Hi,
I would like to know what the best way to map a collection of child
objects, that may have different parent types.
For example, say I have a generic Comment class, which I want to reuse
to track comments associated with other entities such as Project,
Organisation, Document, etc...:
public class Comment
{
public string Comment { get; set; }
public string User { get; set; }
public DateTime CommentDate { get; set; }
....
}
public class Project
{
....
public ISet<Comment> Comments { get; set; }
}
public class Organisation
{
....
public ISet<Comment> Comments { get; set; }
}
If I use a one-to-many relationship for the Comments property in both
Project and Organisation mapping files I will obviously run into the
problem of the Comment records in the DB not knowing whether its
parent/owner is a Project or an Organisation.
There should therefore be something allowing NHibernate to distinguish
what type of parent the comment record belongs to so it can load the
relevant comment records when loading a Project or Organisation.
Is there a good way of supporting this in NHibernate? It seems
Hibernate supports the notion of 'Top-level Collections' (http://
www.xylax.net/hibernate/toplevel.html) to deal with exactly this type
of scenario, but I have found nothing in NHibernate. (It is possible
that it has been depracated in Hibernate as I also found a post
questionning whether this should be supported because it forces you to
break DB referential integrity as you no longer have FKs between child
and various parent records).
Many thanks,
Ian
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