ユーザー用と同じプライベート変数用のDB用に別々のプロパティを作成してみませんか。
public class Foo
{
private string _text;
[BsonElement("text"), BsonRequired]
public string TextDB
{
get { return _text; }
set
{
_text = value;
}
}
[BsonIgnore]
public string Text
{
get { return _text; }
set
{
_text = value;
Bar(_text);
}
}
private void Bar(string text)
{
//Only relevant when Text is set by the user of the class,
//not during deserialization
}
}