Using block visibility

Contributed by istryker and gswsdrupal:

Problem/Motivation

You have a content type that you want to be display on specific pages. You want to use the same system as Drupal core block visibility.

Proposed resolution

Add a textarea field to your content type called visibility, with a machine name of `field_block_visibility`.

Create or add to your endpoint the following code:

  /**
   * Overrides parent viewEntity.
   */
  public function viewEntity($id) {
    global $base_path;
    $request = $this->getRequest();
    $entity_id = $this->getEntityIdByFieldId($id);
    if (!$this->isValidEntity('view', $entity_id)) {
      return;
    }
    $wrapper = entity_metadata_wrapper($this->entityType, $entity_id);
    $wrapper->language($this->getLangCode());
    // Check if there is a visibility filter.
    if (isset($request['visibility'])) {
      $visibility_path = $request['visibility'];
      // if filter path does not match the path, then return.
      // if visibility pattern is not set, then show everywhere by default.
      $visibility_pattern = $wrapper->field_block_visibility->value();
      
      // ** If you need to remove the $base_path from the beginning of path uncomment the line below **
      //$visibility_path = preg_replace('/^' . str_replace('/', '\/', $base_path) . '/', '', $visibility_path);
      
      if (isset($visibility_pattern) && !drupal_match_path($visibility_path, $visibility_pattern)) {
        return;
      }
    }
    return parent::viewEntity($id);

and to your pubicFieldsInfo() function

    $public_fields['visibility'] = array(
      'property' => 'field_block_visibility',
    );

Now if you go to /api/v1.0/[endpoint_name]?visiblity=[specific_path], only the path that will match will be returned.