DataMapper repository issues

config.ru

require 'rubygems'
require 'bundler'

Bundler.require

require './dmtrouble'
run Sinatra::Application

dmtrouble.rb

require "bundler"

enable :inline_templates

# DataMapper
DataMapper.setup(:default, "sqlite3://#{Dir.pwd}/dmtrouble.db")
DataMapper.setup(:mongo, "mongo://localhost:27017/dmtrouble")
DataMapper::Logger.new($stdout, :debug)

DataMapper.finalize

class Default
  include DataMapper::Resource

  property :id,		Serial
  property :name,	String
end

DataMapper.auto_migrate!

DataMapper.repository(:mongo) {
class Mongotest
  include DataMapper::Mongo::Resource

  property :id,         ObjectId
  property :name,        String

  def self.default_repository_name
    :mongo
  end
end

DataMapper.finalize
}

# routes

get "/" do
  @defaults = Default.all
  @mongos = Mongotest.all
  
  haml :index

end

get "/adddefault" do
  newrecord = Default.create(:name => "new test record")
  
  if newrecord.save
    redirect '/'
  end
end

get "/addmongo" do
  newrecord = Mongotest.create( :name => "new mongo record" )
 
  if newrecord.save
    redirect '/'
  end
end

__END__
@@layout
!!!
%html
  %head
    %title "datamapper trouble"
  %body
    #content= yield

@@index
%h1 default data
- if @defaults.empty?
  %p no data
- else
  - @defaults.each do |default|
    %p= default.name
%h1 mongo data_mapper
- if @mongos.empty?
  %p no data
- else
  - @mongos.each do |mongo|
    %p= mongo.name

Gemfile

source "http://rubygems.org"

gem 'sinatra',                  '~> 1.3.2',     :require => 'sinatra'
gem 'data_mapper',              '~> 1.2.0'
gem 'dm-mongo-adapter', :git => 'https://github.com/solnic/dm-mongo-adapter.git', :branch => "dm-1.2-compatible"
gem 'bson_ext',                 '~> 1.4.0'
gem 'mongo',                    '~> 1.4.0'
gem 'mongodb',                  '~> 2.0.0'
gem 'dm-sqlite-adapter'
gem 'haml'

issue was a nilclass error .... solved because DataMapper.finalize wasnt ran within the repository

afterwards i got an argumenterror for :id in mongotest this was solved by overwriting the default_repository_name with the mongo setup

you need bundle for this example!