NAME

DBIx::Class::BitField - Store multiple boolean fields in one integer field

VERSION

version 0.13

SYNOPSIS

package MySchema::Item;

use base 'DBIx::Class';

__PACKAGE__->load_components(qw(BitField Core));

__PACKAGE__->table('item');

__PACKAGE__->add_columns(
  id     =>   { data_type => 'integer' },
  status =>   { data_type => 'integer', 
                bitfield => [qw(active inactive foo bar)],
  },
  advanced_status => { data_type => 'integer', 
                       bitfield => [qw(1 2 3 4)], 
                       bitfield_prefix => 'status_', 
                       accessor => '_foobar',
                       is_nullable => 1,
  },

);

__PACKAGE__->set_primary_key('id');

__PACKAGE__->resultset_class('DBIx::Class::ResultSet::BitField');

1;

Somewhere in your code:

my $rs = $schema->resultset('Item');
my $item = $rs->create({
    status          => [qw(active foo)],
    advanced_status => [qw(status_1 status_3)],
});

$item2 = $rs->create({
      active   => 1,
      foo      => 1,
      status_1 => 1,
      status_3 => 1,
});

# $item->active   == 1
# $item->foo      == 1
# $item->status   == ['active', 'foo']
# $item->_status  == 5
# $item->status_1 == 1
# $item->status_3 == 1

$item->foo(0);
$item->update;

DESCRIPTION

This module is useful if you manage data which has a lot of on/off attributes like active, inactive, deleted, important, etc.. If you do not want to add an extra column for each of those attributes you can easily specify them in one integer column.

A bit field is a way to store multiple bit values on one integer field.

Read this wikipedia article for more information on that topic.

The main benefit from this module is that you can add additional attributes to your result class whithout the need to deploy or change the schema on the data base.

This module encourages to not normalize your schema. You should consider a has_many relationship to a table which holds all the flags instead of this module.

Example

A bit field status with data_type set to int or integer (case insensitive) and active, inactive, deleted will create the following accessors:

$row->status

This is not the value which is stored in the database. This accessor returns the status as an array ref. The array ref is empty if no status is applied.

You can use this method to set the value as well:

$row->status(['active', 'inactive']);
# $row->status == ['active', 'inactive']

$row->active, $row->inactive, $row->deleted

These accessors return either 1 or 0. If you add a parameter they will act like normal column accessors by returning that value.

my $foo = $row->active(1);
# $foo         == 1
# $row->active == 1
# $row->status == ['active']

$row->_status

This accessor will hold the internal integer representation of the bit field.

$row->status(['active', 'inactive']);
# $row->_status == 3

You can change the name of the accessor via the accessor attribute:

__PACKAGE__->add_columns(
    status =>   { data_type => 'integer', 
                  bitfield  => [qw(active inactive deleted)],
                  accessor  => '_status_accessor',
    },
);

ResultSet operations

In order to use result set operations like search or update you need to set the result set class to DBIx::Class::ResultSet::BitField or to a class which inherits from it.

__PACKAGE__->resultset_class('DBIx::Class::ResultSet::BitField');

update

$rs->update({ status => ['active'] });

This will update the status of all items in the result to active. This is done in a single SQL query.

search_bitfield

To search a result set for a specific value of the bitfield use search_bitfield.

You can either make a OR search:

my $new_rs = $rs->search_bitfield([ status2 => 1, status3 => 1 ]);

or AND:

my $new_rs = $rs->search_bitfield({ status2 => 1, status3 => 1 });

This method uses bitwise operators in SQL. Depending on your database it is possible to create an index so the search is as fast as using a single boolean column. =head1 AUTHOR

Moritz Onken <onken@netcubed.de>

COPYRIGHT AND LICENSE

This software is Copyright (c) 2009 by Moritz Onken.

This is free software, licensed under:

The (three-clause) BSD License

cpanm DBIx::Class::BitField

perl -MCPAN -e shell
install DBIx::Class::BitField