How do I examine the symfony event handlers that are active?

Question

The API kernel uses a symfony event system at it's heart.

How on earth do I find out where all those events are going?

Answer 1

This maybe not best practice but something like this will list all the events and their handlers:

 $kernel = \Civi::service('civi_api_kernel');                                
 $this->dispatcher = $kernel->getDispatcher();                             
 $listeners = $this->dispatcher->getListeners();                             
 foreach ($listeners as $event => $event_listeners) {                        
   echo "\n\n# $event\n";                                                    
   foreach ($event_listeners as $n => $listener) {                           
     echo "\n## Listener $n";
     $reflection = new \ReflectionClass($listener[0]);                       
     echo $reflection->getName() . "::" . ($listener[1]);
     echo "\nsource: " . $reflection->getFileName()                          
       . " lines: " . $reflection->getStartLine()
       . "-" . $reflection->getEndLine();
     // echo "\n Methods:" . json_encode(get_class_methods($listener[0]),JSON_PRETTY_PRINT);
   }   
 }