Joins with ordering solution

gistfile1.rb

#Issues     
# THIS WORKS: search = Company.search(:users_orders_line_items_price_gte => "2",  :order => :ascend_by_orders_total )
  #since there is an association in the ordering, the scope returned from the first conditions runs through the stack and hits the join class creating the 
  #necessary join. When this happens it creates a new set of joins values for the scope
  # so I can call joins_values on scope, choose the last one and order based on that.(...order("orders.total ASC"))

#This don't: search = Company.search(:users_orders_line_items_price_gte => "2",  :order => :ascend_by_identifier )
  #Since there is no association in the ordering method, it never runs through the 'joins' class. So when I call joins_values
  #on the current scope i get backk {:users => {:orders => :line_items}} since the last value is line_item, i obviously don't
  #want to order on that. 
  
#Fix:
  #my fix checks to see if the value following ascend_by_ is a column of the current klass, if so it orders using the 
  #current klass (...order("companies.indentifier ASC")) otherwise it assumes that you want to be ordering on the last
  #value in the joins_value hash



def scope
  if applicable?
    ##add specific column to order on in all ordering queries
    klass.joins(join).order("#{order_on.to_s.pluralize}.#{sort_on} DESC")
  end
end

def order_on 
  joins_values = Array(klass.scoped.joins_values.flatten.try(:last)).flatten
  potential_column = /descend_by_/.match(method_name).post_match
  if klass.column_names.include?(potential_column)
    klass.name.underscore.pluralize
  else
    Array(joins_values.last).flatten.last
  end
end