CODEWITHSUNDEEP
hibernatejpa
antonio.fornie
antonio.fornie

Reputation: 1750

JPA : Forcing eager load only for a query

Please, my JPA Query is created using CriteriaQuery and CriteriaBuilder like this:

CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<TaskInfo> cq = cb.createQuery(TaskInfo.class);
Root<TaskInfo> from = cq.from(TaskInfo.class);
cq.select(from);
...
from.get("task").get("id").in(taskList)
...

I want to make sure that I eagerly load the whole graph of objects so that later on I don't have proxies instead of objects when I close the JPA Session.: TaskInfo->Task->TaskData->and so on until object X.

A way to do it is this

for(TaskInfo ti : tiList){
    ti.getTask().getTaskData().getSomethingElse().getX();
}

But this sucks, right? And I don't want to change fetching in general, but only for this specific query. How can I do it? Thanks & cheers

Thanks for the help. But Task has a property

PeopleAssignments peopleAssignments

and PeopleAssignments has a property

List<OrganizationalEntity> businessAdministrators

so this works

from.fetch("task").fetch("peopleAssignments") // Returns a SingularAttributeJoin

but if I do this

from.fetch("task").fetch("peopleAssignments").fetch("businessAdministrators")

I get:

java.lang.ClassCastException: org.hibernate.ejb.metamodel.SingularAttributeImpl cannot be cast to javax.persistence.metamodel.ManagedType

I think it's because this time I'm trying to fetch List. Do you know how to fix this?

Upvotes: 1

Views: 1735

Answers (1)

Simulant
Simulant

Reputation: 20142

you can add a fetch() to your query to guarantee the load of other lazy linked objects as described here in chapter 5.6.2 or here in chapter 9.3.3.

Root<TaskInfo> from = cq.from(TaskInfo.class);
Join<TaskInfo, Task> task = from.fetch("task");
task.fetch("id");
...

I did not test it by myself, so I hope this works.

Upvotes: 1

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