I want to create a hook that will validate a file upload and only allow jpg extension or a multiple array jpg, gif. I am not sure how to do this. If this below can validate the length of the file title.
if (strlen($file ->getFilename()) > 100) { $errors[] = t("The file's name exceeds the 100 characters limit."); }
Then can something simular to this work?
use DrupalCoreFormFormStateInterface; function blank_moda_file_validate(DrupalfileFileInterface $file) { $errors = array(); if ($file ->getMimeType()) !== jpg, gif) { $errors[] = t("The file is not a jpg or gif."); }