Re: [Hibernate] RE: session.filter(Collection, Predicate)?

[Gavin K. <ga...@ap...>]

Yeah, pretty much. The point is really that Hibernate doesn't need to be
involved in that kind of filtering, because it occurs entirely in memory.

----- Original Message -----
From: "Anton van Straaten" <an...@ap...>
To: "hibernate list" <hib...@li...>
Sent: Saturday, September 14, 2002 12:21 AM
Subject: [Hibernate] RE: session.filter(Collection, Predicate)?


> I realized in the cold light of day that what I was asking about below
can't
> possibly work unless the object being filtered has already been fully
> loaded, which I presume would defeat the purpose of the filter.  Is that
> correct?
>
>
> > -----Original Message-----
> > From: Anton van Straaten [mailto:an...@ap...]
> > Sent: Friday, September 13, 2002 1:45 AM
> > To: hibernate list
> > Subject: session.filter(Collection, Predicate)?
> >
> >
> > > Accordingly Ive added filtering
> > > methods to the Session interface like:
> > >
> > >   filteredCollection = session.filter(collection, query)
> > >
> > > A filter is just a query where you can refer to "this", the collection
> > > element. So, for example:
> > >
> > >   blackCats = session.filter( cat.getKittens(), "where
> > this.color='black'
> > > order by this.name" );
> >
> > Slightly tangential question about this: how straightforward (or
> > not) would it be to support an object as the filter parameter?  I
> > use a Predicate interface in my own code:
> >
> > public interface Predicate {
> > // Apply predicate to a specified object and return boolean result
> > boolean apply(Object o);
> > }
> >
> > This can be used to create arbitrary objects to filter on any
> > condition - I use it for filtering Java collections and arrays.
> > You can also use it inline, e.g.:
> >
> > blackCats = session.filter( cat.getKittens(), new Predicate() {
> > public boolean apply(Object o) {
> > return o.color.equals("black");
> > }
> > });
> >
> > I don't know anything about what Hibernate is doing when it's
> > retrieving & filtering a query - if something like this wouldn't
> > require too much internal rearranging, I might take a stab at it,
> > since it would fit in with some of the other code I'm using.  In
> > fact it came up in some code which I've just installed for
> > testing, and I ended up building a query string to do it instead.
> >  In some cases, I prefer the approach I've described since it's
> > subject to static checking, supports refactoring, etc.
> >
> > Anton
> >
>
>
>
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