That's a pretty cool approach, and it solves adding a new record
smoothly. But what it misses is the ability to fetch all a that have a
non-archived b:
SELECT * FROM a JOIN b ON (b.a_id=a.id) WHERE b.archived_at IS NULL
or
My::A::Manager->get_as_iterator(requre_objects => [ 'b' ]);
Here's another approach:
Store a foreign key on A for the one-to-one
CREATE TABLE a (id pri key, b_id foreign key);
and store a foreign key on B for the one-to-many
CREATE TABLE b (id pri key, name text, a_id foreign key)
But I tried this before and I ran into a lot of trouble mapping IDs
back-and-forth, eg. If you set $a->b({ name => 'test' }), will Rose
know to map the b back to the a as well as mapping the a to the b?
Which is a cleaner approach?
On 5/18/07, John Siracusa <[EMAIL PROTECTED]> wrote:
> On 5/18/07, Derek Watson <[EMAIL PROTECTED]> wrote:
> > Am I modeling this wrong? How can I get Rose to archive the previous
> > $a->b when I say $a->b($new_b_record)? Or at least try to save the new
> > 'b' record so that my DB will throw an error about a clashing unique
> > key?
>
> A ...-to-one expects there to just be one thing at the end. So
> there's no "add" method, just get and set. A set implies replacing
> the existing one with a new one, which is what you're seeing: RDBO
> deletes the old and inserts the new.
>
> To get the behavior you want, I think you'll need to use a 1-to-many
> and then wrap the relationship accessor in such a way that a set is
> really an add.
>
> sub b
> {
> my($self) = shift;
>
> $self->add_bs(@_) if(@_);
>
> # bs must be sorted so that the last one is the latest one
> # use manager_args on the "bs" rel to do that.
> my $bs = $self->bs || [];
>
> return $bs->[-1];
> }
>
> Then add a trigger to the b table (or the My::B class) to handle the
> "archiving" or a previous b record when a new one is inserted.
>
> -John
>
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