Class methods and instance methods in codeigniter, how can I use them?

I am very new to codeigniter but understand OOP and MVC as I do a lot of Rails development. One thing I haven't figured out yet is how to write a class level method in codeigniter and access it in a controller. For example, I have

<?php
class User_model extends Model {
    function user_model()
    {
        parent::Model();
    }

    public static function get_total_users_count(){
        $results = $this->db->query("SELECT * FROM bhr_users GROUP BY userid");
        if($results){
            return $results->num_rows();
        }
        return 0;
    }
}
?>

I think what I have done here is established a class level method for my model that I should be able to call with User_model::get_total_users_count() Now in my controller which a previous programmer called "Welcome" I have something like:

<?php

class Welcome extends Controller {

    function Welcome()
    {
        parent::Controller();   
        $this->load->model('bhr_model');
            $this->load->model('user_model');
    }

    function index()
    {

        $invite =    $this->uri->segment(3);
        if($invite == 'invitefriends') {
            $pagedata['invitefriends'] = $invite;
        } else {
            $pagedata['invitefriends'] = '';
        }

        $pagedata['numberofpeople'] = User_model::get_total_users_count();
        $this->load->view('default_page', $pagedata);
    }
}

The above method call to get_total_users_count does not work because it says because I am using the db method on a class level function in get_total_users_count. In other words $this has no db method when I reference a class.

So now my question is a bit more theoretical. I always though开发者_如何学JAVAt that instance methods should only be used when a method is acting on a specific instance of an class. Makes sense, right? However, get_total_users_count is acting on all "users" and counting them. It just seems like that should be a class level method. Do you agree? If do, do you know how I can access the database from withing the framework inside a class level function?

Thanks!

Since you are not instantiating User_model, you must get the CI instance, then use that for your db queries.

Inside get_total_users_count():

$ci_ins =& get_instance();
$ci_ins->db->query();

You can make your class as a helper so it will not be load as a instance. Only the code will be included so you can just call it as:

$sample = class_name::method();

CodeIgnighter works is by instantiating your models as you load them. What Thorpe Obazee said is the correct codeIgnighter way to use your Model.

What you are asking is if you can use a static method as you'd expect in most circumstances, which just isn't how CI works.

To accomplish what you're after, mives points out get_instance() which is the correct way to get at the main CI object. I use that way myself to do what you're doing.

get_total_user_count is more of a function for a user table gateway.

User model should have things like getUsername and getLastLogin.

User Table Gateway should have things like findUserById, createNewUser, and getTotalUserCount

 $pagedata['numberofpeople'] = $this->user_model->get_total_users_count();

That's the CI way.