Ignore field in NHibernate merge

Question

I have mapped ModifiedDate in my NHibernate configuration for most of my entities. Each entity inherits this:

public interface IAuditable {
    string ModifiedBy { get; set; }
    DateTime ModifiedDate { get; set; }
}

Each class maps these fields to the database, as we want these values read into each entity. I use fluent configuration and map classes.

I have implemented IPreInsert and IPreUpdate event listeners to update the modified by and modified date. This way the audit values will be updated by the framework. I used the code here: http://ayende.com/blog/3987/nhibernate-ipreupdateeventlistener-ipreinserteventlistener

How do I ensure that no matter what values are in ModifiedBy and ModifedDate they are never considered dirty and don't themselves make the entity dirty? The entity must be dirty only when the other fields have changed.

You might be looking to create a custom NHibernate event listener. You can create one that inherits from NHibernate.Event.Default.DefaultMergeEventListener and handle those dates explicitly. — valverij

kliszaq kliszaq · Accepted Answer · 2013-06-18T12:30:20

Could you please clarify what do you mean by Modified date ? As far as I understand: You have some entity wit the security audit data, for instance:

public class SomeEntity {
   ...
   public DateTime CreatedDate { get; set; }
   public DateTime? ModifiedDate { get; set; }
   ...
}

And do you try to use ISession.Merge function to merge the entites?

What do you mean by the statement below? Could you give more explanation?

I wish to save and load the dates but I want the NHibernate merge function to ignore modified date for the purposes of finding changes

Ignore field in NHibernate merge

1 Answers