代码点火器将数据传输到模型中会产生错误

我想在Codeigniter中保存表单中的数据。

控制器：home.php

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
class Home extends CI_Controller {
function __construct(){
        parent::__construct();
        $this->load->model('insert_model');
    }
public function index(){
    $this->load->library('form_validation');
    $this->form_validation->set_error_delimiters('<div class="error">', '</div>');
    $this->form_validation->set_rules('custName', 'Customer Name', 'required|min_length[1]|max_length[50]');
    $this->form_validation->set_rules('custPhone', 'Contact No.', 'required|min_length[1]|max_length[50]');

    if ($this->form_validation->run() == FALSE) {
        $this->load->view('home');
    } else {
        $data = array(
            'custName'      => $this->input->post('custName'),
            'custPhone'     => $this->input->post('custPhone')
            );
        // Transferring Data To Model
        $this->insert_model->insertData($data);
        $this->load->view('home');
    }
}
}

型号：insert_model

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

class Insert_model extends CI_Model{
    function __construct(){
        parent::__construct();
    }
    function insertData($data){
        $this->db->insert('branches', $data);
    }
}

视图：home.php

<div id="container">
<?php echo form_open('home'); ?>
<h1>Save Data</h1>
<?php echo form_label('Customer Name :'); ?> <?php echo form_error('custName'); ?>
<?php echo form_input(array('id' => 'custName', 'name' => 'custName')); ?><br />
<?php echo form_label('Contact No. :'); ?> <?php echo form_error('custPhone'); ?>
<?php echo form_input(array('id' => 'custPhone', 'name' => 'custPhone')); ?><br />
<?php echo form_submit(array('id' => 'submit', 'value' => 'Save'));?>
<?php echo form_close(); ?>
</div>

当我运行它时，它会给出错误

A PHP Error was encountered
Severity: Notice
Message: Undefined property: Home::$db
Filename: core/Model.php
Line Number: 52

WAMP服务器提供Fatal error: Call to a member function insert() on a non-object in C:'wamp'www'code'admin'application'models'insert_model.php on line 11

这个错误在我的insert_model ($this->db->insert('branches', $data);)中。

我该怎么办？如何更改CI Core文件？

注意：我找到了此解决方案，但错误仍然存在。

请不要让这篇文章重复，因为我尝试了几次搜索Stackoverflow并在代码中实现，但都失败了。