlAttributes attrs = new XmlAttributes();

    attrs.XmlIgnore = true;

    XmlAttributeOverrides ovr = new XmlAttributeOverrides();

    ovr.Add(typeof(XPCustomObject), "GCRecord", attrs);

    XmlSerializer s = new XmlSerializer(typeof(YourObject), ovr);

It's much easier to implement conversion of persistent objects to XML in XPO 6.x. Here is some sample code for XPO 6.1:

[C#]





public class SerializablePerson : XPObject {

  public SerializablePerson() { }

  public SerializablePerson(Session session) : base(session) { }

  public SerializablePerson(string name, int age)  {

    this.name = name;

    this.age = age;

  }



  private string name;

  public string Name {

    get { return name; }

    set { name = value; }

  }



  private int age;

  public int Age {

    get { return age; }

    set { age = value; }

  }



  private SerializablePerson parent;

  [XmlIgnore] // This would loop, and it's not needed

  [Association("Person-Children")]

  public SerializablePerson Parent {

    get { return parent; }

    set { parent = value; }

  }



  [XmlIgnore] // We'll serialize the helper instead

  [Association("Person-Children"), Aggregated]

  public XPCollection<SerializablePerson> Children {

    get { return GetCollection<SerializablePerson>("Children"); }

  }



  AssociationXmlSerializationHelper childenSerializationHelper;

  [XmlArray("Children")]

  [XmlArrayItem(typeof(SerializablePerson))] // extend this as necessary

  public AssociationXmlSerializationHelper ChildrenSerializationHelper {

    get {

      if (childenSerializationHelper == null)

        childenSerializationHelper = new AssociationXmlSerializationHelper(Children);

      return childenSerializationHelper;

    }

  }

}



[TestFixture]

public class Tests {

  [Test]

  public void Test( ) {

    XmlSerializer xmlSerializer = new XmlSerializer(typeof(SerializablePerson));

    TextWriter textWriter = new StringWriter( );



    SerializablePerson parent = new SerializablePerson("Willy Webb", 53);

    parent.Children.Add(new SerializablePerson("Billy Blab", 14));



    xmlSerializer.Serialize(textWriter, parent);

    string str = textWriter.ToString( );



    Console.WriteLine(str);



    TextReader textReader = new StringReader(str);

    SerializablePerson loadedParent = (SerializablePerson) xmlSerializer.Deserialize(textReader);



    Assert.IsFalse(object.ReferenceEquals(parent, loadedParent));

    Assert.AreEqual(parent.Name, loadedParent.Name);

    Assert.AreEqual(parent.Age, loadedParent.Age);

    Assert.AreEqual(parent.Children.Count, loadedParent.Children.Count);

    Assert.AreEqual(parent.Children[0].Name, loadedParent.Children[0].Name);

    Assert.AreEqual(parent.Children[0].Age, loadedParent.Children[0].Age);

  }

}