Selective serialization with NetDataContractSerializer

Serializing this class works fine. However, sometimes I'd like to exclude the field. Is this possible?

[DataContract]
class Foo
{
    [DataMember]
    Foo _Foo;
}

Setting the field to null temporarily is impossible.

In case someone stumbles upon the same issue, I'll show the solution I went by.

The idea is to facade the original field like this:

[DataContract]
class Foo
{
    Foo _FooOriginal;

    [DataMember]
    Foo _Foo {
        get {
            return whatever ? _FooOriginal : null;
        }
        set {
            _FooOriginal = value;
        }
    }
}