get workflow message through code

 WorkflowTrackingStatusTable wfTrackingTable;

 WorkflowTrackingTable       wfTracking;

 select firstonly wfTrackingTable

     order by wfTrackingTable.CreatedDateTime desc

             where wfTrackingTable.ContextTableId == tablenum(tablename)

             && wfTrackingTable.ContextRecId   == _purchTable.RecId;

 select firstonly   wfTracking

         order by wfTracking.CreatedDateTime asc

         where wfTracking.WorkflowTrackingStatusTable == wfTrackingTable.RecId

            && wfTracking.TrackingType == WorkflowTrackingType::Approval

             && wfTracking.TrackingContext==WorkflowTrackingContext::WorkItem

info(wfTracking.commentTable().getLocalizeTrackingMessage());