![](/img/trans.png)
[英]JPA Inheritance entitymanager.find produces ClassCastException
[英]Jpa 2.0 - EntityManager.find (SomeEntity.class,PK) need to fill Descriminator value to key
我有一個問題,我有兩個實體Job和JobPK
Job class looks like this sample code :
@Entity
@IdClass(JobPK.class)
@Table(name="JOB")
@Inheritance
@DiscriminatorColumn(name="JOB_TYPE")
public abstract class Job implements Serializable {
@Id
@Column(name="FOLDER_ID")
private BigDecimal folderId;
@Id
@ColumnDefinition(position = 1)
private String name;
@Column(name="JOB_TYPE",insertable=false,updatable=false)
private String jobType;
...
}
和JobPk:
public class JobPK implements Serializable {
private static final long serialVersionUID = -3266336718203527905L;
@Column(name="JOB_TYPE",insertable=false,updatable=false)
private String jobType;
@Id
private String name;
@Id
@Column(name="FOLDER_ID")
private BigDecimal folderId;
......
}
我有兩個類擴展了Job:CalculatingJob和ImportingJob現在我不會使用:
getEntityManager().find(CalculatingJob.class, new JobPK (BigDecimal.valueOf(folderId),name))
我有問題,因為我必須填寫我的JobPK descriminator值字段。 如果我不這樣做,我就會得到Null Pointer Exception。 默認情況下,我認為描述符值是密鑰,但我不希望在JobPk創建期間將有關descriminator值的信息顯示出來。 我認為從Job擴展的實體將自動填充此字段。 任何想法繞過這個問題,也許我可以從CalculatingJob獲取Annotation @DescriminatorVale然后放入構造函數JobPk
感謝幫助
對層次結構嘗試此配置
Job.java
@Table(name = "JOB")
@Inheritance
@IdClass(JobPK.class)
@DiscriminatorColumn(name = "JOB_TYPE", discriminatorType = DiscriminatorType.STRING)
public abstract class Job implements java.io.Serializable {
}
CalculatingJob.java
@Entity
@DiscriminatorValue("CalculatingJob")
public class CalculatingJob extends Job {
}
ImportingJob.java
@Entity
@DiscriminatorValue("ImportingJob")
public class ImportingJob extends Job {
}
JobPK.java
public class JobPK implements Serializable {
}
鑒別符值由hibernate輸入。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.