在复合键中使用 JoinColumns 时的 TypeDescriptor 错误

Posted 2023-04-11

【中文标题】在复合键中使用 JoinColumns 时的 TypeDescriptor 错误

【英文标题】：Wrong TypeDescriptor when using JoinColumns in a composite Key

【发布时间】：2015-10-19 19:59:30

【问题描述】：

我一直在摸索，试图弄清楚以下映射有什么问题。我了解以下映射对于 ORM 并不理想，但数据库就是这样，我无法更改其结构。我正在使用 JPA 2.1 和 Hibernate 5.0.2.Final。

@MappedSuperclass    
public abstract class BaseEntity<T extends Serializable> implements Serializable 

    protected T id;

    @Id
    public T getId() 
        return id;
    

    protected void setId(T id) 
        this.id = id;
    

---

@Table(name = "campaign")
@AttributeOverride(name = "id", column = @Column(name = "campaign_id") )
public class Campaign extends BaseEntity<String> 
    // attributes, getters and setters

---

@Embeddable
public class CampaignBroadcastPK implements Serializable 

    @ManyToOne
    @JoinColumn(name = "campaign_id", insertable = false, updatable = false)
    private Campaign campaign;

    @Column(name = "broadcast_date")
    private LocalDate broadcastDate;

    // getters and setters

---

@Entity
@Table(name = "campaign_broadcast")
public class CampaignBroadcast implements Serializable 

    @EmbeddedId
    private CampaignBroadcastPK id;

    // attributes, getters and setters

---

@Embeddable
public class CampaignBroadcastProcessPK implements Serializable 

   @ManyToOne
   @JoinColumns( 
       @JoinColumn(name = "campaign_id", insertable = false, updatable = false),
       @JoinColumn(name = "broadcast_date", insertable = false, updatable = false) 
    )
    private CampaignBroadcast broadcast;

    @Column(name = "process_date)
    private LocalDate processDate;

    // getters and setters

---

@Entity
@Table(name = "campaign_broadcast_process")
public class CampaignBroadcastProcess implements Serializable 

    @EmbeddedId
    private CampaignBroadcastProcessPK id;

    // attributes, getters and setters

---

除了这个结构，我还有一个转换器来处理LocalDate到java.sql.Date，它被autoApply=true注解。

当我尝试从entityManager.find() 加载CampaignBroadcastProcess 时，休眠尝试将campaign_id 转换为日期，即使它被映射为字符串，导致java.sql.Date 抛出IllegalStateException，因为字符串传递给valueOf 不是有效的日期字符串。

我怀疑 Hibernate 混淆了 CampaignBroadcastProcessPK 上的 JoinColumns 类型，将它们都作为 LocalDate 处理。

有人遇到过这个问题吗？

【参考方案1】：

我不完全确定为什么，但是改变两个@JoinColum 的顺序解决了这个问题。现在的映射如下：

@ManyToOne
@JoinColumns( 
    @JoinColumn(name = "broadcast_date", insertable = false, updatable = false),
    @JoinColumn(name = "campaign_id", insertable = false, updatable = false)     
)
private CampaignBroadcast broadcast;

【讨论】：

这就是我所说的——错误的隐式映射。考虑使用显式绑定而不是依赖来自注释的隐式顺序

不，事实并非如此，因为即使使用 referencedColumnName 映射也不起作用。

【参考方案2】：

尝试将明确的 referencedColumnName 添加到您的 @JoinColumn。您描述的错误可能是由于复合键列的隐式映射顺序错误

@ManyToOne
@JoinColumns(
    @JoinColumn(name = "campaign_id", referencedColumnName = "campaign_id", ...),
    @JoinColumn(name = "broadcast_date", referencedColumnName = "broadcast_date", ...) )
private CampaignBroadcast broadcast;

【参考方案3】：

我认为这是因为 hibernate 选择了第一个数据类型，它是数据类型并将其映射到 Join 列