virtus
This is a partial extraction of the DataMapper Property API with various modifications and improvements. The goal is to provide a common API for defining attributes on a model so all ORMs/ODMs could use it instead of reinventing the wheel all over again. It is also suitable for any other usecase where you need to extend your ruby objects with attributes that require data type coercions.
Installation
terminal
$ gem install virtus
or
``` ruby # ./Gemfile
gem ‘virtus’ ```
IMPORTANT: If you are still using Ruby 1.8.7 then you also have to install backports gem!
Examples
``` ruby require ‘virtus’
class User include Virtus
attribute :name, String attribute :age, Integer attribute :birthday, DateTime end
user = User.new :name => ‘Piotr’, :age => 28 user.attributes # => { :name => “Piotr”, :age => 28 }
user.name # => “Piotr”
user.age = ‘28’ # => 28 user.age.class # => Fixnum
user.birthday = ‘November 18th, 1983’ # => #<DateTime: 1983-11-18T00:00:00+00:00 (4891313/2,0/1,2299161)> ```
Default values
``` ruby require ‘virtus’
class Page include Virtus
attribute :title, String attribute :views, Integer, :default => 0 attribute :slug, String, :default => lambda { |page, attribute| page.title.downcase.gsub(‘ ‘, ‘-‘) } end
page = Page.new :title => ‘Virtus Is Awesome’ page.slug # => ‘virtus-is-awesome’ page.views # => 0 ```
Embedded Value
``` ruby class City include Virtus
attribute :name, String end
class Address include Virtus
attribute :street, String attribute :zipcode, String attribute :city, City end
class User include Virtus
attribute :name, String attribute :address, Address end
user = User.new(:address => { :street => ‘Street 1/2’, :zipcode => ‘12345’, :city => { :name => ‘NYC’ } })
user.address.street # => “Street 1/2” user.address.city.name # => “NYC” ```
Collection Member Coercions
``` ruby # Support “primitive” classes
class Book include Virtus
attribute :page_numbers, Array[Integer] end
book = Book.new(:page_numbers => %w[1 2 3]) book.page_numbers # => [1, 2, 3]
Support EmbeddedValues, too!
class Address include Virtus
attribute :address, String attribute :locality, String attribute :region, String attribute :postal_code, String end
class PhoneNumber include Virtus
attribute :number, String end
class User include Virtus
attribute :phone_numbers, Array[PhoneNumber] attribute :addresses, Set[Address] end
user = User.new( :phone_numbers => [ { :number => ‘212-555-1212’ }, { :number => ‘919-444-3265’ } ], :addresses => [ { :address => ‘1234 Any St.’, :locality => ‘Anytown’, :region => “DC”, :postal_code => “21234” } ])
user.phone_numbers # => [#<PhoneNumber:0x007fdb2d3bef88 @number=”212-555-1212”>, #<PhoneNumber:0x007fdb2d3beb00 @number=”919-444-3265”>]
user.addresses # => #<Set: @address=”1234 Any St.”, @locality=”Anytown”, @region=”DC”, @postal_code=”21234”>> ```
Value Objects
``` ruby class GeoLocation include Virtus::ValueObject
attribute :latitude, Float attribute :longitude, Float end
class Venue include Virtus
attribute :name, String attribute :location, GeoLocation end
venue = Venue.new( :name => ‘Pub’, :location => { :latitude => 37.160317, :longitude => -98.437500 })
venue.location.latitude # => 37.160317 venue.location.longitude # => -98.4375
Supports object’s equality
venue_other = Venue.new( :name => ‘Other Pub’, :location => { :latitude => 37.160317, :longitude => -98.437500 })
venue.location === venue_other.location # => true ```
Adding Coercions
Virtus comes with a builtin coercion library. It’s super easy to add your own coercion classes. Take a look:
``` ruby require ‘virtus’ require ‘digest/md5’
Our new attribute type
class MD5 < Virtus::Attribute::Object primitive String coercion_method :to_md5 end
Defining the Coercion method
module Virtus class Coercion class String < Virtus::Coercion::Object def self.to_md5(value) Digest::MD5.hexdigest value end end end end
And now the user!
class User include Virtus
attribute :name, String attribute :password, MD5 end
user = User.new :name => ‘Piotr’, :password => ‘foobar’ user.name # => ‘Piotr’ user.password # => ‘3858f62230ac3c915f300c664312c63f’ ```
Custom Attributes
``` ruby require ‘virtus’ require ‘json’
module MyAppClass
# Defining the custom attribute(s) module Attributes class JSON < Virtus::Attribute::Object primitive Hash
def coerce(value)
::JSON.parse value
end
end end
class User include Virtus
attribute :info, Attributes::JSON end end
user = MyApp::User.new user.info = ‘“email”:”john@domain“email”:”[email protected]”’ # => “email”=>”john@domain“email”=>”[email protected]” user.info.class # => Hash ```
Credits
- Dan Kubb (dkubb)
- Chris Corbyn (d11wtq)
- Emmanuel Gomez (emmanuel)
- Ryan Closner (rclosner)
- Yves Senn (senny)
Contributing
- Fork the project.
- Make your feature addition or bug fix.
- Add tests for it. This is important so I don’t break it in a future version unintentionally.
- Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)
- Send me a pull request. Bonus points for topic branches.
License
Copyright (c) 2011 Piotr Solnica
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.