def distinct_values_for_column(column)  #:nodoc:
      column.model.select("distinct #{column.name}").order("#{column.name} asc").collect do|ar|
        ar[column.name]
      end.reject(&:blank?).map { |i| [i, i] }
    end
def distinct_values_for_column(column)  #:nodoc:
      column.model.select("distinct #{column.name}").order("#{column.name} asc").collect do|ar|
        ar[column.name]
      end.reject(&:blank?).map { |i| [i, i] }
    end
with this variant we get even those values which do not appear in the resultset