How can I ignore properties according to their value with XmlSerializer

Question

I'd like the XML created by XmlSerializer to exclude properties if they have a default value. Is this possible with XmlSerializer or am I going to have to look into IXmlSerializable?

For example, I may have the following class:

public class PositionedObject
{
   public float X
   { get; set; }

   public float Y
   { get; set;}
}

I'd like to tell the XmlSerializer that when it serializes an instance of PositionedObject, to not include X if the value is 0 (and same with Y if it is 0).

Answer 1

Thomas' way is probably simplest way to what you want. However you may want to consider that technically value types always have a value, and you probably should serialize it. Note that XmlSerializer will skip adding X element if you were to declare it as string or other reference type.
Of course declaring X coordinate as string would be silly, but you can declare it as nullable float?, which will serialize as <X xsi:nil="true" />, which may be closer to what you actually want... unless you just want to make your XML pretty looking, then got with Thomas' suggestion.

Answer 2

Just declare a method named ShouldSerializeX that returns true when the value is not 0:

public bool ShouldSerializeX()
{
    return X != 0;
}

The serializer will call this method to decide whether the property should be serialized or not.