public function request_course($course_id)
{
require_once 'models/course_model.php';
$course_model = new course_model();
$student_id = $_SESSION['student_id'];
// student courses
$courses = $course_model->get_student_courses($student_id);
// cuorse prerequesites
$preCourses = $course_model->get_course_prerequisites($course_id);
$accept = $this->check($preCourses, $courses);
if ($accept) {
$course_model->insert_student_course($student_id, $course_id);
header('Location: ' . $this->base_url('course/courses'));
} else {
require_once 'views/course_prequisites.php';
}
}