I have a weird bug in controller with Symfony4

Question

This is my controller

    $entretien = new Entretien();
    $form3 = $this->createForm(EntretienType::class, $entretien); // entretien type has a attribute debutRdv
    $form3->add('duree', TimeType::class, [
        'placeholder' => [
            'hour' => 'Heure', 'minute' => 'Minute', 'second' => 'Seconde',
        ],
        'with_seconds' => true,
        "mapped" => false,
    ]);

$form3->handleRequest($request);

    if($form3->isSubmitted())
                {
                    $debutRdv= $entretien->getDebutRdv(); // getdata from form

                    $duree =$form3->get("duree")->getData();

                    $duree = $duree->format('\P\TH\Hi\Ms\S');
/*------------Here the probleme--------*/
                        $finRdv = $debutRdv->add(new \DateInterval($duree));
/*-------------------------------------*/
...

The problem is when I write $debutRdv->add(...) the attribute $debutRdv changes to $finRdv like I've done $debutRdv = $finRdv;

For example $debutRdv: "2019-03-25 16:30:00" $duree : "0:30:00"

When I write this

$finRdv = $debutRdv->add(new \DateInterval($duree));

$duree and $debutRdv change to 2019-03-25 17:00:00 but I only want $duree got 2019-03-25 17:00:00

I want to solve this problem because $entretien->getDebutRdv() also changes to 2019-03-25 17:00:00 Like I have done $entretien->setDebutRdv($duree)

Answer 1

This is the default behaviour of \DateTime instances: add method changes object it is called from. If you don't want $debutRdv to be changed, you can clone it to $finRdv and apply add:

$finRdv = clone $debutRdv;
// see, here's no `=` as `add()` will directly change `$finRdv`
$finRdv->add(new \DateInterval($duree));