Accessing Mojolicious helpers from a module using Mojo::Base?

Question

I have an existing application (my website) that I'm doing some code tidying in, and the tidy up is following the same sort of idea as the Mojo::Pg example here, with separate model and controller files to keep things defined. My site accesses both Flickr and Last.fm's APIs, and I have a helper defined in Site::Helpers:

$app->helper(
    get_base_rest_url => sub {
        my ( $self, $config ) =  @_;

        sswitch ( $config ) {
            case 'photos': {
                my $base_url = 'https://api.flickr.com/services/rest/';
                my $user_id  = '7281432@N05';
                my $api_key  = $self->app->config->{ 'api_token' }{ 'flickr' };

                my $url =
                    "$base_url"
                    . "?user_id=$user_id"
                    . "&api_key=$api_key"
                    . "&per_page=" . $self->session->{ per_page }
                    . '&format=json'
                    . '&nojsoncallback=1';

                return $url;
            }

            case 'music': {
                my $base_url = 'https://ws.audioscrobbler.com/2.0/';
                my $username = 'virtualwolf';
                my $api_key  = $self->app->config->{ 'api_token' }{ 'last_fm' };
                my $per_page = $self->session->{ 'per_page' };

                my $url = "$base_url?user=$username&limit=$per_page&api_key=$api_key&format=json";

                return $url;
            }
        }
    }
);

The problem I'm running into is that I don't know how to access that helper from the Site::Model::Photos module. The error is

Can't locate object method "get_base_rest_url" via package "Site::Model::Photos"

which is fair enough, but I can't work out how to actually get at that get_base_rest_url helper (or alternatively, how to access the api_token config).

Answer 1

The problem is that your module have not got app attribute/method which get access to your app.

So, when you create instance of Site::Model::Photos you need to pass app to it in param and make it weaken something like that:

package Site::Model::Photos
use Scalar::Util 'weaken';
sub new {
  my $class = shift;
  my $app = shift;
  my $hash = {app => $app, ...};
  weaken $hash->{app};
  return bless $hash, $class;
}

sub your_method {
  my $self = shift;
  $self->{app}->get_base_rest_url(...);
}

1;

Or you may to use this module https://metacpan.org/release/Mojolicious-Plugin-Model which do it for you:

package Site::Model::Photos
use Mojo::Base 'MojoX::Model';

... code of your module ...

sub your_method {
  my $self = shift;
  $self->app->get_base_rest_url(...);
}

1;

And in your App.pm need to add this:

$app->plugin('Model', {namespaces => ['Site::Model']});

And use it that in controller:

$c->model('photos');
$c->app->model('photos');