Base Model In CodeIgniter

I always use this Base Model for My CodeIgniter App Development, It makes my app portable and flexible.We can define all Global methods and settings in Base Model (Inheritable) so that all Child Models share some common methods and properties. Here is my Base Model Class.

application/core/MY_Model.php

class MY_Model extends CI_Model
{

    protected $_table_name = '';
    protected $_primary_key = 'id';
    protected $_primary_filter = 'intval';
    protected $_order_by = '';
    public $rules = array();
    protected $_timestamps = false;

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

    public function array_from_post($fields)
    {
        $data = array();
        foreach ($fields as $field) {
            $data[$field] = $this->input->post($field);
        }
        return $data;
    }

    public function get($id = null, $single = false)
    {

        if ($id != null) {
            $filter = $this->_primary_filter;
            $id = $filter($id);
            $this->db->where($this->_primary_key, $id);
            $method = 'row';
        } elseif ($single == true) {
            $method = 'row';
        } else {
            $method = 'result';
        }

        if (!count($this->db->ar_orderby)) {
            $this->db->order_by($this->_order_by);
        }
        
        return $this->db->get($this->_table_name)->$method();
    }

    public function get_by($where, $single = false,$limit = false,$offset = false)
    {
        $this->db->where($where);
        
        if($limit)
        $this->db->limit($limit,$offset);
        
        return $this->get(null, $single);
    }

    public function save($data, $id = null)
    {

        // Set timestamps
        if ($this->_timestamps == true) {
            $now = date('Y-m-d H:i:s');
            $id || $data['created'] = $now;
            $data['modified'] = $now;
        }

        // Insert
        if ($id === null) {
            !isset($data[$this->_primary_key]) || $data[$this->_primary_key] = null;
            $this->db->set($data);
            $this->db->insert($this->_table_name);
            $id = $this->db->insert_id();
        }
        // Update
        else {
            $filter = $this->_primary_filter;
            $id = $filter($id);
            $this->db->set($data);
            $this->db->where($this->_primary_key, $id);
            $this->db->update($this->_table_name);
        }

        return $id;
    }

    public function delete($id)
    {
        $filter = $this->_primary_filter;
        $id = $filter($id);

        if (!$id) {
            return false;
        }
        $this->db->where($this->_primary_key, $id);
        $this->db->limit(1);
        $this->db->delete($this->_table_name);
    }
}