Add WHERE IN clause to JPA Specification - spring-boot

Question

I'm trying to implement search functionality limited by IN clause:
I want to implement search implementation with filter limitation:
#GetMapping("find")
public Page<MerchantUserDTO> getAllBySpecification(
#And({
#Spec(path = "name", spec = LikeIgnoreCase.class),
#Spec(path = "login", spec = LikeIgnoreCase.class),
#Spec(path = "email", spec = LikeIgnoreCase.class),
}) Specification<Users> specification,
#SortDefault(sort = "login", direction = Sort.Direction.DESC) Pageable pageable
) {
return merchantUserService.getAllBySpecification(specification, pageable)
.map(g -> MerchantUserDTO.builder()
.id(g.getId())
.login(g.getLogin())
.build()
);
}
#Override
public Page<Users> getAllBySpecification(Specification<Users> specification, Pageable pageable) {
return dao.findAllByTypeIn(specification, pageable, "MerchantUser");
}
Repository:
#Repository
public interface MerchantUserRepository extends JpaRepository<Users, Integer>, JpaSpecificationExecutor<Users> {
Page<Users> findAllByTypeIn(Pageable page, String... types);
Page<Users> findAllByTypeIn(Specification<Users> specification, Pageable pageable, String... types);
}
What is the proper way to extend the specification with IN clause?
specification.and(path.in(types)) path is a attribute but how to implement it properly?

Answer 1

Generally this can be achieved this way:
1) Create specification implementation
public class MerchantUserSpecification implements Specification<Users> {
private final List<String> types;
public MerchantUserSpecification(List<String> types) {
this.types = types;
}
#Override
public Predicate toPredicate(Root<Users> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
if (types != null && !types.isEmpty()) {
return root.get(Users_.type).in(types);
} else {
// always-true predicate, means that no filtering would be applied
return cb.and();
}
}
2) Use method Page findAll(#Nullable Specification spec, Pageable pageable); inherited from JpaSpecificationExecutor interface instead of using your custom findAllByTypeIn(Specification<Users> specification....)
#Override
public Page<Users> getAllBySpecification(Specification<Users> specification, Pageable pageable) {
// combine original specification (passed from outside) and filter-by-types specification
Specification<Users> finalSpec = specification
.and(new MerchantUserSpecification(Arrays.asList("MerchantUser")))
return dao.findAll(finalSpec, pageable)
}
P.S.
With Java 8+ and for simple cases (like yours) the code may be reduced even more. Instead of implementing Specification<T> in separate class you can just create a method
private Specification<Users> typeIn(List<String> types) {
return (root, query, cb) -> {
if (types != null && !types.isEmpty()) {
return root.get(Users_.type).in(types);
} else {
// always-true predicate, means that no filtering would be applied
return cb.and();
}
}
}
#Override
public Page<Users> getAllBySpecification(Specification<Users> specification, Pageable pageable) {
// combine original specification (passed from outside) and filter-by-types specification
Specification<Users> finalSpec = specification
.and(typeIn(Arrays.asList("MerchantUser")))
return dao.findAll(finalSpec, pageable)
}
UPDATE: Shortest way
#Override
public Page<Users> getAllBySpecification(Specification<Users> specification, Pageable pageable) {
// combine original specification (passed from outside) and filter-by-types specification
Specification<Users> finalSpec = specification
.and((root, query, cb) -> root.get(Users_.type).in(Arrays.asList("MerchantUser"))
return dao.findAll(finalSpec, pageable)
}