Question

I have 2 classes with @ManyToMany relationship

first class: Clip
second class: Location

the main idea is that a clip can be available in several locations

this is the clip class.

@Entity
@Table(name = "CLIP")
public class Clip {

    private Long id;
    private List<Location> locations;

    @Id @GeneratedValue(strategy=GenerationType.AUTO)
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }

    @ManyToMany( )
           @JoinTable(name="CLIP_LOCATION",joinColumns=@JoinColumn(name="CLIP_ID",nullable=false),inverseJoinColumns=@JoinColumn(name="LOCATION_ID",nullable=false) )
    @ForeignKey(name="FK_CLIP_LOCATION",inverseName="FK_LOCATION_CLIP")
    public List<Location> getLocations() {
        return locations;
    }
    public void setLocations(List<Location> locations) {
        this.locations = locations;
}
}

this is the Location class

@Entity
@Table(name = "LOCATION")
public class Location {
}

this is not a bi-directional relationship

My Question:
When i remove a location from the user interface , i want the relevant row in the join-table to be removed automatically,

Can i do that?

what annotation should i use?

Note that the Location class and Clip class are used in other relationships too

Thanks
Maayan
Am i using the wrong relationship?

Answer 1

This is not possible. You have to remove the location from the lists of locations before deleting the location. Since your association is unidirectional, you’ll have to execute a query to find all the clips available on the location, and remove the location from each clip.

Another option is to execute a native SQL query to remove rows from the join table, but keep in mind that the entities aready loaded in the session won’t be aware of the change.