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Re: DBIx::Class and many-to-many searching

by zby (Vicar)
on May 30, 2006 at 12:25 UTC ( [id://552479]=note: print w/replies, xml ) Need Help??


in reply to DBIx::Class and many-to-many searching

Update: Added code to generate the params.

Hmm - that might be pretty hard (I assume that you want an article that is linked to all of the tags in @with instead of the castaway's interpretation). Here are some loose thoughts.

Lets take a bit simplified case where the @with contains the articlelinks ids and not think about the @without part at all. Than you need a query like:

SELECT * FROM article, articlelinks, articlelinks articlelinks_2, articlelinks artic +lelinks_3 ... WHERE article.id = articlelinks.article AND articlelinks.id = $with[0] AND article.id = articlelinks_1.article AND articlelinks_1.id = $with[1] A +ND ...
To produce this with DBIC you need something like:
my %params; $params{'articlelinks.id'} = $with[0]; for my $i ( 2 .. (scalar @with) - 1 ){ $params{"articlelinks_$i.id"} = $with[$i - 1]; } my @articles = $schema->resultset('articles')->search( \%params, { join => [ 'articlelinks' x scalar( @with ) ] } );
The @without part is a bit simpler, thanks to De Morgan lows. But how to compose those two parts? In raw SQL I would use 'EXCEPT' but in DBIC? And how to go from the list of 'articlelinks' ids to tags?

More questions than answers here - but I've heard mst was looking for hard cases so perhaps some day he shall simplify that? I'm interested - as I use a similar structure in my bookmarking app.

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