silverstripe-dms/docs/en/manage-page-relations.md

Manage page relations

Documents are associated to pages via "document sets". You can retrieve document sets for a page, then retrieve documents that belong to those sets. You can still retrieve all documents for a page if you want to.

Get document sets for a page

$dms = DMS::inst();
$sets = $dms->getDocumentSetsByPage($myPage);

You can also request sets directly from the SiteTree instance:

$sets = $page->getDocumentSets();

Get all related documents for a page

DMS::getByPage will exclude currently embargoed documents by default. To include embargoed documents as well add true as the second argument.

$dms = DMS::inst();

$documents = $dms->getByPage($myPage);
$documentsIncludingEmbargoed = $dms->getByPage($myPage, true);

You can also request this directly from the SiteTree instance:

$documents = $myPage->getAllDocuments();