nHibernate join query - nhibernate

Question

i have two tables (graph representation - one table is nodes, other is link between nodes), and i want to write this query in nHibernate:
SELECT
distinct(t.id), t.NodeName, e.Fk_linkOne, e.Fk_linkTwo, e.RelationName
FROM Nodes t
INNER JOIN NodeRelation e ON t.Id=e.Fk_linkOne OR t.Id=e.Fk_linkTwo
where (e.Fk_linkOne =84 OR e.Fk_linkTwo=84 ) AND t.Id!=84
I did not find how to connect two tables wiht join, that have OR in it..
ICriteria criteriaSelect = Session
.CreateCriteria(typeof(NodeRelation ), "nodeRelations")
.CreateCriteria("nodeRelations.Node", "node",
NHibernate.SqlCommand.JoinType.InnerJoin)

Answer 1

You can only define your joins as per the associations you have defined in your mappings. As far as I know you can't define OR style relationships in Nhibernate. Consider using a self referential style graph representation.
public class Node
{
public IList<Node> Parents { get; set; }
public IList<Node> Children { get; set; }
}
<bag name="Parents" table="Node_Relation">
<key column="ChildId" />
<many-to-many class="Node" column="ParentId" />
</bag>
<bag name="Children" table="Node_Relation">
<key column="ParentId" />
<many-to-many class="Node" column="ChildId" />
</bag>

Answer 2

You should be using DetachedCriteria to get the same done. I am not sure about your query but I will jsut give a shot.
var dc1= DetachedCriteria.For(typeof( NodeRelation )).Add(Restrictions.Eq("Fk_linkOne", 84))
.SetProjection(Projections.Property("Fk_linkOne"));
var dc2= DetachedCriteria.For(typeof( NodeRelation )).Add(Restrictions.Eq("Fk_linkTwo", 84))
.SetProjection(Projections.Property("Fk_linkTwo"));
Session.CreateCriteria(typeof(Nodes))
.Add(Subqueries.PropertyIn("Id", dc1))
.Add(Subqueries.PropertyIn("Id", dc2))
.Add(Restrictions.Eq("Id", 84)).List<Nodes>;
Hope the above query is corrrect. please let me know if you cant get it to work after obs trying smethings and let me know wat u tried.

Answer 3

It always depends on your classes and not so much on your tables. Remember, you are using a ORM and you are working with a class model.
Assumed that your classes look like this:
class Node
{
List<Node> Relations { get; private set; }
List<Node> InverseRelations { get; private set; }
}
You may map it like this:
<class name="Node">
<!-- .... -->
<bag name="Relations" table="NodeRelation">
<key name="Fk_linkOne">
<many-to-many class="Node" column="Fk_linkTwo"/>
</bag>
<bag name="InverseRelations" table="NodeRelation" inverse="true">
<key name="Fk_linkTwo">
<many-to-many class="Node" column="Fk_linkOne"/>
</bag>
</class>
This way you get asymetrical relations (this means: when Node A relates to Node B, B isn't necessarily related to A, except of the InverseRelation of course). I don't know what you actually need, so this is an assumption based on your database design.
Your query may look like this:
from Node n
where
:x in elements(n.Relations)
or :x in elements(n.InverseRelations)
Note: x is an entity type, not just an id (you need to load it using session.Load<Node>(84)),
Another way for the samy query:
select distinct n
from Node n
inner join n.Relations e1
inner join n.InverseRelations e2
where e1.id = 84 or e2.id = 84
Or another way without the use of the inverse relations:
select n
from Node n, Node n2 inner join n.Relations e
where
(n = n2 and e.id = 84)
OR (n = e and n2.id = 84)
In criteria I would take the second solution and write it like this:
session.CreateCriteria<Node>("n")
.SetProjection(Projections.Distinct("n"))
.CreateCriteria("Relations", "e1")
.CreateCriteria("InverseRelations", "e2")
.Add(Expression.Or(
Expression.Eq("e1.id", 84),
Expression.Eq("e2.id", 84));