java - JPA - 按需多对一

Question

我有实体工作流，它与 ValidationResults 类具有 @OneToMany 关系。它是延迟获取的，但有时我想获取所有工作流程并对其访问 ValidationResults 进行交互。在那一刻，我希望 jpa 急切地获取所有数据，而不是每次访问 ValidationResults 时都查询。我用的是springDataJpa，怎么做，有什么办法可以用@Query来做吗？

我尝试实现类似的目标，但我不知道如何实现

   //here all the workflows has corresponding data eagerly
    List<Workflow> workflows = workflowService.getAllWorkflowsWithValidationResultsEagerly();

    //here validationResults ref is lazy, when I try to access it it does query
    List<Workflow> workflows = workflowService.getAllWorkflowsUsually();

这是我的实体。

@Entity
@Table(name = "workflow")
public class Workflow {

     ..............   

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "workflow", cascade = CascadeType.ALL)
    private Set<ValidationResults> validationResultsSet = new HashSet<>();

    public Set<ValidationResults> getValidationResultsSet(){return this.validationResultsSet;}
    ...............
}

和 ValidationResult 类

@Entity
@Table(name = "validation_results")
public class ValidationResults {
...
    @ManyToOne
    @JoinColumn(name = "workflow_id", insertable = false, updatable = false)
    private Workflow workflow;

 ....
}

Answer 1

执行此操作的 spring boot-ish 方法是使用 @EntityGraph如文档中所述。