JPA repository findBy foreign key for ManyToMany relationship - spring

Question

I have the following relationship in the data base
Database Diagram
And these are the entities
Apartment.java
#Entity
#Table(name = "apartment")
#Data
public class Apartment {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id_apartment")
private long id;
#ManyToMany
#JoinTable(
name = "apartment_facility",
joinColumns = #JoinColumn(name = "id_apartment"),
inverseJoinColumns = #JoinColumn(name = "id_facility"))
#Column(name = "city")
private String city;
#Column(name = "country")
private String country;
}
Facility.java
public class Facility {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id_facility")
private long id;
#Column(name = "name")
private String name;
}
My question is how can I create a findBy method in JpaRepository in order to find all Apartments having the required facilities
I'm thinking of the result of this request:
api/apartments/findByFacilities?facilities=gym,pool,parking
I have tried to do a query but couldn't quite get it. Also tried using Jpa as following
List<Apartment> findByFacilities(#RequestParam("facilities") List<String> facilities);
But I'm getting the following error. Is there a walkaround?
Failed to convert from type [java.lang.String] to type [java.lang.Long]

Answer 1

In your first code block List <Facility> facilities = new ArrayList<>(); I guess you forgot to add the code line.
When I look at your link below, I understand that you want to search by the name of the facility.
api/apartments/findByFacilities?facilities=gym,pool,parking
For this, your code in Repository should be as follows:
List<Apartment> findDistinctByFacilitiesNameIn(List<String> facilities);
If we don't add distinct supported keyword here, each record repeats as many as the facilities it contains.
If you want to search differently like, not like, etc., See the supported keywords inside method names table here: Query Creation document.