I found an article on what you suggest with doing a HasMany() with a composite element: http://blogs.hibernatingrhinos.com/nhibernate/archive/2008/08/15/a-fluent-interface-to-nhibernate-part-3-mapping.aspx
It uses a method called HasManyComponent which doesn't seem to exist in the current release of Fluent. But this is an old article. Is there a new way to do this? As you guessed, I want my child to not exist without a parent. And I want to be able to cause the child to be inserted by simply adding it into the Parent's collection, since that most closely represents that requirement. Am I on the right track here? Thanks, Kevin On Dec 29, 3:19 pm, Hudson Akridge <hudson.akri...@gmail.com> wrote: > Inverse is only required if it's got a bi-directional back. Inverse at this > point would be the opposite of what we'd want, we want to declare the > collection side to be the parent. > > The way a typical HasMany association works is that it's the child side that > saves the reference back to the parent, so there's an insert that gets fired > to insert the child, then an update on the child side that updates the > parent with the key reference. > > Failing that, you may actually be wanting to do a HasMany() with a composite > element, rather than map the child in a separate mapping without a parent. > That is how a true parent/child works, the child cannot exist without the > parent. > > If you want the child to exist without the parent then it needs to have a > reference back to the parent, otherwise you will encounter a situation where > the child attempts to be deleted, but it can't be because of the FK > violation to the parent, because the parent hasn't been told the child needs > to be deleted out of the collection, and so you'll get a failure in NH > stating that an object you're attempting to delete will be re-saved via a > cascade. > > To sum: > Child exist without parent - Bi-Directional > Child exist only with parent - composite element or bi-directional > > To quote the NHibernate documentation, 6.4: > > > Very Important Note: If the <key> column of a <one-to-many> association is > > declared NOT NULL, NHibernate may cause constraint violations when it > > creates or updates the association. To prevent this problem, you must use > > a bidirectional association with the many valued end (the set or bag) > > marked as inverse="true". See the discussion of bidirectional associations > > later in this chapter. > > That's your scenario problem explained. > > On Tue, Dec 29, 2009 at 2:05 PM, kberridge <kevin.w.berri...@gmail.com>wrote: > > > > > > > Nope, didn't change the behavior. > > > Thanks, > > Kevin > > > On Dec 29, 2:58 pm, Eric Ridgeway <ang3lf...@gmail.com> wrote: > > > Try setting inverse on the has many mapping and see if that helps > > > > On Dec 29, 2009 11:54 AM, "kberridge" <kevin.w.berri...@gmail.com> > > wrote: > > > > I have a simple parent child relationship where the parent class has a > > > collection of children, but the child class doesn't have a reference > > > to the parent. I'm mapping it with a HasMany. > > > > In my database, the foreign key column does not allow nulls, but when > > > NH tries to insert into these tables it is bombing out because it's > > > trying to insert the child first (with null in the FK col) and come > > > back and update the FK column after it inserts the parent. > > > > I found an earlier message on this group that briefly discusses this > > > issue: > >http://www.mail-archive.com/fluent-nhibernate@googlegroups.com/msg051... > > > > Is the only way I can get around this problem still to add the > > > reference to the parent on the child class? > > > > Thanks, > > > Kevin Berridge > > > > -- > > > > You received this message because you are subscribed to the Google Groups > > > "Fluent NHibernate" group. > > > To post to this group, send email to fluent-nhibern...@googlegroups.com. > > > To unsubscribe from this group, send email to > > > fluent-nhibernate+unsubscr...@googlegroups.com<fluent-nhibernate%2Bunsubscr > > > i...@googlegroups.com><fluent-nhibernate%2Bunsubscr > > i...@googlegroups.com> > > > . > > > For more options, visit this group athttp:// > > groups.google.com/group/fluent-nhibernate?hl=en. > > > -- > > > You received this message because you are subscribed to the Google Groups > > "Fluent NHibernate" group. > > To post to this group, send email to fluent-nhibern...@googlegroups.com. > > To unsubscribe from this group, send email to > > fluent-nhibernate+unsubscr...@googlegroups.com<fluent-nhibernate%2Bunsubscr > > i...@googlegroups.com> > > . > > For more options, visit this group at > >http://groups.google.com/group/fluent-nhibernate?hl=en. > > -- > - Hudsonhttp://www.bestguesstheory.comhttp://twitter.com/HudsonAkridge -- You received this message because you are subscribed to the Google Groups "Fluent NHibernate" group. To post to this group, send email to fluent-nhibern...@googlegroups.com. To unsubscribe from this group, send email to fluent-nhibernate+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/fluent-nhibernate?hl=en.
