如何创建一个同时包含基元和复合主键作为表复合键 (Spring JPA) 的 JoinTable？

Question

I have a Users, Players, CoopGames, and CoopGamesPlayers tables. Conceptually, I am essentially trying to recreate the Order/OrderProducts type relationship. In my case, every CoopGamesPlayers entry has as its key the CoopGame id and the Player id. However, I am stuck because in my case my Player class has a composite primary key itself: generated player id, and also User id foreign key. I am kind of lost. I have set this up following a tutorial for Order.OrderProducts but I am not a JPA expert and have never really used composite keys in a JoinTable. Code:

public class PlayerPK implements Serializable {

    @ManyToOne(optional = false, fetch = FetchType.EAGER)
    @JoinColumn(name = "id")
    private Player player;

    @ManyToOne(optional = false, fetch = FetchType.EAGER)
    @JoinColumn(name = "userid")
    private User user;
}

@Entity
@Table(name = "players")
public class Player implements Serializable {

    @EmbeddedId
    private PlayerPK pk;

    @Column(name = "image")
    private String image;
}

@Entity
@Table(name = "coop_games")
public class CoopGame {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @OneToMany(mappedBy = "pk", fetch = FetchType.EAGER)
    private List<CoopGamesPlayers> players;
}

public class CoopGamesPlayersPK implements Serializable {

    @JsonBackReference
    @ManyToOne(optional = false, fetch = FetchType.EAGER)
    @JoinColumn(name = "coop_game_id")
    private CoopGame game;

    @ManyToOne(optional = false, fetch = FetchType.EAGER)
    @JoinColumns({
        @JoinColumn(name="playerid", referencedColumnName="id"),
        @JoinColumn(name="userid", referencedColumnName="userid")
    })
    @MapsId("pk")
    private Player player;
}

@Entity
@Table(name = "coop_games_players")
public class CoopGamesPlayers {

    @EmbeddedId
    private CoopGamesPlayersPK pk;

    public CoopGamesPlayers(CoopGame game, Player player) {
        pk = new CoopGamesPlayersPK();
        pk.setGame(game);
        pk.setPlayer(player);
    }
}

@Entity
@Table(name = "coop_games")

public class CoopGame {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @OneToMany(mappedBy = "pk", fetch = FetchType.EAGER)
    private List<CoopGamesPlayers> players;
}

Answer 1

I think you should better rethink your data model with all relationships (Which problem should be solved? ..).

As for your CoopGamesPlayers Table: if you just want to use CoopGamesPlayers as a jointable, you don't need the CoopGamesPlayersPK.

CoopGame und CoopGamesPlayers should look something like this:

@Entity
@Table(name = "coop_games")
public class CoopGame {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @OneToMany(mappedBy = "game", fetch = FetchType.EAGER)
    private List<CoopGamesPlayers> players;
}

@Entity
@Table(name = "coop_games_players")
public class CoopGamesPlayers {

    @EmbeddedId
    private PlayerPK pk;

    @JsonBackReference
    @ManyToOne(optional = false, fetch = FetchType.EAGER)
    @JoinColumn(name = "coop_game_id")
    private CoopGame game;

    @ManyToOne(optional = false, fetch = FetchType.EAGER)
    @JoinColumns({
            @JoinColumn(name = "playerid", referencedColumnName = "id"),
            @JoinColumn(name = "userid", referencedColumnName = "userid")
    })
    @MapsId("id") 
    private Player player;
}

@MapsId("id") - id because you want player id as fk or?