[LiveComponent] Calling a property using a getter (i.e. computed) doesn't update component state (another component property)?

[gremo]

In my AttendancePanel I'm using getLastState to fetch a remote resource and, as soon as the method ends, I update the property lastUpdated (set it to the current date/time).

In Twig, I'm using this.lastState (or computed.lastState). Either way lastUpdated is null, despite the fact that the method actually update the variable:

<div {{ attributes }}>
    <p>Last action returned: {{ this.lastState ? 'object' : 'null' }}</p>
    <p>Last updated: {{ lastUpdated ? lastUpdated|format_datetime() : 'never' }}</p>
</div>

On the contrary, if I call record() using a button (data-action-name="record") the last update time is updated just fine:

<?php

namespace App\Twig\Components\Attendance;

use App\Entity\User;
use App\Messenger\Attendance\GetLastAttendanceStateMessage;
use App\Messenger\Attendance\RecordAttendanceMessage;
use App\Model\Attendance\AttendanceRecord;
use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\Messenger\MessageBusInterface;
use Symfony\Component\Messenger\Stamp\HandledStamp;
use Symfony\UX\LiveComponent\Attribute\AsLiveComponent;
use Symfony\UX\LiveComponent\Attribute\LiveAction;
use Symfony\UX\LiveComponent\Attribute\LiveProp;
use Symfony\UX\LiveComponent\DefaultActionTrait;

#[AsLiveComponent]
class AttendancePanel extends AbstractController
{
    use DefaultActionTrait;

    #[LiveProp]
    public User $user;

    public ?\DateTimeImmutable $lastUpdated = null;

    public function __construct(
        private readonly MessageBusInterface $messageBus,
    ) {
    }

    #[LiveAction]
    public function record()
    {
        $this->messageBus->dispatch(new RecordAttendanceMessage(
            $this->user->getProfile(),
            $this->user
        ));

        $this->lastUpdated = new \DateTimeImmutable();  // Value will be updated
    }

    public function getLastState(): ?AttendanceRecord
    {
        $evevelope = $this->messageBus->dispatch(new GetLastAttendanceStateMessage(
            $this->user->getProfile(),
            $this->user,
        ));

        $this->lastUpdated = new \DateTimeImmutable();  // Value will NOT be updated

        return $evevelope->last(HandledStamp::class)->getResult();
    }
}

[smnandre]

Did you forget #[LiveProp] on $lastUpdated ?

And #[LiveAction] on getLastState ?

[gremo]

@smnandre #[LiveProp] has no effect. About #[LiveAction], why do I need it if this is just a getter? Thanks

[smnandre]

LiveProp is the way LiveComponent keep a property "state".

LiveAction is the way LiveComponent can act on its model while keeping previous "state".

If you use neither LiveAction nor LiveProp, your property will not be updated with its new value.

[gremo]

Oh I see, thank you. Sorry for being so naive, it was not clear to me!

[smnandre]

No problem :)