these are lower level concerns within NH that a developers shouldn't
need to think about. the session itself implements an identity map
which is responsible for ensuring exactly 1 instance of an entity
exists per session.
Get() and Load() use the identity map to determine if the entity is
already loaded so you don't query the database twice. a query will
retrieve the entity from the database, but if the entity is already
loaded in the session that instance will be returned instead of the
results from the database. for example
//table Entity
//columns Id int, Name varchar
//row 1, "old name"
var entity = session.Get<Entity>(1);
// result from database is row [1, "old name"]
// entity[1] loaded into session's identity map (IM)
entity.Name = "new name";
// entity[1] in IM Name property is changed
var entity = session
.CreateQuery("from Entity where id = :id")
.SetParameter("id", 1)
.Unique<Entity>();
// result from database is row [1, "old name"]
// entity[1] already exists in the IM as Entity{Id = 1, Name = "new
name"}
Assert.That(entity.Name, Is.EqualTo("new name"));
// should pass
Hopefully that clears things up.
On Dec 10, 7:55 am, Jacob Madsen <[email protected]> wrote:
> Hi there,
>
> Hope one of you can help me with 2 questions:
>
> 1) How do I ask a session if a specific entity is dirty / has changed?
>
> 2) Will ISession.Contains(entity) return true for any session-tracked
> entity, no matter how the entity was loaded / queried / retrieved?
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