JPA继承无法确定类型 [英] JPA inheritance Could not determine type for

问题描述

我有一个简单的JPA映射，但我一直得到无法确定类型的异常。

@Entity
@Inheritance（strategy = InheritanceType。 JOINED）
public class SupervisionCommand {

@Id
@GeneratedValue
保护长ID;

}

@实体
公共类MySupervisionCommand扩展SupervisionCommand {

}

@实体
public class Job {

@Id
@GeneratedValue
private Long id;

私人SupervisionCommand命令;

完整的异常信息：可能不确定类型：com.family.model.SupervisionCommand，在table：job，for columns：[org.hibernate.mapping.Column（command）]

 
  @ManyToOne 
私人SupervisionCommand命令; 
  

字段的默认映射是 @Column 。而Hibernate不知道使用哪种类型的列（varchar？number？）来存储SuperVisionCommand实例。如果它实现了Serializable，Hibernate会将其序列化并将其存储在BLOB列中，但这不是您想要的。

I have a simple JPA mapping but I keep getting a Could not determine type for exception. Setters and getters are omitted.

@Entity
@Inheritance(strategy = InheritanceType.JOINED)
public class SupervisionCommand {

    @Id
    @GeneratedValue
    protected Long id;

}

@Entity
public class MySupervisionCommand extends SupervisionCommand {

}

@Entity
public class Job {

    @Id
    @GeneratedValue
    private Long id;

    private SupervisionCommand command;

}

The full exception message: Could not determine type for: com.family.model.SupervisionCommand, at table: job, for columns: [org.hibernate.mapping.Column(command)]

解决方案

You need a OneToOne or ManyToOne annotation (depending on the actual cardinality) on command:

@ManyToOne
private SupervisionCommand command;

The default mapping for fields is @Column. And Hibernate doesn't know which type of column to use (varchar? number?) to store a SuperVisionCommand instance. If it implemented Serializable, Hibernate would serialize it and store it in a BLOB column, but this is not what you want.

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