How to provide Symfony routing parameter programatically?

Okay, after some investigation I've found this question Which lead me to this helpful answer.

My controller action (with @Route annotation) looks like this:

/**
 * @Route("/board/{board}/card/{card}", name="card_show", methods={"GET"})
 */
public function show(Card $card): Response
{
}

We just have one argument ($card) in method signature, but two arguments in route.

This is how to call the route in twig:

path("card_show", {card: card.id})

No board parameter required, thanks to a custom router.

This is how the custom router looks like:

<?php // src/Routing/CustomCardRouter.php

namespace App\Routing;

use App\Repository\CardRepository;
use Symfony\Component\Routing\RouterInterface;

class CustomCardRouter implements RouterInterface
{
    private $router;
    private $cardRepository;

    public function __construct(RouterInterface $router, CardRepository $cardRepository)
    {
        $this->router = $router;
        $this->cardRepository = $cardRepository;
    }

    public function generate($name, $parameters = [], $referenceType = self::ABSOLUTE_PATH)
    {
        if ($name === 'card_show') {
            $card = $this->cardRepository->findOneBy(['id' => $parameters['card']]);
            if ($card) {
                $parameters['board'] = $card->getLane()->getBoard()->getId();
            }
        }
        return $this->router->generate($name, $parameters, $referenceType);
    }

    public function setContext(\Symfony\Component\Routing\RequestContext $context)
    {
        $this->router->setContext($context);
    }

    public function getContext()
    {
        return $this->router->getContext();
    }

    public function getRouteCollection()
    {
        return $this->router->getRouteCollection();
    }

    public function match($pathinfo)
    {
        return $this->router->match($pathinfo);
    }
}

Now, the missing parameter board is provided programatically, by injecting and using the card repository. To enable the custom router, you need to register it in your services.yaml:

App\Routing\CustomCardRouter:
    decorates: 'router'
    arguments: ['@App\Routing\CustomCardRouter.inner']