+
+ def subscribe(user)
+ subscribers << user
+ end
+
+ def unsubscribe(user)
+ subscribers.delete(user)
+ end
+
+ def subscribed?(user)
+ subscribers.exists?(user.id)
+ end
+
+ def size_limit
+ @size_limit ||= ActiveRecord::Base.connection.select_value(
+ "SELECT api_size_limit($1)", "api_size_limit", [user_id]
+ )
+ end