Rendered entity reference field (list-group) disappears, when user can't access the referenced items. Why?

Question

I have been trying to find the reason for this problem for a few days now... without any luck. Which is why I would like to ask for help here...

In a nutshell: I'm working on a simple LMS and have defined a content type Course that contains an entity reference field field_lessons, which refers to another content type Lesson. In the template file node--course--full.html.twig I'm using the following code to render a "table of contents" in the sidebar:

...
<aside>
  {{ content.field_lessons }}
</aside>
...

In addition I'm using a template file field--node--field-lessons--course.html.twig for rendering the field:

...
<nav class="list-group">
  {% for item in items %}
    {% if (item.viewaccess) %}
      <a class="list-group-item list-group-item-action" href="...">
    {% else %}
      <span class="list-group-item list-group-item-action disabled">
    {% endif %}
      <div class="list-group-item-heading">
        {{ item.title }}
      </div>
      ...
    {% if (item.viewaccess) %}
      </a>
    {% else %}
      </span>
    {% endif %}        
  {% endfor %}
</nav>
...

(Note that I deliberately left out a few insignificant details in the code: These are marked with "...".)

So, depending on whether the current user can access a single lesson (I'm using the variable item.viewaccess, which depends on hook_node_access() and is set in hook_preprocess_node()), each lesson is rendered as active or disabled list-group-item. So far, this works perfectly.

Something weird happens, however, as soon as all lessons are locked for the current user: In this case, none of the lessons gets rendered and the whole table of contents (i.e. the whole <nav> block) disappears.

I'm totally stumped at this point. Can anyone offer an idea as to why this happens? Any help would be much appreciated.

Answer 1

FWIW :

The entity reference field formatters that are in core use the method getEntitiesToView() (From class EntityReferenceFormatterBase) to load the referenced entities.

This method honors entity access :

$access = $this->checkAccess($entity);
// ...
if ($access->isAllowed()) {
  // ...
     $entities[$delta] = $entity;
    }
//...
return $entities;

so yes, it seems normal that nothing is rendered.