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.
$dms = DMS::inst();
$sets = $dms->getDocumentSetsByPage($myPage);
You can also request sets directly from the SiteTree instance:
$sets = $page->getDocumentSets();
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();