nhibernate manytomany query - nhibernate

Question

I am new to nhibernate and trying to create a query on a database with manytomany links between items and categories.
I have a database with 3 tables : items, categories and a lookup table categoryitem like this:
categorys - primary key categoryId
items - primary key itemId
categoryItem - categoryId column and itemId column
I want a query returning items for a particular category and have tried this and think i am along the right lines:
public IList<Item> GetItemsForCategory(Category category)
{
//detached criteria
DetachedCriteria itemIdsCriteria = DetachedCriteria.For(typeof(Category))
.SetProjection(Projections.Distinct(Projections.Property("Item.Id")))
.Add(Restrictions.Eq("Category.Id", category.Id));
criteria.Add(Subqueries.PropertyIn("Id", itemIdsCriteria));
return criteria.List<Item>() as List<Item>;
}
I only have business objects for category and item.
how do i create a repository method to find items for a particular category?

Answer 1

I assume that your classes look like this:
class Item
{
// id and stuff
IList<Category> Categories { get; private set; }
}
class Category
{
// id and stuff
}
query (HQL)
session.CreateQuery(#"select i
from Item i
inner join i.Categories c
where
c = :category")
.SetEntity("category", category)
Criteria
session
.CreateCriteria(typeof(Item))
.CreateCriteria("Categories", "c")
.Add(Restrictions.Eq("c.Id", category.Id))