java - 如何在 spring-data 中使用 CrudRepository 强制预加载？

Question

我有一个包含 List 的实体，因此默认加载 lazy:

interface MyEntityRepository extends CrudRepository<MyEntity, Long> {

}

@Entity
public class MyEntity {
    @Id
    private Long id;

    @OneToMany(mappedBy = "bar") //lazy by default
    private List<Bar> bars;
}

@Entity
public class Bar {
    //some more
}

问题:如何在执行repository.findOne(id)时强制预加载？

Answer 1

您可以使用 left join fetch 强制预先获取编写自定义 HQL 查询，例如:

interface MyEntityRepository extends CrudRepository<MyEntity, Long> {
    @Query("select e from MyEntity e left join fetch e.bar b where e.id = ?1")
    MyEntity findOne(long id)
}