# NAME

DBIx::Class::VirtualColumns - Add virtual columns to DBIx::Class schemata

# SYNOPSIS

 package Your::Schema::Class;
 use strict;
 use warnings;
 

 use base 'DBIx::Class';
 

 __PACKAGE__->load_components(
   "VirtualColumns",
   "PK",
   "Core",
 );
 

 __PACKAGE__->table("sometable");
 __PACKAGE__->add_columns(qw/dbcol1 dbcol2/);
 __PACKAGE__->add_virtual_columns(qw/vcol1 vcol2 vcol3/);
 

 # =========================================================
 # Somewhere else
 

 my $item = $schema->resultset('Artist')->find($id);
 $item->vcol1('test'); # Set 'test'
 $item->get_column('vcol1'); # Return 'test'
 

 my $otheritem = $schema->resultset('Artist')->create({
     dbcol1 => 'value1',
     dbcol2 => 'value2',
     vcol1  => 'value3',
     vcol2  => 'value4',
 });
 

 $otheritem->vcol1(); # Now is 'value3'
 

 # Get the column metadata just like for a regular DBIC column
 my $info = $result_source->column_info('vcol1');

# DESCRIPTION

This module allows to specify 'virtual columns' in DBIx::Class schema
classes. Virtual columns behave almost like regular columns but are not
stored in the database. They may be used to store temporary information in
the [DBIx::Class::Row](http://search.cpan.org/search?mode=module&query=DBIx::Class::Row) object and without introducting an additional
interface.

Most [DBIx::Class](http://search.cpan.org/search?mode=module&query=DBIx::Class) methods like `set_column`, `set_columns`, `get_column`,
`get_columns`, `column_info`, ... will work with regular as well as 
virtual columns.

# USAGE

Use this module if you want to add 'virtual' columns to a DBIC class 
which behave like real columns (e.g. if you want to use the `set_column`, 
`get_column` methods)

However if you only want to add non-column data to [DBIx::Class::Row](http://search.cpan.org/search?mode=module&query=DBIx::Class::Row) 
objects, then there are easier/better ways:

 __PACKAGE__->mk_group_accessors(simple => qw(foo bar baz));

# METHODS

## add_virtual_columns 

Adds virtual columns to the result source. If supplied key => hashref pairs,
uses the hashref as the column_info for that column. Repeated calls of this 
method will add more columns, not replace them.

 $table->add_virtual_columns(qw/column1 column2/); 
 OR 
 $table->add_virtual_columns(column1 => \%column1_info, column2 => \%column2_info, ...); 

The column names given will be created as accessor methods on your 
`DBIx::Class::Row objects`, you can change the name of the accessor by 
supplying an "accessor" in the column_info hash. 

The following options are currently recognised/used by 
DBIx::Class::VirtualColumns:

- * accessor

Use this to set the name of the accessor method for this column. If not set, 
the name of the column will be used.

## add_virtual_column

Shortcut for [add_virtual_columns](http://search.cpan.org/search?mode=module&query=add_virtual_columns)

## has_any_column

Returns true if the source has a virtual or regular column of this name, 
false otherwise.

## has_virtual_column

Returns true if the source has a virtual column of this name, false otherwise.

## remove_virtual_columns

 $table->remove_columns(qw/col1 col2 col3/);
  

Removes virtual columns from the result source.

## remove_virtual_column

Shortcut for [remove_virtual_columns](http://search.cpan.org/search?mode=module&query=remove_virtual_columns)

## _virtual_filter

Splits attributes for regular and virtual columns

## new

Overloaded method. L<DBIx::Class::Row/"new">

## get_column

Overloaded method. L<DBIx::Class::Row/"get_colum">

## get_columns

Overloaded method. L<DBIx::Class::Row/"get_colums">

## store_column

Overloaded method. L<DBIx::Class::Row/"store_column">

## set_column

Overloaded method. L<DBIx::Class::Row/"set_column">

## column_info

Overloaded method. L<DBIx::Class::ResultSource/"column_info">

Additionally returns the HASH key 'virtual' which indicates if the requested
column is virtual or not.

## update

Overloaded method. L<DBIx::Class::Row/"update">

# CAVEATS

The best way to add non-column data to DBIC objects is to use 
[Class::Accessor::Grouped](http://search.cpan.org/search?mode=module&query=Class::Accessor::Grouped). 

 __PACKAGE__->mk_group_accessors(simple => qw(foo bar baz));

Use [DBIx::Class::VirtualColumns](http://search.cpan.org/search?mode=module&query=DBIx::Class::VirtualColumns) only if you rely on [DBIx::Class::Row](http://search.cpan.org/search?mode=module&query=DBIx::Class::Row) 
methods like `set_column`, `get_column`, ... 

# SUPPORT

This module was just a proof of concept, and is not actively developed 
anymore. Patches are still welcome though.

Please report any bugs to 
`bug-dbix-class-virtualcolumns@rt.cpan.org`, or through the web interface at
<http://rt.cpan.org/Public/Bug/Report.html?Queue=DBIx::Class::VirtualColumns>.
I will be notified, and then you'll automatically be notified of progress on 
your report as I make changes.

# AUTHOR

    Maroš Kollár
    CPAN ID: MAROS
    maros [at] k-1.com
    L<http://www.revdev.at>

# ACKNOWLEDGEMENTS 

This module was written for Revdev <http://www.revdev.at>, a nice litte
software company I run with Koki and Domm (<http://search.cpan.org/~domm/>).

# COPYRIGHT

DBIx::Class::VirtualColumns is Copyright (c) 2008 Maroš Kollár 
- <http://www.revdev.at>

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

The full text of the license can be found in the
LICENSE file included with this module.