controller

<?php
    if(!defined('BASEPATH')) exit('No direct script allowed');

    class Login extends CI_Controller {
        public function __construct() {
            parent::__construct();
            $this->load->library('form_validation');
            $this->load->model("f-m_datapengguna/m_datapengguna", "d_pengguna", TRUE);
        }

        public function index() {
            $data["title"] = "SIASI";
            $data["subheader"] = "SIASI | LOGIN";
            if($param=$this->input->post()){
            $this->form_validation->set_rules('nama_pengguna', 'Nama Pengguna', 'required', ['required' => "<div class='alert alert-warning' style='max-width: 500px; margin: auto;'><span class='glyphicon glyphicon-alert'></span><button type='button' class='close' data-dismiss='alert' aria-label='Close' aria-hidden='true'>&times;</button> %s tidak boleh kosong.</p></div>"]);
            $this->form_validation->set_rules('kata_sandi', 'Kata Sandi', 'required|callback_check_database', ['required' => "<div class='alert alert-warning' style='max-width: 500px; margin: auto;'><span class='glyphicon glyphicon-alert'></span><button type='button' class='close' data-dismiss='alert' aria-label='Close' aria-hidden='true'>&times;</button> %s tidak boleh kosong.</p></div>"]);

             if($this->form_validation->run() == FALSE) {
                $this->load->view("v_login", $data);
            }
            else {
                redirect(base_url("beranda"));
            }
            }
            else{
                $this->load->view("v_login", $data);
            }
        }

        public function check_database() {
            $kata_sandi    = $this->input->post('kata_sandi', TRUE);
            $nama_pengguna = $this->input->post('nama_pengguna', TRUE);

            $sql_respon1 = $this->d_pengguna->cek_data_pengguna($nama_pengguna);
            if($sql_respon1){
                if(password_verify($kata_sandi, $sql_respon1->kata_sandi)){
                    $id_pengguna = $sql_respon1->id_pengguna;
                    $this->session->set_userdata("id_pengguna", $id_pengguna);
                }else{
                    $this->form_validation->set_message('check_database', "<div class='alert alert-warning' style='max-width: 500px; margin: auto;'><span class='glyphicon glyphicon-alert'></span><button type='button' class='close' data-dismiss='alert' aria-label='Close' aria-hidden='true'>&times;</button> {field} tidak terdaftar.</p></div>");
                    return FALSE;
                }
            }else{
                $this->form_validation->set_message('check_database', "<div class='alert alert-warning' style='max-width: 500px; margin: auto;'><span class='glyphicon glyphicon-alert'></span><button type='button' class='close' data-dismiss='alert' aria-label='Close' aria-hidden='true'>&times;</button> Nama Pengguna tidak terdaftar.</p></div>");
                return FALSE;
            }
        }
    }