Before Save

Herman Kheyfets · **Posted:** Sat Oct 07, 2006 8:15 pm

I have a question, i have all tables setup with CreateDate and UpdateDate,
CreateDate currently get populated using MS SQL GetDate() as default value.
When object got updated and persist,i want to update UpdateDate. Is it possible with nHibernate nice way??? Currently i always have to do object.UpdateDate = DateTime.Now. Is better solution exist???

luedi · **Joined:** Tue Feb 21, 2006 9:50 am **Posts:** 107

in the NHibernate documentation you will find a chapter about interceptors. See

http://www.hibernate.org/hib_docs/nhibernate/html/manipulatingdata.html#manipulatingdata-interceptors

Regards
Klaus

mnichols · **Joined:** Mon Aug 21, 2006 9:18 am **Posts:** 179

Yah, or you if your entities all inherit from a superclass, you can implement the ILifecycle interface and be able to do exactly what you are looking for . Here's a snippet from my DomainObject superclass from which all persisted entities derive:

Code:

        private static string GetCurrentUserName()
        {
            if (Thread.CurrentPrincipal == null ||
                Thread.CurrentPrincipal.Identity == null ||
                Thread.CurrentPrincipal.Identity.Name == null)
            {
                return WindowsIdentity.GetCurrent().Name;
            }
            else
            {
                return Thread.CurrentPrincipal.Identity.Name;
            }
        }
        
        #region NHibernate Interceptor Methods
        public LifecycleVeto OnSave(ISession s)
        {
            if (_createdBy == null)
            {
                _createdBy = GetCurrentUserName();
            }

            if (_lastModifiedBy == null)
            {
                _lastModifiedBy = GetCurrentUserName();
            }

            if (!_dateCreated.HasValue)
            {
                _dateCreated = DateTime.Now;
            }

            return LifecycleVeto.NoVeto;
        }

        public LifecycleVeto OnUpdate(ISession s)
        {
            _lastModifiedBy = GetCurrentUserName();

            _lastModified = DateTime.Now;
            return LifecycleVeto.NoVeto;
        }

        public LifecycleVeto OnDelete(ISession s)
        {
            return LifecycleVeto.NoVeto;
        }

        public void OnLoad(ISession s, object id)
        {
            //Do Nothing
        }
        #endregion

guymahieu · **Joined:** Sat Sep 09, 2006 5:55 am **Posts:** 23

Does the ILifeCycle approach work for you?

The documentation clearly states:

Quote:

LifecycleVeto OnUpdate( ISession s ):
Called when an entity is passed to ISession.Update().
This method is not called every time the object's state is persisted during a flush.

I've done some tests and indeed the OnUpdate method is not always called, rendering the values in the date_modified database field useless as they do not necessarily represent the correct situation.

grennis · **Joined:** Sat Mar 25, 2006 9:16 am **Posts:** 150

The easiest way is simply to use a <timestamp...> mapping in your class file (or <version type="timestamp"...>). This then gives you concurrency checking for free, as well.