retrospring/app/models/announcement.rb

class Announcement < ApplicationRecord
  belongs_to :user

  validates :content, presence: true
  validates :starts_at, presence: true
  validates :link_href, presence: true, if: -> { link_text.present? }
  validate :starts_at, :validate_date_range

  def link_present?
    link_text.present?
  end

  def validate_date_range
    if starts_at > ends_at
      errors.add(:starts_at, "Start date must be before end date")
    end
  end
end