gitlab-org--gitlab-foss/app/models/sent_notification.rb

class SentNotification < ActiveRecord::Base
  belongs_to :project
  belongs_to :noteable, polymorphic: true
  belongs_to :recipient, class_name: "User"

  validate :project, :recipient, :reply_key, presence: true
  validate :reply_key, uniqueness: true

  validates :noteable_id, presence: true, unless: :for_commit?
  validates :commit_id, presence: true, if: :for_commit?

  def self.for(reply_key)
    find_by(reply_key: reply_key)
  end

  def for_commit?
    noteable_type == "Commit"
  end

  def noteable
    if for_commit?
      project.commit(commit_id) rescue nil
    else
      super
    end
  end
end