On Sun, Jun 24, 2007 at 06:27:29AM -0700, Matt Rosin wrote:
> Hello,
>
> Thanks for your reply, Matt. I've boiled down code from my Catalyst project
> as follows.
> A bit disconcerting that the problem remains even though I've refactored it
> into a command line program.
Not really, the root of the problem is in the database design, see below.
> In CatMgrDB::Listing below, I have added a number from 1 to 4 after the
> comment, so that 4 different relationships can be tried.
>
> When the relation in Listing.pm is "belongs_to" (i.e. case 4) inflation works
> and the output is:
> # ./reltest.pl
> Name: Telebody Inc.
> Offer: Free website estimate
>
> However when it is changed to "might_have" (case 1) the output is:
> # ./reltest.pl
> Name: Telebody Inc.
> Coupon is undefined
>
> It also fails for case 2 (has_one) but (why??) it works for case 3 (wierd
> misuse of has_one, I think).
No, actually, case 3 is the closest you've come so far to something sane :)
> Listings follow.
>
> Any light you can shed on this would be greatly appreciated.
>
> Meanwhile I have discovered something interesting, if I delete a coupon
> without zeroing the listing.coupon field, a new coupon with the same id is
> autovivified but with zeroes in all other fields. Which makes it impossible
> to delete with the existing code that looks at coupon.listing ...
>
> I really would like a way to disable autovivification. I don't believe it is
> "doing the right thing" if it keeps surprising me. Well I suppose I should be
> using might_have (if inflation would work with it) or allow nulls in the
> table.
It keeps surprising you because the defaults work for a normalised schema.
Yours isn't.
> [EMAIL PROTECTED] [/app/reltest]# cat CatMgrDB/Listing.pm
> package CatMgrDB::Listing;
> use base qw/DBIx::Class/;
> __PACKAGE__->load_components(qw/PK::Auto Core/);
> __PACKAGE__->table('listing');
> __PACKAGE__->add_columns(qw/id category customer banner whitepages type
> flagged disabled name address address2 city state zip phone offertext site
> directions locations menu template usermemo adminmemo codememo package coupon
> modified/);
Drop the coupon field, it's duplicate information.
> __PACKAGE__->set_primary_key('id');
> #__PACKAGE__->might_have(coupon => CatMgrDB::Coupon); #1 inflation fails with
> this
This is right, and will work perfectly once you've made the other changes
outlined below.
> 1;
> [EMAIL PROTECTED] [/app/reltest]# cat CatMgrDB/Coupon.pm
> package CatMgrDB::Coupon;
> use base qw/DBIx::Class/;
> __PACKAGE__->load_components(qw/PK::Auto Core/);
> __PACKAGE__->table('coupon');
> __PACKAGE__->add_columns(qw/id listing available flagged offer terms
> usermemo/); # and other columns
Drop the id field, it's unecessary since you only have at most one coupon per
listing.
> __PACKAGE__->set_primary_key('id');
Set listing as the primary key (and consider renaming to listing_id and
altering the third arg to the belongs_to rel appropriately).
> __PACKAGE__->belongs_to( listing => 'CatMgrDB::Listing', 'listing',
> {join_type => 'left'});
> 1;
Drop the join_type, it's wrong unless you can have coupons without a listing,
which from what you've said so far you can't.
And with the above done, your might_have and belongs_to relations will work
fine, there'll be no unexpected autovivification -and- your database will
be in something approaching normal form.
Plus, you'll be able to set up a foreign key to match the belongs_to from
listing to coupon so your database is enforcing relational integrity - your
current design with circular relationships strongly suggests to me you
don't have foreign keys at all, which is a little on the dangerous side.
--
Matt S Trout Need help with your Catalyst or DBIx::Class project?
Technical Director Want a managed development or deployment platform?
Shadowcat Systems Ltd. Contact mst (at) shadowcatsystems.co.uk for a quote
http://chainsawblues.vox.com/ http://www.shadowcatsystems.co.uk/
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