Question

我正在尝试在我的应用上制作自定义验证工具。

我已经配置了我的config.autoload.paths并且装载正常。

问题在于验证器本身。

binding pry

的结果

instance variables: @attributes  @options  @with
locals: _  _dir_  _ex_  _file_  _in_  _out_  _pry_  attribute  record  value
[12] pry(#<FileCountValidator>)> value
=> [#<Attachment id: 60, description: nil, file: "cache_600_1__img_948867_5770137d84a6c79ac825886938e...", attachable_type: "Post", attachable_id: 15, created_at: "2012-03-10 14:50:54", updated_at: "2012-03-10 14:50:54">,
 #<Attachment id: 61, description: nil, file: "cache_600_1__img_948867_90f64e01b9c871ec656a884e015...", attachable_type: "Post", attachable_id: 15, created_at: "2012-03-10 14:50:54", updated_at: "2012-03-10 14:50:54">,
 #<Attachment id: 62, description: nil, file: "cache_600_1__img_948867_85eda3946c27fa90566403ac941...", attachable_type: "Post", attachable_id: 15, created_at: "2012-03-10 14:50:54", updated_at: "2012-03-10 14:50:54">,
 #<Attachment id: nil, description: nil, file: nil, attachable_type: "Post", attachable_id: 15, created_at: nil, updated_at: nil>]
[13] pry(#<FileCountValidator>)> value > @with
TypeError: compared with non class/module
from /home/kleber/.rvm/gems/ruby-1.9.3-p125/gems/activerecord-3.2.1/lib/active_record/relation/delegation.rb:20:in `>'
[14] pry(#<FileCountValidator>)> value.size > @with
=> true
[15] pry(#<FileCountValidator>)> value.size
=> 4
[16] pry(#<FileCountValidator>)> @with
=> 3
[17] pry(#<FileCountValidator>)>

所以，我试图使这个比较完全像我在pry调试控制台上做的那样。

def validate_each(record, attribute, value)
  #binding.pry
   record.errors.add(attribute,"#{@with} attachments per post only. #{attribute['file'].size} detected.") if value.size > @with
  end

但是这样做，请将错误归还给我：

NoMethodError (undefined method `size' for nil:NilClass):
  lib/validators/file_count_validator.rb:11:in `validate_each'
  app/controllers/posts_controller.rb:61:in `block in update'
  app/controllers/posts_controller.rb:60:in `update'

在进入value方法之前有没有办法抓住validate_each？

Answer 1

很抱歉，但传递的值似乎是正确的。 value意味着该记录的该属性的值，即record.send(attribute)应该等于该值。

调用validates :attachments, :photo_count => 2不会将validate_each方法作为参数value发送2。您可以执行:photo_count => true，这是我通常所做的，甚至是:photo_count => "foo"。 photo_count语句中的validates用于通过传递嵌入在选项哈希中的值（即，2或true或“foo”，用于所述示例）来调用验证器。

这是一种的方式，但没有通过验证器的限制。

创建Constants类并定义MAX_ATTACHMENTS常量。我通常在models / constants.rb。

class Constants
  MAX_ATTACHMENTS = 1
end

然后，在验证器中，你可以做

class PhotoCountValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    record.errors.add(attribute,"#{Constants::MAX_ATTACHMENTS} attachments per post only.") if record.send(attribute).size > Constants::MAX_ATTACHMENTS
  end
end

将参数传递给验证器的另一种方法：

validates :attachments, :photo_count => 3 #desired_limit

覆盖PhotoCountValidator类的initialize方法，并初始化一个类变量：

def initialize(options)
  @@max_objects = options[:with] # the options hash will be as {:attributes=>[:attachments], :with=>3}, where :with contains the desired limit passed
  super
end

然后在validate_each方法中：

record.errors.add(attribute,"#{@@max_objects} attachments per post only.") if record.send(attribute).size > @@max_objects

Rails 3 - 自定义验证器

1 个答案: