Rails 中 Virtus 的默认值答案

【问题标题】：default values for Virtus in railsRails 中 Virtus 的默认值
【发布时间】：2017-08-22 18:27:48
【问题描述】：

我正在使用带有 rails (5.0.2) 的 virtus(1.0.5)。我将 Virtus 用于模型，因为它具有基于正在访问的页面的验证。

我的组织模型如下

class Organization < ApplicationRecord
  validates :name, presence: true
end

使用virtus创建的表单是as

class OrganizationProfileForm
  include ActiveModel::Model
  include Virtus.model

  attribute :call_center_number, String, default: :org_call_center_number

  validates :call_center_number, presence: true

  def initialize(organization)
    @organization = organization
  end

  private

  def org_call_center_number
    @organization.call_center_number
  end

end

很遗憾，上面的代码不起作用

Loading development environment (Rails 5.0.2)
2.3.0 :001 > of = OrganizationProfileForm.new(Organization.last)
Organization Load (0.6ms)  SELECT  "organizations".* FROM "organizations" ORDER BY "organizations"."id" DESC LIMIT $1  [["LIMIT", 1]]
=> #<OrganizationProfileForm:0x007f9d61edd6a8 @organization=# <Organization id: 1, name: "Some name", call_center_number: "4892374928", created_at: "2017-03-29 09:35:22", updated_at: "2017-03-29 09:37:59">>
2.3.0 :002 > of.call_center_number
=> nil

【问题讨论】：

标签： ruby-on-rails-5 virtus

【解决方案1】：

尝试删除private 行，因为这可能会阻止对方法org_call_center_number 的调用。 Virtus repo 上的默认值示例使用公共实例方法，而不是私有实例方法。

见：What are the differences between "private", "public", and "protected methods"?

【讨论】：

【解决方案2】：

我们需要在initialize方法中调用super()。

【讨论】：