Linq-To-Nhibernate multiples joins with conditionals - join

Question

I'm using Fluent-Nhibernate version 1.3 and I'm trying to make a query envolving 5 tables. I created a sql query for an oracle database and I'm trying to replicate with linq-to-nhibernate.
Following a sample of my entities and mapping.
Entities:
public class A
{
public virtual int idA { get; set; }
public virtual String codA { get; set; }
public virtual String tipoA { get; set; }
public virtual IList<B> listB { get; set; }
}
public class B
{
public virtual C objectC { get; set; }
public virtual A objectA { get; set; }
public virtual DateTime dtBegin { get; set; }
public virtual DateTime dtEnd { get; set; }
}
public class C
{
public virtual int idC { get; set; }
public virtual String codeC { get; set; }
public virtual IList<B> listB { get; set; }
public virtual IList<D> listD { get; set; }
}
public class D
{
public virtual C objectC { get; set; }
public virtual string flgD { get; set; }
public virtual DateTime dtBegin { get; set; }
public virtual DateTime dtEnd { get; set; }
public virtual E objectE { get; set; }
}
public class E
{
public virtual int idE { get; set; }
public virtual String dsE { get; set; }
public virtual DateTime dtBegin { get; set; }
public virtual DateTime dtEnd { get; set; }
public virtual IList<D> listD { get; set; }
}
My mapping:
class AMap : ClassMap<A>
{
public AMap()
{
Table("A");
Id(x => x.idA, "ID_A").GeneratedBy.Sequence("StringA");
Map(x => x.tipoA, "TP_A");
Map(x => x.codA, "CODE_A");
HasMany(x => x.listB).Cascade.All().KeyColumn("ID_A");
}
}
class BMap : ClassMap<B>
{
public BMap()
{
Table("B");
CompositeId()
.KeyReference(x => x.objectC, "ID_C")
.KeyReference(x => x.objectA, "ID_A")
.KeyProperty(x => x.dtBegin, "DT_BEGIN");
Map(x => x.dtEnd, "DT_END");
}
}
class CMap : ClassMap<C>
{
public CMap()
{
Table("C");
Id(x => x.idC, "ID_C").GeneratedBy.Sequence("StringC");
Map(x => x.codeC, "CODE_C");
HasMany(x => x.listB).Cascade.All().KeyColumn("ID_C");
HasMany(x => x.listD).Cascade.All().KeyColumn("ID_D");
}
}
class DMap : ClassMap<D>
{
public DMap()
{
Table("D");
CompositeId()
.KeyReference(x => x.objectC, "ID_C")
.KeyProperty(x => x.flgD, "FLG_D")
.KeyProperty(x => x.dtBegin, "DT_BEGIN");
References(x => x.objectE, "CODE_E");
Map(x => x.dtEnd, "DT_END");
}
}
class EMap : ClassMap<E>
{
public EMap()
{
Table("E");
Id(i => i.idE, "ID_E").GeneratedBy.Assigned();
Map(m => m.dsE, "DSC_E");
Map(m => m.dtBegin, "DT_BEGIN");
Map(m => m.dtEnd, "DT_END");
HasMany(x => x.listD).Cascade.All().KeyColumn("ID_E");
}
}
My SQL Query(it works):
SELECT C.CODE_C, E.CODE_E, E.DT_BEGIN
FROM TABLEA A, TABLEB B, TABLEC C, TABLED D, TABLEE E
WHERE A.CODE_A = '0000' AND A.ID_A = B.ID_A AND B.ID_C = C.ID_C AND B.DT_END IS NULL
AND C.ID_C = D.ID_C AND D.DT_END IS NULL AND D.CODE_E = E.CODE_E AND E.DT_END IS NULL;
I tried to use multiple join but then some relathionship are collections so I would have to make a where inside the join.
So my question is: is possible to make this same Sql query as linq-to-nhibernate or is better to make a sequence of selects? And no i can't change the database.
Thanks in advance.

Answer 1

the is null query is only possible using DateTime? as type
var query = from b in B
from c in b.C
from d in c.listD
from e in d.E
where b.A.Code == "0000" && b.EndDate == null & ...
select new { Ccode = c.Code, Ecode = e.Code, E_BeginDate = e.BeginDate }
Update: to answer the third comment
grouping the results has to be done in memory because grouping in sql can only return aggregations
var results = query.AsEnumerable()
.GroupBy(a => a.Ccode, a => a.Ecode, (key, values) => new { Ccode = Key, Ecodes = values.ToList() })
.List();