Codeigniter: array múltiple en formularios.

Ejemplo de validación de formularios con CodeIgniter y arrays múltiples.

View: welcome.php

<?php echo validation_errors('<div class="msgerror">', '</div>'); ?>
        <form action="" method="post" >
            <input type="hidden" name="totalusers" value="21" />
            <?php
            for ($x = 0; $x < 21; $x++) {
                ?>
                <p>
                    <label >Nombre de usuario:</label>                                
                    <input  type="text" name="user[<?php echo $x; ?>][login]" value="<?php echo set_value('user[' . $x . '][login]'); ?>"  />    
                </p>
                <p>
                    <label>Email:</label>                                
                    <input type="text" name="user[<?php echo $x; ?>][email]" value="<?php echo set_value('user[' . $x . '][email]'); ?>"  />    
                </p>

                <?php
            }
            ?>
            <input type="submit" value="Enviar" />
        </form>

Controller: welcome.php

function index() {
        $this->load->model('Welcome_model');
        //$this->output->enable_profiler(TRUE);
        if ($_POST) {
            $totalusers = $this->input->post('totalusers');
        } else {
            $totalusers = 0;
        }
        $rules = $this->Welcome_model->formarray_rules($totalusers);
        $this->form_validation->set_rules($rules);
        if ($this->form_validation->run()) {

        }
        $this->load->view('formarray');
    }

Model: welcome_model.php

function formarray_rules($total=0) {
        $array = array();
        for ($x = 0; $x < $total; $x++) {
            $array[] = array(
                'field' => 'user[' . $x . '][login]',
                'label' => 'Nombre de usuario ' . ($x + 1) . ' ',
                'rules' => 'required|trim'
            );
            $array[] = array(
                'field' => 'user[' . $x . '][email]',
                'label' => 'Email ' . ($x + 1) . '',
                'rules' => 'required|valid_email|trim'
            );
        }
        return $array;
    }