Form validation and native PHP functions

If you always want required rules to run first you can do the following

Create a MY_Form_validation class in ./application/libraries/
Add this code to it

PHP Code:

<?php  

defined('BASEPATH') OR exit('No direct script access allowed');

class MY_Form_validation extends CI_Form_validation {

    protected function _prepare_rules($rules)
    {
        $new_rules = array();
        $required_rules = array();
        $callbacks = array();

        foreach ($rules as &$rule)
        {
            // Let 'required' always be the first (non-callback) rule
            if ($rule === 'required')
           {
               array_unshift($required_rules, 'required');
            }
            // 'isset' is a kind of a weird alias for 'required' ...
            elseif ($rule === 'isset' && (empty($new_rules) OR $new_rules[0] !== 'required'))
            {
               array_unshift($required_rules, 'isset');
            }
            // The old/classic 'callback_'-prefixed rules
            elseif (is_string($rule) && strncmp('callback_', $rule, 9) === 0)
            {
                $callbacks[] = $rule;
            }
            // Proper callables
            elseif (is_callable($rule))
            {
            $callbacks[] = $rule;
            }
            // "Named" callables; i.e. array('name' => $callable)
            elseif (is_array($rule) && isset($rule[0], $rule[1]) && is_callable($rule[1]))
            {
                 $callbacks[] = $rule;
            }
            // Everything else goes at the end of the queue
            else
            {
            $new_rules[] = $rule;
        }
    }

    // Merge required rules with the callbacks, setting the required rules as the first rules to be run
    $callbacks = array_merge($required_rules, $callbacks);
    return array_merge($callbacks, $new_rules);
    }
}