[Dbix-class] Avoid DB hit with many_to_many rel

[Moritz Onken]

Hi,

I have a table 'categories' which has a many_to_many relationship to  
itself using a table 'map_categories'.

I found out that prefetching the many_to_many rel does not work. So I  
prefetched the has_many rel to 'map_categories' (parents) and prefetch  
the belongs_to rel (parent) from 'map_categories' to 'categories' ($rs- 
>search({},{prefetch => {'parents' => 'parent'}})->all). This does  
the sql statement I expect but when I call $row->parents->all (or $row- 
>parents->first->parent) on a row of this rs it hits the database  
again. Although the resultset already contains all rows it needs.

Any ideas what I did wrong?

cheers,

moritz

package Schema::Categories;

use strict;
use warnings;

use base 'DBIx::Class';

__PACKAGE__->load_components("PK::Auto", "Core");
__PACKAGE__->table("categories");
__PACKAGE__->add_columns(
  "title",
  {
    data_type => "character varying",
    default_value => undef,
    is_nullable => 1,
    size => 100,
  },
  "id",
  {
    data_type => "integer",
    is_nullable => 0
  });

__PACKAGE__->set_primary_key("id");

__PACKAGE__->has_many("parents" => 'MapCategories' => "child");

#__PACKAGE__->many_to_many(many_parents => "parents" => "parent");

1;

package Schema::MapCategories;

use strict;
use warnings;

use base 'DBIx::Class';

__PACKAGE__->load_components("PK::Auto", "Core");
__PACKAGE__->table("map_categories");
__PACKAGE__->add_columns(
  "child",
  {
    data_type => "integer",
    is_nullable => 0,
  },
  "parent",
  {
    data_type => "integer",
    is_nullable => 0
  });

__PACKAGE__->belongs_to("child" => "Schema::Categories", "child");
__PACKAGE__->belongs_to("parent" => "Schema::Categories", "parent");
__PACKAGE__->add_unique_constraint([ qw/child parent/ ]);


1;

_______________________________________________
List: http://lists.scsys.co.uk/cgi-bin/mailman/listinfo/dbix-class
IRC: irc.perl.org#dbix-class
SVN: http://dev.catalyst.perl.org/repos/bast/DBIx-Class/
Searchable Archive: http://www.grokbase.com/group/[EMAIL PROTECTED]