How to handle multiple source fields in message mapping

Hi,

My source message has the following structure for my source field:

<ParentSegment>
  <DAT01></DAT01>
  <DAT02></DAT02>
  <DAT03></DAT03>
  ...
  <DAT24></DAT24>
  <DAT25></DAT25>
</ParentSegment>

I need to check each of the DAT fields starting from field 1 to field 25 for the first field that contains a value and then map that field value to a single target field. I know this can be done using the available functions in the graphical mapping to check each field one at a time and map the field that contains a value. However, I wanted to know if there is a better way of doing it such as iterating over the total number of fields and accessing each of the field dynamically to determine which contains a value? If this is possible, can you please show me how this can be done?

Thanks in advance for any help.

Regards,

Elbert