rails 4.2.0 的参数数量错误（1..2 为 0）

Question

我想在我的 rails 项目中使用 gem 'stuff-classifier'。首先，我在带有 rails 4.1.7 的新项目中对此进行了测试，并像我预期的那样工作。 但是当我在我的目标项目中做同样的事情时，我遇到了 ArgumentError 的问题：参数数量错误（0 代表 1..2）。但是当我初始化 StuffClassifier::Bayes 类时，我给出了 StuffClassifier::Bayes.new("Music_Classifier")

下面我展示了我所做的：

首先添加到 gemfile gem 'stuff-classifier'

接下来生成带有music_classifier文本属性的模型分类器

class Classifier < ActiveRecord::Base
  serialize :music_classifier, StuffClassifier::Bayes
  before_create :initialize_clfr

  private 

  def initialize_clfr
    cls = self.music_classifier = StuffClassifier::Bayes.new("Music_Classifier")

    cls.train(:alternative, "Art Punk Alternative-Rock")
    cls.train(:latin, "Alternativo & Rock Latino ")
  end
end

在我的 db/seeds.rb 文件中，我有 Classifier.create!

然后我在控制台rake db:seed 中尝试，这给了我这个错误消息：

rake aborted!
ArgumentError: wrong number of arguments (0 for 1..2)
/home/pnc/.rvm/gems/ruby-2.1.3/gems/stuff-classifier-0.5/lib/stuff-classifier/bayes.rb:7:in `initialize'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/coders/yaml_column.rb:24:in `new'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/coders/yaml_column.rb:24:in `load'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/type/serialized.rb:52:in `default_value?'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/type/serialized.rb:16:in `type_cast_from_database'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute.rb:94:in `type_cast'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute.rb:42:in `original_value'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute.rb:37:in `value'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute.rb:54:in `changed_in_place_from?'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute_methods/dirty.rb:74:in `attribute_changed_in_place?'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute_methods/dirty.rb:149:in `block in changed_in_place'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute_methods/dirty.rb:148:in `select'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute_methods/dirty.rb:148:in `changed_in_place'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute_methods/dirty.rb:141:in `attributes_changed_in_place'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute_methods/dirty.rb:62:in `changed_attributes'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activemodel-4.2.0/lib/active_model/dirty.rb:173:in `attribute_changed?'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute_methods/dirty.rb:115:in `old_attribute_value'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute_methods/dirty.rb:90:in `write_attribute'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/timestamp.rb:52:in `block in _create_record'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/timestamp.rb:49:in `each'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/timestamp.rb:49:in `_create_record'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/persistence.rb:501:in `create_or_update'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/callbacks.rb:302:in `block in create_or_update'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activesupport-4.2.0/lib/active_support/callbacks.rb:88:in `call'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activesupport-4.2.0/lib/active_support/callbacks.rb:88:in `_run_callbacks'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activesupport-4.2.0/lib/active_support/callbacks.rb:734:in `_run_save_callbacks'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/callbacks.rb:302:in `create_or_update'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/persistence.rb:142:in `save!'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/validations.rb:43:in `save!'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute_methods/dirty.rb:29:in `save!'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/transactions.rb:291:in `block in save!'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/transactions.rb:347:in `block in with_transaction_returning_status'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/database_statements.rb:213:in `block in transaction'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/transaction.rb:188:in `within_new_transaction'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/connection_adapters/abstract/database_statements.rb:213:in `transaction'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/transactions.rb:220:in `transaction'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/transactions.rb:344:in `with_transaction_returning_status'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/transactions.rb:291:in `save!'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/persistence.rb:51:in `create!'
/home/pnc/sites/spolisty/db/seeds.rb:8:in `<top (required)>'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:268:in `load'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:268:in `block in load'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:240:in `load_dependency'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activesupport-4.2.0/lib/active_support/dependencies.rb:268:in `load'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/railties-4.2.0/lib/rails/engine.rb:547:in `load_seed'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/tasks/database_tasks.rb:250:in `load_seed'
/home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/railties/databases.rake:180:in `block (2 levels) in <top (required)>'
Tasks: TOP => db:seed
(See full trace by running task with --trace)

当我在 Rails 控制台中尝试这个时，我有同样的错误消息。

c = Classifier.new

    Loading development environment (Rails 4.2.0)
2.1.3 :001 > c = Classifier.new
ArgumentError: wrong number of arguments (0 for 1..2)
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/stuff-classifier-0.5/lib/stuff-classifier/bayes.rb:7:in `initialize'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/coders/yaml_column.rb:24:in `new'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/coders/yaml_column.rb:24:in `load'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/type/serialized.rb:52:in `default_value?'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/type/serialized.rb:16:in `type_cast_from_database'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute.rb:94:in `type_cast'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute.rb:42:in `original_value'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute.rb:37:in `value'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute_set.rb:31:in `fetch_value'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute_methods/read.rb:93:in `_read_attribute'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute_methods/read.rb:87:in `read_attribute'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/attribute_methods.rb:305:in `attribute_for_inspect'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/core.rb:443:in `block in inspect'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/core.rb:441:in `collect'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/activerecord-4.2.0/lib/active_record/core.rb:441:in `inspect'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/railties-4.2.0/lib/rails/commands/console.rb:110:in `start'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/railties-4.2.0/lib/rails/commands/console.rb:9:in `start'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:68:in `console'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
    from /home/pnc/.rvm/gems/ruby-2.1.3/gems/railties-4.2.0/lib/rails/commands.rb:17:in `<top (required)>'
    from bin/rails:4:in `require'
    from bin/rails:4:in `<main>'2.1.3 :002 > 

我尝试在 Stack 上用这个 topic 解决这个问题，因为之前我有 rails 4.2.0.rc3 但是在将 rails 升级到 4.2.0 后我仍然遇到这个问题。

我怎样才能解决这个错误，或者我怎样才能以其他方式使用东西分类器？

谢谢帮助。

编辑： db/seeds.rb的内容

Classifier.create!

Answer 1

这与您调用 StuffClassifier::Bayes.new 无关，与您尝试让 ActiveRecord 序列化它有关。

所有涉及的代码都是开源的，如果您查看堆栈跟踪，您会看到导致错误的行是：

.../gems/activerecord-4.2.0/lib/active_record/coders/yaml_column.rb:24:in `new'

此项目可在您的浏览器中免费查看：

https://github.com/rails/rails/blob/v4.2.0.rc3/activerecord/lib/active_record/coders/yaml_column.rb#L24

有问题的行是：

def load(yaml)
  return object_class.new if object_class != Object && yaml.nil?
  # ...

如您所见，当您的序列化 YAML 返回为 nil 时，ActiveRecord 假定它可以调用 .new 而对用于序列化的类没有任何参数。这使得没有无参数初始化程序的StuffClassifier::Bayes 无法用作 ActiveRecord 序列化类，除非您具有先前的序列化值。

你有很多前进的方向：

• Monkey-path StuffClassifier::Bayes 以便它可以在没有参数的情况下进行初始化
• 在 Github 上 fork gem，进行修改并尝试将它们合并到原始存储库中
• 生成您自己的类StuffclassifierSerializer，它可以作为 ActiveRecord 和 gem 之间的适配器