Class::DBI::Plugin::PseudoColumns version 0.03
==============================================

NAME
    Class::DBI::Plugin::PseudoColumns - an interface to use some pseudo columns

SYNOPSIS
     package Music::CD;
     use base 'Music::DBI';
 
     Music::CD->table('cd');
     Music::CD->columns(All => qw/cdid artist title year reldate properties/);
     use Class::DBI::Plugin::PseudoColumns;
     Music::CD->pseudo_columns(properties => qw/asin tag/);
 
     use Music::CD;
     my $cds = Music::CD->search(artist => 'Steve Vai');
     while (my $cd = $cds->next) {
         if ($cd->title =~ /^Real\s+Illusions/i) {
             $cd->asin('B0007GADZO');
         }
         $cd->tag(['rock', 'guitar', 'tricky play']);
         $cd->update;
     }

     my $bought_cd = Music::CD->create({
         artist  => 'Rolling Stones',
         title   => 'A Bigger Bang',
         year    => 2005,
         reldate => '2005-11-22',
         asin    => 'B000BP86LE',
         tag     => ['rock', 'blues', 'favorite'],
     });
     $bought_cd->set(
         artist => 'The Rolling Stones',
         title  => 'A Bigger Bang - Special Edition',
     );
     $bought_cd->update;

DESCRIPTION
    This module provides an easy way to use pseudo column in your
    "Class::DBI" based table classes. The ``pseudo column'' means a kind of
    column that is including an optical hashref string (via "Data::Dumper",
    by default). You can get and set with using the pseudo column accessors
    (same as always). But, you can't use the columns' name into your SQL,
    SQL interfaced methods, "ORDER BY" clause and "GROUP BY" clause, etc.
    This module is useful when you'd like to add an unimportant column
    without issuing "ALTER TABLE", and when you'd like to have related
    multiple data without normalizing table.

HOW TO USE
  Create a column
    You should create a huge size column into your table. like this:

     CREATE TABLE cd (
       cdid int UNSIGNED auto_increment,
       artist varchar(255),
       title varchar(255),
       year int,
       reldate date,
       properties text, # create for using pseudo column
       PRIMARY KEY (cdid)
     );

  Create a table class
    Almost same as usual.

     package Music::CD;
     use base 'Music::DBI';
 
     Music::CD->table('cd');
     Music::CD->columns(All => qw/cdid artist title year reldate properties/);

  Use it
    You will be able to use pseudo column with only to "use" this module.

     use Class::DBI::Plugin::PseudoColumns;

  Set your pseudo columns as your like
     Music::CD->pseudo_columns(properties => qw/asin tag/);

METHOD
    This module provides following class methods.

    * create(\%data);
        "create" method works almost same as "Class::DBI::create()" if
        there's some pseudo column in %data.

    * set(column => value[, column2 => value2, ...]);
        "set" method works almost same as "Class::DBI::set()" if there's
        some pseudo column in argument.

    * pseudo_columns([parent_colname => ('pseudo_column1'[, 'pseudo_column2'
    ...])]);
        You can set a pseudo columns' name with parent column's name.
        ``pseudo_column1'' ... will provide to you each pseudo column's
        accessor.

        if you want to take a list of pseudo columns, you can pass one
        argument to this method when you want to specify grouped parent
        column name.

         my @p_columns = Music::CD->pseudo_columns('properties');

        And if you want to take all columns list of pseudo columns, you
        don't need to pass any argument to this method.

         my @all_p_columns = Music::CD->pseudo_columns();

    * serializer(parent_colname => \&serializer_sub);
        You can set a specific serializing function for your pseudo columns.

         use Storable ();
         __PACKAGE__->serializer(properties => \&Storable::nfreeze);

        The default serializer is "Data::Dumper::Dumper" (when you don't
        specify).

    * deserializer(parent_coluname => \&deserializer_sub);
        You can set a specific deserializing function for your pseudo
        columns.

         use Storable ();
         __PACKAGE__->deserializer(properties => \&Storable::thaw);

        The default deserializer calls "eval()" (when you don't specify) for
        the dumped optical hashref string.

        NOTE: The subref for serializer/deserializer must return a really
        ``storable'' string for your database. example of above works under
        a MySQL environment, but you have to change to use some another
        ``storable'' filter (like "MIME::Base64") under SQLite environment
        (see t/05_serializer.t)

AUTHOR
    Koichi Taniguchi <taniguchi@livedoor.jp>

COPYRIGHT
    Copyright (c) 2006 Koichi Taniguchi. Japan. All rights reserved.

    This library is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.

SEE ALSO
    Class::DBI, Data::Dumper

