Question

我想使用@EntityGraph在我的实体中加载惰性字段。我有一个简单的实体：

@Data
@Entity
@Table(name = "users")
@EqualsAndHashCode(of = "name")
@ToString(exclude = {"bigField", "role"})
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private int id;
    @Column(name = "name", length = 100)
    private String name;
    @Basic(fetch = FetchType.LAZY)
    @Column(name = "big_field")
    private String bigField;
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "role_id")
    private Role role;

}

和存储库：

public interface UserRepository extends JpaRepository<User, Integer> {

    @EntityGraph(attributePaths = {"role", "bigField"})
    User findById(Integer id);

}

当我尝试使用findById方法吸引用户时：

final User user = userRepository.findById(1);
log.info("USER = {}", user);
log.info("ROLE = {}", user.getRole());
log.info("BIG FIELD = {}", user.getBigField());

休眠生成下一个查询：

Hibernate: 
    select
        user0_.id as id1_1_0_,
        role1_.id as id1_0_1_,
        user0_.name as name3_1_0_,
        user0_.role_id as role_id4_1_0_,
        role1_.name as name2_0_1_ 
    from
        users user0_ 
    left outer join
        role role1_ 
            on user0_.role_id=role1_.id 
    where
        user0_.id=?

如您所见，它会加载role字段，但不会加载bigField。当我尝试获取bigField属性时，会引发异常：

Caused by: org.hibernate.LazyInitializationException: Unable to perform requested lazy initialization [com.example.demo.entity.User.bigField] - no session and settings disallow loading outside the Session
    at org.hibernate.bytecode.enhance.spi.interceptor.Helper.throwLazyInitializationException(Helper.java:164) ~[hibernate-core-5.3.3.Final.jar:5.3.3.Final]
    at org.hibernate.bytecode.enhance.spi.interceptor.Helper.performWork(Helper.java:59) ~[hibernate-core-5.3.3.Final.jar:5.3.3.Final]
    at org.hibernate.bytecode.enhance.spi.interceptor.LazyAttributeLoadingInterceptor.loadAttribute(LazyAttributeLoadingInterceptor.java:76) ~[hibernate-core-5.3.3.Final.jar:5.3.3.Final]
    at org.hibernate.bytecode.enhance.spi.interceptor.LazyAttributeLoadingInterceptor.fetchAttribute(LazyAttributeLoadingInterceptor.java:72) ~[hibernate-core-5.3.3.Final.jar:5.3.3.Final]
    at org.hibernate.bytecode.enhance.spi.interceptor.LazyAttributeLoadingInterceptor.intercept(LazyAttributeLoadingInterceptor.java:61) ~[hibernate-core-5.3.3.Final.jar:5.3.3.Final]
    at org.hibernate.bytecode.enhance.spi.interceptor.LazyAttributeLoadingInterceptor.readObject(LazyAttributeLoadingInterceptor.java:296) ~[hibernate-core-5.3.3.Final.jar:5.3.3.Final]
    at com.example.demo.entity.User.$$_hibernate_read_bigField(User.java) ~[main/:na]

我正在使用Spring Boot v1.5.14.RELEASE和hibernate v5.3.3.Final。

在gradle.build中，我有下一个配置：

hibernate {
    enhance {
        enableLazyInitialization = true
        enableDirtyTracking = true
        enableAssociationManagement = true
        enableExtendedEnhancement = false
    }
}

有人知道这个问题的根源吗，我该如何创建解决方法？

Spring Data JPA @EntityGraph不适用于休眠字节码增强

0 个答案: