mongo initializer to load config from database.yml, authenticate if needed and ensure indexes are created

database.yml

development: &global_settings
  database: textual_development
  host: 127.0.0.1
  port: 27017

test:
  database: textual_test
  <<: *global_settings

production:
  host: hostname
  database: databasename
  username: username
  password: password
  <<: *global_settings

mongo.rb

config = YAML.load_file(Rails.root + 'config' + 'database.yml')[Rails.env]

MongoMapper.connection = Mongo::Connection.new(config['host'], config['port'], {
  :logger         => Rails.logger
})

MongoMapper.database = config['database']
if config['username'].present?
  MongoMapper.database.authenticate(config['username'], config['password'])
end

Dir[Rails.root + 'app/models/**/*.rb'].each do |model_path|
  File.basename(model_path, '.rb').classify.constantize
end
MongoMapper.ensure_indexes!

if defined?(PhusionPassenger)
  PhusionPassenger.on_event(:starting_worker_process) do |forked|
    # if using older than 0.6.5 of MM then you want database instead of connection
    # MongoMapper.database.connect_to_master if forked
    MongoMapper.connection.connect_to_master if forked
  end
end

This Gist seems to get linked from a lot of places so I feel I should mention that most of the code from the mongo.db example above is now integrated in MongoMapper. This means you can replace the entire initalizer with the following two lines:

config = YAML.load_file(Rails.root + 'config' + 'database.yml')
MongoMapper.setup(config, Rails.env, { :logger => Rails.logger })

This gives you logging through the Rails logger to boot, which is useful during development.

Yet another option:

config = YAML.load_file(Rails.root.join('config', 'database.yml'))
MongoMapper.setup(config, Rails.env, { :logger => (Rails.env.development? ? Rails.logger : nil) })

Yeah, this gist is old. Thanks for comment with the update. I typically just throw rails logger on there no matter what as the log level for the driver is just debug which won't show in prod anyway.

It was pointed out to me on the Google group that you don't have to parse the database.yml yourself either. This wil suffice:

MongoMapper.setup(Rails.configuration.database_configuration, Rails.env, :logger => Rails.logger)

Assigning the Rails logger in all environments has worked fine for me, too.

Super-cool. Thanks!