PrestaShop doesn't support excel files, only simple data tables like .csv
. This is because excel files are too complicated, they can by whole programs by themselves.
However, if you're working for a client or your XLS files are just simple data, then surely you can convert XLS to CSV before import.
You just need to make an override for AdminImportController::ajaxProcessUploadCSV
and basically "intercept file upload". Get the uploaded file and convert it to CSV using this library:
https://github.com/PHPOffice/PHPExcel
Then just return are the right values in your override to simulate that "everything is running normal" (basically trick PrestaShop :)) .
It is definitely doable, I've created such module for a client, PHPExcel gave us the ability to work with cells before saving them to CSV.