TheWebFellas - Ruby on Rails Development Specialists UK - Giving composed_of some much needed lovin’ Comments

Comment on 'Giving composed_of some much needed lovin’' by Rob Anderton

2008-10-23T21:58:18Z

Hi - I haven't yet but I'll see if I can knock something together over the weekend for people on Rails 2.0/2.1. It looks like Rails 2.2 is just around the corner so it won't be long until the new, improved composed_of appears in an official release!

Comment on 'Giving composed_of some much needed lovin’' by nachokb

2008-10-22T18:19:33Z

Did you release a plugin for Rails 2.1? Do you have a monkey-patch version of it (against 2.1)?

Thanks!

-- nachokb

Comment on 'Giving composed_of some much needed lovin’' by Rob Anderton

2008-09-11T10:25:25Z

Great news - my patch made it into core!

I updated the original patch with additional documentation and also took the opportunity to tweak some of the existing documentation too, so hopefully the options for composed_of are now a little bit clearer.

Perhaps now composed_of can enjoy a little more popularity.

Comment on 'Giving composed_of some much needed lovin’' by Rob Anderton

2008-08-27T09:51:06Z

Yay! Some feedback has been received from Michael Koziarski on Lighthouse and from Chris Cruft, author of the original patches for composed_of that I linked to above, on the Rails core mailing list. It emerges from this feedback that my IP address example doesn’t fully illustrate why there is a need for separate constructors and converters, so to clarify:

:constructor is called when instantiating the aggregate object and is therefore passed all of the mapped attributes in the order they are defined in the :mapping option.
:converter is called when a value is assigned to the aggregate attribute and therefore passed the single value that is used in the assignment

Here’s an example, that I’ve also added to my patch ticket, that hopefully makes this difference more obvious.

class NetworkResource < ActiveRecord::Base

 composed_of :cidr,
             :class_name => 'NetAddr::CIDR',
             :mapping => [ %w(network_address network), %w(cidr_range bits) ],
             :allow_nil => true,
             :constructor => Proc.new { |network_address, cidr_range| NetAddr::CIDR.create("#{network_address}/#{cidr_range}") },
             :converter => Proc.new { |value| NetAddr::CIDR.create(value.is_a?(Array) ? value.join('/') : value) }

end

# Calls the :constructor proc
n = NetworkResource.new(:network_address => '192.168.0.1', :cidr_range => 24)

# Calls the :converter proc
n.cidr = [ '192.168.2.1', 8 ]
n.cidr = '192.168.0.1/24'

# Doesn't call the :converter proc as the class matches the aggregate class
n.cidr = NetAddr::CIDR.create('192.168.2.1/8')

# Save and reload - uses the :constructor proc on reload
n.save
n.reload