Fluent NHibernate compositeid to mapped class - nhibernate

Question

I'm trying to figure out how to use CompositeId to map another class. Here's a test case:
The tables:
TestParent:
TestParentId (PK)
FavoriteColor
TestChild:
TestParentId (PK)
ChildName (PK)
Age
The classes in C#:
public class TestParent
{
public TestParent()
{
TestChildList = new List<TestChild>();
}
public virtual int TestParentId { get; set; }
public virtual string FavoriteColor { get; set; }
public virtual IList<TestChild> TestChildList { get; set; }
}
public class TestChild
{
public virtual TestParent Parent { get; set; }
public virtual string ChildName { get; set; }
public virtual int Age { get; set; }
public override int GetHashCode()
{
return Parent.GetHashCode() ^ ChildName.GetHashCode();
}
public override bool Equals(object obj)
{
if (obj is TestChild)
{
var toCompare = obj as TestChild;
return this.GetHashCode() != toCompare.GetHashCode();
}
return false;
}
}
The Fluent NHibernate maps:
public class TestParentMap : ClassMap<TestParent>
{
public TestParentMap()
{
Table("TestParent");
Id(x => x.TestParentId).Column("TestParentId").GeneratedBy.Native();
Map(x => x.FavoriteColor);
HasMany(x => x.TestChildList).KeyColumn("TestParentId").Inverse().Cascade.None();
}
}
public class TestChildMap : ClassMap<TestChild>
{
public TestChildMap()
{
Table("TestChild");
CompositeId()
.KeyProperty(x => x.ChildName, "ChildName")
.KeyReference(x => x.Parent, "TestParentId");
Map(x => x.Age);
References(x => x.Parent, "TestParentId"); /** breaks insert **/
}
}
When I try to add a new record, I get this error:
System.ArgumentOutOfRangeException :
Index was out of range. Must be
non-negative and less than the size of
the collection. Parameter name: index
I know this error is due to the TestParentId column being mapped in the CompositeId and References calls. However, removing the References call causes another error when querying TestChild based on the TestParentId.
Here's the code that does the queries:
var session = _sessionBuilder.GetSession();
using (var tx = session.BeginTransaction())
{
// create parent
var p = new TestParent() { FavoriteColor = "Red" };
session.Save(p);
// creat child
var c = new TestChild()
{
ChildName = "First child",
Parent = p,
Age = 4
};
session.Save(c); // breaks with References call in TestChildMap
tx.Commit();
}
// breaks without the References call in TestChildMap
var children = _sessionBuilder.GetSession().CreateCriteria<TestChild>()
.CreateAlias("Parent", "p")
.Add(Restrictions.Eq("p.TestParentId", 1))
.List<TestChild>();
Any ideas on how to create a composite key for this scenario?

Answer 1

I found a better solution that will allow querying and inserting. The key is updating the map for TestChild to not insert records. The new map is:
public class TestChildMap : ClassMap<TestChild>
{
public TestChildMap()
{
Table("TestChild");
CompositeId()
.KeyProperty(x => x.ChildName, "ChildName")
.KeyReference(x => x.Parent, "TestParentId");
Map(x => x.Age);
References(x => x.Parent, "TestParentId")
.Not.Insert(); // will avoid "Index was out of range" error on insert
}
}

Answer 2

Any reason you can't modify your query to just be
_sessionBuilder.GetSession().CreateCriteria<TestChild>()
.Add(Restrictions.Eq("Parent.TestParentId", 1))
.List<TestChild>()
Then get rid of the reference?