JSON Model for Rails

ActiveRecord replacement for pure JSON models.

Installation

Put the following line in your Gemfile:

gem 'json_model', :git => 'git://github.com/pch/json_model.git'

And run bundle install afterwards.

Usage

class Car
  include JsonModel

  attribute :make,  String
  attribute :model, String
  attribute :color, String
  attribute :bought_on, TimeStamp
end

class Address
  include JsonModel

  attribute :street, String
  attribute :postal_code, String
end

class Person
  include JsonModel

  attribute :name, String
  attribute :id, Integer
  attribute :address, Address

  has_many :cars
  has_many :red_cars, :class => Car
  
  before_dump :scientologist_filter
  after_load  :add_nobiliary_particle
  
  def scientologist_filter
    # One of the main principles of the Church of Scientology
    # states that its members cannot be dumped to JSON
    false if self.name == "Tom Cruise"
  end
  
  def add_nobliary_particle
    self.name = self.name.gsub(" ", " von ")
  end
end

person = Person.new(:id => 1, :address => {:street => '5th Ave', :postal_code => '00-000'})
person.to_json

Loading objects from JSON:

person = Person.from_json(json_string)

Updating attributes:

person.update_attributes(:name => "Henry", :address => {:street => '5th Ave', :postal_code => '00-000'})

Using JsonModel with Rails 3 validators and form helpers

In order to ensure Rails 3 compatibility, you'll need to include some ActiveModel modules in your JsonModel classes:

class User
  include ActiveModel::Validations
  include ActiveModel::Conversion  
  extend  ActiveModel::Naming
  include JsonModel
  include JsonModel::ValidationHelper

  attribute :name,  String
  attribute :email, String    

  validates :name,  :presence => true
  validates :email, :presence => true
end

Note on Patches/Pull Requests

• 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.

Credits

• Piotr Chmolowski (http://github.com/pch)
• Oleg Keene (http://github.com/olkeene)
• Grzegorz Kazulak (http://github.com/grzegorzkazulak)