java - 如何在 spring 中的对象内包含的列表上创建 select 语句？

Question

如何在 spring 中创建 select 语句或过滤嵌套在实体内的 List？我有一个看起来像这样的对象...

@Entity
@Table(name = "employee")
public class Employee {

...

    @OneToMany(mappedBy = "_employee", fetch = FetchType.EAGER, cascade = CascadeType.REMOVE)
    @JsonManagedReference
    Set<Deal> _deals;

    @OneToMany(mappedBy = "_employee", fetch = FetchType.EAGER, cascade = CascadeType.REMOVE)
    @JsonManagedReference //This is simply to avoid a stackoverflow error according to this link http://stackoverflow.com/questions/3325387/infinite-recursion-with-jackson-json-and-hibernate-jpa-issue
    Set<Recommendation> _recommendations;


    @OneToMany(mappedBy = "_employee", fetch = FetchType.EAGER, cascade = CascadeType.REMOVE)
    @JsonManagedReference //This is simply to avoid a stackoverflow error according to this link http://stackoverflow.com/questions/3325387/infinite-recursion-with-jackson-json-and-hibernate-jpa-issue
    Set<Event> _events;

  public Employee() {
    }

//getters and setters

....

我为员工提供了一个可以通过服务类访问的存储库。

存储库看起来像这样。

public interface EmployeeRepository extends CrudRepository<Employee, Long> {

    public Employee getEmployeeById(Long _id);

    public Employee getEmployeeBy_username(String username);

}

基本上，当我通过 id 获取员工时，它会返回上述列表。当检索员工时，我需要以某种方式执行选择语句或过滤_deals、_recommendations 和_events。这样只有那些具有 boolean 属性 _active=true 的返回。就像现在一样，所有交易推荐和事件都会返回，无论它们是否处于 Activity 状态。如何从这些列表中仅过滤或选择 Activity 对象？

Answer 1

您几乎总是为每个查询选择一个实体类型，并且最好在数据库中进行过滤。如果您想要属于特定员工的交易、推荐和 Activity ，我通常会将这些方法放入属于我尝试加载的实体类型的存储库中，它可能如下所示:

@Repository
public interface DealRepository extends JpaRepository<Deal, Long> {

    @Query("select d from Deal d where d.active= true and d.employee.id = :employeeId")
    List<Deal> findActiveDeals(@Param("employeeId") long employeeId);
}