Rails 5：添加条件自定义验证

Question

我想为模型添加条件自定义验证

Rails 允许创建方法以创建自定义验证

class Invoice < ApplicationRecord
  validate :expiration_date_cannot_be_in_the_past

  def expiration_date_cannot_be_in_the_past
    if expiration_date.present? && expiration_date < Date.today
      errors.add(:expiration_date, "can't be in the past")
  end
end

它还允许创建条件验证

class Order < ApplicationRecord
  validates :card_number, presence: true, if: :paid_with_card?

  def paid_with_card?
    payment_type == "card"
  end
end

如何混合使用？

我的猜测是这样的

validate :condition, if: :other_condition

但这会产生一个 SyntaxError：

syntax error, unexpected end-of-input, expecting keyword_end

Answer 1

当您将缺少的关闭end 修复为在expiration_date_cannot_be_in_the_past 中打开的if 时，您可以进行以下工作：

validate :expiration_date_cannot_be_in_the_past, if: :paid_with_card?

Answer 2

您可以使用每个验证器。为此，您必须按照以下步骤操作：

• 在您的app 目录中创建一个名为validators 的文件夹。
• 创建一个名为some_validator.rb的文件

• 代码如下：

  class SomeValidator < ActiveModel::EachValidator
   def validate_each(object, attribute, value)
     return unless value.present?
     if some_condition1
       object.errors[attribute] << 'error msg for condition1'
     end
    object.errors[attribute] << 'error msg 2' if condition2
    object.errors[attribute] << 'error msg 3' if condition3
    object.errors[attribute] << 'error msg 4' if condition4
  end
  

  结束

• 现在通过此自定义验证器进行验证，如下所示： validates :attribute_name, some: true

• 确保您在验证器上使用相同的名称。您可以在此自定义验证器中编写多个条件。

Answer 3

你错过了结尾，更正了代码：

class Invoice < ApplicationRecord
  validate :expiration_date_cannot_be_in_the_past

  def expiration_date_cannot_be_in_the_past
    if expiration_date.present? && expiration_date < Date.today
      errors.add(:expiration_date, "can't be in the past")
    end # this end you missed in code
  end
end

Answer 4

class User < ApplicationRecord
  validate :email_not_changeable, on: :update

  private

  def email_not_changeable
    return unless email_changed? && persisted?

    errors.add(:email, "can't be changed")
  end
end