I'm using the Migrate module to import data but I want to compare existing data in my Drupal content for one specific field before I overwrite it during an update migration.
PrepareRow() doesn't seem to have access to the destination data. I was hoping that
Prepare() would as the inputs to
prepare($entity, stdclass $row) suggest it has the entity in hand, however it appears that this entity is the fully constructed row it is about to import rather than the data from the destination object.
Is there any way I can get access to the unaltered destination row to do a comparison with my source row before the import happens?