通过ManyToOne急切地获取时，Spring Data JPA不会设置字段

Question

我是Spring Data JPA的新手，并且我正在使用ManyToOne关系处理两个实体（用户和角色）。定制JpaRepository可以在执行User查询时获取Role，但是，即使select语句包含联接select，也没有设置Role的任何字段，但Role的@Id除外。 我该怎么做才能确保测试用例可以通过？

问题：

java.lang.AssertionError: 
Expecting
  <com.lenovo.dcg.epic.server.user.Role@36511c97>
to have a property or a field named <"displayName"> with value
  <"Administrator">
but value was:
  <null>

和日志：

2018-09-11 23:22:10.885  INFO 56280 --- [    Test worker] o.h.h.i.QueryTranslatorFactoryInitiator  : HHH000397: Using ASTQueryTranslatorFactory
Hibernate: 
    /* select
        generatedAlias0 
    from
        User as generatedAlias0 
    where
        generatedAlias0.username=:param0 */ select
            user0_.userID as userID1_2_0_,
            role1_.roleTypeID as roleType1_1_1_,
            user0_.createdBy as createdB2_2_0_,
            user0_.createdDate as createdD3_2_0_,
            user0_.email as email4_2_0_,
            user0_.firstName as firstNam5_2_0_,
            user0_.lastMaintainedBy as lastMain6_2_0_,
            user0_.lastMaintainedDate as lastMain7_2_0_,
            user0_.lastName as lastName8_2_0_,
            user0_.RoleTypeID as RoleTyp11_2_0_,
            user0_.title as title9_2_0_,
            user0_.username as usernam10_2_0_,
            role1_.createdBy as createdB2_1_1_,
            role1_.createdDate as createdD3_1_1_,
            role1_.displayName as displayN4_1_1_,
            role1_.lastMaintainedBy as lastMain5_1_1_,
            role1_.lastMaintainedDate as lastMain6_1_1_,
            role1_.roleTypeDesc as roleType7_1_1_ 
        from
            users user0_ 
        left outer join
            role_types role1_ 
                on user0_.RoleTypeID=role1_.roleTypeID 
        where
            user0_.username=?
2018-09-11 23:22:11.054 TRACE 56280 --- [    Test worker] o.h.type.descriptor.sql.BasicBinder      : binding parameter [1] as [VARCHAR] - [xxx]

这是我的用户实体。

@NamedEntityGraph(name = "User.detail", includeAllAttributes = true)
@Entity
@Table(name = "users")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    Integer userID;
    @Column(nullable = false, unique = true)
    String username;
    @Column(nullable = false)
    String firstName;
    @Column(nullable = false)
    String lastName;
    @Column(nullable = false)
    String email;
    @ManyToOne
    @JoinColumn(name = "RoleTypeID", nullable = false)
    @JsonProperty(value = "RoleTypeID")
    @JsonDeserialize(using = UserRoleComponent.UserRoleDeserializer.class)
    @JsonSerialize(using = UserRoleComponent.UserRoleSerializer.class)
    Role role;
    String title;
    @JsonIgnore
    @CreationTimestamp
    Timestamp createdDate;
    @Column(nullable = false)
    String createdBy;
    @Column(nullable = false)
    String lastMaintainedBy;
    @JsonIgnore
    @UpdateTimestamp
    Timestamp lastMaintainedDate;
}

这是我的角色实体。

@Entity
@Table(name = "role_types")
public class Role {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    Integer roleTypeID;
    String roleTypeDesc;
    String displayName;
    @CreationTimestamp
    Timestamp createdDate;
    String createdBy;
    @UpdateTimestamp
    Timestamp lastMaintainedDate;
    String lastMaintainedBy;
}

我的存储库：

public interface UserRepository extends JpaRepository<User, Integer> {
    @EntityGraph(value = "User.detail", type = EntityGraphType.LOAD)
    Optional<User> findByUsername(String username);
}

和我的测试用例：

@RunWith(SpringRunner.class)
@DataJpaTest(properties = {"spring.jpa.properties.hibernate.format_sql=true",
        "spring.jpa.properties.hibernate.use_sql_comments=true",
        "logging.level.org.hibernate.type.descriptor.sql.BasicBinder=TRACE"})
public class UserRepositoryTest {

    @Autowired
    private TestEntityManager entityManager;

    @Autowired
    private UserRepository repository;

    private User user;


    private void initRoleType() throws ParseException {
        Role admin = new Role();
        admin.setRoleTypeDesc("Administrator");
        admin.setDisplayName("Administrator");
        admin.setCreatedBy("xxx");
        admin.setLastMaintainedBy("xxx");
        admin = entityManager.persist(admin);
        Role manager = new Role();
        manager.setRoleTypeDesc("Manager");
        manager.setDisplayName("Manager");
        manager.setCreatedBy("xxx");
        manager.setLastMaintainedBy("xxx");
        manager = entityManager.persist(manager);
        Role user = new Role();
        user.setRoleTypeDesc("User");
        user.setDisplayName("User");
        user.setCreatedBy("xxx");
        user.setLastMaintainedBy("xxx");
        user = entityManager.persist(user);
        entityManager.flush();
    }

    @Before
    public void setUp() throws Exception {
        resetIdentity();
        initRoleType();
        user = new User();
        user.setUsername("xxx");
        user.setFirstName("xxx");
        user.setLastName("xxx");
        user.setEmail("xxx@xxx.com");
        Role admin = new Role();
        admin.setRoleTypeID(1);
        user.setRole(admin);
        user.setTitle("Developer");
        user.setCreatedBy("admin");
        user.setLastMaintainedBy("admin");
    }

    private void resetIdentity() {
        EntityManager em = entityManager.getEntityManager();

        Query query = null;
        query = em
                .createNativeQuery("ALTER TABLE role_types ALTER COLUMN roleTypeID RESTART WITH 1");
        query.executeUpdate();
    }


    @Test
    public void testFindUserByName() {
        repository.save(user);
        entityManager.flush();
        Optional<User> user = repository.findByUsername("xxx");
        assertThat(user).isNotEmpty();
        assertThat(user).hasValueSatisfying(u -> {
            assertThat(u).hasFieldOrPropertyWithValue("userID", 1);
            assertThat(u.getRole()).isNotNull();
            assertThat(u.getRole()).hasFieldOrPropertyWithValue("roleTypeID", 1);
            assertThat(u.getRole()).hasFieldOrPropertyWithValue("displayName", "Administrator");
            assertThat(u.getDisplayName()).isEqualTo("Administrator");
        });
    }

}