[Catalyst] Perplexed Catalyst newbie

[J. Shirley]

On Mon, Apr 20, 2009 at 1:51 PM, Sean McAfee <eefacm at gmail.com> wrote:

> On Sun, Apr 19, 2009 at 2:49 PM, J. Shirley <jshirley at gmail.com> wrote:
>
>> Catalyst::Model::DBIC::Schema simply looks at all available result sets
>> and creates a model class that is a transparent wrapper.  It should func=
tion
>> the exact same.
>>
>> The code that does this is:
>>
>>     foreach my $moniker ($self->schema->sources) {
>>         my $classname =3D "${class}::$moniker";
>>         *{"${classname}::ACCEPT_CONTEXT"} =3D sub {
>>             shift;
>>             shift->model($model_name)->resultset($moniker);
>>
>>
>>         }
>>
>>     }
>>
>> As you can see, all it is doing is a short-hand to
>> $c->model('DB')->resultset($moniker) ($moniker being the name, 'Language=
',
>> $class being 'Quiz::Model::DB')
>>
>> That's how it works, but without seeing actual code in your application
>> I'm not sure why you are getting unexpected results.
>>
>
> Okay, I've reduced my app to its most basic components, and renamed its
> elements for simplicity.  A is the highest-level component; it has_many B=
's;
> each B has_many C's.  Here are the source files, using what is hopefully =
an
> intuitively obvious shell-like expansion notation for brevity:
>
> File Quiz/Schema/{A,B,C}.pm:
>
> package Quiz::Schema::{A,B.C};
> use base 'DBIx::Class';
> __PACKAGE__->load_components('Core');
> __PACKAGE__->table('{A,B,C}');
> __PACKAGE__->add_columns('{a,b,c}', {,'a','b'});
> __PACKAGE__->set_primary_key('{a,b,c}');
> 1;
>
> Quiz/Schema/A.pm and Quiz/Schema/B.pm each have one extra configuration
> statement:
>
> __PACKAGE__->has_many({bs,cs} =3D> 'Quiz::Schema::{B,C});
>
> In my database, table A has a single column "a" and two rows with values 1
> and 2.  Table B has columns "b" and "a" and two rows: b=3D1, a=3D1 and b=
=3D2,
> a=3D2.   And table C has columns "c" and "b" and three rows: c=3D1, b=3D1=
; c=3D2,
> b=3D2; and c=3D3, b=3D2.
>
> To sum up: There are two A's, each of which has one B.  Of the two B's, o=
ne
> has one C, and the other has two C's.
>
> In my controller module, I have this routine:
>
> sub index :Path :Args(0) {
>   my ($self, $c) =3D @_;
>   $c->stash->{as} =3D [ $c->model('DB::A')->all ];
>   $c->stash->{template} =3D 'index.tt';
> }
>
> This is the content of my index.tt file:
>
> [% FOR a IN as; FOR b IN a.bs; b.cs; "<br>"; END; END %]
>
> And this is the output in my browser:
>
> Quiz::Model::DB::C=3DHASH(0xc75e78)
> ARRAY(0xc0c96c)
>
> Now the corresponding plain DBIx::Class app, as I understand it, would be
> similar to this:
>
> for my $a ($schema->resultset('A')->all) {
>   for my $b ($a->bs) {
>     my $cs =3D $b->cs;
>     print ref $cs, "\n";
>   }
> }
>
> When I run this program, the output is:
>
> DBIx::Class::ResultSet
> DBIx::Class::ResultSet
>
> I get a ResultSet back when I ask for any B's list of C's.  But when I go
> through Catalyst, I (apparently) get an unblessed array reference back if
> the B in question has more than one C.  So sometimes I get a genuine obje=
ct
> back, other times I get plain old data.  How am I supposed to code around
> that?
>
> Or probably the more correct question:  Where do my expectations diverge
> from Catalyst's reality?
>
>
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>

Your problem is debugging with TT, which does annoying variable magic and
folding arrays.

It's very frustrating, but don't debug with TT.  Use $c->log->debug and
$c->log->_dump to get what you are after.  It'll make sure that you are
staying inside of Perl, and not a very weird dialect that has very weird
ideas about lists.

-J
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