sylow

# --- model
class Announcement < ActiveRecord::Base
  belongs_to :user

  has_many :announcement_rooms, dependent: :delete_all
  has_many :rooms, through: :announcement_rooms
end


# --- controller

sylow

# contract
property :logo, skip_if: :all_blank, 
                prepopulator: ->(options) { self.logo = Image.new },
                populator: ->(fragment, model, options) { model || self.logo = Image.new } do
  property :_destroy, virtual: true
  property :data
end

# models 
#challenge.rb