Getting up and running with MongoDB/MongoMapper

config.enviroment.rb

# config/enviroment.rb

  config.gem 'mongo'
  config.gem 'mongo_mapper'

  # remove AR 
  config.frameworks -= [ :active_record, :active_resource ]

config.initializers.mongodb.rb

# config/initializers/mongodb.rb

include MongoMapper

db_config = YAML::load(File.read(File.join(Rails.root, "/config/mongodb.yml")))

if db_config[Rails.env] && db_config[Rails.env]['adapter'] == 'mongodb'
  mongo = db_config[Rails.env]
  MongoMapper.connection = Mongo::Connection.new(mongo['host'] || 'localhost',
                                                 mongo['port'] || 27017,
                                                :logger => Rails.logger)
  MongoMapper.database = mongo['database']
  
  if mongo['username'] && mongo['password']
    MongoMapper.database.authenticate(mongo['username'], mongo['password'])
  end
end

ActionController::Base.rescue_responses['MongoMapper::DocumentNotFound'] = :not_found

# Used for image uploads
# CarrierWave.configure do |config|
#   mongo = db_config[Rails.env]
#   config.grid_fs_database = mongo['database']
#   config.grid_fs_host = mongo['host'] || 'localhost'
#   config.grid_fs_access_url = "gridfs"
#   config.grid_fs_username = mongo['username']
#   config.grid_fs_password =  mongo['password']
# end

# It's also possible to define indexes in the the model itself; however,
# a few issues are being worked out still. This is a temporary solution.
# Comment.ensure_index([["story_id", 1], ["path", 1], ["points", -1]])
# MongoMapper.ensure_indexes!

# Handle passenger forking.
# if defined?(PhusionPassenger)
#    PhusionPassenger.on_event(:starting_worker_process) do |forked|
#      MongoMapper.database.connect_to_master if forked
#    end
# end

config.mongodb.yml

# config/mongodb.yml
base: &base
  adapter: mongodb
  database: coolapp
#These are needed to authenticate with your db
#should it run on another server
  host: genesis.mongohq.com
  username: your-username
  password: your-password

development:
  <<: *base

test:
  <<: *base
  database: coolapp-test


production:
  <<: *base

install_gems

gem install mongo_mapper 
gem install mongo_ext #the c extensions (for production) 
 

lib.multi_parameter_attributes.rb

# lib/multi_parameter_attributes.rb

module MultiParameterAttributes
  def attributes=(attrs)
    multi_parameter_attributes = []
    attrs.each do |name, value|
      return if attrs.blank?
      if name.to_s.include?("(")
        multi_parameter_attributes << [ name, value ]
      else
        writer_method = "#{name}="
        if respond_to?(writer_method)
          self.send(writer_method, value)
        else
          self[name.to_s] = value
        end
      end
    end
  
    assign_multiparameter_attributes(multi_parameter_attributes)
  end
  
  def assign_multiparameter_attributes(pairs)
    execute_callstack_for_multiparameter_attributes(
      extract_callstack_for_multiparameter_attributes(pairs)
    )
  end
  
  def execute_callstack_for_multiparameter_attributes(callstack)
    callstack.each do |name, values_with_empty_parameters|
      # in order to allow a date to be set without a year, we must keep the empty values.
      # Otherwise, we wouldn't be able to distinguish it from a date with an empty day.
      values = values_with_empty_parameters.reject(&:nil?)

      if values.any?
        key = self.class.keys[name]
        raise ArgumentError, "Unknown key #{name}" if key.nil?
        klass = key.type
        
        value = if Time == klass
          Time.zone.local(*values)
        elsif Date == klass
          begin
            values = values_with_empty_parameters.collect do |v| v.nil? ? 1 : v end
            Date.new(*values)
          rescue ArgumentError => ex # if Date.new raises an exception on an invalid date
            Time.zone.local(*values).to_date # we instantiate Time object and convert it back to a date thus using Time's logic in handling invalid dates
          end
        else
          klass.new(*values)
        end
        writer_method = "#{name}="
        if respond_to?(writer_method)
          self.send(writer_method, value)
        else
          self[name.to_s] = value
        end
      end
    end
  end
  
  def extract_callstack_for_multiparameter_attributes(pairs)
    attributes = { }
  
    for pair in pairs
      multiparameter_name, value = pair
      attribute_name = multiparameter_name.split("(").first
      attributes[attribute_name] = [] unless attributes.include?(attribute_name)
  
      attributes[attribute_name] << [ find_parameter_position(multiparameter_name), value ]
    end
  
    attributes.each { |name, values| attributes[name] = values.sort_by{ |v| v.first }.collect { |v| v.last } }
  end
  
  def find_parameter_position(multiparameter_name)
    multiparameter_name.scan(/\(([0-9]*).*\)/).first.first
  end
  
end

models.comment.rb

# models/comment.rb
class Comment
  # Class Configuration :::::::::::::::::::::::::::::::::::::::::::::
  include MongoMapper::Document
  
  # Attributes ::::::::::::::::::::::::::::::::::::::::::::::::::::::  
  key :message, String
  key :message_html, String 
  key :user_id,    ObjectId
  key :username,   String
  timestamps!
  
  # Validations :::::::::::::::::::::::::::::::::::::::::::::::::::::
  validates_presence_of :message
  
  # Assocations :::::::::::::::::::::::::::::::::::::::::::::::::::::
  belongs_to :user
  
  # Callbacks :::::::::::::::::::::::::::::::::::::::::::::::::::::::
  before_create :set_username, :htmlify
  after_create :increment_comment_count

  private
  def increment_comment_count
    User.increment(user_id, :comment_count => 1)
  end
  
  def htmlify
    self.message_html = RedCloth.new(message).to_html
  end
  
  def set_username
    self.username = self.user.username
  end
   
end

models.user.rb

# models/user.rb
class User
  # Class Configuration :::::::::::::::::::::::::::::::::::::::::::::
  include MongoMapper::Document
  devise :authenticatable, :recoverable, :rememberable

  # Attributes ::::::::::::::::::::::::::::::::::::::::::::::::::::::
  key :email,  String
  key :username,  String
  key :comment_count, Integer
  key :encrypted_password, String
  key :password_salt, String
  key :reset_password_token, String
  key :remember_token, String
  key :remember_created_at, Time
  key :sign_in_count, Integer
  key :current_sign_in_at, Time
  key :current_sign_in_ip, String  
  timestamps!
  
  # Validations :::::::::::::::::::::::::::::::::::::::::::::::::::::
  RegEmailName   = '[\w\.%\+\-]+'
  RegDomainHead  = '(?:[A-Z0-9\-]+\.)+'
  RegDomainTLD   = '(?:[A-Z]{2}|com|org|net|gov|mil|biz|info|mobi|name|aero|jobs|museum)'
  RegEmailOk     = /\A#{RegEmailName}@#{RegDomainHead}#{RegDomainTLD}\z/i
  
  validates_length_of :email, :within => 6..100, :allow_blank => true
  validates_format_of :email, :with => RegEmailOk, :allow_blank => true

  # Assocations :::::::::::::::::::::::::::::::::::::::::::::::::::::
  many :comments

end