自定义验证器抛出 RuntimeError: :attributes 不能为空答案

【问题标题】：Custom validator throws RuntimeError: :attributes cannot be blank自定义验证器抛出 RuntimeError: :attributes 不能为空
【发布时间】：2012-05-22 19:14:38
【问题描述】：

在我的 Rails 应用程序中，我有一个 Like 模型。

### like.rb
### Custom Validator Code:
class UniquenessValidator < ActiveModel::Validator
  def validate(record)
      # Empty   
  end
end

class Like < ActiveRecord::Base
  include ActiveModel::Validations
  validates_with UniquenessValidator

  attr_accessible :user_id

  belongs_to :likeable, polymorphic: true
  belongs_to :user
end

在我的 Rails 控制台中，我尝试执行 Like.all（目前我的 Likes 表是空的）

1.9.2p320 :001 > Like.all
RuntimeError: :attributes cannot be blank
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/activemodel-3.2.3/lib/active_model/validator.rb:141:in `initialize'
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/activerecord-3.2.3/lib/active_record/validations/uniqueness.rb:7:in `initialize'
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/activemodel-3.2.3/lib/active_model/validations/with.rb:84:in `new'
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/activemodel-3.2.3/lib/active_model/validations/with.rb:84:in `block in validates_with'
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/activemodel-3.2.3/lib/active_model/validations/with.rb:83:in `each'
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/activemodel-3.2.3/lib/active_model/validations/with.rb:83:in `validates_with'
        from /Users/user/Programming/WWW/Rails/experiments/test_app/app/models/like.rb:3:in `<class:Like>'
        from /Users/user/Programming/WWW/Rails/experiments/test_app/app/models/like.rb:1:in `<top (required)>'
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/activesupport-3.2.3/lib/active_support/dependencies.rb:469:in `load'
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/activesupport-3.2.3/lib/active_support/dependencies.rb:469:in `block in load_file'
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/activesupport-3.2.3/lib/active_support/dependencies.rb:639:in `new_constants_in'
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/activesupport-3.2.3/lib/active_support/dependencies.rb:468:in `load_file'
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/activesupport-3.2.3/lib/active_support/dependencies.rb:353:in `require_or_load'
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/activesupport-3.2.3/lib/active_support/dependencies.rb:502:in `load_missing_constant'
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/activesupport-3.2.3/lib/active_support/dependencies.rb:192:in `block in const_missing'
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/activesupport-3.2.3/lib/active_support/dependencies.rb:190:in `each'
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/activesupport-3.2.3/lib/active_support/dependencies.rb:190:in `const_missing'
        from (irb):1
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/railties-3.2.3/lib/rails/commands/console.rb:47:in `start'
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/railties-3.2.3/lib/rails/commands/console.rb:8:in `start'
        from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/railties-3.2.3/lib/rails/commands.rb:41:in `<top (required)>'
        from script/rails:6:in `require'
        from script/rails:6:in `<main>'
1.9.2p320 :002 >

这里发生了什么？（顺便说一句，如果我从 Like.rb 中删除 validates_with UniquenessValidator ，我不会收到此错误）

【问题讨论】：

标签： ruby-on-rails ruby-on-rails-3 validation customvalidator

【解决方案1】：

调用您的验证器 MyUniquenessValidator。

UniquenessValidator 已存在在活动记录中。这个字符串from /Users/user/.rvm/gems/ruby-1.9.2-p320@test_app/gems/activerecord-3.2.3/lib/active_record/validations/uniqueness.rb:7:ininitialize'` 正在告诉你。

小心预定义的 ruby 和 RoR 类（数据类型（例如，“Complex”）、rails 验证器等）

【讨论】：

【解决方案2】：

我知道这不是你的情况，但我收到此错误是因为我意外地从 EachValidator 而不是 Validator 子类化。

原来是：

class UserProfileValidator < ActiveModel::EachValidator
  def validate(record)
  end
end

应该是：

class UserProfileValidator < ActiveModel::Validator
  def validate(record)
  end
end

或者：

class UserProfileValidator < ActiveModel::EachValidator
  def def validate_each(record, attribute, value)
  end
end

【讨论】：