母体复合键的JPA注释是儿童复合主键的一部分

Question

我正在尝试绘制有多个比赛的比赛日，无法弄清楚注释。

我想最终得到的是类似的东西（这是一个简化的示例）：

TABLE: race_day
    date (PK)
    venue (PK)
    description
TABLE: race
    date (PK but also FK on race_day table)
    venue (PK but also FK on race_day table)
    race_number (PK)
    description

到目前为止，我想出了以下POJO 注释：

public class RaceDayPK implements Serializable {
    @Column(name="race_date")
    private String raceDate;
    @Column(name="venue")
    private String venue;
...
}
public class RaceDay {
    @EmbeddedId
    private RaceDayPK raceDayPk;
    @OneToMany(mappedBy = "raceDay", orphanRemoval = true, cascade = {CascadeType.ALL}, fetch = FetchType.EAGER)
    private final List<Race> races = new ArrayList<>();
...
}
public class Race {
    @ManyToOne
    @JoinColumns({
        @JoinColumn(name = "race_date", referencedColumnName = "race_date"),
        @JoinColumn(name = "venue", referencedColumnName = "venue")
    })
    private RaceDay raceDay;
    private int raceNumber;
    private String raceTitle;
...
}

如何将Raceday Join Commin和RaceNumber组成的比赛（我猜这就是我需要的）？任何帮助都赞赏。我已经在stackoverflow上看到了数十个joincolumn示例和嵌入式示例，但似乎没有一个可以将两者以我需要的方式结合在一起。

Answer 1

hack徒了，i think 我得到了这样的工作。请注意，在OneTomany注释的Mappyby参数中，嵌套的" Racepk.Racemeeting"：

public class RaceDayPK implements Serializable {
    @Column(name="race_date")
    private String raceDate;
    @Column(name="venue")
    private String venue;
...
}

public class RaceDay {
    @EmbeddedId
    private RaceDayPK raceDayPk;
    @OneToMany(mappedBy = "racePk.raceDay", orphanRemoval = true, cascade = {CascadeType.ALL}, fetch = FetchType.EAGER)
    private final List<Race> races = new ArrayList<>();
...
}

public class RacePk implements Serializable {
    @ManyToOne
    @JoinColumns({
        @JoinColumn(name = "race_date", referencedColumnName = "race_date"),
        @JoinColumn(name = "venue", referencedColumnName = "venue")
    })
    private RaceDay raceDay;
    @Column(name = "race_number")
    private int raceNumber;
...
}

public class Race {
    @EmbeddedId
    private final RacePk racePk = new RacePk();
    private String raceTitle;
...
}

还不知道这是否会在某个时候掉下来，但是MySQL表似乎已经正确生成了。

Answer 2

TABLE: race_day
        id(PK)
        date (PK)
        venue (PK)
        description
TABLE: race
        id(PK but also FK on race_day table)
        date (PK but also FK on race_day table)
        venue (PK but also FK on race_day table)
        race_number (PK)
        description

对于上面给定的表，我能够生成序列并使用以下代码遵循约束。

将数据持续。

    public class RaceDayPK implements Serializable {
        private Long id;
        private String raceDate;
        private String venue;
    ...
    }
    @Entity
    @IdClass(RaceDayPK.class)
    public class RaceDay {
        @Id
        @Column(name="id")
        @GeneratedValue(strategy=GenerationType.SEQUENCE,generator = "R_SEQ")
        @SequenceGenerator(sequenceName = "RD_SEQ", allocationSize = 1, name = "R_SEQ")
        private Long id;
        @Id
        @Column(name="race_date")
        private String raceDate;
        @Id
        @Column(name="venue")
        private String venue;
        @OneToMany(mappedBy = "raceDay", cascade = {CascadeType.ALL}, fetch = FetchType.LAZY)
        private Set<Race> races;
    ...
    }
    public class RacePK implements Serializable {

        private RaceDay raceDay;
        private int raceNumber;
    ...
    }
    @Entity
    @IdClass(RacePK.class)
    public class Race {
        @Id
        @ManyToOne(cascade = CascadeType.ALL)
        @JoinColumns({
            @JoinColumn(name = "race_date", referencedColumnName = "race_date"),
            @JoinColumn(name = "venue", referencedColumnName = "venue"),
            @JoinColumn(name = "id", referencedColumnName = "id")
        })
        @JsonIgnore
        private RaceDay raceDay;
        @Id
        private int raceNumber;
        private String raceTitle;
    ...
    }

DAO代码需要更改以下。

public RaceDay saveRaceDay(RaceDay raceDay){
 if(raceDay.getRaces()!=null){
            raceDay.getRaces().forEach(race ->{
                race.setRaceDay(raceDay);
            });
        }
        }

Answer 3

不确定它是否有效，但请尝试以下方法：

public class RacePK implements Serializable {
    private RaceDayPK raceDay;    
    private String raceNumber;
...
}
@Entity
@IdClass(RacePK.class)
public class Race {
    @Id 
    @ManyToOne...
    private RaceDay raceDay;
    @Id
    private int raceNumber;
    private String raceTitle;
...
}

请注意，PK字段名称应与 @ID-Annotaed字段名称完全相同。Google供衍生标识符了解更多信息。