Dynamic Query in CodeIgniter

[eluser]Unknown[/eluser]
I asked this earlier at StackOverflow but didn't got any solutions from there, so I decided to post my problem in a more appropriate forum.

So, I have form for my project where I can create users into database. There
are three types of user types, admins, moderators and end users.

Code:

CREATE TABLE IF NOT EXISTS users (

id SMALLINT(5) UNSIGNED PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(70) NOT NULL,
email VARCHAR(70) NOT NULL,
username VARCHAR(9) NOT NULL,
password VARCHAR(60) NOT NULL,
user_type ENUM('admin','moderator','enduser'),
phone_number VARCHAR(10) NOT NULL,

school_id SMALLINT(5) UNSIGNED DEFAULT NULL,
CONSTRAINT fk_school_id
FOREIGN KEY (school_id)
REFERENCES schools(id)
ON UPADTE CASCADE ON DELETE RESTRICT,

subject_id SMALLINT(5) UNSIGNED DEFAULT NULL,
CONSTRAINT fk_subject_id
FOREIGN KEY (subject_id)
REFERENCES subjects(id)
ON UPDATE CASCADE ON DELETE RESTRICT

) ENGINE = INNODB;

So the school_id and subject_id are working as foreign keys.

Here's my model:

Code:

<?php
      class User extends CI_Model {

            public function add_user($data) {

   $data = array(
     'username' => $data['username'],
     'name' => $data['name'],
     'email' => $data['email'],
     'password' => $data['password'],
     'user_type' => $data['user_type'],
     'phone_number' => $data['phone_number'],
     'subject_id' => empty($data['subject']) ? null : $data['subject'],
                              'school_id' => empty($data['school']) ?  null : $data['school']
    );

   $this->db->insert('users', $data);
  }
}
?>

Here's my controller (part of it actually):

Code:

$this->load->model('user');

      $name = ucfirst($this->input->post('f_name')). " " .ucfirst($this->input->post('l_name'));

      $data = array (
        'name'    => $name,
        'email'   => $this->input->post('email'),
        'username'   => $username,
        'password'   => $this->phpass->hash($password),
        'user_type'  => $this->input->post('user_type'),
        'phone_number'  => $this->input->post('phone_number'),
        'school_id'  => $this->input->post('school'),
        'subject_id'  => $this->input->post('subject')
       );

      if($this->user->add_user($data))
      {
                    // Send email to user
                }

My first thought was that it's not working because of my another model and controller designed to fetch all those subjects and schools from the database. I will include them in here as well, just in case:

Code:

<?php

class Dashboard extends CI_Controller {

public function __construct()
{

  parent::__construct();
  $this->load->model('subject');
}

public function index() {

  $data['subjects'] = $this->subject->get_all_subjects();
  $data['schools'] = $this->subject->get_all_schools();

   $this->load->view('header');
  $this->load->view('dashboard', $data);
  $this->load->view('footer');
}
}

?>

Code:

<?php

class Subject extends CI_Model
{

public function get_all_subjects()
{
  $this->db->select('*')->from('subjects')->order_by('name', 'asc');
  $query = $this->db->get();
  return $query->result_array();
}

public function get_all_schools()
{

  $this->db->select('*')->from('schools')->order_by('name', 'asc');
  $query = $this->db->get();
  return $query->result_array();
}
}


?>

And the view for my dashboard where that add user form locates

Code:

<?php echo form_open('users/add_user', $attributes); ?>

    <span class="close_form_button_add_user_form">X</span>

    &lt;?php echo validation_errors('<div class="login_error">', '</div>'); ?&gt;

    <div class="form_row">
    &lt;input type="text" name="f_name" placeholder="Etunimi" class="half-width" /&gt;
    &lt;input type="text" name="l_name" placeholder="Sukunimi" class="half-width"  right; margin-right: 24px;"/&gt;
    </div>


    <div class="form_row">
    &lt;input type="email" name="email" placeholder="Uuden käyttäjän sähköpostiosoite" class="user full-width" /&gt;
    </div>


    <div class="form_row">
    &lt;input type="email" name="email_confirm" placeholder="Sähköpostiosoite uudelleen" class="user full-width" /&gt;
    </div>

    <div class="form_row">
    &lt;input type="text" name="phone_number" placeholder="Puhelinnumero (0401234567)" class="full-width" /&gt;
    </div>


    <div class="form_row"  20px;">
    <select name="user_type" class="add_user_select" id="select_user_type">
        <option value="">Käyttäjätyyppi</option>
        <option value="admin">Hallinto</option>
        <option value="moderator">Hallinto 2</option>
        <option value="enduser">Pääkäyttäjä</option>
    </select>

    &lt;input type="submit" name="add_user" value="Luo käyttäjä" class="login_submit" id="submit_user"  5px 24px 0px 0px;"/&gt;
    </div>

    <div class="form_row" id="add_user_optional_information">
    <select name="school" class="add_user_select half-width">
        <option value="">Koulutalo</option>
        &lt;?php  foreach($schools as $school) :?&gt;
        <option value="&lt;?=$school['id']?&gt;">&lt;?=$school['name']?&gt;</option>
        &lt;?php endforeach; ?&gt;
    </select>

    <select name="subject" class="add_user_select half-width">
        <option value="">Laji</option>
        &lt;?php  foreach($subjects as $subject) :?&gt;
        <option value="&lt;?=$subject['id']?&gt;">&lt;?=$subject['name']?&gt;</option>
        &lt;?php endforeach; ?&gt;
    </select>
    </div>

&lt;?php echo form_close(); ?&gt;

After I submitted my form, I opened developer tab, and check the network tab what values were in this post request and everything looked good in there. For some reason, it will always saves those subject_id and school_id as NULL.


Thanks in advance !