Repository lookups by DocumentReference returning empty results

[maxim04]

Using spring-boot-starter-data-mongodb:2.6.6

• spring-boot-starter:2.6.6
• mongodb-driver-sync:4.4.2
• spring-data-mongodb: 3.3.3

I have the following code below with 2 documents, User and Product. Product has a DocumentReference to a User object. Using a repository for each document, lookups by id of type String work as expected. But lookups for Product based on the User DocumentReference using an id of type String return 0 results. However if I do the same lookup using an id of type ObjectId I get back the correct set of results.

I also discovered if I use @MongoId(FieldType.STRING) for the id property, the lookups for Product based on the User DocumentReference using an id of type String returns the correct results, but now lookups for the Product or User using id of type String returns empty results. To get back the right set of results I have to lookup Product or User with an id of type ObjectId, essentially the reverse behaviour of the first observation.

Is it supposed to behave like this? I would expect the same behaviour when looking up documents using an id of type String.

The code:

@SpringBootApplication
@EnableMongoRepositories
public class Demo1Application implements CommandLineRunner {

    @Autowired
    UserRepository userRepository;
    @Autowired
    ProductRepository productRepository;

    public static void main(String[] args) {
        SpringApplication.run(Demo1Application.class, args);
    }

    @Override
    public void run(String... args) throws Exception {
        userRepository.deleteAll();
        productRepository.deleteAll();

        User user = new User();
        userRepository.save(user);

        Product product = new Product();
        product.setOwner(user);
        productRepository.save(product);

        List products1 = productRepository.findAllByOwner_Id(user.getId()); // returns 0 results, wrong

        List products2 = productRepository.findAllByOwner_Id(new ObjectId(user.getId())); // returns 1 result, correct
    }
}

@Document
@Data
class User {
    @Id
    String id;
}

@Document
@Data
class Product {
    @Id
    String id;
    @DocumentReference
    User owner;
}

interface UserRepository extends MongoRepository<User, String> {

}
interface ProductRepository extends MongoRepository<Product, String> {
    List<Product> findAllByOwner_Id(String id);
    List<Product> findAllByOwner_Id(ObjectId id);
}

[christophstrobl]

While we're looking at the issue, using the target object as the reference should work. In this case the given User is considered the source for the pointer referencing the target document.

 List<Product> findAllByOwner(User owner);

[spring-projects-issues]

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[spring-projects-issues]

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[maxim04]

While we're looking at the issue, using the target object as the reference should work. In this case the given User is considered the source for the pointer referencing the target document.

 List<Product> findAllByOwner(User owner);

Thanks, in my case though I want to avoid the unnecessary lookup for the whole object since I know the id of the reference object I am interested in. I see there is a draft to fix this issue, thanks for that, looking forward to the fix.