This is a base pattern for doing simple get/set operations in Codeigniter, with the ability to extend them at will.

Builder Pattern

<?php

class ORMModel extends CI_Model {

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

    public function __call($name, $args) {
        $method = strtolower(substr($name, 0, 3));
        $object = substr($name, 3);

        // Parsing arguments
        $params = (isset($args[0])) ? $args[0] : array();
        $single = (isset($args[1])) ? $args[1] : false;
        $count = (isset($args[2])) ? $args[2] : false;
        $page = (isset($args[3])) ? $args[3] : '';
        $per_page = (isset($args[4])) ? $args[4] : '';

        if ($method === 'get') {
            $this->db->from($object);
        } elseif ($method !== 'set') {
            throw new Exception('Unsupported method ' . $name);
        }

        if (method_exists($this, $name)) {
            $this->{$name}($params);
        } elseif ($method === 'get') {
            $this->__getter($params);
        } else {
            $this->__setter($params);
        };

        if ($method === 'set') {
            // Insert on duplicate method, for both insert/updates, this way the SET can become of the WHERE
            return $this->db->on_duplicate($object);
        }

        $this->db->limit($per_page, $page);
        $result = $this->db->get();
        if (!$result) {
            throw new Exception('No result from ' . $name);
        }

        if ($count) {
            return $result->num_rows;
        }

        if ($single) {
            return $result->row_array();
        } else {
            return $result->result_array();
        }
    }

    private function __getter($params) {
        foreach ($params as $field => $value) {
            if (method_exists($this, $field)) {
                $this->where{$field}($value);
            }
            $this->db->where_in($field, $value);
        }
    }

    private function __setter($params) {
        foreach ($params as $field => $value) {
            $this->db->set($field, $value);
        }
    }

}