PHP & Codeigniter - how to pass parameters to a model?

Question

I am using the following code to initialize a model from within my controller:

$this->load->model('model_name');

Is it possible to modify the above line somehow so that the model constructor recieves a parameter? I want to use the following code in the model constructor:

function __construct($param_var) {
   parent::Model();

   $this->$param_var = $param_var; //I'm not even sure this works in PHP..but different issue
}

This would be very helpful so that I can reuse my model classes. Thanks.

UPDATE: (from one of the answers, my original question is solved..thanks!) Just to explain why I wanted to do this: the idea is to be able to reuse a model class. So basically to give a simple example I would like to be able to pass an "order_by" variable to the model class so that I can reuse the logic in the model class (and dynamically change the order-by value in the sql) without having to create a separate class or a separate function.

Is this poor design? If so could you please explain why you wouldn't do something like this and how you would do it instead?

Answer 1

You can't pass parameters through the load function. You'll have to do something like:

$this->load->model('model_name');
$this->model_name->my_constructor('stuff');

In the model:

function my_constructor($param_var) {
...
}

Response to update:

You could just pass the order_by value when you're calling your model function. I'm assuming in your controller action, you have something like $this->model_name->get($my_id); Just add your order_by parameter to this function. IMO this makes your model logic more flexible/reusable because the way you were doing it, I assume setting order_by in the constructor will set the order_by value for every function.

Answer 2

I see your reasoning for this, but may I suggest looking at Object-Relational Mapping for your database needs. There is a user-made ORM library for CodeIgniter called DataMapper that I've been using lately. You can use tables in your controllers as objects, and it may be a better fit for your problem.

Answer 3

而不是使用DataMapper我建议使用IgnitedRecord，因为DataMapper不再被维护，它已被替换为Ruby

Answer 4

In model

<?php

/* Load Model core model */
/* BASEPATH = D:\xampp\htdocs\ci_name_project\system\ */
include BASEPATH . 'core\\Model.php';

class User_model extends CI_Model {

    /* Properties */
    private $name;


    /* Constructor parameter overload */
    public function __construct($name) {
        $this->set_name($name);
    }    


    /* Set */
    public function set_name($name) {
        $this->name = $name;
    }


    /* Get */
    public function get_name() {
        return $this->name;
    }

}

in controller

<?php

class User_controller extends CI_Controller {

    public function index() {

        /* Load User_model model */
        /* APPPATH = D:\xampp\htdocs\ci_name_project\application\ */
        include APPPATH . 'models\\User_model.php';

        $name = 'love';

        /* Create $object_user object of User_model class */
        $object_user = new User_model($name);     

        echo $object_user->get_name(); // love

    }

}