oma mongomapper setup

mongo.rb

# config/initializers/mongo.rb
#
# MonkeyPatch to fix the error going on in mongomapper + rails3 + ruby 1.9.2
#

MongoMapper::Plugins.class_eval do
   def plugins
      @plugins ||= []
    end

    def plugin(mod)
      # for whatever reason mod.const_defined?(:ClassMethods) doesn't work in ruby192rc2+rails3b4 hence this workaround
      extend mod::ClassMethods if mod.constants.include?(:ClassMethods)

      include mod::InstanceMethods if mod.const_defined?(:InstanceMethods)
      mod.configure(self) if mod.respond_to?(:configure)
      plugins << mod
    end
end

#
# Moved mongo setup to lib/mongo_setup.rb
# To be able to reconnect on Passenger fork from Delayed Job
#
MongoSetup.setup

mongodb.yml

# config/mongodb.yml
development:
  uri: <%= ENV['MONGO_URL'] %>

test:
  uri: mongodb://localhost:27017/myapp_test

staging:
  uri: <%= ENV['MONGOHQ_URL'] %>

monogo_setup.rb

#lib/monogo_setup.rb 
module MongoSetup

  def self.setup
    file_name = File.join(Rails.root, "/config/mongodb.yml")
    mongo_config = YAML::load(ERB.new(File.new(file_name).read).result) #OMG this is ugly

    raise "set correct mongodb.yml!" unless mongo_config || mongo_config[Rails.env]

    mongo = mongo_config[Rails.env]
    begin
      MongoMapper.config = {Rails.env => {'uri' => mongo['uri'] }}
      MongoMapper.connect(Rails.env)
    rescue Mongo::ConnectionFailure => e
      puts "Cannot connect to mongo, did you forget to start mongod? Is the config/mongodb.yml file correct?", e
    end    
  end
end

To supplement rspec example with mongodb for helping out at stackoverflow
http://stackoverflow.com/questions/5796240/tdd-rspec-ruby-mongodb-ruby-mongo-driver/5901577#5901577