Question

请考虑以下代码：

campaign_spec.rb：

describe Campaign do
  before :each do
    @campaign = Campaign.new
  end

  it { should validate_presence_of :position }
end

campaign.rb：

class Campaign < ActiveRecord::Base
  attr_accessible :position

  validates :position, presence: true

  default_scope order(:position)

  before_validation :next_position

  # sets the position to the next id (1 if none exist) before validation
  def next_position
    if self.position.blank?
      self.position = Campaign.select("coalesce(max(position),0) + 1 as position").reorder(nil).first.position
    end
  end
end

规范输出：

Failures:

  1) Campaign should require position to be set
     Failure/Error: it { should validate_presence_of :position }
       Expected errors to include "can't be blank" when position is set to nil, got errors: ["name can't be blank (nil)"]
     # ./spec/models/campaign_spec.rb:9:in `block (2 levels) in <top (required)>'

从我的模型所说的，我应该能够创建一个Campaign而不给它一个位置。如果在验证之前不存在，则设置位置。那么为什么我的规格没有通过呢？我在想，也许它不是在调用我的before_validation方法？

Answer 1

should validate_presence_of将属性的值设置为nil，然后运行验证。由于它为零，nil.blank?返回true，因此执行回调，将其设置回某个值，因此发现验证不起作用。

事实是，如果您确定它永远不会为空，则无需验证此字段。相反，编写测试以检查在设置为nil时是否确实自动填充。

it 'populates position if blank before validations' do
  subject.position = nil
  subject.valid?
  subject.position.should_not be_nil
end

validate_presence_of无法按预期使用增量计数器

1 个答案: