instance method arel_column

# File activerecord/lib/active_record/relation/query_methods.rb, line 1540
      def arel_column(field)
        field = klass.attribute_aliases[field] || field
        from = from_clause.name || from_clause.value

        if klass.columns_hash.key?(field) && (!from || table_name_matches?(from))
          table[field]
        elsif field.match?(/\A\w+\.\w+\z/)
          table, column = field.split(".")
          predicate_builder.resolve_arel_attribute(table, column) do
            lookup_table_klass_from_join_dependencies(table)
          end
        else
          yield field
        end
      end