Rails 3 与composed_of 模型和验证

我有这个域模型：

class Person < ActiveRecord::Base
  composed_of :address,
              mapping: [%w(address_street street), %w(address_city city), %w(address_zip_code zip_code), %w(address_country country)]

  validates :name, presence: true, length: { maximum: 50 }
  validates :surname, presence: true, length: { maximum: 50 }

  validates_associated  :address
end

class Address
  include ActiveModel::Validations
  include ActiveModel::Conversion
  extend ActiveModel::Naming

  attr_reader :street, :city, :zip_code, :country

  validates :street, presence: true
  validates :city, presence: true
  validates :zip_code, presence: true
  validates :country, presence: true

  def initialize(street, city, zip_code, country)
    @street, @city, @zip_code, @country = street, city, zip_code, country
  end

  def ==(other_address)
    street == other_address.street && city == other_address.city && zip_code == other_address.zip_code && country == other_address.country
  end

  def persisted?
    false
  end
end

当我尝试保存无效模型时：

> p = Person.new
=> #<Person id: nil, name: nil, surname: nil, address_street: nil, address_city: nil, address_zip_code: nil, address_country: nil
> p.valid?
=> false
> p.errors
=> {:name=>["can't be blank"], :surname=>["can't be blank"], :address=>["is invalid"]}

这没问题，但我更喜欢用 Address 的错误消息填充错误数组，如下所示：

=> {:name=>["can't be blank"], :surname=>["can't be blank"], :address_street=>["can't be blank"], :address_city=>["can't be blank"], :address_zip_code=>["can't be blank"], :address_country=>["can't be blank"]}

问题是：是否有一种干净的 Rails 方法可以做到这一点？或者只是我必须将验证代码从地址移至人员（相当难看）？还有其他解决方案吗？

非常感谢。

当你定义一个composed_of属性，它本身就成为一个对象。我看到有两种方法可以满足您的需求。

1）在您的中添加错误消息Address class

将当前的验证替换为：

validates_each :street, :city, :zip_code, :country do |record, attr, value|  
  record.errors.add attr, 'should not be blank' if value.blank?
end

这样，您将能够访问执行以下操作的错误消息：

p = Person.new
p.address.errors

2) 仅定制address错误信息

validates_associated  :address, 
                      :message => lambda { |i18n_key, object| self.set_address_error_msg(object[:value]) }

def self.set_address_error_msg address
  errors_array = Array.new
  address.instance_variables.each do |var|
    errors_array << "#{var[1..-1]} should not be blank" if address.send(var[1..-1]).blank?
  end
  errors_array.join(", ")
end       

这会呈现类似：

=> #<OrderedHash {:address=>["country should not be blank, zip_code should not be blank, validation_context should not be blank, city should not be blank"]}> 

最后，您可以在您的中重写验证器Profile类，但正如你所说，它真的很难看。