On Thu, Nov 6, 2008 at 4:56 PM, Ovid <[EMAIL PROTECTED]> wrote:
> Short question (I hope). I have a resultset which inflates objects based
> upon an id. While the ID may exist, it's acceptable for the underlying
> inflated object to not exist. Unfortunately, this means that the
> "$rs->count" might report more objects than actually exist.
>
> This is the correct behavior, but we'd like to be able to create a resultset
> with a filter applied which represents what we really have. Something like:
>
> my $new_rs = $rs->filter( sub { defined $_->inflate_entity } );
>
> '$rs->search_rs' doesn't seem appropriate because regrettably, joining across
> tables doesn't appear to be an option here.
>
> Cheers,
> Ovid
>
> Longer description below for those who are confused.
>
> Note: This is a greatly simplified description of the problem, reducing it
> to its core elements.
>
> Customers require all objects to be searchable via a common ID formats. So
> let's say we have three tables:
>
> brand
> series
> episodes
>
> And we have an 'identifier' table (again, greatly simplified):
>
> identifier
> ----------
> identifier_id int primary key
> identifier varchar(32)
> object_type enum('Brand', 'Series', 'Episode') (yuck)
>
> So if a customer gives me an id, I can check in the identifier table and see
> that it's a key for a brand and this requires a second check in the brand
> table to fetch the item. Here's the problem: if we delete a brand, series
> or episode, we cannot delete the identifier because it must not be reused.
> Though some of these are custom methods, you should be able to understand the
> problem from here:
>
> my $entity = $schema->resultset('Identifier')->search(
> { type => 'pid' }
> )->first->inflate_entity;
>
> my $pid = $entity->pid;
>
> $entity->delete;
>
> my $rs = $schema->resultset('Identifier')->search({
> type => 'pid',
> value => $pid,
> });
> print $rs->count; # prints 1, even though the $entity is gone
How about adding a column that would say if a given pid is deleted to
the Identifier table? Then
my $rs = $schema->resultset('Identifier')->search({
type => 'pid',
value => $pid,
is_deleted => 0,
});
print $rs->count; # prints 0
No joins - just a bit denormalized.
--
Zbigniew Lukasiak
http://brudnopis.blogspot.com/
http://perlalchemy.blogspot.com/
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