Codeigniter - Passing multiple parameters - codeigniter

Question

I am trying to pass multiple parameters to my model from my controller. It seems that the $scholId that I am trying to pass won't go through to the model after I submit the form. However, the $userId goes through to the database just fine. Is there something wrong with $this->uri->segment(4) that won't pass through correctly?
function apply()
{
$this->load->helper('form');
$this->load->library('form_validation');
$scholId = $this->uri->segment(4);
$userId = '2'; //User query -> this will be taken from session
$this->data['scholarship'] = $this->scholarship_model->getScholarship($scholId);
$this->data['title'] = "Apply";
$this->form_validation->set_rules('essay', 'Essay', 'required');
if ($this->form_validation->run() === FALSE)
{
$this->load->view('templates/header', $this->data);
$this->load->view('student/page_head', $this->data);
$this->load->view('student/form', $this->data);
$this->load->view('templates/footer', $this->data);
}else{
// Validation passes
$this->users_model->applySchol($userId,$scholId);
redirect('/scholarships');
}
}

Answer 1

you need to check up the segment whether it exists or not before passing it Like:
if ($this->uri->segment(4) === FALSE)
{
$schoId = 0; //or anything else so that you know that does not exists
}
else
{
$schoID= $this->uri->segment(4);
}
or simply:
$product_id = $this->uri->segment(4, 0);
//which will return 0 if it doesn't exists.