gitcart.rb

#
# I wanted to build a really common example app but use Git as the backend
# instead of a database or the filesystem. And so here we are.
#
# (c) Copyright 2008 Adam Keys. MIT licensed or some-such.
#

require 'fileutils'
require 'rubygems'

gem 'mojombo-grit'
gem 'json'
gem 'money'
require 'grit'
require 'json'
require 'money'

# A product for sale
class Item
  attr_reader :name, :price
  
  # Create a new product.
  #   name  - the name of the item
  #   price - the price of the item in cents
  def initialize(name, price)
    @name, @price = name, price
  end
  
  # Convert this item to JSON
  def to_json
    {:name => name, :price => price}.to_json
  end
end

# A collection of items for a store
class Inventory
  
  attr_accessor :items
  
  def initialize(items=[])
    @items = items
  end
end

# A collection of items some may call a store
class Store
  module GitPersistence
    # Save the store to a Git repository named for the store
    def to_git_repo
      create_store
      create_repo
    end
    
    private
    
    # Create the directory structure for the store data
    def create_store
      FileUtils.mkdir(name)
      inventory.items.each_with_index do |item, index| 
        File.open(filename_for(index), 'w') do |f|
          f.write(item.to_json)
        end
      end
    end
    
    # Create and populate the Git repository for saving the store
    def create_repo
      repo_path = "#{name}/.git"
      Grit::GitRuby::Repository.init(repo_path)
      repo = Grit::Repo.new(repo_path)
      inventory.items.each_with_index do |item, index|
        repo.add(filename_for(index))
      end
      repo.commit_index('Create store')
    end
    
    # Generate the filename for a store item
    def filename_for(index)
      "#{name}/item-#{index}.json"
    end
  end
  
  include GitPersistence
  
  attr_reader :name, :inventory
  
  # Create a new store
  #   name - the name of the store
  def initialize(name)
    @name = name
    @inventory = Inventory.new
  end
  
end

store = Store.new('TheStore')
store.inventory.items = [Item.new('shirt', Money.us_dollar(1999)), 
                         Item.new('pants', Money.us_dollar(5999))]
store.to_git_repo