Implement search for JPA and Spring

Question

I'm trying to implement properly search functionality for database table. I tried this approach:

Controller:

 @GetMapping
 public Page<TransactionDTO> find(TransactionFilterDTO filter, Pageable page) {
 return searchRepository
 .findTransactionsByFilter(mapper.toFilter(filter), page)
 .map(mapper::toDTO);
 }

Filer DTO:

public class TransactionFilterDTO {
 private String name;
 private Integer id;
 @DateTimeFormat(iso = DateTimeFormat.ISO.DATE_TIME)
 private LocalDateTime from;
 @DateTimeFormat(iso = DateTimeFormat.ISO.DATE_TIME)
 private LocalDateTime to;
 ... // getters and setter
}

Search implementation:

@Repository
public class TransactionSearchRepositoryImpl implements TransactionSearchRepository {
 @Autowired
 private TransactionRepository transactionRepository;
 @Autowired
 private TransactionSpecification specification;
 @Override
 public Page<Transaction> findTransactionsByFilter(TransactionFilter filter, @Nullable Pageable page) {
 List<Transaction> transactions = transactionRepository
 .findAll(specification.getFilter(filter));
 int totalCount = transactions.size();
 if(page != null) {
 transactions = transactions
 .stream()
 .skip(page.getOffset())
 .limit(page.getPageSize())
 .collect(Collectors.toList());
 }
 return new PageImpl<>(transactions, page, totalCount);
 }
}

Repository:

public interface TransactionSearchRepository {
 Page<Transaction> findTransactionsByFilter(TransactionFilter filter, Pageable page);
}

Is there some better way to implement a search functionality? This solution is very ugly in my view.

Answer 1

In JPA you could use JpaSpecificationExecutor<T> in repository, with that you could utilize it's method.

TransactionRepository

public interface TransactionRepository extends JpaRepository<Transaction, Long>,
 JpaSpecificationExecutor<Transaction> {
}

If you look at the source of JpaSpecificationExecutor it has,

Page< T > findAll(@Nullable Specification<T> spec, Pageable pageable);

With that you just pass the specification and Pageable to return what you expected.

Specification

@AllArgsConstructor
class TransactionSpecification implements Specification<Transaction> {
 private TransactionFilter transactionFilter;
 @Override
 public Predicate toPredicate(Root<DataImport> root, CriteriaQuery<?> query, CriteriaBuilder criteriaBuilder) {
 // You could add multiple Predicates based on the transactionFilter
 return criteriaBuilder.equal(root.get("table_name"), "value");
 }
}

Controller

 @Autowired
 private TransactionRepository transactionRepository;
 @GetMapping
 public Page<TransactionDTO> find(TransactionFilterDTO filter, Pageable page) {
 TransactionFilter transactionFilter = mapper.toFilter(filter);
 return transactionRepository.findAll(new TransactionSpecification(transactionFilter), page);
 }

I am pretty late answering but you could give it a try