webapp.rb

require "sinatra/base"
require "dm-core"
require "dm-serializer"

Bundler.require(:default, ENV["RACK_ENV"] || :development) if defined?(Bundler)

DataMapper.setup(:default, :adapter => :in_memory)
Dir[File.join(File.dirname(__FILE__), "models/**/*.rb")].each { |f| require f }
DataMapper.finalize

module Spesa
  module ReflectiveRoutes
    def reflect_routes(model)
      name = model.storage_name.gsub(/^spesa_/, "")
      reflect_collection_route(name, model)
      reflect_resource_route(name, model)
    end

    def reflect_collection_route(name, model)
      get "/#{name}" do
        content_type :json
        model.all.to_json
      end
    end

    def reflect_resource_route(name, model)
      get "/#{name}/:id" do |id|
        content_type :json
        model.get!(id).to_json
      end
    end
  end

  class Application < Sinatra::Base
    extend ReflectiveRoutes

    Spesa.constants.map { |c| Spesa.const_get(c) }.select { |k| k.kind_of?(DataMapper::Model) }.each do |model|
      reflect_routes(model)
    end

    error DataMapper::ObjectNotFoundError do
      404
    end
  end
end

Spesa::Customer.create(:full_name => "Bob")
Spesa::Customer.create(:full_name => "Fred")