FindAll after SaveOrUpdate not returning updates

Question

I have a method that queries the database (in this case a view) for parent records, gets and updates a child of each parent record, saves the child record, and then queries for the parent records. There is a one-to-one relationship between the child and parent but the relationship is not defined in the mapping files. I can see that the updates are being saved to the database by issuing a select to the database directly but when I do the second query in code the updates are not included in the results. Why is the second query not returning the updates?

Rough outline of code:

public void UpdateRecords(long aParentId)
{
   IList<Parent> parents = parentRepository.GetParentById(aParentId);
   foreach (Parent parent in parents)
   {
      Child childToUpdate = childRepository.GetChildById(parent.GetChildId());

      ... Update Child ...

      childRepository.SaveChild(childToUpdate);
   }
   IList<Parent> parents = parentRepository.GetParentById(aParentId);
}

class ParentRepository : NHRepository
{
   public IList<Parent> GetParentById(long anId)
   {
      DetachedCriteria criteria = 
         DetachedCriteria.For<Parent>()
         .Add(Restrictions.Eq("Id", anId));

      return FindAll(criteria).ToList();
   }
}

class ChildRepository : NHRepository
{
   public Child SaveChild(Child aChild)
   {
      Child savedChild = null;
      using (UnitOfWork.Start())
      {
         savedChild = base.SaveOrUpdate(aChild);
         UnitOfWork.Current.Flush(); // commit
      }
      return savedChild;
   }
}

Answer 1

What does your FindAll() method look like? It's possible that it's using same UnitOfWork/Session for both GetParentById() calls and that child repository is using another UnitOfWork/Session.

If that's the case, then the second GetParentById() call is returning object from session (first level) cache without hitting the database.

Edit: You can browse the source code of Rhino.Commons on:

https://rhino-tools.svn.sourceforge.net/svnroot/rhino-tools/trunk/commons/Rhino.Commons.NHibernate/

Session is encapsulated in Rhino.Commons.UnitOfWork class. I'm not familiar with Ayende's implementation of UnitOfWork, so I won't be able to give you the best solution for this, but here's something to get you started....

Try to call

Session.Clear();

at the top of your GetParentById() method.

I repeat, you'll probably need to find a better way to do this (probably by using UnitOfWork), but this should clear all objects from your session cache and hence load new ones from database on next request.

Answer 2

Try surrounding your SaveUpdate() in a transaction. Then commit the transaction when done, this will ensure your changes are written to the database right when you commit:

Something like this is fairly common to see:

using (var trans = session.BeginTransaction()) {
  session.SaveUpdate(e);
  trans.Commit()
} catch (Exception) {
  trans.Rollback()
}