Symfony EventDispatcher订户无法正常工作

Question

The following code

use Application\Events\TransactionCreatedEvent;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\EventDispatcher\EventDispatcher;

class Transaction implements EventSubscriberInterface
{
    protected $date;
    protected $name;
    protected $address;
    protected $phone;
    protected $price_with_vat;
    protected $transaction_type;
    protected $receipt;
    protected $currency;


    protected function __construct($date, $name, $address, $phone, $price_with_vat, $transaction_type, $receipt, $currency)
    {
        $dispatcher = new EventDispatcher();
        $dispatcher->addSubscriber($this);
        $dispatcher->dispatch(TransactionCreatedEvent::NAME, new TransactionCreatedEvent($date, $name, $address, $phone, $price_with_vat, $transaction_type, $receipt, $currency));
    }

    public static function CreateNewTransaction($date, $name, $address, $phone, $price_with_vat, $transaction_type, $receipt, $currency){
        return new Transaction($date, $name, $address, $phone, $price_with_vat, $transaction_type, $receipt, $currency);
    }

    private function onCreateNewTransaction($Event){
        $this->date = $Event->date;
        $this->name = $Event->name;
        $this->address = $Event->address;
        $this->phone = $Event->phone;
        $this->price_with_vat = $Event->price_with_vat;
        $this->transaction_type = $Event->transaction_type;
        $this->receipt = $Event->receipt;
        $this->currency = $Event->currency;
    }

    public static function getSubscribedEvents()
    {
        return array(TransactionCreatedEvent::NAME => 'onCreateNewTransaction');
    }
}

it suppose to dispatch a TransactionCreated event and get caught by the class itself and the onCreatedNewTransaction function get invoke in order to set the properties of the class.

The Transaction class instantiated like

$Transaction = Transaction::CreateNewTransaction('6/6/2016', 'John'....);

but when i debug the project the $Transaction object have null values. I set a breakpoint at onCreateNewTransaction method and I found that thus function does not get invoked.

UPDATED

Problem solved

`onCreateNewTransaction' should be public instead of private

Answer 1

Your method CreateNewTransaction is static, so no instances of Transaction is created and therefore __constructor is never called.

This is regarding why this code doesn't work.

But, besides, I must say it's a total misuse of Event system of Symfony. Using framework (no EventDispatcher component), you must not create EventDispatcher yourself. It's beeing created by FrameworkBundle and you should only inject event_dispatcher service into whatever you need.

Otherwise, you can get lost very quickly with different scopes (each dispatcher has it's own subscribers and it's own events), and besides, it' sa waste of resources.