near zip named_scope.rb

# Building on the zips_near_zip procedure in this gist: http://gist.github.com/319908
# I added a named scope to my model which has an attribute of "service_address_id":

# call to sanitize_sql_array to avoid sql injection.

named_scope :near_zip, lambda { |zip, miles| 
   { :joins=>sanitize_sql_array(["join addresses 
                on service_address_id=addresses.id 
              join zips_near_zip(?,?) 
                on zip_code = zip",zip, miles]) }
  }