The last file operation that we will work with is logging. We will begin by looking at how information can be logged to web server logs and build a simple logging library that can be used across the application. Let's begin by using the error_log function provided by PHP to log information into the web server logfiles. For this example, let's use the export action that we created in the last section to add a message that will be logged.

The following codec needs to be added to the controllers/students.php file:

public function export(){
  $data = $this->model->getStudents();
  $handle = fopen(ROOT_DIR.'/assets/files/students.csv', 'w+');
  foreach ($data as $student) {
    fputcsv($handle, array($student['student_id'], $student['first_name'], $student['last_name'], $student['address'],$student['city'],$student['state']));
  }
  fclose($handle);

  header('Content-Disposition: attachment; filename="students.csv"');
  header('Content-Type:application/csv');

  readfile(ROOT_DIR...