Ruby on rails 如何使用getter by symbol在SimpleForm中添加选择字段？

我从下面的符号中添加了getter和setter：

class User < ActiveRecord::Base
  GENDER = { male: 2, female: 1}

  def gender
    GENDER.key(read_attribute(:gender))
  end

  def gender=(g)
    write_attribute(:gender, GENDER[g.to_sym])
  end
end

---

如果要使用集合，请参见此处的文档：

= simple_form_for [:member, @member] do |f|
  = f.input :gender

 <%= f.input :gender, collection: User::GENDER.keys %>