public function bookExportHtml(NodeInterface
$node) { if (!
isset($node->book
)) { throw new \
Exception();
} $tree =
$this->bookManager->
bookSubtreeData($node->book
);
$contents =
$this->
exportTraverse($tree,
[$this, 'bookNodeExport'
]);
$node =
$this->entityRepository->
getTranslationFromContext($node);
return [ '#theme' => 'book_export_html',
'#title' =>
$node->
label(),
'#contents' =>
$contents,
'#depth' =>
$node->book
['depth'
],
'#cache' =>
[ 'tags' =>
$node->
getEntityType()->
getListCacheTags(),
],
];
}