Validator problem - file not attached

Hi all, can anyone help me with setting validator, so that it allowed me to send form without attached file?

This is corresponding rule in SourcesTable.php:


This is my add action (click to enlarge image):

Thank you very much!

  1. Input files are not scalar, so remove the ->scalar()
  2. maxLength on a input field also doesn’t make sense, remove that
  3. allowEmptyString() is also not what you want here. You want

Thank you very much.