如果只有非时间戳字段被修改，我可以配置Hibernate / JPA更新实体记录吗？ [英] Can I configure Hibernate/JPA to update an entity record when only non-timestamp fields have been modified?

问题描述

  @Entity 
 @Table（name = entity）
 public class Entity implements Serializable {
 
 private static final long serialVersionUID = 2040757598327793105L; 
 
 @Id 
 @Column 
 private int id; 
 
 @Column 
私有字符串数据; 
 
 @Column（name =last_modified）
 @Temporal（TemporalType.TIMESTAMP）
 private last lastModified; 
} 
  

我发现即使非时间戳字段没有被修改（即 data 字段），调用 merge 仍会更新时间戳。我希望时间戳只在其他数据字段发生更改时才更新。

有没有办法阻止对 merge UPDATE ？

更新（感谢评论）：

由于Hibernate的v4 @ 解决方案已弃用实体批注，并且为了允许动态更新，您应该使用 @DynamicUpdate（true）（与 @SelectBeforeUpdate如果你想防止未经修改的字段被包含在UPDATE查询中，那么你可以使用这些字段，

$ p $ @ org.hibernate.annotations.Entity（dynamicUpdate = true）//只更新已更改的字段
public class ...





At the moment I have an Hibernate entity class as follows:

@Entity
@Table(name = "entity")
public class Entity implements Serializable {

    private static final long serialVersionUID = 2040757598327793105L;

    @Id
    @Column
    private int id;

    @Column
    private String data;    

    @Column(name = "last_modified")
    @Temporal(TemporalType.TIMESTAMP)
    private Date lastModified;
}

I've found that even when the non-timestamp fields are not modified (i.e. the data field) a call to merge still updates the timestamp. I would like the timestamp to only update when other data fields have changed.

Is there anyway I can prevent calls to merge making a SQL UPDATE when all other data fields are not modified, or do I have to explicitly check for this myself in the code?

解决方案

Update (thanks to comment):

Since v4 of Hibernate @Entity annotation is deprecated and for allowing dynamic updates you should use @DynamicUpdate(true) (in conjunction with @SelectBeforeUpdate(true))

---

If you want to prevent unmodified fields to be included in UPDATE queries, add this on your entity:

@org.hibernate.annotations.Entity(dynamicUpdate=true) // update only changed fields
public class ...

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