Jakarta Data

1.0

@Entity
class City {
    @Id
    long id;
    String name;
    String stateName;
    LocalDate founded;
    int population;

    // constructors, getters, setters, and other methods ...
}

@Repository
interface Cities extends CrudRepository<City, Long> {

    @Find
    Optional<City> named(@By("name") String city,
                         @By("stateName") String state);

    @Find
    @OrderBy("stateName")
    @OrderBy("name")
    List<City> foundedOn(@By("founded") LocalDate foundedOn);

    @Find
    Page<City> inState(@By("stateName") String state,
                       Order<City> sortBy,
                       PageRequest pageReq);

    @Query("""
            UPDATE City
               SET population = ?3
             WHERE city = ?1 AND stateName = ?2
            """)
    boolean setPopulation(String city, String state, int newPopulation);
}

@Inject
Cities cities;

void exampleUsage() {
    // Using a built-in CrudRepository method:
    cities.insert(City.of(1, "Rochester", "Minnesota",
                          LocalDate.of(1854, 7, 12),
                          121395));

    // Using a @Find method and another built-in CrudRepository method:
    City city = cities.named("Rochester", "Minnesota").orElseThrow();
    city.population = 123624;
    city = cities.update(city);

    // Using a @Query method:
    cities.setPopulation("Rochester", "Minnesota", 124648);

    // Using a @Find method with a PageRequest
    Order<City> sorts = Order.by(Sort.desc("population"),
                                 Sort.asc("name"));
    Page<City> page1 = cities.inState("Minnesota",
                                      sorts,
                                      PageRequest.ofSize(10));

    // Obtaining a next page
    Page<City> page2 = cities.inState("Minnesota",
                                      sorts,
                                      page1.nextPageRequest());
}