Spring Data JPA findBy a collection

Question

Im working on a route planing system in Java, using JPA. I need to create a findBy method to find an route by a list of the cities its containing. Here are the classes:

@Entity
public class Route {

    @ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    private List<City> cities = new ArrayList<>();
    .
    .
}

@Entity
public class City {
    .
    .
}

Now I tried, but wasn't surprised it didn't work, the following:

@Repository
public interface RouteRepository extends JpaRepository<Route, Long> {
    Optional<Route> findByCities(List<City> city);
}

Is there an easy way to do it with JPA, or do I have to write a difficult own @Query and somehow iterate, to find an entity by a collection?

Why doesn't it work? According to docs, it should. – Taylor Dec 04 '18 at 18:35 — Taylor, Dec 04 '18 at 18:35
Can you show your City class in full? – Jonck van der Kogel Dec 04 '18 at 19:23 — Jonck van der Kogel, Dec 04 '18 at 19:23
Do the cities match exactly? Or are they a subset? – Dean Dec 04 '18 at 20:51 — Dean, Dec 04 '18 at 20:51

Stefan Repcek · Answer 1 · 2018-12-04T22:24:49.603

10

You can change the signature of your method in RouteRepository, to use IN operator.

@Repository
public interface RouteRepository extends JpaRepository<Route, Long> {
    Optional<Route> findByCitiesIn(List<City> cities);
}

Then it should work. However be aware it is not exact match. Check more on

https://docs.spring.io/spring-data/jpa/docs/2.1.x/reference/html/#jpa.query-methods

edited Dec 04 '18 at 22:24

answered Dec 04 '18 at 21:24

Stefan Repcek

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Spring Data JPA findBy a collection

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