app/models/email.rb
class Email < ActiveRecord::Base
include ActiveModel::Conversion
attr_accessor :all_rebels, :rebel_ids, :subject, :message, :error_message
# has_rich_text :message
def valid?
set_error_message_if_no_rebel unless rebel_ids&.any?
rebel_ids&.any? and !subject.empty?
end
def set_error_message_if_no_rebel
self.error_message = "You must choose at least one rebel to email."
end
end