add: setting of system notification

app/models/system_notification.rb

@@ -12,6 +12,15 @@
 
 class SystemNotification < ApplicationRecord
 
+  default_scope { order(created_at: :desc)}
+
   has_many :system_notification_histories
   has_many :users, through: :system_notification_histories
+
+  scope :is_top, lambda { where(is_top: true) }
+
+
+  def read_member?(user_id)
+    self.system_notification_histories.where(user_id: user_id).present? ? true : false
+  end
 end