I have the following Specification
that I use to query for any Contact
entities that are tied to certain ManagedApplication
entities. I pass in a Collection<Long>
that contains the ids of the ManagedApplication
entities that I am searching for.
public static Specification<Contact> findByApp(final Collection<Long> appIds) {
return new Specification<Contact>() {
@Override
public Predicate toPredicate(Root<Contact> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
final Predicate appPredicate = root.join(Contact_.managedApplications)
.get(ManagedApplication_.managedApplicationId).in(appIds);
}
}
}
I pass this specification to the .findAll()
method of my PagingAndSoringRepository
to retrieve a Page<Contact>
that will contain all Contact
entities that meet the search criteria.
Here is the Repository
.
@Repository
public interface PagingAndSortingContactRepository extends PagingAndSortingRepository<Contact, Long>, JpaSpecificationExecutor<Contact> {
}
And here is how I'm calling the .findAll()
method.
final Page<Contact> contacts = pagingAndSortingContactRepository.findAll(ContactSpecification.findByApp(appIds), pageable);
This works and returns all Contact
entities that are tied to any of the ManagedApplication
entities that correspond to the ids passed in. However, since I am calling .join()
to join the Contact
entity with the ManagedApplication
entity, if one Contact
has multiple ManagedApplication
entities in the list of app ids, then the query will return duplicate Contact
entities.
So what I need to know is, how can I get only distinct Contact
entities returned from my query using this Specification
?
I know that CriteriaQuery
has a .distinct()
method that you can pass a boolean value to, but I am not using the CriteriaQuery
instance in the toPredicate()
method of my Specification
.
Here are the relevant sections of my metamodels.
Contact_.java:
@StaticMetamodel(Contact.class)
public class Contact_ {
public static volatile SingularAttribute<Contact, String> firstNm;
public static volatile SingularAttribute<Contact, String> lastNm;
public static volatile SingularAttribute<Contact, String> emailAddress;
public static volatile SetAttribute<Contact, ManagedApplication> managedApplications;
public static volatile SetAttribute<Contact, ContactToStructure> contactToStructures;
}
ManagedApplication_.java
@StaticMetamodel(ManagedApplication.class)
public class ManagedApplication_ {
public static volatile SingularAttribute<ManagedApplication, Integer> managedApplicationId;
}
Use the query
parameter in your toPredicate
method to invoke the distinct method.
Sample below:
public Predicate toPredicate(Root<Contact> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
final Predicate appPredicate = root.join(Contact_.managedApplications)
.get(ManagedApplication_.managedApplicationId).in(appIds);
query.distinct(true);
...