How to use a JVM or database auto-generated UUID identifier with JPA and Hibernate
Introduction In this article, we are going to see how to use a UUID entity identifier that is auto-generated by Hibernate either in the JVM or using database-specific UUID functions. Our Post entity looks as follows: The Post entity has a UUID identifier and a title. Now, let’s see how we can map the Post entity so that the UUID identifier be auto-generated for us.
How to use the Hibernate Query Cache for DTO projections
Introduction On the Hibernate forum, I noticed the following question which is about using the Hibernate Query Cache for storing DTO projections, not entities. While caching JPQL queries which select entities is rather typical, caching DTO projections is a lesser-known feature of the Hibernate second-level Query Cache.
Hibernate HSQLDB ARRAY Type
Introduction As previously explained, although Hibernate does not support database ARRAY column types by default, you can easily implement a custom Hibernate ArrayType. While the previous solution worked on PostgreSQL, in this article, you are going to see that it is fairly easy to adapt it to HSQLDB.
How to map a JSON collection using JPA and Hibernate
Introduction The open-source Hypersistence Utils project allows you to map Java objects or Jackson JsonNode as JPA or Hibernate entity properties, and, thanks to our awesome contributors, we have added support for storing type-safe JSON collections. In this article, you are going to see how to achieve this goal.
How to bootstrap JPA programmatically without the persistence.xml configuration file
Introduction One of my Twitter followers asked me if there is any documentation for bootstrapping JPA programmatically so that we can replace the persistence.xml configuration file with a Java configuration: Previously, I wrote an article about bootstrapping Hibernate without the persistence.xml, but that solution was based on the Hibernate-specific EntityManagerFactoryBuilderImpl. In this article, I’m going to give you a solution that works with any JPA provider since it’s based on standard Java Persistence API.
How to order entity subclasses by their class type using JPA and Hibernate
Introduction In this article, we are going to see how to order entity subclasses when executing a JPA query with Hibernate.
How to map a JPA @ManyToOne relationship to a SQL query using the Hibernate @JoinFormula annotation
Introduction Someone asked me to answer the following StackOverflow question, and, because the question is very interesting from an SQL perspective, I decided to turn the answer it into a blog post. In this article, we are going to see how to map a JPA @ManyToOne association to the result of a SQL query using the Hibernate-specific @JoinFormula annotation.
How to emulate @CreatedBy and @LastModifiedBy from Spring Data using the @GeneratorType Hibernate annotation
Introduction Hibernate comes with many additions to the standard JPA specification. One such example is the @GeneratorType annotation which allows you to customize the way a given entity property value is automatically generated. If you’re using Spring Data, you can simply use the @CreatedBy and @LastModifiedBy annotations and the annotated entity properties are going to be populated with the currently logged user. If you’re not using Spring Data, then you can easily emulate the same behavior using the Hibernate-specific @GeneratorType annotation and the ValueGenerator callback mechanism.
The best way to map a @NaturalId business key with JPA and Hibernate
Introduction In this article, you are going to learn what the Hibernate natural id is and how you can use it to fetch entities based on a business key. As I explained in this free chapter of my book, Hibernate offers many benefits over standard JPA. One such example is the @NaturalId mapping. In this article, you are going to see what is the best way to map a natural business key when using Hibernate.
