java - relacionar - Cómo unir tablas en clave no principal usando JPA e Hibernate

relacion manytomany jpa

Question

Tengo 3 modelos User , House , UserHouseMap . Y necesito acceder a la casa de un usuario a través del mapa. El único problema es que este es un DB anterior y no puedo cambiar el hecho de que necesito asignar User a UserHouseMap usando user.name , que es una clave no primaria.

Hibernate sigue dándome errores diciendo que necesito tenerlo como la clave principal o recibo errores que dicen A JPA error occurred (Unable to build EntityManagerFactory): Unable to find column with logical name: name in org.hibernate.mapping.Table(users) and its related supertables and secondary tables

He intentado con @Formula como una solución, pero eso no funcionó. También probé @JoinColumnOrFormula pero tampoco funcionó. Aquí está mi solución con @Formula

@Expose
@ManyToOne(targetEntity = House.class)
@Formula("(select * from houses inner join user_house_map on houses.house_name = user_house_map.house_name where user_house_map.user_name=name)")
public House house;

Aquí estaba mi intento de una solución @JoinColumnOrFormula .

@Expose
@ManyToOne(targetEntity = House.class)
@JoinColumnsOrFormulas({
@JoinColumnOrFormula(formula=@JoinFormula(value="select name from users where users.id= id", referencedColumnName="name")),
@JoinColumnOrFormula(column = @JoinColumn(name= "house_name", referencedColumnName="house_name"))
})
public House house;

Aquí está mi mapeo

@Id
@GeneratedValue
@Expose
public Long id;
@Expose
@Required
@ManyToOne
@JoinTable(
name="user_house_map",
joinColumns=
@JoinColumn(unique=true,name="user_name", referencedColumnName="name"),
inverseJoinColumns=
@JoinColumn(name="house_name", referencedColumnName="house_name"))
private House house;

Aquí están los esquemas DB

Usuarios

 Table "public.users"
Column | Type | Modifiers
-----------------------+-----------------------------+-----------------------------
name | character varying(255) |
id | integer | not null
Indexes:
"user_pkey" PRIMARY KEY, btree (id)
Foreign-key constraints:
"housing_fkey" FOREIGN KEY (name) REFERENCES user_house_map(user_name) DEFERRABLE INITIALLY DEFERRED

Casas

 Table "public.houses"
Column | Type | Modifiers
---------------+------------------------+-----------
house_name | character varying(255) | not null
address | text |
city | text |
state | text |
zip | integer |
zip_ext | integer |
phone | text |
Indexes:
"house_pkey" PRIMARY KEY, btree (house_name)
Referenced by:
TABLE "user_house_map" CONSTRAINT "house_map_fkey" FOREIGN KEY (house_name) REFERENCES house(house_name) DEFERRABLE INITIALLY DEFERRED

UserHouseMap

 Table "public.user_house_map"
Column | Type | Modifiers
-------------+------------------------+-----------
user_name | character varying(255) | not null
house_name | character varying(255) | not null
Indexes:
"user_house_map_pkey" PRIMARY KEY, btree (user_name)
"user_house_map_house_key" btree (house_name)
Foreign-key constraints:
"user_house_map_house_fkey" FOREIGN KEY (house_name) REFERENCES houses(house_name) DEFERRABLE INITIALLY DEFERRED
Referenced by:
TABLE "users" CONSTRAINT "housing_fkey" FOREIGN KEY (name) REFERENCES user_house_map(user_name) DEFERRABLE INITIALLY DEFERRED

Answer 1

Así es como debe verse su mapeo:

@Entity
public class User {
@Id
private Long id;
private String name;
@OneToMany(mappedBy = "user")
private List<UserHouseMap> houses = new ArrayList<>();
}
@Entity
public class House {
@Id
@Column(name = "house_name", nullable = false, unique = true)
private String house_name;
private String address;
@OneToMany(mappedBy = "house")
private List<UserHouseMap> users = new ArrayList<>();
}
@Entity
public class UserHouseMap implements Serializable {
@Id @ManyToOne
@JoinColumn(name = "user_name", referencedColumnName = "name")
private User user;
@Id @ManyToOne
@JoinColumn(name = "house_name", referencedColumnName = "house_name")
private House house;
}

Tanto el User como la House tienen acceso a sus entidades UserHouseMap asociadas, que coinciden con el esquema de la base de datos.

Usar dos asociaciones de uno a muchos siempre es mejor que confiar en relaciones de muchos a muchos.