EntityAccessCheck.php

<?php

namespace Drupal\Core\Entity;

use Drupal\Core\Access\AccessResult;
use Drupal\Core\Routing\Access\AccessInterface;
use Drupal\Core\Routing\RouteMatchInterface;
use Drupal\Core\Session\AccountInterface;
use Symfony\Component\Routing\Route;

/**
 * Provides a generic access checker for entities.
 */
class EntityAccessCheck implements AccessInterface {
    
    /**
     * Checks access to the entity operation on the given route.
     *
     * The route's '_entity_access' requirement must follow the pattern
     * 'slug.operation'. Typically, the slug is an entity type ID, but it can be
     * any slug defined in the route. The route match parameter corresponding to
     * the slug is checked to see if it is entity-like, that is: implements
     * EntityInterface. Available operations are: 'view', 'update', 'create', and
     * 'delete'.
     *
     * For example, this route configuration invokes a permissions check for
     * 'update' access to entities of type 'node':
     * @code
     * pattern: '/foo/{node}/bar'
     * requirements:
     *   _entity_access: 'node.update'
     * @endcode
     * And this will check 'delete' access to a dynamic entity type:
     * @code
     * example.route:
     *   path: foo/{entity_type}/{example}
     *   requirements:
     *     _entity_access: example.delete
     *   options:
     *     parameters:
     *       example:
     *         type: entity:{entity_type}
     * @endcode
     *
     * @see \Drupal\Core\ParamConverter\EntityConverter
     *
     * @param \Symfony\Component\Routing\Route $route
     *   The route to check against.
     * @param \Drupal\Core\Routing\RouteMatchInterface $route_match
     *   The parametrized route
     * @param \Drupal\Core\Session\AccountInterface $account
     *   The currently logged in account.
     *
     * @return \Drupal\Core\Access\AccessResultInterface
     *   The access result.
     *
     * @link https://www.drupal.org/docs/8/api/routing-system/parameters-in-routes
     */
    public function access(Route $route, RouteMatchInterface $route_match, AccountInterface $account) {
        // Split the entity type and the operation.
        $requirement = $route->getRequirement('_entity_access');
        [
            $entity_type,
            $operation,
        ] = explode('.', $requirement);
        // If $entity_type parameter is a valid entity, call its own access check.
        $parameters = $route_match->getParameters();
        if ($parameters->has($entity_type)) {
            $entity = $parameters->get($entity_type);
            if ($entity instanceof EntityInterface) {
                return $entity->access($operation, $account, TRUE);
            }
        }
        // No opinion, so other access checks should decide if access should be
        // allowed or not.
        return AccessResult::neutral();
    }

}