MODEL MIXINS

  package MyApp::FasterSwallow;
  use base qw/ Jifty::DBI::Record::Plugin /;
  
  use Jifty::DBI::Schema;
  use Jifty::DBI::Record schema {
      column swallow_type =>
          type is 'text',
          valid are qw/ african european /,
          default is 'african';
  };

@EXPORT

A mixin may define an @EXPORT variable, which works exactly as advertised in Exporter. That is, given the name of any methods or variable names in the mixin, the host model will gain those methods.

  our @EXPORT = qw( autocomplete_swallow_type );

  sub autocomplete_swallow_type {
      my $self  = shift;
      my $value = quotemeta(shift);

      # You should probably find a better way than actually doing this...

      my @values;
      push @values, 'african'  if 'african'  =~ /$value/;
      push @values, 'european' if 'european' =~ /$value/;

      return @values;
  }

That way if you have any custom methods you want to throw into the host model, just define them in the mixin and add them to the @EXPORT variable.

register_triggers

Your mixin may also want to register triggers for the records to which it will be added. You can do this by defining a method named "register_triggers":

  sub register_triggers {
      my $self = shift;
      $self->add_trigger( 
          name      => 'before_create', 
          callback  => \&before_create,
          abortable => 1,
      );
  }

  sub before_create {
      # do something...
  }

See Class::Trigger.

register_triggers_for_column

In addition to the general "register_triggers" method described above, the mixin may also implement a "register_triggers_for_column" method. This is called for each column in the table. This is primarily helpful for registering the "after_set_*" and "before_set_*" columns.

For example:

  sub register_triggers_for_column {
      my $self   = shift;
      my $column = shift;

      return unless $column ne 'updated_on';

      $self->add_trigger( 
          name      => 'after_set_'.$column, 
          callback  => \&touch_update_time,
          abortable => 1,
      );
  }

  sub touch_update_time {
      my $self = shift;
      $self->set_updated_on(DateTime->now);
  }

This has the additional advantage of being callable when new columns are added to a table while the application is running. This can happen when using database-backed models in Jifty (which, as of this writing, has not been released or made part of the development trunk of Jifty, but is part of the virtual-models branch).

See Class::Trigger.

MODELS USING MIXINS

  package MyApp::Model::User;

  use Jifty::DBI::Schema;
  use MyApp::Record schema {
  };

  # Mixins
  use MyApp::FavoriteColor;
  use MyApp::FasterSwallow;
  use Jifty::Plugin::User::Mixin::Model::User;
  use Jifty::Plugin::Authentication::Password::Mixin::Model::User;