CakePHP 3: Accessing current user in model - authentication

Question

Since i'm new to CakePHP, I have simple problems I cannot figure out.
I use CakePHP 3.4. I try to write a simple logger functionality. Every change applied to a record, I want to be logged to the ChangeLog model.
Using afterSave() event, I have following code:
public function afterSave($event, $entity, $options) {
$logTable = TableRegistry::get('ChangeLogs');
foreach ($entity->getDirty() as $key) {
if($key != 'modified') {
$record = $logTable->newEntity();
$record->previous_value = $entity->getOriginal($key);
$record->new_value = $entity[$key];
$record->table_name = 'Stars';
$record->column_name = $key;
$record->row_id = $entity->id;
$record->user_id = [what should i put here?]
$record->user_id = $_SESSION['Auth']['user']['id'];
$logTable->save($record);
}
}
It works well, but I also want to know which user performed operation and I don't know how can I obtain current user in the Model.
I try to avoid passing argument in controller, because I want user to be detected automaticly, and as a developer I don't want to remember about it every time I try change/add new functionalities in controller.

Answer 1

Do not fiddle with superglobals directly in CakePHP, this will surely bite you at some point, especially in the test environment! Always use the abstracted methods (like the session object) to access such data!
That being said, you could use events to inject the current user into the model callback/event flow. For example register globally to Model.afterSave, and pass the current user into the options.
Here's a basic example to demonstrate the principle. Imagine somthing like this in your app controller:
use Cake\Datasource\EntityInterface;
use Cake\Event\Event;
use Cake\Event\EventManager;
// ...
public function initialize()
{
parent::initialize();
// ...
EventManager::instance()->on(
'Model.afterSave',
['priority' => -1],
function (Event $event, EntityInterface $entity, \ArrayObject $options) {
// retrieve the user id from the auth component
$options['user_id'] = $this->Auth->user('id');
}
);
}
Given the priority of -1 (the default priority is 10) it will be invoked before the model callback for that event, so that in your table class you'll have access to user_id via the $options argument.
$record->user_id = $options['user_id'];
For something more reusable you'd probably use a custom listener class. Also check out events like Auth.afterIdentify, Model.initialize, and Controller.intialize/startup, these could be leaveraged to register your model events listener and to retrieve the current user.
See also
Awesome CakePHP > Auditing / Logging
Cookbook > Events System
Cookbook > Events System > Registering Listeners
Cookbook > Events System > Establishing Priorities
Cookbook > Database Access & ORM > Table Objects > Lifecycle Callbacks
Cookbook > Controllers > Request Life-cycle Callbacks

Answer 2

This solution seems to allow you to pass the logged in user into the model layer:
https://github.com/UseMuffin/Footprint
It is not hooked into the model layer through events like the solution above.