I’m trying to use hibernate to create a map with the properties of a tripartite.

SQL:

-- Rec
insert into rec(id, name) values(1, 'Rec 1');
insert into rec(id, name) values(2, 'Rec 2');
insert into rec(id, name) values(3, 'Rec 3');

-- Param
insert into params(id, name) values(1, 'PARAM1');
insert into params(id, name) values(2, 'PARAM2');

-- Rec Param
insert into rec_param(id, rec, param, param_value) values(1, 1, 1, 'REC 1 - Param1');
insert into rec_param(id, rec, param, param_value) values(2, 1, 2, 'REC 1 - Param2');
insert into rec_param(id, rec, param, param_value) values(3, 2, 2, 'REC 2 - Param2');

I got my three entities
Params

@Getter
@Entity
@Table(
        name = "params",
        uniqueConstraints = {@UniqueConstraint(columnNames={"name"}) }
)
public class Params {

    @Id
    @GeneratedValue
    long id;

    @NaturalId
    @Column(name = "name", insertable = false, updatable = false)
    String name;

    @Override
    public boolean equals(Object o) {

        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Params params = (Params) o;
        return name.equals(params.name);
    }

    @Override
    public int hashCode() {

        return Objects.hash(name);
    }
}

REC

@Getter
@Entity
@Table(name = "rec")
public class Rec {

    @Id
    @GeneratedValue
    long id;

    @Basic
    String name;


    @OneToMany(mappedBy = "rec", fetch = FetchType.EAGER)
    @MapKeyColumn(name="param")
    Map<String, RecParam> paramMap = new HashMap<>();

}

RecParam:

@Getter
@Entity
@Table(
        name = "rec_param",
        uniqueConstraints = {@UniqueConstraint(columnNames={"rec", "param"}) })
public class RecParam {

    @Id
    @GeneratedValue
    long id;

    @NaturalId
    @JoinColumn(name = "rec")
    @ManyToOne
    Rec rec;

    @NaturalId
    @JoinColumn(name = "param", insertable = false, updatable = false)
    @ManyToOne
    Params param;

    @Basic
    String paramValue;
}

With this code, I manage to create a Map with
-> Key -> String representing the ID of the Params (“1”, or “2”)
-> Value -> The associated RecParam Object

What I’m trying to get is a map composed by the param name, and the rec param value.
For example, for rec1, it would be:

• ‘PARAM1’ -> ‘REC 1 – Param1’
• ‘PARAM2’ -> ‘REC 1 – Param2’

Do you know if it is possible?
if not, can have at lease the param name as a key, instead of the object id?

Thanks,
Nicolas