Read more * @button_label Add Mount Point * @a-no-accordion 1 * @a-order 2 * @a-pro The field must be not required or have default value! */ public array $mountPoints; public function saveToPostContent(array $postFields = []): bool { $commonMountPoints = []; foreach ($this->mountPoints as $mountPoint) { // both into one array, as IDs and postTypes are different and can't be mixed up $commonMountPoints = array_merge($commonMountPoints, $mountPoint->postTypes); $commonMountPoints = array_merge($commonMountPoints, $mountPoint->posts); } $commonMountPoints = array_values(array_unique($commonMountPoints)); $postFields = array_merge($postFields, [ static::POST_FIELD_MOUNT_POINTS => join(',', $commonMountPoints), ]); return parent::saveToPostContent($postFields); } }