LittleMapper

Early stage simple datamapper/repository backed by ActiveRecord (only, for the moment). Still working out the best DSL. Currently in use on an internal project.

Installation

Add this line to your application's Gemfile:

gem 'little_mapper', :github => 'simonrobson/little-mapper'

And then execute:

$ bundle

Or install it yourself as:

$ gem install little_mapper

Usage

Define one or more plain ruby classes:

class Person < OpenStruct
  attr_accessor :phone_numbers
  def initialize(*args)
    super
    @phone_numbers = []
  end
end

class PhoneNumber
  attr_accessor :id, :code, :number
  def initialize(opts = {})
    opts.each_pair {|k, v| self.send("#{k}=", v)}
  end
end

Define the mappers:

class PersonMapper
  include LittleMapper
  entity Person
  persistent_entity Persistent::Person
  maps :name, :age
  map :phone_numbers, :as => [PhoneNumber]
  # see integration test for more complex example
  # map :all_cats, :as => [Cat], :entity_collection_adder => :receive_cat,
  #    :to => :cats
  map :spouse, :as => Person
end

class PhoneNumberMapper
  include LittleMapper
  entity PhoneNumber
  persistent_entity Persistent::PhoneNumber
  maps :code, :number
end

Define the ActiveRecord classes (and their migrations, not shown):

module Persistent
  class Person < ActiveRecord::Base
    has_many :phone_numbers
    belongs_to :spouse, :class_name => 'Person'
  end

  class PhoneNumber < ActiveRecord::Base
    belongs_to :person
  end
end

Exercise the code:

jane = Person.new(:name => 'Jane', :age => 28)
LittleMapper[Person] << jane # stores jane
john = Person.new(:name => 'John', :age => 27, :spouse => o)
LittleMapper[Person] << john
found = LittleMapper[Person].find_by_id(john.id)
puts found.spouse.name # Jane - found and spouse are plain Ruby objects

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request