如何验证数组字段的成员？

Question

我有这个型号:

class Campaign

  include Mongoid::Document
  include Mongoid::Timestamps

  field :name, :type => String
  field :subdomain, :type => String
  field :intro, :type => String
  field :body, :type => String
  field :emails, :type => Array
end

现在我想验证emails数组中的每个电子邮件是否格式正确.我读了Mongoid和ActiveModel :: Validations文档,但我没有找到如何做到这一点.

你能告诉我指针吗？

Answer 1

您可以定义自定义ArrayValidator.放置如下app/validators/array_validator.rb:

class ArrayValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, values)
    Array(values).each do |value|
      options.each do |key, args|
        validator_options = { attributes: attribute }
        validator_options.merge!(args) if args.is_a?(Hash)

        next if value.nil? && validator_options[:allow_nil]
        next if value.blank? && validator_options[:allow_blank]

        validator_class_name = "#{key.to_s.camelize}Validator"
        validator_class = begin
          validator_class_name.constantize
        rescue NameError
          "ActiveModel::Validations::#{validator_class_name}".constantize
        end

        validator = validator_class.new(validator_options)
        validator.validate_each(record, attribute, value)
      end
    end
  end
end

您可以在模型中使用它:

class User
  include Mongoid::Document
  field :tags, Array

  validates :tags, array: { presence: true, inclusion: { in: %w{ ruby rails } }
end

它将针对散列中指定的每个验证器验证数组中的每个元素.array

Answer 2

Milovan的回答得到了我的支持,但实施有一些问题:

1. 展平嵌套数组会更改行为并隐藏无效值.

2. nil字段值被视为[nil],这似乎不正确.

3. 提供的示例presence: true将生成NotImplementedError错误,因为PresenceValidator未实现validate_each.

4. 在每次验证时为数组中的每个值实例化一个新的验证器实例效率很低.

5. 生成的错误消息未显示数组元素无效的原因,从而导致用户体验不佳.

这是一个更新的可枚举和数组验证器,可以解决所有这些问题.为方便起见,下面包含代码.

# Validates the values of an Enumerable with other validators.
# Generates error messages that include the index and value of
# invalid elements.
#
# Example:
#
#   validates :values, enum: { presence: true, inclusion: { in: %w{ big small } } }
#
class EnumValidator < ActiveModel::EachValidator

  def initialize(options)
    super
    @validators = options.map do |(key, args)|
      create_validator(key, args)
    end
  end

  def validate_each(record, attribute, values)
    helper = Helper.new(@validators, record, attribute)
    Array.wrap(values).each do |value|
      helper.validate(value)
    end
  end

  private

  class Helper

    def initialize(validators, record, attribute)
      @validators = validators
      @record = record
      @attribute = attribute
      @count = -1
    end

    def validate(value)
      @count += 1
      @validators.each do |validator|
        next if value.nil? && validator.options[:allow_nil]
        next if value.blank? && validator.options[:allow_blank]
        validate_with(validator, value)
      end
    end

    def validate_with(validator, value)
      before_errors = error_count
      run_validator(validator, value)
      if error_count > before_errors
        prefix = "element #{@count} (#{value}) "
        (before_errors...error_count).each do |pos|
          error_messages[pos] = prefix + error_messages[pos]
        end
      end
    end

    def run_validator(validator, value)
      validator.validate_each(@record, @attribute, value)
    rescue NotImplementedError
      validator.validate(@record)
    end

    def error_messages
      @record.errors.messages[@attribute]
    end

    def error_count
      error_messages ? error_messages.length : 0
    end
  end

  def create_validator(key, args)
    opts = {attributes: attributes}
    opts.merge!(args) if args.kind_of?(Hash)
    validator_class(key).new(opts).tap do |validator|
      validator.check_validity!
    end
  end

  def validator_class(key)
    validator_class_name = "#{key.to_s.camelize}Validator"
    validator_class_name.constantize
  rescue NameError
    "ActiveModel::Validations::#{validator_class_name}".constantize
  end
end

Answer 3

您可能希望为电子邮件字段定义自己的自定义验证程序.

因此,您将在课程定义后添加,

validate :validate_emails

def validate_emails
  invalid_emails = self.emails.map{ |email| email.match(/^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/i) }.select{ |e| e != nil }
  errors.add(:emails, 'invalid email address') unless invalid_emails.empty?
end

正则表达式本身可能并不完美,但这是基本的想法.您可以按如下方式查看导轨指南:

http://guides.rubyonrails.org/v2.3.8/activerecord_validations_callbacks.html#creating-custom-validation-methods