Spring Data JPA JpaRepository.save（entity）不返回数据库默认值

问题描述

我有一个相当简单的问题。在一次交易中，我的代码看起来像这样：

  MyClass c = new MyClass（）; 
 c.setPropA（A）; 
 
 c = myClassRepository.save（c）; 
 
 c.setPropC（C）; 
  

如果我的实体看起来像这样：

 @Entity 
 @Table（name =MY_CLASS）
 public class MyClass {
 private String propA; 
私有字符串propB; 
私人字符串propC; 
 
 @Id 
 @Column（name =PROP_A，unique = true，nullable = false，updatable = false）
 public String getPropA（）{return propA; } 
 public void setPropA（String propA）{this.propA = propA; } 
 
 @Column（name =PROP_B，insertable = false）
 public String getPropB（）{return propB; } 
 public void setPropB（String propB）{this.propB = propB; } 
 
 @Column（name =PROP_C）
 public String getPropC（）{return propC; } 
 public void setPropC（String propC）{this.propC = propC; } 
} 
  

并且数据库设置为这样（Dialect = Oracle 11G）

  CREATE TABLE MY_CLASS {
 PROP_A VARCHAR2 NOT NULL PRIMARY KEY，
 PROP_B VARCHAR2 DEFAULT'B'NOT NULL ，
 PROP_C VARCHAR2 
} 
  

所以，基于代码来坚持实体，我想我会得到像这样的查询：

  MyClass c = new MyClass（）; 
 c.setPropA（A）; 
 
 c = myClassRepository.saveAndFlush（c）; 
 //插入MY_CLASS（PROP_A，PROP_C）VALUES（A，NULL）
 // SELECT PROP_A，PROP_B，PROP_C FROM MY_CLASS  - 刷新`c` 
 
 c.setPropC（C）; 
 
 //事务结束后，刷新到`c.propC` 
 // UPDATE MY_CLASS SET PROP_B =B，PROP_C =CWHERE PROP_A =A
  

...但是 SELECT 永远不会发生。为什么实体没有刷新？

由于<立方数）跟在<$ c 更新 $ c> INSERT 和 c.propB 仍然是 null 。我得到一个的ORA-01407：无法更新（MY_SCHEMA。MY_CLASS。PROP_B）为NULL 堆栈跟踪。

我知道在Java中使用 @PrePersist 或在 columnDefinition 中设置默认值的方法，但我不应该重复默认值。

注意：这在我使用 org.hibernate.Session.saveOrUpdate（），而不是Spring Data JPA。

感谢您的帮助！

@Generated annotation 。

I have a fairly simple problem. In a single transaction, my code looks something like this:

MyClass c = new MyClass();
c.setPropA("A");

c = myClassRepository.save(c);

c.setPropC("C");

Where my entity looks like this:

@Entity
@Table(name = "MY_CLASS")
public class MyClass {
  private String propA;
  private String propB;
  private String propC;

  @Id
  @Column(name = "PROP_A", unique = true, nullable = false, updatable = false)
  public String getPropA() { return propA; }
  public void   setPropA(String propA) { this.propA = propA; }

  @Column(name = "PROP_B", insertable = false)
  public String getPropB() { return propB; }
  public void   setPropB(String propB) { this.propB = propB; }

  @Column(name = "PROP_C")
  public String getPropC() { return propC; }
  public void   setPropC(String propC) { this.propC = propC; }
}

And the database is set up like this (Dialect = Oracle 11G)

CREATE TABLE MY_CLASS {
  PROP_A VARCHAR2 NOT NULL PRIMARY KEY,
  PROP_B VARCHAR2 DEFAULT 'B' NOT NULL,
  PROP_C VARCHAR2
}

So, based on the code to persist the entity, I would think I'd get queries that look something like this:

MyClass c = new MyClass();
c.setPropA("A");

c = myClassRepository.saveAndFlush(c);
// INSERT INTO MY_CLASS (PROP_A, PROP_C) VALUES ("A", NULL)
// SELECT PROP_A, PROP_B, PROP_C FROM MY_CLASS -- to refresh `c`

c.setPropC("C");

// After transaction ends, flush change to `c.propC`
// UPDATE MY_CLASS SET PROP_B = "B", PROP_C = "C" WHERE PROP_A = "A"

... but the SELECT never happens. Why is the entity not refreshed?

This breaks because of the UPDATE that (immediately) follows the INSERT and c.propB is still null. I get a ORA-01407: cannot update ("MY_SCHEMA"."MY_CLASS"."PROP_B") to NULL stack trace.

I realize there are ways around this using @PrePersist or setting default values on columnDefinition in Java, but I shouldn't have to duplicate defaults.

Note: This worked before when I was using org.hibernate.Session.saveOrUpdate() instead of Spring Data JPA for this action.

Thanks in advance for any help!

解决方案

Hibernate doesn't know that B is generated by the database, and that it has to read it after insert, unless you tell it to do so using the @Generated annotation.

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