java - How to properly handle empty resultset with Hibernate and Spring Boot -

i have spring app using hibernate , spring data jpa's crudrepository. seems work if data queried exists in database. however, if there query returns no result, crudrepository returns null , nullpointerexception. example http://localhost:8080/api/id=3 if there row id 3 in database works fine. if there isn't row id of 3 fails a:

there unexpected error (type=internal server error, status=500)

on client side , nullpointerexception on server side.

what proper way of dealing simple case of "no results" query?

inspect return value, if it's not null, return representation of 200 ok response. otherwise, return 404 not found. in end, have controller like:

@requestmapping(...) public responseentity<?> getone(...) {     something = repository.findone(...);     if (something == null)         return responseentity.notfound().build();      return responseentity.ok(something); } 

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can refactor preceding code incorporate java 8's optional<t>, jb nizet mentioned in comments. basically, optional<t> container may or may not hold value of type t. can use type return type of spring data jpa methods, following:

public interface somethingrepository extends crudrepository<something, long> {     optional<something> findbyid(long id); } 

then define 1 exception 404 not found:

@responsestatus(httpstatus.not_found) public class notfoundexception extends runtimeexception {} 

if throw exception of type notfoundexception in controllers, spring mvc's exception resolver catch exception , convert 404 not found http response.

finally controller like:

@requestmapping(...) public getone(...) {     return repository.findbyid(id).orelsethrow(notfoundexception::new); } 

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more detailed discussions on:

• spring data jpa's optional<t> support, read here.
• spring mvc's exception resolvers, read here.
• java 8's optional<t>, read here.
• rest best practices, can check out rest in practice book.