1. Create a Repsitory

If you have no idea about EzyJPA, please take a look the introduction. And now, let's say we have a Book class like this:

    @Entity
    public class Book extends CommonEntity {
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Long id;
        private Long categoryId;
        private Long authorId;
        private String name;
        private BigDecimal price;
        private LocalDate releaseDate;
        private LocalDateTime releaseTime;
        private LocalDateTime createdAt;
        private LocalDateTime updatedAt;
    }

To create a repository, you just need add a repository like this:

    @EzyRepository
    public interface BookRepository extends EzyDatabaseRepository {}

2. Available methods

EzyJPA contains some method:

save: to save one or many entities
delete: to delete one or many entities
find: to entities by id, ids, by field or find all
count: count all entities

example:

    bookRepository.save(book);
    bookRepository.delete(bookId);
    Book book = bookRepository.findById(bookId);
    bookRepository.count()

For a completed example, you can look at here.

3. Custom method

EzyJPA supports you create a custom method to query SQL database. Let's say, we want to find a book by name and authorId, we can do like this:

    Book findByNameAndAuthorId(String name, Long authorId);

In this method, name is Book's name field and authorId is Book's authorId field. It means you can use this template to create a lot of query methods, like:

    List<Book> findByCategoryIdOrAuthorId(long category, long authorId);
    List<Book> findByCategoryIdAndName(long category, long authorId, Next next);
    int countByAuthorId(long authorId);

4. Custom query method

If you have a complicated query and can not create a custom method, you can annotate your method with @EzyQuery annotation like this:

    @EzyQuery("select e from Book e order by e.price desc, e.id desc")
    List<Book> findBooksOrderByPriceAndId(Next next);
    @EzyQuery(
        value = "select * from book e " +
            "where e.price > ?0 or (e.price = ?0 and e.id > ?1) " +
            "order by e.price desc, e.id desc",
        nativeQuery = true
    )
    List<Book> findBooks(
        BigInteger priceExclusive,
        long idExclusive,
        Next next
    );
    @EzyQuery("select e from Book e where e.name < ?0 order by e.name")
    List<Book> findByNameLt(String name, Next next);
    @EzyQuery("select e from Book e where e.name > ?0 order by e.name")
    List<Book> findByNameGt(String name, Next next);
    @EzyQuery(value = "select sum(e.price) as sum from Book e", nativeQuery = true)
    SumBookPriceResult sumPrice();

4. Pagination

EzyJPA use Next class to help you specific skip and limit value, you can create Next by:

    Next.fromSkipLimit(skip, limit)
    // or
    Next.fromPageSize(page, size)

Full source code of examples is available on Github

You can take a look how to use custom query result.

EzyJPA: Query Data

1. Create a Repsitory

2. Available methods

3. Custom method

4. Custom query method

4. Pagination

Next