RoR: ActiveRecord, NoMethodError in models that are extended from AR

I have the following models set up:

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

But when saving/validating a model I keep hitting the following NoMethodErrors:

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

Eg:

e = Qa::ErrorType.first

e.valid?

produces

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_pagin开发者_StackOverflow社区ate'
    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?'

I have used the same code pattern elsewhere in the same application before and that portion still works fine (all the validations work as they are supposed to).

Can someone shed some light on what I am doing wrong.

---

Figured out what the problem was:

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

This declaration overrides the errors association/object that ActiveRecord provides hence we loose all validation functionality provided by ActiveRecord::Validations. Renaming the association to a more specific thing resolves the problem.

Correct implementation of the class:

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

All validations will work as they are meant to after this change. I think renaming the class Qa::Error as Qa::TransactionError is optional. I just did that so my naming convention is consistent throughout the application.