JPA如何在持久保存后从数据库获取值 [英] JPA How to get the value from database after persist

问题描述

  entityManager.persist 
 如何获得保存到数据库的值c> 

在调用后，我可以从数据库获取主键值，但不会存在任何其他值。
E.g。



  public void create（Project project）{
 entityManager.persist（project）; 
 System.out.println（Id  - + project.getProjectId（））; 
 System.out.println（no  - + project.getProjectNo（））; 
 
 $ / code> 

从上面的代码中，我可以从 project.getProjectId ，但无法获得 project.getProjectNo

为什么我能得到 projectId 是因为它是主键？

我怎样才能得到 试着刷新实体数据库来获取插入的触发器值。

  public void create（Project project）{
 entityManager.persist（project） ; 
 entityManager.getTransaction（）。commit（）; 
 project = entityManager.find（Project.class，project.getProjectId（））; 
 entityManager.refresh（project）; 
 System.out.println（Id  - + project.getProjectId（））; 
 System.out.println（no  - + project.getProjectNo（））; 
} 
  

文档

How to get the value which being saved to database after

entityManager.persist

I am able to get the primary key value from database after calling persist not any other values. E.g.

public void create(Project project) {
    entityManager.persist(project);     
    System.out.println("Id    -- " + project.getProjectId());
    System.out.println("no -- " + project.getProjectNo());
}

From the above code I am able to get the newly inserted value from project.getProjectId, however not able to get project.getProjectNo

The reason why I am able to get projectId is because it is primary key?

How can I get the value of getProjectNo after persist?

解决方案

Try refreshing the entity with the database to get the inserted trigger value.

public void create(Project project) {
        entityManager.persist(project);
        entityManager.getTransaction().commit();
        project = entityManager.find(Project.class, project.getProjectId());
        entityManager.refresh(project);
        System.out.println("Id    -- " + project.getProjectId());
            System.out.println("no -- " + project.getProjectNo());
    }

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