nHibernate one-to-many best practice persintence to avoid INSERT NULL - nhibernate

Question

I've a One to Many mapping.
An entity with a collection persisted on two table 1:N
This is the class and the mapping:
public class Test
{
public virtual string Id { get; set; }
public virtual string Description { get; set; }
public virtual IList<TestItem> Items { get; set; }
public Test()
{
Items = new List<TestItem>();
}
}
public class TestItem
{
public virtual string Id { get; set; }
public virtual Test Test { get; set; }
public virtual string ItemCode { get; set; }
public virtual string ItemData { get; set; }
}
public class TestMap : ClassMapping<Test>
{
public TestMap()
{
Id(x => x.Id, m => m.Column("IDTest"));
Bag(x => x.Items, c =>
{
c.Key(k =>
{
k.NotNullable(true);
k.Column("IDTest");
});
c.Cascade(Cascade.DeleteOrphans);
c.Lazy(CollectionLazy.NoLazy);
c.Inverse(true);
}, r => r.OneToMany(m =>
{
m.NotFound(NotFoundMode.Exception);
m.Class(typeof(TestItem));
}));
}
}
public class TestItemMap : ClassMapping<TestItem>
{
public TestItemMap()
{
Id(x => x.Id, m => m.Column("IDTestItem"));
ManyToOne(x => x.Test, m =>
{
m.Column("IDTest");
m.NotNullable(false);
m.Lazy(LazyRelation.NoLazy);
});
Property(x => x.ItemCode);
Property(x => x.ItemData);
}
}
And this is the code.
If I remove the marked line I get the error.
var session = SessionFactory.OpenSession();
using (var tr = session.BeginTransaction())
{
var test = new Test();
test.Id = "T01";
test.Description = "Desc TEST 01";
session.SaveOrUpdate(test); // If Removed Get INSERT ERROR on TestItem
var item = new TestItem { Id = "NEW01", ItemCode = "A", Test = test, ItemData = "New T01A" };
test.Items.Add(item);
session.SaveOrUpdate(item);
session.SaveOrUpdate(test);
tr.Commit();
}
My question is:
Is this the best practice to persist a "one to many" relation ?
It is possible to use the code below and save all only saving the header Row (test) and automatically cascading all inserts on the child table??
var session = SessionFactory.OpenSession();
using (var tr = session.BeginTransaction())
{
var test = new Test();
test.Id = "T01";
test.Description = "Desc TEST 01";
//session.SaveOrUpdate(test); // If Removed Get INSERT ERROR on TestItem
var item = new TestItem { Id = "NEW01", ItemCode = "A", Test = test, ItemData = "New T01A" };
test.Items.Add(item);
//session.SaveOrUpdate(item);
session.SaveOrUpdate(test);
tr.Commit();
}
I suppose I need to change something on my mapping code but i do not undestand what!!!
Many days of work, googling, stackoverflowing but nothing change the result.
Thank you!!!

Answer 1

Q: Is this the best practice to persist a "one to many" relation ?
A: If you're talking about a "composition" relationship, the cascading approach can be a good choice.
Q: It is possible to use the code below and save all only saving the header Row (test) and automatically cascading all inserts on the child table??
A: Yes it is possible. But your code should look like this:
public class TestMap : ClassMapping<Test>
{
public TestMap()
{
Id(x => x.Id, m => m.Column("IDTest"));
Bag(x => x.Items, c =>
{
c.Key(k =>
{
k.NotNullable(true);
k.Column("IDTest");
});
c.Cascade(Cascade.All | Cascade.DeleteOrphans); //<- My suggestion
c.Lazy(CollectionLazy.NoLazy);
c.Inverse(true);
}, r => r.OneToMany(m =>
{
m.NotFound(NotFoundMode.Exception);
m.Class(typeof(TestItem));
}));
}
}