[Dbix-class] Relations for multi-class object inflation from one table

[Wallace Reis]

On Thu, Jul 23, 2009 at 4:12 PM, Oleg Kostyuk<cub.uanic at gmail.com> wrote:
> Hello all,
>
> I read about "Dynamic Sub-classing DBIx::Class proxy classes" in
> DBIx::Class::Manual::Cookbook, and have question.
>
> package My::Schema::Result::Company;
> use base qw/DBIx::Class/;
> __PACKAGE__->load_components(qw/Core/);
> __PACKAGE__->table('companies');
> __PACKAGE__->add_columns(qw/company_id ....../);
> __PACKAGE__->set_primary_key('company_id');
> __PACKAGE__->has_many('admins', 'My::Schema::Result::User::Admin', ????);
> __PACKAGE__->has_many('users', 'My::Schema::Result::User', ????);
> __PACKAGE__->has_many('all_users', 'My::Schema::Result::User', ????);
>
> My questions is:
>
> 1) what should be instead of '????' in has_many() calls above? I
> think, this should be something like this (for first has_many): {
> 'foreign.company_id' => 'self.company_id', 'foreign.admin' => 1 } - is
> this correct?

You can't define rels using constants in FK definitions like
'foreign.admin' => 1. You have to define just the 'all_users' rel with
{ 'foreign.company_id' => 'self.company_id' } and create result class
methods for 'users' and 'admins' like:
sub users_rs {
    my $self = shift;
    return $self->all_users_rs({ admin => '0' });
}

sub users {
    my $self = shift;
    my $rs = $self->users_rs;
    return wantarray ? $rs->all : $rs;
}

sub admins_rs {
    my $self = shift;
    return $self->all_users_rs({ admin => '1' });
}

sub admins {
    my $self = shift;
    my $rs = $self->admins_rs;
    return wantarray ? $rs->all : $rs;
}

Or you can create a base result class called Person, then Admin and
User classes as a views (CREATE VIEW) over Person, thus you can define
the rels like:
__PACKAGE__->has_many('admins', 'My::Schema::Result::User::Admin',
{ 'foreign.company_id' => 'self.company_id' });
__PACKAGE__->has_many('users', 'My::Schema::Result::User',
{ 'foreign.company_id' => 'self.company_id' });
__PACKAGE__->has_many('all_users', 'My::Schema::Result::Person',
{ 'foreign.company_id' => 'self.company_id' });

> 3) do I need write belongs_to(company) in User::Admin too, or only in
> User will be enough?

Just in User should be enough.


-- 
     wallace reis/wreis         Catalyst and DBIx::Class consultancy with a clue
     Software Developer		and a commit bit: http://shadowcat.co.uk/catalyst/
 Shadowcat Systems Limited
 http://www.shadowcat.co.uk     http://www.linkedin.com/in/wallacereis