Codeigniter : Validating two fields - codeigniter

Question

I have two numeric fields to collect data from users. Need to validate it using codeigniter form validation class.
Conditions:
First field can be zero
Second field cannot be zero
First field should not be equal to second field
Second field should be greater than first field
Currently I use
$this->form_validation->set_rules('first_field', 'First Field',
'trim|required|is_natural');
$this->form_validation->set_rules('second_field', 'Second Field',
'trim|required|is_natural_no_zero');
But, how to validate for 3rd and 4th condition mentioned above?
Thanks in advance.

Answer 1

Thanks dm03514. I got it working by the below callback function.
$this->form_validation->set_rules('first_field', 'First Field', 'trim|required|is_natural');
$this->form_validation->set_rules('second_field', 'Second Field', 'trim|required|is_natural_no_zero|callback_check_equal_less['.$this->input->post('first_field').']');
and the callback function is:
function check_equal_less($second_field,$first_field)
{
if ($second_field <= $first_field)
{
$this->form_validation->set_message('check_equal_less', 'The First &/or Second fields have errors.');
return false;
}
return true;
}
Everything seems to be working fine now :)

Answer 2

You can write your own validation function for 3, and 4 using callbacks
http://ellislab.com/codeigniter/user-guide/libraries/form_validation.html#callbacks
Example from doc
<?php
class Form extends CI_Controller {
public function index()
{
$this->load->helper(array('form', 'url'));
$this->load->library('form_validation');
$this->form_validation->set_rules('username', 'Username', 'callback_username_check');
$this->form_validation->set_rules('password', 'Password', 'required');
$this->form_validation->set_rules('passconf', 'Password Confirmation', 'required');
$this->form_validation->set_rules('email', 'Email', 'required|is_unique[users.email]');
if ($this->form_validation->run() == FALSE)
{
$this->load->view('myform');
}
else
{
$this->load->view('formsuccess');
}
}
public function username_check($str)
{
if ($str == 'test')
{
$this->form_validation->set_message('username_check', 'The %s field can not be the word "test"');
return FALSE;
}
else
{
return TRUE;
}
}
}
?>

Answer 3

If you are using HMVC and the accepted solution doesn't work then
add the following line after initialization in your controller
$this->form_validation->CI =& $this;
So it will be
$this->load->library('form_validation');
$this->form_validation->CI =& $this;
in your controller.