问题
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?
回答1:
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
来源：https://stackoverflow.com/questions/53619322/spring-data-jpa-findby-a-collection