javax.persistence @JoinColumn 不工作

Question

我正在嘗試連接 2 個表 (ManytoMany)，但出現此錯誤：

由以下原因引起：org.hibernate.AnnotationException：com.MD.Medicine.Models.Meds.assignedMeds 的 referencedColumnNames(planDate, planId, weekday) 引用 com.MD.Medicine.Models.Plans 未映射到單個屬性

我的實體，Plans.java：

@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
@Table(name = "plans")
@EqualsAndHashCode(exclude = "assignedMeds")
public class Plans {
    @EmbeddedId
    private PlansPKId plansPKId;

    @Column
    private String planName;

    @Column
    private String weekday;

    @ManyToMany
    @JoinTable(name = "Plan_Meds", joinColumns = {
            @JoinColumn(name = "planDate", referencedColumnName = "planDate"),
            @JoinColumn(name = "planId", referencedColumnName = "planId"),
            @JoinColumn(name = "weekday", referencedColumnName = "weekday"), }, inverseJoinColumns = @JoinColumn(name = "id"))
    private Set<Meds> assignedMeds = new HashSet<>();

}

PlansPKId.java（用於計划模型）：

@Data
@AllArgsConstructor
@NoArgsConstructor
@EqualsAndHashCode
@Embeddable
public class PlansPKId implements Serializable {

    private Date planDate; // format: yyyy-mm-dd
    private long planId;

  

}

葯物.java：

@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
@Table(name = "meds")

public class Meds {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    @Column
    private String name;

    @Column
    private BigDecimal price;

    @Column
    private String category;

    @Column
    private int pillNumber;

    @Column
    private Date date;

    @JsonIgnore
    @ManyToMany(mappedBy = "assignedMeds")
    private Set<Plans> plans = new HashSet<>();

}

當我只加入這個時：

@ManyToMany
    @JoinTable(name = "Plan_Meds", joinColumns = {
            @JoinColumn(name = "planDate", referencedColumnName = "planDate"),
            @JoinColumn(name = "planId", referencedColumnName = "planId"), }, 
            inverseJoinColumns = @JoinColumn(name = "id"))
    private Set<Meds> assignedMeds = new HashSet<>();

它工作正常，但如果我有“工作日”列，我就會開始收到錯誤消息。 我不應該那樣加入他們嗎？

Answer 1

是的，基本上， @JoinTable的目的是創建一個僅包含每個參與者表的鍵的中間表。

@ManyToMany
    @JoinTable(name = "Plan_Meds", joinColumns = {
            @JoinColumn(name = "planDate", referencedColumnName = "planDate"),
            @JoinColumn(name = "planId", referencedColumnName = "planId"),
            @JoinColumn(name = "weekday", referencedColumnName = "weekday"), }, inverseJoinColumns = @JoinColumn(name = "id"))
    private Set<Meds> assignedMeds = new HashSet<>();

在這種情況下，

joinColumns = {
            @JoinColumn(name = "planDate", referencedColumnName = "planDate"),
            @JoinColumn(name = "planId", referencedColumnName = "planId")}

將引用您的Plans實體planPKId的密鑰，並且

inverseJoinColumns = @JoinColumn(name = "id")

將引用Meds實體的密鑰id 。 由於weekday @JoinColumn(name = "weekday", referencedColumnName = "weekday") ，它沒有引用任何鍵，它不應該在這里。

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如果您需要在連接表中添加更多字段，請手動創建自己的連接表並改用@ManyToOne： manytomany