CI Form Validation

<?php

//libraries/MY_Form_validation
class MY_Form_validation extends CI_Form_validation {

    public function errors_array() {
        return $this->_error_array;
    }

}

//core/MY_Model
class MY_Model extends CI_Model {

    protected $validation_rules = [];

    public function __construct() {
        parent::__construct();
    }

    public function validate(array $rulesKeys = null, $returnErrors = false) {
        if (!$rulesKeys) {//skip validation
            return $returnErrors ? [] : true;
        }
        if (!$this->load->is_loaded('form_validation')) {
            $this->load->library('form_validation');
        }
        $rules = array_intersect_key($this->validation_rules, array_flip($rulesKeys));
        foreach ($rules as $rule) {
            $this->form_validation->set_rules(
                    $rule['field'],
                    $rule['label'],
                    $rule['rules'],
                    isset($rule['errors']) ? $rule['errors'] : []
            );
        }
        $valid = $this->form_validation->run();
        return $returnErrors ? $this->form_validation->errors_array() : $valid;
    }

}

//models/FundsModel
class FundsModel extends MY_Model {

    protected $validation_rules = [
        'type' => [
            'field' => 'funds[type]',
            'label' => 'Funds type',
            'rules' => [
                'required'
            ],
            'errors' => [
                'required' => 'Please select funds type'
            ]
        ],
        'program' => [
            'field' => 'funds[program]',
            'label' => 'Funds program',
            'rules' => [
                'required'
            ],
            'errors' => [
                'required' => 'Please select funds program'
            ]
        ]
    ];

    public function __construct() {
        parent::__construct();
    }

}

//controllers/Funds
class Funds extends PrivateController {

    public function __construct() {
        parent::__construct();
        $this->load->model('FundsModel');
    }

    public function form() {
        $post = $this->input->post();
        if ($post) {
            $rulesKeys = ['type'];
            if (isset($post['funds']['type']) && $post['funds']['type'] == 'program') {
                array_push($rulesKeys, 'program');
            }
            if ($this->FundsModel->validate($rulesKeys)) {
                //save form data, set message and redirect
            }
        }
        $this->load->view('form');
    }

}