continent_country_seed.rb

{ 
  'North America' => ['Canada', 'USA'],
  'South America' => ['Argentina', 'Bolivia', 'Chile'],
  'Europe' => ['France', 'Netherlands', 'Norway', 'Scotland', 'Spain', 'Sweden'],
  'United Kingdom' => ['England', 'Ireland'],
  'Africa' => ['South Africa'],
  'Asia' => ['China', 'India', 'Japan', 'Malaysia', 'Singapore', 'South Korea', 'Taiwan', 'United Arab Emirates'],
  'Australasia' => ['Australia', 'Indonesia'] 
}.map do |continent, countries| 
  #mongomapper doesn't seem to support passing blocks to Model.create!
  continent = Continent.create!({:name => continent })
  countries.each do |country_name|
    continent.countries << Country.create!({:name => country_name})
  end
  continent.save!
end