We use CiviCRM's import data functionality (and api-csv-import-gui) to import partner's contributions from CSV files. This is working great because the CSV columns can be mapped to CiviCRM fields via a graphical user interface.
However, we've recently had the need to preprocess one of these fields and transform their data on import. This process can't be done outside CiviCRM for security reasons.
Can I still use CiviCRM's point-and-click mapping functionality while being able to preprocess a specific CSV column in PHP? Unfortunately I can't just map the columns-fields in code because the CSV columns change.