Model Library for Codeigniter

I have made a model library for codeigniter. It is based on the article http://maestric.com/doc/php/codeigniter_models

if ( ! defined('BASEPATH')) exit('No direct script access allowed');
class MY_Model extends Model {
    
    var $table = "";
    
    function My_Model() {
        parent::Model();
        $this->load->database();
    }
    
    function find($type = 'all', $options = array()) {
        if ($type == 'first') {
            $this->db->limit(1);
        }
        if(array_key_exists('fields', $options)) {
            $this->db->select(implode(",", $options['fields']));
        }
        if(array_key_exists('where', $options)) {
            foreach ($option['where'] as $key=>$value) {
                $this->db->where($key, $value);
            }
        }
        if(array_key_exists('order', $options)) {
            foreach ($option['where'] as $key=>$value) {
                $this->db->order_by($key, $value);
            }
        }
        if(array_key_exists('limit', $options)) {
            $limit = $options['limit'];
            if(array_key_exists('limit', $limit) && !array_key_exists('offset', $limit)) {
                $this->db->limit($limit['limit']);
            }
            if(array_key_exists('limit', $limit) && array_key_exists('offset', $limit)) {
                $this->db->limit($limit['limit'], $limit['offset']);
            }
        }
        $query = $this->db->get($this->table);
        $result = $query->result_array();
        return (count($result) > 0 ? $result[0] : NULL);
    }
    
    function find_first($options) {
        return $this->find('first', $options);
    }
    
    function find_all($options) {
        return $this->find('all', $options);
    }
    
    function find_id($id) {
        if ($id == NULL) {
            return NULL;
        }
        return $this->find('first', array('where'=>array('id'=>$id)));
    }
    
    function insert($data) {
        $this->db->insert($this->table, $data);
        return $this->db->insert_id();
    }
    
    function update($id, $data) {
        $this->db->where('id', $id);
        $this->db->update($this->table, $data);
    }
    
    function delete($id) {
        if ($id != NULL) {
            $this->db->where('id', $id);
            $this->db->delete($this->table);
        }
    }
}