On 2/20/06 4:49 AM, Michael Lackhoff wrote:
> I have three tables in a relationship like 'cities', 'states' and
> 'countries'. Now I would like to say something like
> print $city->country->name;
Given classes like this:
package MyApp::State;
...
__PACKAGE__->meta->relationships
(
country =>
{
type => 'many to one',
class => 'MyApp::Country',
column_map => { country_id => 'id' },
},
);
...
package MyApp::City;
...
__PACKAGE__->meta->relationships
(
state =>
{
type => 'many to one',
class => 'MyApp::States',
column_map => { state_id => 'id' },
},
);
...
Why not just add a method like this to MyApp::City to get the country for a
city?
sub country { shift->state->country }
That's probably less typing than an auto-magical multi-level shortcut
relationship would be anyway :)
> p.s.: After some more experimenting I came up with this object
> method:
> sub country {
> my $self = shift;
> my $state = MyApp::States->new(id => $self->state_id)->load();
> my $country = $state->country();
> return $country;
> }
Since you already have a state() accessor in MyApp::City, there's no reason
to repeat all that relationship "linking" information in the method. (e.g.,
id => $self->state_id)
> This is o.k. for me as a solution but if there is a way to do it the
> "meta->relationship" way I would prefer it because it is more
> readable if everything is in one place.
Compare your p.s. example above with the one-liner I posted. They both do
basically the same thing, but mine doesn't include any redundant information
about the way that a state is related to a city. That info remains solely
in relationship setup. The only info encoded in the method is the fact that
the state has a country, with nothing about exactly how the two are linked.
-John
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