Mapping many-to-many IN statement into JPA (Spring Boot) - spring-boot

Question

I have created two entities in JPA, Listing and ItemType - these exist in a many-to-many relationship (Hibernate auto-generates a junction table). I'm trying to find the best way to create a query which accepts a dynamic list of item type Strings and returns the IDs of all listings which match the specified item types, but I am a recent initiate in JPA.
At present I'm using JpaRepository to create relatively simple queries. I've been trying to do this using CriteriaQuery but some close-but-not-quite answers I've read elsewhere seem to suggest that because this is in Spring, this may not be the best approach and that I should be handling this using the JpaRepository implementation itself. Does that seem reasonable?
I have a query which doesn't feel a million miles away (based on Baeldung's example and my reading on WikiBooks) but for starters I'm getting a Raw Type warning on the Join, not to mention that I'm unsure if this will run and I'm sure there's a better way of going about this.
public List<ListingDTO> getListingsByItemType(List<String> itemTypes) {
List<ListingDTO> listings = new ArrayList<>();
CriteriaQuery<Listing> criteriaQuery = criteriaBuilder.createQuery(Listing.class);
Root<Listing> listing = criteriaQuery.from(Listing.class);
//Here Be Warnings. This should be Join<?,?> but what goes in the diamond?
Join itemtype = listing.join("itemtype", JoinType.LEFT);
In<String> inClause = criteriaBuilder.in(itemtype.get("name"));
for (String itemType : itemTypes) {
inClause.value(itemType);
}
criteriaQuery.select(listing).where(inClause);
TypedQuery<Listing> query = entityManager.createQuery(criteriaQuery);
List<Listing> results = query.getResultList();
for (Listing result : results) {
listings.add(convertListingToDto(result));
}
return listings;
}
I'm trying to understand how best to pass in a dynamic list of names (the field in ItemType) and return a list of unique ids (the PK in Listing) where there is a row which matches in the junction table. Please let me know if I can provide any further information or assistance - I've gotten the sense that JPA and its handling of dynamic queries like this is part of its bread and butter!

Answer 1

The criteria API is useful when you need to dynamically create a query based on various... criteria.
All you need here is a static JPQL query:
select distinct listing from Listing listing
join listing.itemTypes itemType
where itemType.name in :itemTypes
Since you're using Spring-data-jpa, you just need to define a method and annotate it with #Query in your repository interface:
#Query("<the above query>")
List<Listing> findByItemTypes(List<String> itemTypes)