[hibernate-issues] [JIRA] (HHH-14051) typesafe references to named queries, result set mappings, and entity graphs

Gavin King ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=5ed3929... ) *updated* an issue Hibernate ORM ( https://hibernate.atlassian.net/browse/HHH?atlOrigin=eyJpIjoiYzUyMWQxMTkz... ) / New Feature ( https://hibernate.atlassian.net/browse/HHH-14051?atlOrigin=eyJpIjoiYzUyMW... ) HHH-14051 ( https://hibernate.atlassian.net/browse/HHH-14051?atlOrigin=eyJpIjoiYzUyMW... ) typesafe references to named queries, result set mappings, and entity graphs ( https://hibernate.atlassian.net/browse/HHH-14051?atlOrigin=eyJpIjoiYzUyMW... ) Change By: Gavin King ( https://hibernate.atlassian.net/secure/ViewProfile.jspa?accountId=5ed3929... ) Currently, named queries, entity graphs, and SQL result set mappings are identified by stringly-typed keys. It would be better if the metamodel generator would generate a typesafe element that identifies each of these things defined within a certain persistence unit. The reference can in principle even encode the result type of the query. Thus, you would be able to write: {{TypedQuery<Book> q =  book session.createNamedQuery(NamedQueries_.bookWithAuthor);}} Or: {{TypedQuery<Book> q =  book session.createNativeQuery(sqlQuery, ResultSetMappings_.bookWithAuthor);}} Or: {{Book book = session.find(Book.class, EntityGraphs_.bookWithAuthor);}} Or whatever, and have that all be completely typesafe. Now, a challenge for this is how to determine the "return type" for each sort of thing. * For {{@SqlResultSetMapping}} and {{@NamedNativeQuery}}, it's explicit in the annotation. * For {{@NamedEntityGraph}}, it could reasonably be inferred from the entity class on which the annotation occurs. * For {{@NamedQuery}} we have a problem. Now, the query-validator project shows how it's in-principle possible to typecheck a named JPA query at compile time, however, that approach is currently limited to Java 8. There do seem to be some clever ways to infer the result type of a {{@NamedQuery}} in specific cases, without typechecking the entire query. For example: * If there's more than one element in the {{select}}, it's totally trivial (must be {{Object[]}}). * If there's no {{select}} clause at all, the problem is also pretty easy: either you've got a {{from}} with no {{join}}, in which case the thing after {{from}} is the name of the entity, or you have a {{from}} and a {{join}}, in which case you're back to {{Object[]}}. However, for the specific case of exactly one element in the ` {{select}} ` clause, we have a problem. So one option would be to add a result type member to the Hibernate {{@NamedQuery}} annotation, so that the user can specify it explicitly (defaulting to {{Object}}, of course). Ultimately this would be a great feature to contribute back to the JPA spec. ( https://hibernate.atlassian.net/browse/HHH-14051#add-comment?atlOrigin=ey... ) Add Comment ( https://hibernate.atlassian.net/browse/HHH-14051#add-comment?atlOrigin=ey... ) 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#100127- sha1:2c97aec )