I'm interested in the reasons for NOT mapping your model. What you have now
is a DB model, not a domain model.
If you mapped your collection, it would be as easy as:
select f, d
from Folder f
left join f.Documents d
But you don't even need that. You can use "from Folder" and then just
navigate the Documents relationship as convenient.
If you set batch-size on the collection to a reasonable number, you avoid
the SELECT N+1 problem in one single step.
Diego
On Wed, Sep 15, 2010 at 00:22, rsr <[email protected]> wrote:
>
> Each document has a FolderID column, which is a foreign key to its
> containing folder.
>
> Normally, in NH, I you'd map this as a many-to-one on Document,
> pointing at Folder, and a collection of some sort on Folder,
> containing Documents. Right? But like I say, I'm not using any
> association mappings
> (i have my reasons, trust me).
>
> Supposing my select was
> select f, d from ....
>
> then ideally, I'd get back something like a list of tuples where the
> first item is the folder and the second is a document. Yes, I'd get
> a separate result for each document, with the same instance of the
> Folder as the other children of the same folder. I'd have to gather
> them up and build the collection by folder. No problem there.
> Empty folders would be represented by a tuple with folder and a null
> document.
> Or maybe every folder would have an entry with a folder and a null,
> whether it is empty or not.
>
> Make sense?
>
> On Sep 14, 7:05 pm, Diego Mijelshon <[email protected]> wrote:
> > If you have a FolderID in the Document, you are NOT mapping it as I would
> > imagine...
> >
> > Also, what are you trying to retrieve with your query? all folders with
> all
> > their documents?
> >
> > Diego
> >
> > On Tue, Sep 14, 2010 at 22:26, rsr <[email protected]> wrote:
> > > Say I've got two tables Folder and Document related as you can
> > > imagine, and mapped in NH using just a simple property FolderID on the
> > > Document entity. i.e. - no many-to-one mapping.
> >
> > > I can do an HQL inner join by using
> > > from Folder f, Document d where f.FolderID = d.FolderID
> > > and that's great.
> >
> > > My question is - how can I turn that into a left join, so that I can
> > > get folders that have no documents?
> >
> > > Thanks.
> >
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