I'm actually using D9 to build a system with entities using sub-entities. The main entity system use the following path : /item/{item} Each sub entity is related to a main entity and use this path : /item/{item}/sub_item/{sub_item}

So to access the edit or delete form, the following pathes are required :

/item/{item}/sub_item/{sub_item}/edit /item/{item}/sub_item/{sub_item}/delete

For example : /item/1/sub_item/4/edit

I declared the following route :

  path: '/item/{item}/sub_item/{sub_item}/edit'
    _entity_form: 'sub_item.edit'
    _title: 'Edit sub item'
    _admin_route: TRUE
        type: entity:item
        with_config_overrides: TRUE
        type: entity:sub_item
        with_config_overrides: TRUE
    _permission: 'administer site configuration'

Edit and Delete links are generated by list builder from getOperations. The list builder is on the following route : /item/1/sub_items (this is the "collection" to show the sub-items attached to main item).

I was hoping that the fact the current URL contained item/{item} can be directly re-used by the link generator, but it's not the fact...

Symfony\Component\Routing\Exception\MissingMandatoryParametersException : Some mandatory parameters are missing ("item") to generate a URL for route "entity.sub_item.edit_form". in Drupal\Core\Routing\UrlGenerator->doGenerate() (line 181 of /core/lib/Drupal/Core/Routing/UrlGenerator.php).

I tried to build a specific htmlRouteProvider class for my sub-item entity class but in this case too, the routes are built when cache are cleared, and I don't have access to the item in the URL to set it...

So... My question is : I'm missing something to do it easily, or must I re-implement the "toUrl()" method of my sub-item entity class to include the new "item" parameter "on the fly" ?

Thanks in advance for any suggestion.

PS : it's the solution I have actually in my sub-item entity class :

  public function toUrl($rel = 'canonical', array $options = []) {
    $uri = parent::toUrl($rel, $options);
    $uri->setRouteParameter('item', \Drupal::routeMatch()->getRawParameter('item'));
    return $uri;

But maybe a better solution can be found ?

  • You didn't show the code you are using to generate the URL that is causing the error.
    – Jaypan
    Feb 13, 2022 at 17:10
  • 1
    I should add, I'd probably not mess with the path to the sub element, and rather create an alias to it for the path you want.
    – Jaypan
    Feb 13, 2022 at 18:46
  • No code, this is EntityListBuilder::getDefaultOperations who build automatically the links showed in the "operations" column of the list. So I can override it, or override sub-method like Entity::toUrl or Entity::urlRouteParameters like suggested by @4k4. I asked myself if there is another "magic way", like declaring specific element into the routing.yml file, ie : options: parameters: item: type: entity:{item} # <- using brackets for example ?
    – titouille
    Feb 14, 2022 at 12:58

1 Answer 1


I would override SubItem::urlRouteParameters() and make this independent from the current route match so that the entity can build links on all pages:

  protected function urlRouteParameters($rel) {
    $parameters = parent::urlRouteParameters($rel);
    // assuming the parent relationship is a reference field
    $parameters['item'] = $this->parent->target_id;
    // if the reference field is in the parent you have to run an entity query
    return $parameters;
  • Ok. entity->toUrl() call entity->urlRouteParameters() to retrieve parameters of route. It's just a level higher. But if there is no other way I'm ok to override one of these two method. Thanks for your suggestion.
    – titouille
    Feb 14, 2022 at 13:02
  • 1
    IMHO this protected method exists only to be overridden in such use cases.
    – 4uk4
    Feb 14, 2022 at 13:10

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