Eagerly fetch child when loading parent spring data jpa - spring

Question

Link.java
#Entity
#Table(name = "LINK")
#AttributeOverride(name="id", column=#Column(name="LINK_ID"))
public class Link extends AbstractAuditableEntity<Integer> {
/**
*
*/
private static final long serialVersionUID = 3825555385014396995L;
#Column(name="NAME")
private String name;
#Column(name="UI_SREF")
private String uiSref;
#ManyToOne
#JoinColumn(name="PARENT_LINK_ID")
private Link parentLink;
#OneToMany(mappedBy="parentLink", fetch = FetchType.EAGER)
private List<Link> childLinks;
/**
* #return the name
*/
public String getName() {
return name;
}
/**
* #param name the name to set
*/
public void setName(String name) {
this.name = name;
}
/**
* #return the uiSref
*/
public String getUiSref() {
return uiSref;
}
/**
* #param uiSref the uiSref to set
*/
public void setUiSref(String uiSref) {
this.uiSref = uiSref;
}
/**
* #return the parentLink
*/
public Link getParentLink() {
return parentLink;
}
/**
* #param parentLink the parentLink to set
*/
public void setParentLink(Link parentLink) {
this.parentLink = parentLink;
}
/**
* #return the childLinks
*/
public List<Link> getChildLinks() {
return childLinks;
}
/**
* #param childLinks the childLinks to set
*/
public void setChildLinks(List<Link> childLinks) {
this.childLinks = childLinks;
}
}
LinkRepository .java
public interface LinkRepository extends BaseRepository<Integer, Link> {
#Query("select distinct p from Link l JOIN fetch l.parentLink p where l.id in (select lar.link.id from LinkAccessRole lar where lar.accessRoleLu in ?1) and p.id in (select lar.link.id from LinkAccessRole lar where lar.accessRoleLu in ?1)")
public List<Link> getNavigationByaccessRoleLuList(List<AccessRoleLu> accessRoleLu);
}
Link_Table
Link_Access_Role Table
generated Queries:
SELECT DISTINCT t0.LINK_ID, t0.CREATED_BY_ID, t0.CREATED_DATE, t0.LAST_MODIFIED_BY_ID, t0.LAST_MODIFIED_DATE, t0.NAME, t0.UI_SREF, t0.PARENT_LINK_ID FROM LINK t0, LINK t1 WHERE ((t1.LINK_ID IN (SELECT t2.LINK_ID FROM LINK_ACCESS_ROLE t3, LINK t2 WHERE ((t3.ACCESS_ROLE_ID IN (?,?)) AND (t2.LINK_ID = t3.LINK_ID))) AND t0.LINK_ID IN (SELECT t4.LINK_ID FROM LINK_ACCESS_ROLE t5, LINK t4 WHERE ((t5.ACCESS_ROLE_ID IN (?,?)) AND (t4.LINK_ID = t5.LINK_ID)))) AND (t0.LINK_ID = t1.PARENT_LINK_ID))
bind => [4 parameters bound]
SELECT LINK_ID, CREATED_BY_ID, CREATED_DATE, LAST_MODIFIED_BY_ID, LAST_MODIFIED_DATE, NAME, UI_SREF, PARENT_LINK_ID FROM LINK WHERE (PARENT_LINK_ID = ?)
bind => [1 parameter bound]
SELECT LINK_ID, CREATED_BY_ID, CREATED_DATE, LAST_MODIFIED_BY_ID, LAST_MODIFIED_DATE, NAME, UI_SREF, PARENT_LINK_ID FROM LINK WHERE (PARENT_LINK_ID = ?)
bind => [1 parameter bound]
I get one query for each child related to the fetched parent Regardless it has the access role or not.
i want to fetch the parents and its childs that have access role not all childs that related to that parent.

Answer 1

The only way that you can fetch a parent entity and have one of its collections populated with a subset of entries based on some criteria is by using Hibernate's proprietary filters.
I'm not certain whether the other JPA providers provide some proprietary solution either, but JPA itself doesn't offer this directly.
You first need to register a filter definition using #FilterDef and then you need to reference the filter's definition using the #Filter on your collection property.
The hard part here is that you can't rely on Spring data's #Query or their repository implementation generation process to help. You will need to use a real implementation so that you can manually enable this hibernate filter before you query the parent entity.
Filter filter = session.enableFilter( "link-with-restrictions-by-roles" );
filter.setParameter( "roles", yourRolesList );
return session.createQuery( ... ).getResultList();
The documentation describes the use of #Filter and #FilterDef in detail. You can also find another post of mine where I give slightly more implementation details here.