CODEWITHSUNDEEP
javahibernatejpa
Clyde Barrow
Clyde Barrow

Reputation: 2102

JPA - Eager ManyToOne on demand

I have entity Workflow which has @OneToMany relation with ValidationResults class. It's fetch Lazy but sometimes I would like to get all the Workflows and interate on them accessing the ValidationResults. In that moment I want jpa to get all the data eagerly not query each time I access ValidationResults. I use springDataJpa, How to do it, is there any way to do it with @Query ?

I try to achieve something like that but I don't know how

   //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();

Here are my entities.

@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;}
    ...............
}

And ValidationResult class

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

 ....
}

Upvotes: 0

Views: 858

Answers (3)

NiVeR
NiVeR

Reputation: 9786

The spring boot-ish way of doing this is by using the @EntityGraph as described in the documentation.

Upvotes: 1

Gnk
Gnk

Reputation: 720

If you don't want to create another query, just call .size() of your list

Upvotes: 0

Jorge C
Jorge C

Reputation: 508

You can use fetch join in order to do it on @Query https://www.logicbig.com/tutorials/java-ee-tutorial/jpa/fetch-join.html

@Query("SELECT DISTINCT e FROM Employee e INNER JOIN FETCH e.tasks t")

Upvotes: 1

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