> Would it work in your case to reattach the objects you are about to
> modify in the new ISession, modify them, and then letting NHibernate's
> cascading handle the removal?
Well at the moment the transaction Logic is complete nested in the
Dal. For every Type of Entity I've got a Dal. Inside the Dal I use one
Session for each method (e.g. FooDal.Save, FooDal.Load and so on).
Typically it looks like this:
public void Save(Foo foo)
{
using (var session = SessionFactory.OpenSession())
using (var tx = session.BeginTransaction())
{
session.Save(foo);
tx.Commit();
session.Flush();
}
}
The next problem is that currently my UI is more or less directly
bound to the Foos and if I remove a Bar from Foo it is also removed
from the UI. I could modify it so that the deleted Bars are just
marked as deleted and removed when saving. But you will agree that
that's not what the user is used to. If I delete something it shall
disappear from the UI. If I hit the save Button later the changes go
to the database. If I don't hit the save button the changes are
discarded. The Binding would get pretty tough if would keep the
deleted items in the Foo.Bar Collection till the User pushes the save
button.
Can't I tell NHibernate that it should remove the whole thing instead
of just the reference to the parent? The easiest way would be to just
set of an SQL command to the database DELETE FROM BAR_TABLE WHERE
ID_BAR = :myDeletedBarId. But I can't imagine that this isn't possible
with NHibernate.
On Oct 28, 4:58 pm, Oskar Berggren <[email protected]> wrote:
> 2010/10/28 reflection <[email protected]>:
>
> > I tried this, but NHibernate can't track the change because my Entity
> > is detached. I think the problem is that at the moment if I call
>
> > session.Delete(bar)
>
> > It tries to remove the association between the parent and the child,
> > but it is not allowed to child the foreign key to null because the
> > column has a not-null constraint. But I want to delete the whole
> > record from the database.
>
> Would it work in your case to reattach the objects you are about to
> modify in the new ISession, modify them, and then letting NHibernate's
> cascading handle the removal?
>
> > Shall I refactor my Dal to use a Singleton for the Session? Then the
> > entities would never get detached...
>
> You most certainly shall not. :) But you said session-per-request
> previously... what is your definition of request in your winforms app?
>
> /Oskar
>
>
>
> > This is a Windows Forms Application.
>
> > On Oct 28, 3:23 pm, Jason Meckley <[email protected]> wrote:
> >> inverse=true and cascade=all-delete-orphan
>
> >> var bar = session.Load<Bar>(1);
> >> session.Get<Foo>(2).Bars.Remove(bar);
>
> >> by removing bar from the collection of bars within Foo it becomes
> >> orphaned. nh detects the orphan and deletes it.
> >> by setting bar.Foo = null you are attempting to update the mapped
> >> column to null, which causes a foreign key reference error.
>
> >> On Oct 28, 8:24 am, reflection <[email protected]> wrote:
>
> >> > I think I can't get the full picture. Can you tell me how this helps
> >> > in my situation? I understand what it means, but I can't see how this
> >> > can be helpfull too me -.-
>
> >> > Thanks a lot!!!
>
> >> > On Oct 28, 1:34 pm, Oskar Berggren <[email protected]> wrote:
>
> >> > > See the last paragraph of 6.4
> >> > > inhttp://nhforge.org/doc/nh/en/index.htmlforastartinghint regarding
> >> > > inverse.
>
> >> > > /Oskar
>
> >> > > 2010/10/28 reflection <[email protected]>:
>
> >> > > > Hello,
>
> >> > > > I've read a lot on the Internet but I can't find a solution for my
> >> > > > problem :(
>
> >> > > > Example:
>
> >> > > > public class Foo
> >> > > > {
> >> > > > public IList<Bar> Bars { get; set; }
> >> > > > }
>
> >> > > > public class Bar
> >> > > > {
> >> > > > public Foo Foo { get; set; }
> >> > > > }
>
> >> > > > So it's a classical many-to-one mapping.
>
> >> > > > The mapping:
>
> >> > > > Foo:
>
> >> > > > ...
> >> > > > <bag name="Bars" inverse="true" cascade="none" lazy="true">
> >> > > > <key column="ID_FOO" />
> >> > > > <one-to-many class="Bar"/>
> >> > > > </bag>
> >> > > > ...
>
> >> > > > Bar:
>
> >> > > > ...
> >> > > > <many-to-one fetch="select" index="IDX_BAR_FOO" name="Foo"
> >> > > > class="Foo"
> >> > > > column="ID_FOO" cascade="none" not-null="true" foreign-
> >> > > > key="FK_BAR_FOO" />
> >> > > > ...
>
> >> > > > I use Session per Request pattern. So I do only have detached
> >> > > > entities
> >> > > > in my code.
>
> >> > > > Now if I load a Foo with some Bars from the Database, the tree may
> >> > > > look like this:
>
> >> > > > Foo1
> >> > > > |->Bar1
> >> > > > |->Bar2
> >> > > > |->Bar3
>
> >> > > > Now I remove one Bar from Foo1:
>
> >> > > > Foo1.Bars.Remoe(Bar1);
> >> > > > Bar1.Foo = null;
>
> >> > > > The problem is that I can't do
>
> >> > > > session.Delete(Bar1);
>
> >> > > > It always tells me that Foo can't be NULL. That's OK. But how do I
> >> > > > tell NHibernate to delete the whole row? If the entities would not be
> >> > > > detached I could use delete-orphan on the collection, but since the
> >> > > > childs are detached this doesn't work neither :(
>
> >> > > > I hope anybody has an idea how to solve this.
>
> >> > > > Thanks in advance!!!!
>
> >> > > > Greetings
>
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