Mongoid find and update, or create

findup_or_create.rb

# === Example
# class User
#   include Mongoid::Document
#   extend FindupOrCreate
#
#   field :name,    type: String
#   field :locale,  type: String
#   field :password,type: String
# end
#
# # basic usage
# user = User.findup_or_create_with(:name, name: 'username', locale: 'Shanghai, China', password: RandPasswd)
# unless user.persisted?
#   raise user.errors.full_messages
# else
#   sign_in(user)
# end
#
# # with block
# User.findup_or_create_with(:name, name: 'username', locale: 'Shanghai, China') do |user, is_new|
#   if is_new && user.errors?
#     raise user.errors.full_messages
#   else
#     sign_in(user)
#   end
# end
module FindupOrCreate
  def findup_or_create_with *args, &block
    attrs, keys = args.extract_options!.symbolize_keys, args.collect(&:to_sym)
    new_obj, query = true, attrs.select{|k,v| args.include?(k) }
    return nil if query.blank?
    if obj = self.where(query).first
      new_obj = false
      obj.update_attributes(attrs.select{|k,v| !args.include?(k) })
    end
    obj ||= self.create(attrs)
    yield(obj, new_obj) if block_given?
    obj
  end
end