Nested Projections do not work with One-To-One Mapping

Nested projections are returning null

Spring-Boot: 2.4.3 Spring-Data-JPA: 2.4.5 Hibernate-Core: 5.4.28 PostgreSQL: 12

I have the following Schema

schema.sql

CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

CREATE TABLE product (
	id uuid NOT NULL DEFAULT uuid_generate_v4(),
	"name" varchar(100) NOT NULL,
	description text NULL,
	featured_media varchar(200) NOT NULL,
	status varchar(10) NOT NULL DEFAULT 'DRAFT'::character varying,
	tags _varchar NULL,
	created_date timestamptz NOT NULL,
	price numeric NULL DEFAULT 0,
	last_modified_date timestamptz NOT NULL,
	created_by varchar(100) NOT NULL,
	last_modified_by varchar(100) NOT NULL,
	CONSTRAINT product_id_pk PRIMARY KEY (id),
	CONSTRAINT product_name_unq UNIQUE (name)
);

CREATE TABLE product_details (
	id uuid NOT NULL,
	cost_price numeric NULL,
        CONSTRAINT product_detials_id_pk PRIMARY KEY (id)
);

ALTER TABLE product_details ADD CONSTRAINT product_details_id_fk FOREIGN KEY (id) REFERENCES product(id) ON UPDATE CASCADE ON DELETE CASCADE

data.sql

INSERT INTO product(id, name, featured_media, created_date, last_modified_date, created_by, last_modified_by, status) VALUES
('1fb9e691033d4092b32699088d401ec9', 'Jordans', '/files/products/jordans.jpeg', '2020-12-21 22:25:00+01:00', '2020-12-21 22:26:00+01:00', 'juliuskrah', 'juliuskrah', 'ACTIVE'),
('050976729f414a51ac6c3c673644cdc0', 'Hoodie', '/files/products/hoodie.jpeg', '2020-12-21 22:28:00+01:00', '2020-12-21 22:28:50+01:00', 'juliuskrah', 'juliuskrah', 'DRAFT');

INSERT INTO product_details(id, cost_price) VALUES
('1fb9e691033d4092b32699088d401ec9', 350.00),
('050976729f414a51ac6c3c673644cdc0', 250.00)

And the following classes

@MappedSuperclass
@EntityListeners(AuditingEntityListener.class)
public abstract class AbstractAuditEntity implements Auditable<String, UUID, OffsetDateTime>, Serializable {
	private static final long serialVersionUID = 1111111L;
	@Id
	@GeneratedValue
	private UUID id;
	private OffsetDateTime createdDate;
	private OffsetDateTime lastModifiedDate;
	private String createdBy;
	private String lastModifiedBy;
	@Transient
	private boolean isNew = true;

	@Override
	public UUID getId() {
		return id;
	}

	public void setId(UUID id) {
		this.id = id;
	}

	@Override
	public Optional<String> getCreatedBy() {
		return Optional.of(this.createdBy);
	}

	@Override
	public void setCreatedBy(String createdBy) {
		this.createdBy = createdBy;
	}

	@Override
	public Optional<String> getLastModifiedBy() {
		return Optional.of(this.lastModifiedBy);
	}

	@Override
	public void setLastModifiedBy(String lastModifiedBy) {
		this.lastModifiedBy = lastModifiedBy;
	}

	@Override
	public Optional<OffsetDateTime> getCreatedDate() {
		return Optional.of(this.createdDate);
	}

	@Override
	public void setCreatedDate(OffsetDateTime createdDate) {
		this.createdDate = createdDate;
	}

	@Override
	public Optional<OffsetDateTime> getLastModifiedDate() {
		return Optional.of(this.lastModifiedDate);
	}

	@Override
	public void setLastModifiedDate(OffsetDateTime lastModifiedDate) {
		this.lastModifiedDate = lastModifiedDate;
	}

	@Override
	public boolean isNew() {
		return isNew;
	}

	@PrePersist
	@PostLoad
	void markNotNew() {
		this.isNew = false;
	}
}

public enum ProductStatus {
    ACTIVE,
    DRAFT
}

@Data
@Entity
@EqualsAndHashCode(callSuper = false)
@org.hibernate.annotations.TypeDef(name = "list-array", typeClass = com.vladmihalcea.hibernate.type.array.ListArrayType.class)
public class Product extends AbstractAuditEntity {

    private static final long serialVersionUID = 222222L;
    private String name;
    @Column(columnDefinition = "text")
    private String description;
    private URI featuredMedia;
    private Double price;
    @Enumerated(EnumType.STRING)
    private ProductStatus status = ProductStatus.DRAFT;
    @org.hibernate.annotations.Type(type = "list-array")
    @Column(columnDefinition = "varchar[]")
    private List<String> tags;
}

@Data
@Entity
public class ProductDetails implements Serializable {
    private static final long serialVersionUID = 3333L;

    @Id
    private UUID id;
    @MapsId
    @JoinColumn(name = "id")
    @OneToOne
    private Product product;
    private Double costPrice;
}

@Converter(autoApply = true)
public class UriAttributeConverter implements AttributeConverter<URI, String> {

    @Override
    public String convertToDatabaseColumn(URI entityValue) {
        return (entityValue == null) ? null : entityValue.toString();
    }

    @Override
    public URI convertToEntityAttribute(String databaseValue) {
        return (org.springframework.util.StringUtils.hasLength(databaseValue) ? URI.create(databaseValue.trim()) : null);
    }
}

public interface ProductDetailsRepository extends CrudRepository<ProductDetails, UUID> {
    <T> Optional<T> findById(UUID id, Class<T> clazz);
}

public interface StoreAdminProduct {
    UUID getId();
    Double getCostPrice();
    ProductView getProduct();

    static interface ProductView {
        String getName();
        URI getFeaturedMedia();
    }
}

// Tests
public class ProductRepositoryTest {
    // Omitting boostrap code and test containers
    @Autowired
    private ProductDetailsRepository detailsRepository;

    @Test
    void fetchProjectedProductWithDetailsTest() {
        var storeFrontProduct = detailsRepository.findById( 
            UUID.fromString("1fb9e691-033d-4092-b326-99088d401ec9"), StoreAdminProduct.class);

        assertThat(storeFrontProduct).isPresent()
             .get(InstanceOfAssertFactories.type(StoreAdminProduct.class)) 
             .hasFieldOrPropertyWithValue("costPrice", 350.0)
             .extracting(StoreAdminProduct::getProduct).isNotNull() // Fails here
             .hasFieldOrPropertyWithValue("featuredMedia", URI.create("/files/products/jordans.jpeg"));
    }
}

Below is the query generated

    select
        productdet0_.id as col_0_0_,
        productdet0_.cost_price as col_1_0_,
        product1_.id as col_2_0_,
        product1_.id as id1_9_,
        product1_.created_by as created_2_9_,
        product1_.created_date as created_3_9_,
        product1_.last_modified_by as last_mod4_9_,
        product1_.last_modified_date as last_mod5_9_,
        product1_.description as descript6_9_,
        product1_.featured_media as featured7_9_,
        product1_.name as name9_9_,
        product1_.status as status10_9_,
        product1_.tags as tags11_9_,
    from
        product_details productdet0_ 
    left outer join
        product product1_ 
            on productdet0_.id=product1_.id 
    where
        productdet0_.id=?

As you can see, the query is clearly selecting more columns than I specified in my closed projection

[schauder]

I created an issue with the Hibernate team: https://hibernate.atlassian.net/browse/HHH-14556

[schauder]

Thanks for the reproducer. I poked around and currently I’m thinking this might be a Hibernate issue.

The following test recreates basically the criteria query created by Spring Data and demonstrates, that it’s result has null values where a Product instance should be.

CriteriaQuery<Object> query = em.getCriteriaBuilder().createQuery(Object.class);
Root<ProductDetails> root = query.from(ProductDetails.class);
query = query.multiselect(root.get("id"), root.get("costPrice"), root.get("product"));

List<Object> resultList = em.createQuery(query).getResultList();

SoftAssertions.assertSoftly(softly -> resultList.forEach(o -> {
	assertThat(o).isInstanceOf(Object[].class);
	softly.assertThat(((Object[]) o)[2]).isNotNull();
}));

It’s getting late here. If on Monday I still think this is a Hibernate issue I’ll open a ticket with them.