Ruby on rails RubyonRails验证复选框的存在

下面的模型我有以下表格：

    = simple_form_for @mem, :url => signup_path, :html => {:id => 'signup_form'}, :method => :post do |f|

        = f.input :interest, label: "I would like to learn more about:", collection: [ ['Interest 1', 'Interest 1' ], ['Interest 2', 'Interest 2']], :as => :check_boxes
        %br
        = f.input :full_name, :as => :string, required: true
        = f.input :email, :as => :string, required: true
        = f.input :telephone, :as => :string, required: true

        = f.submit "Submit"

型号：

class User
    include ActiveModel::Validations
    include ActiveModel::Conversion
    extend ActiveModel::Naming
    attr_accessor :full_name, :email, :telephone, :interest
    validates :interest, presence: { :message => "Please select your interest."}

我能够成功验证表单中的其他3个字段，但是我在验证复选框字段是否存在时遇到问题

：interest

。我希望确保用户选择一个或两个选项。谢谢你的帮助

你可以试试

接受：正确

在你的模型中

validates :interest, acceptance: true

---

起初我认为这是可行的，因为当两个选项都为空时，它会抛出一个错误，但当选择其中一个或两个选项时，我似乎无法让它进行验证。