RoR：ActiveRecord，NoMethodError在从AR扩展的模型中

2018-06-29 01:20:37

我建立了以下模型：

class Qa::Base < ActiveRecord::Base
  self.abstract_class = true
  Qa::Base.establish_connection("qa_audit_#{RAILS_ENV}")
end

class Qa::ErrorType < Qa::Base
  set_table_name "error_types"

  # Associations
  has_many :errors, :class_name => 'Qa::Error'
  has_many :evaluations, :class_name => 'Qa::Evaluation', :through => :errors

  # Validations
  validates_presence_of :content
  validates_uniqueness_of :content
end

但是，当保存/验证模型时，我不停地击中以下NoMethodErrors：

NoMethodError (undefined method `add_on_blank' for #Class:0x23a3020):

例如：

e = Qa::ErrorType.first

e.valid?

产生

NoMethodError: undefined method add_on_blank' for #<Class:0x223eeb4>
    from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/base.rb:1994:inmethod_missing_without_paginate'
    from /opt/local/lib/ruby/gems/1.8/gems/will_paginate-2.3.14/lib/will_paginate/finder.rb:170:in method_missing'
    from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/associations/association_collection.rb:380:insend'
    from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/associations/association_collection.rb:380:in method_missing_without_paginate'
    from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/base.rb:2178:inwith_scope'
    from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/associations/association_proxy.rb:207:in send'
    from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/associations/association_proxy.rb:207:inwith_scope'
    from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/associations/association_collection.rb:376:in method_missing_without_paginate'
    from /opt/local/lib/ruby/gems/1.8/gems/will_paginate-2.3.14/lib/will_paginate/finder.rb:170:inmethod_missing'
    from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/validations.rb:599:in validates_presence_of'
    from /opt/local/lib/ruby/gems/1.8/gems/activesupport-2.3.8/lib/active_support/callbacks.rb:182:incall'
    from /opt/local/lib/ruby/gems/1.8/gems/activesupport-2.3.8/lib/active_support/callbacks.rb:182:in evaluate_method'
    from /opt/local/lib/ruby/gems/1.8/gems/activesupport-2.3.8/lib/active_support/callbacks.rb:166:incall'
    from /opt/local/lib/ruby/gems/1.8/gems/activesupport-2.3.8/lib/active_support/callbacks.rb:90:in run'
    from /opt/local/lib/ruby/gems/1.8/gems/activesupport-2.3.8/lib/active_support/callbacks.rb:90:ineach'
    from /opt/local/lib/ruby/gems/1.8/gems/activesupport-2.3.8/lib/active_support/callbacks.rb:90:in send'
    from /opt/local/lib/ruby/gems/1.8/gems/activesupport-2.3.8/lib/active_support/callbacks.rb:90:inrun'
    from /opt/local/lib/ruby/gems/1.8/gems/activesupport-2.3.8/lib/active_support/callbacks.rb:276:in run_callbacks'
    from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/validations.rb:1110:invalid_without_callbacks?'
    from /opt/local/lib/ruby/gems/1.8/gems/activerecord-2.3.8/lib/active_record/callbacks.rb:315:in `valid?'

我之前在同一个应用程序中的其他地方使用了相同的代码模式，并且该部分仍然正常工作（所有验证都按照它们应有的方式工作）。

有人可以阐明我做错了什么。

找出问题所在：

class Qa::ErrorType < Qa::Base
  set_table_name "error_types"

  # Associations
  has_many :errors, :class_name => 'Qa::Error'
  has_many :evaluations, :class_name => 'Qa::Evaluation', :through => :errors

  # Validations
  validates_presence_of :content
  validates_uniqueness_of :content
end

这个声明覆盖了ActiveRecord提供的错误关联/对象，因此我们放弃了ActiveRecord :: Validations提供的所有验证功能。将关联重命名为更具体的事情可以解决问题。

正确实施课堂：

class Qa::ErrorType < Qa::Base
  set_table_name "error_types"

  # Associations
  has_many :transaction_errors, :class_name => 'Qa::TransactionError'
  has_many :evaluations, :class_name => 'Qa::Evaluation', :through => :transaction_errors

  # Validations
  validates_presence_of :content
  validates_uniqueness_of :content
end

所有验证都将按照这些更改后的意图进行工作。我认为将Qa :: Error错误重命名为Qa :: TransactionError是可选的。我只是这么做的，所以我的命名约定在整个应用程序中都是一致的。

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