The Dynamic, typesafe queries in JPA 2.0 article is a very good one on this topic, actually the best one I’ve found so far online, even better than the Chapter 23 Using the Criteria API to Create Queries from the Java EE 6 tutorials (that contains some mistakes).
Some remarks: Since you have a bi-directional association, you need to add a mappedBy attribute to declare the owning side of the association. Also don’t forget that you need to manage both sides of the link when working with bi-directional associations and I suggest to use defensive methods for this (shown below). And you must … Read more
It’s a bug in Hibernate. Surprisingly, it’s not reported yet, feel free to report it. Operations against non-initialized lazy collections are queued in order to execute them after collection is initialized, and Hibernate doesn’t handle the situation when these operations conflict with the data from the database. Usually it’s not a problem, because this queue … Read more
With the help of Spring I did this in a JPA compliant way. My “persistence.xml” looks empty, with no entities listed within the <persistence-unit> element. I then wrote a class that implemented PersistenceUnitPostProcessor like so: import java.util.Set; import javax.persistence.Entity; import javax.persistence.MappedSuperclass; import org.reflections.Reflections; import org.reflections.scanners.TypeAnnotationsScanner; import org.springframework.orm.jpa.persistenceunit.MutablePersistenceUnitInfo; import org.springframework.orm.jpa.persistenceunit.PersistenceUnitPostProcessor; public class ReflectionsPersistenceUnitPostProcessor implements PersistenceUnitPostProcessor { … Read more
Custom Shortcut Annotations I know, that I could create a custom annotation, but that seems unnatural. No, this is exactly the use case for a Custom Annotation. Here’s a quote from Custom Shortcut Annotations in the Spring Reference: If you find you are repeatedly using the same attributes with @Transactional on many different methods, then … Read more
To sum everything (L2 cache and query cache) up: The first thing to do is to add cache provider (I recommend using EhCache) to your classpath. Hibernate < 5.3 Add the hibernate-ehcache dependency. This library contains EhCache 2 which is now discontinued. <dependency> <groupId>org.hibernate</groupId> <artifactId>hibernate-ehcache</artifactId> <version>your_hibernate_version</version> </dependency> Hibernate >=5.3 In newer versions of Hibernate caches … Read more
If I understand well, you want to Join ScheduleRequest with User and apply the in clause to the userName property of the entity User. I’d need to work a bit on this schema. But you can try with this trick, that is much more readable than the code you posted, and avoids the Join part … Read more
By default the access type is defined by the place where you put your identifier annotation (@Id). If you put it on the field – it will be AccessType.FIELD, if you put it on the getter – it will be AccessType.PROPERTY. Sometimes you might want to annotate not fields but properties (e.g. because you want … Read more
You can use a plugin like Eclipse Dali to do the trick for you. You can refer to the documentation, section 3.11 Generating Entities from Tables. I do not know of any specific vendor independent tool to do this, though.
Fixed it by removing CascadeType.MERGE on Permission entity