Order of execution in CodeIgniter - php

Question

class Index extends CI_Controller {
private $data = array();
private $content_data = array();
public function __construct() {
parent::__construct();
if (isset($_GET['m2w'])) {
$stw = switch_to_web();
}
if (isset($_GET['w2m'])) {
$stm = switch_to_mobile();
}
// load mobile or desktop view
}
// Called within an helper function
function switch_to_web() {
return set_cookie('load-web', 'true', '86500');
}
function switch_to_mobile() {
return delete_cookie('load-web');
}
function is_mobile() {
// return true;
$CI = & get_instance();
if ($CI->input->cookie('load-web'))
return false;
$CI->load->library('user_agent');
if ($CI->agent->is_mobile()) {
return true;
}else
return false;
}
I have the above block of code to determine if to load the mobile or web view.
Expected order of execution:
if m2w is set, set the load-web cookie (this is done before the is_mobile function is called
is_mobile function sees the load-web cookie has been set and loads the desktop version
Actual order of execution:
if m2w is set, load-web cookie is called to be set, however the is_mobile function doesn't see it as set hence the desktop version is not loaded
the cookie is set after the is_mobile function has returned true, i check my browser cookies and observed that the cookie was actually set but not at when expected
What am I not getting right?

Answer 1

CI's cookies uses the native setcookie() method of PHP. Cookies requires to be sent in the HTTP headers before being available in the native $_COOKIE variable.
From the PHP doc :
Once the cookies have been set, they can be accessed on the next page load with the $_COOKIE or $HTTP_COOKIE_VARS arrays.
Here's the cookie() method from CI :
function cookie($index = '', $xss_clean = FALSE)
{
// Simply fetch from the $_COOKIE array and do XSS_Clean if needed.
return $this->_fetch_from_array($_COOKIE, $index, $xss_clean);
}
In short, you set your cookie correctly, but it won't be available until your next request. It's all because the new value isn't in $_COOKIE array.
You have multiple alternatives to fix that.
You could extend the CI_Input class and modify the set_cookie method to also add your new value to the $_COOKIE array.
You could edit your is_mobile function to also check for the $_GET['m2w'] value. (Not just the cookie.)
Personalty, I think the 2nd solution is the cleanest and easiest to do, but I don't know the full scope of your project.
Hope this helps!