Hi!
many_to_many is no relationship but a relationship helper, so it can't be
prefetched.
You can of course prefetch the two relationships it consists of.
-Alex
________________________________
Von: Moritz Onken [EMAIL PROTECTED]
Gesendet: Mittwoch, 25. Juni 2008 11:42
An: DBIx::Class user and developer list
Betreff: [Dbix-class] Avoid DB hit with many_to_many rel
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]
*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*
T-Systems Austria GesmbH Rennweg 97-99, 1030 Wien
Handelsgericht Wien, FN 79340b
*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*
Notice: This e-mail contains information that is confidential and may be
privileged.
If you are not the intended recipient, please notify the sender and then
delete this e-mail immediately.
*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*"*
_______________________________________________
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]
