Releasing CI Models in javacript! [ajax proxy]

[eluser]GreatSlovakia[/eluser]
Imagine you could directly call your models right from your javascript. Just think a few seconds what that would mean... thought about it? In ColdFusion there is native functionality for this and now I build it into codeigniter as well

EXAMPLE

Let's first explore how it looks like:

A fairly normal model, except for the new "__JS" method. This method defines that the model can be used from javascript (the allow some more customization which I will explain later on)

exampleModel.php:

Code:

<?php
class Modelname extends CI_Model {

    function __JS(){
        return true;
    }

    function hello($name='world'){
        return array("hello" => $name);
    }

    function sql(){
        $this->db->select()->from('data');
        return $this->db->get()->result();
    }

}

Next there is some configuration stuff I will skip, so let's look at the most simplistic controller possible:

exampleController.php

Code:

<?php
class Test extends CI_Controller {

    public function index(){
        $this->load->ajax_model("exampleModel");
    }

}

And that's it, now if you would enter into the console exampleModel you will get back a javascript object with the same functions and functionality as the original php model: (or look below at the attached file)

Code:

data=exampleModel.sql();
alert(data[0].text);

INSTALLATION

Lets get to the installation stuff, first add the MY_Loader.php to the core directory (copy it from here). Next either create a new controller or add a method to an existing controller containing

Code:

$this->load->ajax_proxy();

and reference this point from your config file by adding

Code:

/*
|--------------------------------------------------------------------------
| Ajax proxy gateway
|--------------------------------------------------------------------------
|
| Define the controller/method which will act as the ajax proxy gateway
| for php models in javascript. The controller/method should contain
| the following call: $this->load->ajax_proxy();
|
*/
$config['ajax_proxy'] = "ajax/index";

And that's it already, you're ready to go

CUSTOMIZATION

THE __JS() FUNCTION
Exclude specific methods from being accessed from javascript

Code:

function __JS(){
    return array(
        "type"=>"exclude",
        "methods"=>Array("sql")
    );
}

Or specifically specify which methods can be called (e.g. if you want to call the constructor function you will need to specify it here by hand). The following will ONLY allow you to call the sql function:

Code:

function __JS(){
    return array(
        "type"=>"included",
        "methods"=>Array("sql")
    );
}

THE ajax_model() FUNCTION

Just like with the normal model function it is possible to specify a second parameter containing the name which the model should use, e.g.

Code:

public function index(){
    $this->load->ajax_model("exampleModel","modelName");
}

will cause an object to be available in javascript called modelName

Tips, Tricks & Security with the __JS() function
Exposing models to the outside world might be quite dangerous to do, however using the __JS function you can protect your model whilst keeping all your checks outside the functions themselves. Take for example

Code:

function __js(){
    $CI =& get_instance();
    if($CI->ion_auth->logged_in()){
        return true;  
    }else{
        return false;  
    }
}

which won't allow anybody to access the functions whilst not being logged in and you can take this to the next level by checking the $_POST['data'] array to see whether the requested action is allowed, for example quite often it is possible to check whether the user has access to the relevant record ($_POST['data']['id']) or allow users access to different methods depending on the groups they are in. This is normally not necessary of course (the last part), but it does show the countless possibilities provided by the __JS function.

FAQ

Why did I place this inside an Loader.php extend?
Despite the fact that this could just as well be used as a stand alone library (just a few small changes would be necessary), I created it like this because I am currently working on implementing a number of functions from coldfusion in codeigniter and I would like these functions to be part of the core, as that's unlikely to happen anytime soon (due to the way the impregnable guidelines which protect codeigniter) I want to at least treat and design it as much as core stuff as possible. Secondly I am still trying to build a neat solution which would make "ajax" a reserved controller name and bypass the need of the ajax_proxy() function. I got quite close to this by building a hellish MY_Router.php file, but it was so ugly that I didn't dare to release it .

So what does this exactly do?
Look at the image which you doubtlessly missed, as ExpresionEngine seems to not support img tags or something :S or check out the attachment below.

How does this work?
When you call one of the javascript functions it will JSON.stringify the arguments and call the ajax proxy controller method which in turn will call the model for your, which will json_encode() the return value for you which will be returned by the javascript function to your script. However, in essence, you probably should worry about that and simply use it. The only thing you might need to be aware of is that you should only return arrays or simple types (integers, strings, etc.) inside your model, although objects will sometimes work as well.

... why is there a 6000 character limit :S...