How can we show error alert using bootstrap alert components in CodeIgniter 3 - codeigniter

Question

I am creating upload, edit and delete in Codeigniter and I want bootstrap alert should display uploading errors(if any) in div alert. Code for the controller is mentioned below, please assist.
code for Controller starts here
<?php
defined('BASEPATH') OR exit ('No direct script access allowed');
/**
*
*/
class Admin_Controller extends CI_Controller
{
function __construct()
{
parent::__construct();
$this->load->library("session");
}
public function registerAdminDetails()
{
$config['upload_path'] = 'assets/img/uploads/reg_Admin/';
$config['allowed_types'] = 'jpg|jpeg|png';
$config['max_size'] = '2048';
$this->load->library('upload', $config);
if(! $this->upload->do_upload('avatar'))
{
$error = array('error' => $this->upload->display_errors());
$this->session->set_flashdata('error', $error);
$this->load->view('admin_access/admin_add_new');
}
else
{
$avatar_upload = $this->upload->data();
$data = array(
'admin_name' => $this->input->post('admin_name'),
'admin_username' => $this->input->post('admin_username'),
'admin_email' => $this->input->post('admin_email'),
'admin_password' => $this->input->post('password'),
'admin_profile_pic' => $this->input->post('avatar'),
'admin_profile_pic' => $config['upload_path'].$avatar_upload['file_name']);
$this->db->insert('admin_profile',$data);
echo "<script>alert('New Admin Successfully Enrolled')</script>";
$this->load->view('admin_access/profile/admin_add_new');
}
}
}
?>

Answer 1

$result = $this->add_model->save($fields,array('id' => $id));
if($result)
{
$this->session->set_flashdata('message', array('message' => 'Updated Successfully','class' => 'alert alert-success fade in'));
}
else
{
$this->session->set_flashdata('message', array('message' => 'Something went wrong, please try again','class' => 'alert alert-danger fade in'));
}

Answer 2

Controller :
if($result <= 0) {
$this->session->set_flashdata('error', 'There is error');
} else {
$this->session->set_flashdata('success', 'Yey!');
}
My example view (yes i am using bootstrap) :
<div class="col-sm-12">
<?php
$this->load->helper('form');
$error = $this->session->flashdata('error');
if($error) {
?>
<div class="alert alert-danger alert-dismissable">
<button type="button" class="close" data-dismiss="alert" aria-hidden="true">×</button>
<?php echo $this->session->flashdata('error'); ?>
</div>
<?php } ?>
<?php
$success = $this->session->flashdata('success');
if($success)
{
?>
<div class="alert alert-success alert-dismissable">
<button type="button" class="close" data-dismiss="alert" aria-hidden="true">×</button>
<?php echo $this->session->flashdata('success'); ?>
</div>
<?php } ?>
<div class="row">
<div class="col-md-12">
<?php echo validation_errors('<div class="alert alert-danger alert-dismissable">', ' <button type="button" class="close" data-dismiss="alert" aria-hidden="true">×</button></div>'); ?>
</div>
</div>
</div>