[hibernate-issues] [JIRA] (HSEARCH-4838) Conisder adding `fromRoot` projection

Marko Bekhta ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) *created* an issue Hibernate Search ( https://hibernate.atlassian.net/browse/HSEARCH?atlOrigin=eyJpIjoiZDc1YTRh... ) / New Feature ( https://hibernate.atlassian.net/browse/HSEARCH-4838?atlOrigin=eyJpIjoiZDc... ) HSEARCH-4838 ( https://hibernate.atlassian.net/browse/HSEARCH-4838?atlOrigin=eyJpIjoiZDc... ) Conisder adding `fromRoot` projection ( https://hibernate.atlassian.net/browse/HSEARCH-4838?atlOrigin=eyJpIjoiZDc... ) Issue Type: New Feature Assignee: Unassigned Created: 20/Apr/2023 05:19 AM Fix Versions: 7.0-backlog Priority: Major Reporter: Marko Bekhta ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=557058%... ) From the original ticket ( https://hibernate.atlassian.net/browse/HSEARCH-4827 ): *If* we feel that it’s useful to allow it, but only when the user is explicitly requesting it, we can expose something like the (currently SPI) rootContext method: org.hibernate.search.engine.search.projection.spi.SearchProjectionBuilderFactory#rootContext. We’d end up with something like this: List<MyBookProjection> hits = searchSession.search( Book.class ) .select( f -> f.composite() .from( f.field( "title", String.class ), f.object( "authors" ) .from( f.fromRoot( f.id() ), // We EXPLICITLY tell HSearch to use the root ID f.field( "authors.firstName", String.class ), f.field( "authors.lastName", String.class ) ) .as( MyBookProjection.Author::new ) .multi() ) .as( MyBookProjection::new ) ) .where( f -> f.matchAll() ) .fetchHits( 20 ); Note there’s a similarity between this fromRoot projection and Elasticsearch's concept of reverse_nested aggregations: https://www.elastic.co/guide/en/elasticsearch/reference/current/search-ag.... Maybe we could introduce that kind of things later, but that’s definitely beyond the scope of this issue. ( https://hibernate.atlassian.net/browse/HSEARCH-4838#add-comment?atlOrigin... ) Add Comment ( https://hibernate.atlassian.net/browse/HSEARCH-4838#add-comment?atlOrigin... ) Get Jira notifications on your phone! Download the Jira Cloud app for Android ( https://play.google.com/store/apps/details?id=com.atlassian.android.jira.... ) or iOS ( https://itunes.apple.com/app/apple-store/id1006972087?pt=696495&ct=Em... ) This message was sent by Atlassian Jira (v1001.0.0-SNAPSHOT#100222- sha1:57eb20e )