Question

我正在尝试在Rails应用程序中以两种方式之一验证表单字段，具体取决于传入的参数。如果我的对象具有参数allow_negative: true，我想要：

validates :amount, numericality: {less_than_or_equal_to: 0}

否则我想：

validates :amount, numericality: {greater_than_or_equal_to: 0}

当我尝试这样做时：

validates :amount, numericality: {greater_than_or_equal_to: 0}, unless: :allow_negative
validates :amount, numericality: {less_than_or_equal_to: 0}, if: :allow_negative

它只执行validates :amount

的第二个实例

供参考，这是我的全班：

class ViewModel
    include ActiveModel::Model

    validates :description, presence: true
    validates :amount, numericality: {greater_than_or_equal_to: 0}, unless: :allow_negative
    validates :amount, numericality: {less_than_or_equal_to: 0}, if: :allow_negative

    attr_reader :amount
    attr_reader :description
    attr_reader :allow_negative
    attr_reader :order

    def initialize(user, params)
      @amount = params[:amount]
      @description = params[:description]
      @allow_negative = params[:allow_negative]
      @order = Order.find(params[:order_id])
    end

  end

Answer 1

如果传递了一个实际的布尔值，事实证明上述工作。我传递了一串真或假。一旦我将allow_negative的值转换为真正的bool，它就会很好用。

Answer 2

您的代码正在执行的操作是根据:allow_negative的状态强制执行正值或负值。使用你在那里的结构称它:force_negative会更准确。

如果您希望:allow_negative值允许正值和负值，那么您需要这样的内容：

validates :amount, numericality: true
validates :amount, numericality: {greater_than_or_equal_to: 0}, unless: :allow_negative

Answer 3

您可能需要进行自定义验证，例如：

class ViewModel
  include ActiveModel::Model

  validates :amount, numericality: true
  validate :force_negative

  private

  def force_negative
    if allow_negative && amount > 0
      errors.add(:amount, "must be less than or equal to 0")
    elsif amount < 0
      errors.add(:amount, "must be greater than or equal to 0")
    end
  end
end

如果为true，则ActiveModel验证表单具有负值，否则验证表单具有正值

3 个答案: