dump_fixtures.rake

namespace :spec do
  namespace :db do
    namespace :fixtures do
      
      desc 'Create YAML spec fixtures from data in an existing database. Defaults to development database.  Set RAILS_ENV to override. You can also set tables to dump with rake spec:db:fixtures:dump TABLES=posts,pages'
      task :dump => :environment do
        sql  = "SELECT * FROM %s"
        skip_tables = ["schema_info", "schema_migrations"]

        ActiveRecord::Base.establish_connection(RAILS_ENV)
        tables = ENV['TABLES']
        tables ||= (ActiveRecord::Base.connection.tables - skip_tables)
        tables.each do |table_name|
          i = "000"
          fixture = "#{RAILS_ROOT}/spec/fixtures/#{table_name}.yml"
          data = ActiveRecord::Base.connection.select_all(sql % table_name)
          if File.exist?(fixture)
            File.rename(fixture, "#{fixture}.bak")
          end
          File.open(fixture, 'w') do |file|
            file.write data.inject({}) { |hash, record|
              hash["#{table_name}_#{i.succ!}"] = record
              hash
            }.to_yaml
          end
        end

      end
    end
  end
end