How to properly call a function with instance in Symfony 4

Question

I'm trying to send an email with SMTP in Symfony 4 and I have the following function as per the docs.

public function send_smtp(\Swift_Mailer $mailer)
{
    $message = (new \Swift_Message('Hello Email'))
        ->setFrom('[email protected]')
        ->setTo('[email protected]')
        ->setBody('test email content');
    $mailer->send($message);
}

However, I want to call this function from a different one like

$this->send_smtp();

But it complains about 'No parameters are passed' and

$this->send_smtp(\Swift_Mailer);

also gives the error message

Undefined constant 'Swift_Mailer'

What can be the problem and how could it be solved?

Answer 1

There are a few solutions possible. You can add the parameter with typehinting in your action and then use it to call your function:

/**
 * @Route("/something")
 */
public function something(\Swift_Mailer $mailer)
{
    $this->send_smtp($mailer);
}

or you can retrieve the service from the container in the send_smtp function:

public function send_smtp()
{
    $mailer = $this->get('mailer');

    $message = (new \Swift_Message('Hello Email'))
        ->setFrom('[email protected]')
        ->setTo('[email protected]')
        ->setBody('test email content');

    $mailer->send($message);

}