如何使 validates_inclusion_of 的错误消息显示允许的选项列表？

Question

我的模型中有一个validates inclusion:，但我认为“不包含在列表中”的默认错误消息完全没有用。

如何让它在错误消息本身中显示允许的选项列表？ （例如，"is not one of the allowed options (option 1, option 2, or option 3)"?

更具体地说，让以下测试通过的最优雅的方法是什么：

describe Person do
  describe 'validation' do
    describe 'highest_degree' do
      # Note: Uses matchers from shoulda gem
      it { should     allow_value('High School').       for(:highest_degree) }
      it { should     allow_value('Associates').        for(:highest_degree) }
      it { should     allow_value('Bachelors').         for(:highest_degree) }
      it { should     allow_value('Masters').           for(:highest_degree) }
      it { should     allow_value('Doctorate').         for(:highest_degree) }
      it { should_not allow_value('Elementary School'). for(:highest_degree).with_message('is not one of the allowed options (High School, Associates, Bachelors, Masters, or Doctorate)') }
      it { should_not allow_value(nil).                 for(:highest_degree).with_message('is required') }
      it { subject.valid?; subject.errors[:highest_degree].grep(/is not one of/).should be_empty }
    end
  end
end

，给定以下模型：

class Person
  DegreeOptions = ['High School', 'Associates', 'Bachelors', 'Masters', 'Doctorate']
  validates :highest_degree, inclusion: {in: DegreeOptions}, allow_blank: true, presence: true
end

?

这是我目前在 config/locales/en.yml 中的内容：

en:
  activerecord:
    errors:
      messages:
        blank: "is required"
        inclusion: "is not one of the allowed options (%{in})"

Answer 1

这是一个 custom Validator，它自动提供 %{allowed_options} 插值变量以在您的错误消息中使用：

class RestrictToValidator < ActiveModel::EachValidator
  ErrorMessage = "An object with the method #include? or a proc or lambda is required, " <<
                  "and must be supplied as the :allowed_options option of the configuration hash"

  def initialize(*args)
    super
    @allowed_options = options[:allowed_options]
  end

  def check_validity!
    unless [:include?, :call].any?{ |method| options[:allowed_options].respond_to?(method) }
      raise ArgumentError, ErrorMessage
    end
  end

  def allowed_options(record)
    @allowed_options.respond_to?(:call) ? @allowed_options.call(record) : @allowed_options
  end
  def allowed_options_string(record)
    allowed_options = allowed_options(record)
    if allowed_options.is_a?(Range)
      "#{allowed_options}"
    else
      allowed_options.to_sentence(last_word_connector: ', or ')
    end
  end

  def validate_each(record, attribute, value)
    allowed_options = allowed_options(record)
    inclusion_method = inclusion_method(allowed_options)
    unless allowed_options.send(inclusion_method, value)
      record.errors.add(attribute, :restrict_to,
                        options.except(:in).merge!(
                          value: value,
                          allowed_options: allowed_options_string(record)
                        )
      )
    end
  end

private

  # In Ruby 1.9 <tt>Range#include?</tt> on non-numeric ranges checks all possible values in the
  # range for equality, so it may be slow for large ranges. The new <tt>Range#cover?</tt>
  # uses the previous logic of comparing a value with the range endpoints.
  def inclusion_method(enumerable)
    enumerable.is_a?(Range) ? :cover? : :include?
  end
end

包含在您的 config/locales/en.yml 中：

en:
  activerecord:
    errors:
      messages:
        restrict_to: "is not one of the allowed options (%{allowed_options})"

你可以这样使用它：

  DegreeOptions = ['High School', 'Associates', 'Bachelors', 'Masters', 'Doctorate']
  validates :highest_degree, restrict_to: {allowed_options: DegreeOptions},
    allow_blank: true, presence: true
  # => "highest_degree is not one of the allowed options (High School, Associates, Bachelors, Masters, or Doctorate)"

或者有一个范围：

  validates :letter_grade, restrict_to: {allowed_options: 'A'..'F'}
  # => "letter_grade is not one of the allowed options (A..F)"

或者使用 lambda/Proc：

  validates :address_state, restrict_to: {
    allowed_options: ->(person){ Carmen::states(country)
  }

欢迎评论！您认为应该将这样的内容添加到 Rails (ActiveModel) 核心吗？

这个验证器有更好的名字吗？ restrict_to_options? restrict_to?

Answer 2

嗯！看起来 Rails 明确排除了（使用except(:in)）我们在将参数传递给 I18n 之前传入的 :in 选项！

这里是来自 activemodel/lib/active_model/validations/inclusion.rb 的 rails 源代码：

class InclusionValidator < EachValidator
  def validate_each(record, attribute, value)
    delimiter = options[:in]
    exclusions = delimiter.respond_to?(:call) ? delimiter.call(record) : delimiter
    unless exclusions.send(inclusion_method(exclusions), value)
      record.errors.add(attribute, :inclusion, options.except(:in).merge!(:value => value))
    end
  end
end

为什么要这样做？

无论如何，将原始 array 插入到错误消息中并不是很有用。我们需要的是一个 string 参数（由数组构建），我们可以直接插值。

当我将 validates 更改为此时，我设法通过了测试：

  validates :highest_degree, inclusion: {
    in:              DegreeOptions,
    allowed_options: DegreeOptions.to_sentence(last_word_connector: ', or ')}
  }, allow_blank: true, presence: true

并将 en.yml 更改为：

        inclusion: "is not one of the allowed options (%{allowed_options})"

但是不得不通过两个不同的哈希键传递 DegreeOptions 是很丑的。

我的意见是验证器本身应该为我们构建该密钥（并将其传递给 I18n 以插入到消息中）。

那么我们有哪些选择？创建自定义验证器，修改现有的 InclusionValidator，或向 Rails 团队提交补丁...