[Dbix-class] Confused by search_related

[Paul Makepeace]

On 10/6/07, John Napiorkowski <jjn1056 at yahoo.com> wrote:
>
> --- Paul Makepeace <paulm at paulm.com> wrote:
>
> > In the docs
> >
> http://search.cpan.org/~ash/DBIx-Class-0.08007/lib/DBIx/Class/Relationship.pm
> > there's an example of search_related doing a "select
> > *" which I think
> > is misleading as it's actually only selecting from
> > the related
> > resultset not the base(?) resultset, at least in my
> > experiments.
> >
> > I have SavedView with,
> >
> > __PACKAGE__->belongs_to('web_chart_spec' =>
> > 'IDL::Schema::WebChartSpec' =>
> > 'web_chart_spec_uid');
> >
> > My controller does,
> >
> >   my @saved_views :Stashed =
> >
> $c->model('DBIC_Readonly')->resultset('SavedView')->search_related(
> >               'web_chart_spec' => {service_profile_uid =>
> > $chart->{service_profile_uid}});
> >
> > I get results but nothing from SavedView, just
> > WebChartSpec! Debugging
> > the SQL reveals it's only selecting on
> > web_chart_spec.*. I dunno, if I
> > called "resultset('SavedView')" I'm expecting stuff
> > with SavedView in
> > it.
>
> When you do a search_related you get a new resultset
> from the related result_source (in this case it's
> WebChartSpec, which is the resultset you specify in
> the relationship).

(Yep. I find this counter-intuitive, but whatever.) Do you agree then
the SQL in the docs is misleading? It's saying "*" is being returned
whereas in fact only related_result_class.* is.

>  It should also 'limit' the related
> resultset by any conditions you've already done. so
> for example:
>
> $schema->resultset('rs1')->related_resultset('rs2');
>
> should return a resultset of rs2 where all rs
> 'belong_to' rs1 (assuming a definition similar to the
> one you described).
>
> On the other hand:
>
> $schema
>   ->resultset('rs1')
>   ->search({value=>$search})
>   ->related_resultset('rs2');
>
> returns a resultset of rs2 that belong to rs1 and
> where 'value=$search' in rs1.

Is this just the same as
resultset('rs1')->search_related('me.value'=>$search}) ?

>
> Remember the SQL doesn't actually get run until you
> want some values, so you can continue to add
> conditions until you get the exact query you need.

Yeah, but I can't get back rs1 :-)

>
> >
> > How can I achieve what I'm intending here? In
> > essence,
> >
> > select sv.* from saved_view sv
> > join web_chart_spec ws on ws.uid =
> > sv.web_chart_spec_uid
> > where ws.service_profile_uid = ?;
> >
> >   my @saved_views :Stashed =
> >
> $c->model('DBIC_Readonly')->resultset('SavedView')->search(
> >               {'web_chart_spec.service_profile_uid' =>
> > $chart->{service_profile_uid}},
> >               {join => ['web_chart_spec']});
> >
> > Works but maybe there's a nicer way.
> >
> > P
>
> This is correct, if you want to limit a resultset via
> it's relations, you need to join those relations.
>
> The only cleaning thing I can think of is to make this
> into a custom resultset class method so that you can
> just do:
>
> my $rs = $c->model('DBIC::SavedView')->custom_rs;
>
> In your controller.
>
> There's examples of making a custom resultset in the
> cookbook and also there is a new feature that makes it
> simple to add custom resultsets.  See:
>
> http://search.cpan.org/~ash/DBIx-Class-0.08007/lib/DBIx/Class/Schema.pm#load_namespaces
>
> for some of this.  With this plus the ability to set a
> custom result_class in your resultset methods, it
> makes it much easier to link your physical model (AKA
> the result_sources) to true domain logic.

Is this the sort of thing you mean?

My::Schema::SavedView,
__PACKAGE__->resultset_class('My::ResultSet::SavedView');

#...

package My::ResultSet::SavedView;
use base 'DBIx::Class::ResultSet';

sub search_by_profile_uid {
  my ($self, $profile_uid) = @_;
  $self->search(
    {'web_chart_spec.service_profile_uid' => $profile_uid},
    {join => ['web_chart_spec']});
}

1;

Thanks for the tips, P

>
> Just stay away from the 'ResultSetManager' component,
> which has been superceded by the above methods.
>
> --John
>
> >
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