You can create a base class for all your mapped objects with a must inherit requirement. That allows you to create a single implementation and then reuse it (DRY).
John Davidson On Thu, May 13, 2010 at 3:25 AM, Dathan <[email protected]> wrote: > That seem like it addresses the problem - because NHibernate reads the > value from the property when saving, if the internally-stored value is > null, the property will return my "NULL" value, and NHibernate will > attempt to serialize that to the DB, rather than the NULL value that I > actually want to store. > > It seems like a custom user type would fit the bill, because it > supports NullSafeGet and NullSafeSet methods (sorry if I'm misstating > the actual method names - the idea is right, though, right?). Using > that, I could override Equals() on each of my classes, and the > UserType for the class would do something like "if (! > obj.Equals(ObjectClassType.Null)) return obj else return null;". > Would that work? I'd prefer an approach that doesn't require me to > implement a custom UserType per model class, though, so if there are > any other options, I'm eager to hear them. > > Thanks! > > Dathan > > On May 7, 6:45 pm, nadav s <[email protected]> wrote: > > use a field that will get the data, and a property that in its get > method, > > checks if the field is null and if so, returns the default > > > > > > > > On Sat, May 8, 2010 at 1:12 AM, Dathan <[email protected]> wrote: > > > Hi, all. > > > > > I'm trying to strengthen my domain by eliminating null in favor of > > > "Null" objects with explicit semantics. E.g., > > > > > class Category > > > { > > > private static Category @default; > > > > > static Category() > > > { > > > // init @default here > > > } > > > > > public virtual int ID { get; set; } > > > public virtual string Name { get; set; } > > > public virtual Category Parent { get; set; } > > > public static Category None { get { return @default; } } > > > } > > > > > My categories support nesting (hence the Parent property), but top- > > > level categories won't have parents. I'd like to represent this in my > > > model by having the category's Parent set to Category.None. My > > > question is, in terms of NHibernate, what's the best way to map this? > > > Should I have a category record in my database called None with a null > > > ParentID, and have all "top-level categories" store that ID as their > > > parent? Or, should I serialize all references to Category.None as > > > NULL categoryID's, and replace all NULL CategoryID's with > > > Category.None upon retrieval? (If so, how?) What's the best practice > > > here? > > > > > Thanks! > > > > > ~Dathan > > > > > -- > > > You received this message because you are subscribed to the Google > Groups > > > "nhusers" group. > > > To post to this group, send email to [email protected]. > > > To unsubscribe from this group, send email to > > > [email protected]<nhusers%[email protected]> > <nhusers%[email protected]<nhusers%[email protected]> > > > > > . > > > For more options, visit this group at > > >http://groups.google.com/group/nhusers?hl=en. > > > > -- > > You received this message because you are subscribed to the Google Groups > "nhusers" group. > > To post to this group, send email to [email protected]. > > To unsubscribe from this group, send email to > [email protected]<nhusers%[email protected]> > . > > For more options, visit this group athttp:// > groups.google.com/group/nhusers?hl=en. > > -- > You received this message because you are subscribed to the Google Groups > "nhusers" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<nhusers%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/nhusers?hl=en. > > -- You received this message because you are subscribed to the Google Groups "nhusers" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/nhusers?hl=en.
