為什么FetchType.EAGER在單元測試中不起作用？

Question

我的JPA（休眠）和Spring應用程序。 我的崇拜者是：

部

@Entity
@Table(schema = "myschema")
public class Department {

    @Id
    @GeneratedValue(generator = "uuid")
    @GenericGenerator(name = "uuid", strategy = "uuid2")
    @Column(columnDefinition = "BINARY(16)", length = 16 )
    private UUID uuid;

    @Column(name = "name", length = 200, nullable = false)
    private String name;

    @OneToMany(fetch = FetchType.EAGER, mappedBy = "department", cascade = CascadeType.ALL, orphanRemoval = true)
    List<User> users = new ArrayList<>();
}

用戶

@Entity
@Table(schema = "myschema")
public class User {

    @Id
    @GeneratedValue(generator = "uuid")
    @GenericGenerator(name = "uuid", strategy = "uuid2")
    @Column(columnDefinition = "BINARY(16)", length = 16 )
    private UUID uuid;

    @NotNull
    @Column(name = "login", length = 100, nullable = false)
    private String login;

    @ManyToOne
    @JoinColumn(name = "department_fk", nullable = false)
    private Department department;

}

部門DAO ：

@Repository("departmentDao")
public class DepartmentDao {

    @PersistenceContext
    private EntityManager entityManager;

    @Transactional
    public UUID save(Department entity) {
        log.info("Department entity will be persisted", entity);
        entityManager.persist(entity);
        return entity.getUuid();
    }

    @Transactional
    public List<Department> getAllWithUsers() {
        log.info("Select all departments");
        CriteriaQuery<Department> criteria = entityManager.getCriteriaBuilder().createQuery(Department.class);
        Root<Department> root = criteria.from(Department.class);
        criteria.select(root);
        return entityManager.createQuery(criteria).getResultList();
    }
}

我在Main類中運行代碼時，它會連接實體：

主要

ApplicationContext context = new ClassPathXmlApplicationContext("META-INF/spring.xml");
UserDao userDao = (UserDao) context.getBean("userDao");
DepartmentDao departmentDao = (DepartmentDao) context.getBean("departmentDao");

Department newDep = new Department("WebDepartment", new Date());
departmentDao.save(newDep);

User newUser1 = new User("Test1", newDep);
User newUser2 = new User("Test2", newDep);
userDao.save(newUser1);
userDao.save(newUser2);

List<Department> deps = departmentDao.getAllWithUsers();

//deps
//[Department{name='WebDepartment', users = ['Test1', 'Test2']}]

我使用相同的代碼運行單元測試時，部門的用戶列表為空：

@ContextConfiguration(locations = "classpath:META-INF/spring-test.xml")
@RunWith(SpringJUnit4ClassRunner.class)
public class DaoTests {

    @Autowired
    private DepartmentDao departmentDao;

    @Autowired
    private UserDao userDao;

    @Test
    @Transactional
    public void daoTests() throws NoSuchAlgorithmException {

        Department newDep = new Department("WebDepartment", new Date());
        departmentDao.save(newDep);

        User newUser1 = new User("Test1", newDep);
        User newUser2 = new User("Test2", newDep);
        userDao.save(newUser1);
        userDao.save(newUser2);
        List<Department> deps = departmentDao.getAllWithUsers();

        //deps
        //[Department{name='WebDepartment', users = []}]
    }
}

因此，我的問題是：為什么EAGER在Main中起作用，但在測試中卻不起作用？

Answer 1

我假設您沒有將新用戶添加到該部門的用戶列表中。

您的構造函數必須如下所示：

public User(
            // other fields, 
            Department department) {
   // set all fields.

   department.getUsers().add(this);
}

在Main中，它之所以起作用是因為您有兩個事務，而在讀數中是一個單獨的事務，並且從DB中獲取了Department。

但是在單元測試中，它從用戶列表為空的內存中返回部門。

保存實體之前，正確設置您的關系非常重要。