[NHibernate] Mapping a domain entity to multiple tables

Question

I've got a object (Filter) that's defined something like this

public class Filter
{
    public int FilterId { get; set; }

        public string Name { get; set; }

        public IList<User> Users { get; set; }
}

If possible, I'd like to store the object in multiple tables (sometimes spanning multiple rows)

Given an initialization of the Filter like this:

Filter myFilter = new Filter();
myFilter.FilterId = 1;
myFilter.Name = "Name of my filter";
myFilter.Users.Add(new User("Joe", 10));
myFilter.Users.Add(new User("Jim", 20));

..I'd like it to be persisted in tables "Filter" and "Filter_User"

Filter would end up with:

1 Name of my Filter

Filter_User would contain

1 10 (ref. to Joe's ID) 1 20 (ref. to Jim's ID)

I've been looking at the documentation and all I can find is using the element in my mapping file. But as far as I can tell it will only let me do that with a component-relationship (i.e. Employee and EmployeeDetails - 1:1)

Anyone to point me in the right direction?

Answer 1

I think you're just looking for a many-to-many association ? You're not constrained using a component relationship.

You could take a look at the many-to-many mapping type ?

<set name="Users" table="Filter_User">
  <key column="filterid" />
  <many-to-many column="userid" class="User" />
</set>

Answer 2

Hi Frederik.

I had no idea it could be done this easy.

I changed to to make it work with an IList.

Thank you for your help. I really appreciate it.