class Message
  include Mongoid::Document
  include Mongoid::Timestamps::Created

  #fields
  field :subject, :type => String
  field :body, :type => String
  field :place, :type => String
  field :has_been_read, :type => String

  # Relationships
  belongs_to :sender, :class_name => 'User', :inverse_of => :messages_sent
  belongs_to :receiver,   :class_name => 'User', :inverse_of => :messages_received

  #state machine has been read message?
    state_machine :has_been_read, :initial => :unread do
    event :read_message do
    transition :from => :unread, :to => :read
   end
   event :mark_unread do
     transition :from => :read, :to => :unread
   end
  end
  #state machine status can be in_box, sent, draft, trash, spam
end

class User
 include Mongoid::Document
 include Mongoid::Timestamps::Created
.
.
.
  has_many :messages_sent, :class_name => 'Message', :inverse_of => :sender
  has_many :messages_received, :class_name => 'Message', :inverse_of => :receiver
.
.
.
end