Fluent Nhibernate & SQLite mapping component
-
05-12-2019 - |
Domanda
I have a component on an entity that may be null. This works in a unit test with an InMemory database, but does not work on a file based SQLite database. I use a boolean flag to indicate whether the component was set, but this seems to be a hack.
Is this a NHibernate or a SQLite Bug? Or am i missing something?
Here are my mappings stripped of business value:
public sealed class EntityMap : ClassMap<Entity>
{
public EntityMap()
{
Not.LazyLoad();
Id(m => m.Uid);
Map(m => m.HasComponent).Not.Nullable();
Component(m => m.Component).ColumnPrefix("Component");
}
}
public sealed class MyComponentMap : ComponentMap<MyComponent>
{
public MyComponentMap()
{
Map(c => c.SomeBasicProperty).Nullable();
HasMany(c => c.ListOfValues).AsList(li => li.Column("Number"))
.Component(part =>
{
part.Map(s => s.Name);
part.Map(s => s.Value);
}
.Table("ComponentValues")
.Cascade.AllDeleteOrphan().Not.LazyLoad();
}
}
With the memory database the component on the entity is null when all columns for it are null. This is what i expect.
When using a file based database the component is empty. So i cannot use entity.Component==null
to check if the Component has already been set.
Soluzione
i tested your code with inmemory and it returns Component != null
for an inmemory database as expected. In NHibernate a collection is never null but can be empty and a component is only null if all properties are null hence the component should never be null. i guess that you tested like
using (var tx = session.BeginTransaction())
{
id = session.Save(new Entity());
tx.Commit();
}
var entity = session.Get<Entity>(id);
Console.WriteLine(entity.Component == null);
Get returns the same instance which has Component set to null.
using (var tx = session.BeginTransaction())
{
id = session.Save(new Entity());
tx.Commit();
}
session.Clear();
var entity = session.Get<Entity>(id);
Console.WriteLine(entity.Component == null);
Get returns the loaded instance which has Component set to non-null.