```ruby
module Saasable::ScopedDocument
  @scoped_documents = []
  
  def self.included klass
    @scoped_documents << klass unless @scoped_documents.include? klass
    
    klass.class_eval do
      field :saas_id, :type => BSON::ObjectId
    end
  end
  
  def self.scoped_documents
    @scoped_documents
  end
end```

Fix validations of uniqueness so it always scope by saas_id on the scoped documents.
user
```ruby
module Saasable::ScopedDocument
  @scoped_documents = []
  
  def self.included klass
    @scoped_documents << klass unless @scoped_documents.include? klass
    
    klass.extend ClassMethods
    klass.class_eval do
      field :saas_id, :type => BSON::ObjectId
    end
  end
  
  def self.scoped_documents
    @scoped_documents
  end
  
  module ClassMethods
    def validates_uniqueness_of(*args)
      attributes = _merge_attributes(args)
      attributes[:scope] ||= []
      attributes[:scope] << :saas_id unless attributes[:scope].include?(:saas_id)
      
      validates_with(Mongoid::Validations::UniquenessValidator, attributes)
    end
  end
end```
assistant