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Manual Reference Pages  -  DBIX::CLASS::DYNAMICSUBCLASS (3)

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NAME

DBIx::Class::DynamicSubclass - Convenient way to use dynamic subclassing.

CONTENTS

SYNOPSIS



    package My::Schema::Game;

    __PACKAGE__->load_components(qw/DynamicSubclass Core/);
    __PACKAGE__->add_column(qw/id name data type/);

    __PACKAGE__->typecast_map(type => {
        1 => My::Schema::Game::Online,
        2 => My::Schema::Game::Shareware,
        3 => My::Schema::Game::PDA,
    });

    $game = $schema->resultset(Game)->new({..., type => 1});
    #  ref $game = My::Schema::Game::Online

    @games = $game->search({type => 2});
    # @games are all of class My::Schema::Game::Shareware

    $game->type(3); # game is now of class My::Schema::Game::PDA

    $game =  $schema->resultset(Game)->new({});
    # or
    $game->type(undef);
    # game is now of type My::Schema::Game


    #Dynamic properties with DBIx::Class::FrozenColumns
    package My::Schema::Game;
    __PACKAGE__->load_components(qw/... FrozenColumns .../);

    package My::Schema::Game::Online;
    use base My::Schema::Game;
    __PACKAGE__->add_frozen_columns(data => qw/flash server_host server_port/);

    package My::Schema::Game::Shareware;
    use base My::Schema::Game;
    __PACKAGE__->add_frozen_columns(data => qw/price download_url/);

    ...

    $game->type(1); #game would have now additional columns flash, server_host, etc.
    $game->server_host(...); #(stored in data)

    $game->type(2);
    $game->server_host; #error
    $game->price($3.00); #ok

    $game = $rs->new({
        type  => 1,
        flash => game.swf,
    }); #ok

    #More flexible way

    package My::Schema::Game;
    __PACKAGE__->typecast_column(type);

    sub classify { #called each time the object gets or losses its type
        my $self = shift;
        #decide which class do you want
        bless $self, $class;
    }



DESCRIPTION

This plugin implements methodics described here Dynamic_Sub-classing_DBIx::Class_proxy_classes_(AKA_multi-class_object_inflation_from_one_table) in DBIx::Class::Manual::Cookbook.

DynamicSubclass has 2 ways to work: static defining and dynamic defining.

Static defining is used in most cases. This is when you define



    __PACKAGE__->typecast_map(defining_column => {column_value => subclass, ...});



The plugin preloads all of the subclasses and changes the class of the row object when you are creating new object or fetching it from a database or changing ’defining_column’ value. If the value is not exists in the ’typecast_map’ then object is blessed into the base class and losses all of its additional methods/columns/etc.

Dynamic defining is when you only say



    __PACKAGE__->typecast_column(defining_column);



and define a method ’classify’ that would bless a row object into proper class. This method is called when object is created, fetched or have its ’defining_column’ value changed.

METHODS

    typecast_map

Arguments: $column, %typecast_hash

%typecast_hash is a hash with keys equal to possible $column values and with subclasses as values.

    classify

A standart method for static subclassing. You should redefine this method in your result source in order to use dynamic subclassing (second way).

OVERLOADED METHODS

new, inflate_result, store_column

SEE ALSO

DBIx::Class, DBIx::Class::FrozenColumns.

AUTHOR

Pronin Oleg <syber@cpan.org>

LICENSE

You may distribute this code under the same terms as Perl itself.
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perl v5.20.3 DBIX::CLASS::DYNAMICSUBCLASS (3) 2008-06-24

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