Encapsulating PHP Session - php

Question

One of my colleagues moved to a different company and I got his source code of an existing project.
I was shocked how messy the code looked. I am not a PHP developer so maybe this is a stupid question but it seems to me that he uses the $_SESSION too much and we get many errors regarding the Sessions. I was wondering if it would be good to encapsulate the $_SESSION and write for each value he uses an own method.
The problem I see with this code is that he uses the session object like this
$_SESSION['customer']['items'] = getItems() //returns an array
$_SESSION['article'][$Id]['name'] = utf8_decode[$received[1]];
So from my point of view I would store all his stuff in simple Popos and place those into the Session.
So the Popo for the customer would look like this
class CustomerPopo
{
private $_id;
private $_salutation;
private $_name;
private $_surename;
public function getId()
{
return $this->_id;
}
public function setId($value)
{
$this->_id = $value;
}
public function getSalutation()
{
return $this->_salutation;
}
public function setSalutation($value)
{
$this->_salutation = $value;
}
public function getName()
{
return $this->_name;
}
public function setName($value)
{
$this->_name = $value;
}
public function getSurename()
{
return $this->_surename;
}
public function setSurename($value)
{
$this->_surename = $value;
}
function CustomerPopo() {
}
}
And I imagined the SessionManager like this
class SessionManager
{
private static function getValue($valueName)
{
$value = SessionManager::getValueFromSession($valueName);
if (is_null($value)) {
//Handle stuff and do further checks
}
return $value;
}
private static function getValueFromSession($valueName)
{
$value = null;
if (isset($_SESSION[$valueName])) {
$value = $_SESSION[$valueName];
}
return $value;
}
private static function setValue($valueName, $value)
{
$_SESSION[$valueName] = $value;
}
private static function clearValue($valueName)
{
if (isset($_SESSION[$valueName])) {
unset($_SESSION[$valueName]);
}
}
public static function getCustomer()
{
$customer = '';
try {
$customer = SessionManager::getValue('customer');
} catch (Exception $e) {
$customer = '';
}
return $customer;
}
public static function setCustomer($customer)
{
SessionManager::setValue('customer', $customer);
}
}
With this I could kill some of the errors which arise from different spellings of the word customer/Customer/cusomter.
I imagine the SessionManager would grow big because we have ~30 Session variables in the code.
Is there a design pattern which I could follow to implement such a SessionManager without making it worse in the end ? as stated I am not very familiar with PHP (yet).
EDIT:
Since the approach seems to be valid how can I handle the 30 Session variables i mentioned ? If I have a set/get and maybe a clear method for each value i will end up with 60-90 methods

Answer 1

It is a good idea to have an object encapsulating the access to global variables such as $_SERVER, $_GET, $_POST or $_SESSION as in your example. It is common practice in MVC architecture to do so.
Should the class have methods for IDE completition? That is actually up to you, but common practice at workplaces where I worked was not to have them but make const string identifiers of the fields instead, which are then used to specifying the index in the global $_SESSION variable through an object, such as your SessionManager.
But even then, I would probably ditch the static methods and go with an instance of the manager instead. Having a class with static methods may prevent typos, but does not fix the global state issue, which can be a huge problem when unit testing your applicaion.

Answer 2

I absolutely agree that using the $_SESSION like your college did is messy, since you have a hard time to figure out what is actually stored in the session.
In my opinion, the CustomerPopo is a very good idea, since it is very easy to understand the available data. Also, an IDE will be able to understand it either and offer this information to you as code completion and checks.
I also like your SessionManager, but I would try to get rid of these getValue/setValue functions and move to move verbose functions like getCustomer/setCustomer.
I guess you are not using a PHP framework. I think you should have a look at them, they are very handy (for instance Symfony or Yii2).
One last thing: Always keep in mind that all data stored in the session object will be loaded and parsed for each request, nevertheless if you use it or not. So if you store a lot of data which you only just for specific request, you should consider using another place to store it, like an external cache.
Also, the Session introduces state, which you should avoid if any possible.