Here's a suggestion. Ideally, you'd have a method in the parent that adds
the child:
public void Add( Child item )
{
_children.Add( item );
if ( item.IsOpen )
ChildCount++;
}
public virtual int ChildCount {get ; private set;}
This is how i would control calculated fields.
cliff
On Thu, May 13, 2010 at 10:53 AM, pvginkel <[email protected]> wrote:
> The reason I would like this to work is because the value I am
> calculating is a value that is being used very often. It is used to
> display a flag in a grid with many records that update quite often.
>
> What I'm wondering is why this is regarded as hacking. I though that
> the concept of stored calculated fields was something quite normal.
> The only problem I have is that I do not know where to update this
> value.
>
> Do you have alternatives to the interceptor or the event listener
> mechanism? Or is there a way to implement this using the interceptor
> or event listener mechanism?
>
> On May 13, 4:08 pm, Diego Mijelshon <[email protected]> wrote:
> > I think using an interceptor for this is the wrong approach.
> > Instead, you can define your property as follows:
> >
> > public virtual int ChildCount
> > {
> > get { return Children.Count(c => c.IsOpen); }
> > }
> >
> > And map it as
> >
> > <property name="ChildCount" access="readonly" />
> >
> > And you're done. No hacking.
> > This is exactly how I'm doing it now.
> >
> > Diego
> >
> >
> >
> >
> >
> > On Wed, May 12, 2010 at 15:14, pvginkel <[email protected]> wrote:
> > > I am using NHibernate 2.1.2.4000 with LinFu proxy generater and I have
> > > the following problem.
> >
> > > Basically, I have a parent child mapping:
> >
> > > <class name="Parent">
> > > <id name="Id">
> > > <generator class="native" />
> > > </id>
> > > <property name="ChildCount" />
> > > <set name="Children" inverse="true">
> > > <key column="ParentId" />
> > > <one-to-many class="Child" />
> > > </set>
> > > </class>
> >
> > > <class name="Child">
> > > <id name="Id" column="Id">
> > > <generator class="native" />
> > > </id>
> > > <property name="IsOpen"/>
> > > <many-to-one name="Parent" column="ParentId" />
> > > </class>
> >
> > > When I a child is added, deleted or the IsOpen flag changes, the
> > > ChildCount must be updated. I do this in an interceptor. Creating or
> > > deleting the child works perfectly, and the count gets correctly
> > > updated. Changing the child, updating the ChildCount in the
> > > OnFlushDirty interceptor method however does not work.
> >
> > > I've tried everything I could think of. In a few of my tries, I got an
> > > exception in the transaction.Commit that the object could not be
> > > reassociated because it had a dirty collection.
> >
> > > My current hypothesis is that NHibernate specifically disallows these
> > > kinds of updated to e.g. prevent against circular references and never
> > > ending cascade update cycles. If this is the case, does anybody have
> > > an alternative to implement these kinds of cascade updates for cached
> > > field values?
> >
> > > I'm quite out of ideas and would like some assistance.
> >
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thanks
cliff
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