EzyMongo: Query data

1. Create a Repsitory

If you have no idea about EzyMongo, please take a look the introduction. And now, let's say we have a Book class like this: 
@EzyCollection
public class Book {
    @EzyId
    private Long id;
    private Long categoryId;
    private Long authorId;
    private String name;
    private BigDecimal price;
    private LocalDate releaseDate;
    private LocalDateTime releaseTime;
}
To create a repository, you just need add a repository like this: 
@EzyRepository
public interface BookRepository extends EzyMongoRepository<Long, Book> {}

2. Available methods

EzyMongo contains some method:
  1. save: to save one or many entities
  2. delete: to delete one or many entities
  3. find: to entities by id, ids, by field or find all
  4. 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

EzyMongo supports you create a custom method to query mongodb. 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("{$query:{name:{$lt:?0}}, $orderby:{name:1}}")
List<Book> findByNameLt(String name, Next next);

@EzyQuery("{$query:{name:{$gt:?0}}, $orderby:{name:1}}")
List<Book> findByNameGt(String name, Next next);

@EzyQuery("[{ $group: { _id : 'sum', sum : { $sum: {$toDecimal: '$price'}} } }]")
SumBookPriceResult sumPrice();

@EzyQuery("{authorId:{$gt:?0}}")
int countByAuthorIdGt(long authorId);

@EzyQuery("{authorId:{$gt:?0}}")
void deleteByAuthorIdGt(long authorId);

4. Pagination

EzyMongo 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

Next

You can take a look how to use custom query result