def one_line_filter

      if (attributes.keys - COMMON_ATT_KEYS - %w[ ref original_ref ]).empty?
        return nil
      end

      [ attributes.remap { |(k, v), h|
        if v.nil?
          h['field'] = k
        else
          h[k] = v
        end
      } ]
    end
def one_line_filter

      if (attributes.keys - COMMON_ATT_KEYS - %w[ ref original_ref ]).empty?
        return nil
      end

      [ attributes.remap { |(k, v), h|
        if v.nil?
          h['field'] = k
        else
          h[k] = v
        end
      } ]
    end
Filter thanks to the attributes of the expression.

   pdef = Ruote.process_definition do
     filter 'x', :type => 'string', :record => true
     filter 'y', :type => 'number', :record => true
   end