Agree with Oliver on long and unreadable method names, but nevertheless and for the sake of argument, you can achieve desired result by using the equivalency A /\ (B \/ C) <=> (A /\ B) \/ (A /\ C) A and (B or C) <=> (A and B) or (A and C) So in your … Read more
TL;DR T findOne(ID id) (name in the old API) / Optional<T> findById(ID id) (name in the new API) relies on EntityManager.find() that performs an entity eager loading. T getOne(ID id) relies on EntityManager.getReference() that performs an entity lazy loading. So to ensure the effective loading of the entity, invoking a method on it is required. … Read more
First of all, I know we’re raising the bar here quite a bit but this is already tremendously less code than you had to write without the help of Spring Data JPA. Second, I think you don’t need the service class in the first place, if all you do is forward a call to the … Read more
I think the easiest way to do that is to use so called projection. It can map query results to interfaces. Using SqlResultSetMapping is inconvienient and makes your code ugly :). An example right from spring data JPA source code: public interface UserRepository extends JpaRepository<User, Integer> { @Query(value = “SELECT firstname, lastname FROM SD_User WHERE … Read more
There is another way to have multiple dataSources by using @EnableAutoConfiguration and application.properties. Basically put multiple dataSource configuration info on application.properties and generate default setup (dataSource and entityManagerFactory) automatically for first dataSource by @EnableAutoConfiguration. But for next dataSource, create dataSource, entityManagerFactory and transactionManager all manually by the info from property file. Below is my example … Read more
As of Spring Data JPA 1.7.0 (Evans release train). You can use the newly introduced Top and First keywords that allow you to define query methods like this: findTop10ByLastnameOrderByFirstnameAsc(String lastname); Spring Data will automatically limit the results to the number you defined (defaulting to 1 if omitted). Note that the ordering of the results becomes … Read more
The OSIV Anti-Pattern Instead of letting the business layer decide how it’s best to fetch all the associations that are needed by the View layer, OSIV (Open Session in View) forces the Persistence Context to stay open so that the View layer can trigger the Proxy initialization, as illustrated by the following diagram. The OpenSessionInViewFilter … Read more
My apologies in advance, this is pretty much summing up the original question and the comment from Janar, however… I run into the same problem: I found the Example 50 of Spring Data as the solution for my need of having a native query with pagination but Spring was complaining on startup that I could … Read more
You can create a data.sql file in your src/main/resources folder and it will be automatically executed on startup. In this file you can add some insert statements, eg.: INSERT INTO users (username, firstname, lastname) VALUES (‘lala’, ‘lala’, ‘lala’), (‘lolo’, ‘lolo’, ‘lolo’); Similarly, you can create a schema.sql file (or schema-h2.sql) as well to create your … Read more