Good practice? PHP MVC Controller Ajax - php

Question

Is this a good practice to handle normal and ajax calls with one controller:
<?php
class SomeController extends Controller {
function index() {
if(!$this->input->is_ajax_request()) {
// load model
// create form
// pass data to view
// ...
} else {
// validate input
// load model
// write data to database
// return with some json string
}
}
}
What are the advantages and disadvantages?

Answer 1

Short answer: it depends.
Only real difference between XHR (what marketing people call "AJAX") and ordinary browser request is that XHR expects a different form of response.
In the MVC-inspired patterns for web the part that is responsible for generating response are the view instances. The view should recognize, which kind of response it has to produce, and act accordingly. Controllers role in this scenario would only be to change the state of current view.
Alternatively, you can, at the bootstrap stage, detect the Accept HTTP header, and based on that initialize a different view instance.
With "fully implement view" I mean an instance, which contains UI logic in the MVC triad and can decide which for to respond. This response can be HTML document, composed from multiple templates, a JSON/XML file or just a simple HTTP header.
Pros: proper separation of concerns, easier to maintain
Cons: have to implement full MVC
.. but most of people do not use full MVC implementations.
If you are one of people, who, instead of MVC-inspired patters, uses Rails-like variation about page controller pattern, then you will be force to create a separate controller for handling XHR.
In this scenario the is no real view. It is replace by dumb template, while UI logic has been merged in the page controller. In this situation the only pragmatic option is to create a separate controller to deal with XHR.
Pros: simpler to implement in small projects
Cons: possible code repetition, harder to maintain

Answer 2

Even if it's an AJAX request, you still have to validate the input. It's not you sending your app the input (via AJAX), it's the browser, which you cannot trust.
As a general design principle, avoid special cases (here: ajax vs. non-ajax). In general, you want to treat all cases equally, so you end up with an orthogonal approach.
And as you can see
class SomeController extends Controller {
function index() {
if(!$this->input->is_ajax_request()) {
// validate input <-- XXX here we need to validate it too
// load model
// create form
// pass data to view
// ...
} else {
// validate input
// load model
// write data to database
// return with some json string
}
}
}
this leads to duplicate code (hard to maintain and keep in sync).
Your code, orthogonal approach:
class SomeController extends Controller {
function index() {
// load model (takes care of his own validation, the self-containment principle of OOP)
// coordinate same business logic done by different models
// return models/data to the view, the framework will decide whether it uses the html or the json view file
}
}
Instead, the model (it could be the same model class, or a Form model like there is in Zend Framework, or a hydrating approach like there is in ZF2 could do most of the jobs (together with a Table Gateway, DAO (like in Doctrine 2), or similar classes for models), and you could create two sepparate views for HTML and JSON.
In Zend Framework 2 for instance, the right view is chosen transparently for you, so there really wouldn't be any if/else regarding "is this AJAX or not?".
You should try out a modern PHP framework (5.3+) to get a feel of how to approach the design of your app in PHP.

Answer 3

I think this is developer choice, consider this:
I think this is developer choice, consider this. Development of a client Mobile site I have seen. They have a store for web and a model store:
/store/model/order.php
/store/controller/order.php
/store/view/order.php
Rather than
/store/model/order_mobile.php
/store/controller/order_mobile.php
/store/view/order_mobile.php
The management is a nightmare. Seperate images, css, multiple coding duplicates for mobile clients. The solution for them now is to convert the entire site into a responsive design
/new-dev-store-responsive/model/order.php
/new-dev-store-responsive/controller/order.php
/new-dev-store-responsive/view/order.php
Same code but cleaner. And I would have AJAX calls inside my templates with the PHP structure on some code and others not. Again it can be difficult to manage. It would better to handle using JSON or external static files - so the PHP is driven using GET, POST etc.. and if they have JavaScript the AJAX works WITH the PHP.. PHP code should stay PHP IMO..
/new-dev-store-responsive/model/order.php
/new-dev-store-responsive/controller/order.php
/new-dev-store-responsive/view/order.php
//new-dev-store-responsive-cdn.com/assets/js/order.js
//new-dev-store-responsive-cdn.com/assets/css/order.css
//new-dev-store-responsive-cdn.com/assets/imgs/order/checkout.jpg

Answer 4

There are a few advantages and disadvantages in your method.
For Posting public data there is no problem.
For Getting public data I usually prefer to do it in separate controller, many time I don't even put ajax check, because my data is public and I want it to go as far as it can..
For Posting/Getting private data I prefer not to use this two sides method because its better to have good and clean (secured) Code...
How ever.. all depends on your choice. Everything is possible! And there aren't constants which is right and which is not..