rails spreadsheet processing and exceptions

In my rails app I am using Roo to process spreadsheet and I want to handle TypeError exception if the file is not a spreadsheet.

begin
  xls = Roo::Excelx.new(@file_upload.file.path)       
rescue TypeError
  return redirect_to students_url, :flash => { :error => t("wrong_file_format") } 
end

How do I add a case that also tries if the file is an open office?

xls = Roo::OpenOffice.new(@file_upload.file.path)

This can be done conveniently by basing the decision on the file extension.

begin
  case File.extname(file_path = @file_upload.file.path) # file's extension
    when ".xlsx" # excel extension
      xls = Roo::Excelx.new(file_path)
    when ".ods" # openoffice extension
      xls = Roo::OpenOffice.new(file_path)
    else
      raise TypeError
  end
rescue TypeError
  return redirect_to students_url, flash: {error: t("wrong_file_format")}
end

I hope I got the extensions right. If not, you can easily modify them in the code.