osem-fcy/app/models/venue.rb

class Venue < ActiveRecord::Base
  belongs_to :conference
  has_many :rooms, dependent: :destroy
  before_create :generate_guid

  validates :name, :street, :city, :country, presence: true
  validates :conference_id, presence: true, uniqueness: true

  has_attached_file :photo,
                    styles: { thumb: '100x100>', large: '300x300>' }
  validates_attachment_content_type :photo,
                                    content_type: [/jpg/, /jpeg/, /png/, /gif/],
                                    size: { in: 0..500.kilobytes }

  after_update :send_mail_notification

  def address
    "#{street}, #{city}, #{country_name}"
  end

  def country_name
    name = ISO3166::Country[country]
    name.name if name
  end

  def location?
    !(latitude.blank? || longitude.blank?)
  end

  private

  def send_mail_notification
    Mailbot.send_email_on_venue_updated(conference).deliver_later if notify_on_venue_changed?
  end

  def notify_on_venue_changed?
    return false unless conference.email_settings.send_on_venue_updated
    # do not notify unless the address changed
    return false unless self.name_changed? || self.street_changed? || self.city_changed? || self.country_changed?
    # do not notify unless the mail content is set up
    (!conference.email_settings.venue_updated_subject.blank? && !conference.email_settings.venue_updated_body.blank?)
  end

  # TODO: create a module to be mixed into model to perform same operation
  # event.rb has same functionality which can be shared
  # TODO: rename guid to UUID as guid is specifically Microsoft term
  def generate_guid
    loop do
      @guid = SecureRandom.urlsafe_base64
      break if !Venue.where(guid: guid).any?
    end
    self.guid = @guid
  end
end