Hibernate - ManyToOne - 保存 - org.hibernate.TransientObjectException： [英] Hibernate - ManyToOne - Save - org.hibernate.TransientObjectException:

问题描述

当我尝试保存顶级实体（使用JPA）时，是否需要从数据库中新鲜地获取ManyToOne映射实体并设置它，或者我不能只设置Id（manyToOne映射实体并保存顶级实体？
当没有得到新的实体时，它抛出：org.hibernate.TransientObjectException：

我们使用的表结构：

  DEPARTMENT（DEPARTMENT_ID BIGINT，NAME VARCHAR（128））
 
 EMPLOYEE（EMPLOYEE_ID BIGINT，NAME VARCHAR（128），DEPARTMENT_ID BIGINT）
 
实体：
类别部门
 {
 @Id 
 Long departmentId; 
字符串名称; 
 @版本
长版本号; 
} 
 
班员工
 {
 @Id 
长员工ID; 
字符串名称; 
 @ManyToOne 
部门部门; 
 @版本
长版本号码
} 
  

类具有所有字段和默认构造函数的构造函数和getter方法，这是构造函数主键作为参数）
现在，如果我想用departmentId保存Employee（例如100），是否需要首先获取Department记录，然后将其设置在员工中？

无法直接创建Department实例（通过设置主键（departmentId））并在Employee中设置Department实例并保存Employee？
当我这样做时，它会抛出org.hibernate.TransientObjectException。

有关此最佳实践的任何建议吗？

预先感谢您

解决方案

谢谢ChssPly76和Wysawyg。

解决方案之一可能是：
我们将更新Employee POJO，如下所示：

  ManyToOne（fetch = FetchType.EAGER）
 @ ** JoinColumn **（name =DEPARTMENT_ID，referencedColumnName =DEPARTMENT_ID，** insertable = false，updatable = false **）
私人部门部门; 
 
 @Column（name =department_id）
 private long departmentId; 
  

（department和DepartmentId都有setter和getter方法）

和现在在这里（请参阅department和departmentId映射到同一列（DEPARTMENT_ID）
，我们只使用 department 来获取部门详细信息
和departmentId插入或更新员工

但我担心这是否是更好的方法。

While I try to save top level entity (using JPA), do I need to get the ManyToOne mapped entity freshly from database and set it or cannot I just set Id (of manyToOne mapped entity and save top level entity? When do not get fresh entity it throws: org.hibernate.TransientObjectException:

Table structures we are using:

DEPARTMENT(DEPARTMENT_ID BIGINT, NAME VARCHAR(128))

EMPLOYEE(EMPLOYEE_ID BIGINT, NAME VARCHAR(128), DEPARTMENT_ID BIGINT)

Entities:
class Department
{
   @Id
   Long departmentId;
   String name;
   @Version
   Long versionNumber;
}

class Employee
{
   @Id
   Long employeeId;
   String name;
   @ManyToOne
   Department department;
   @Version
   Long versionNumber
}

(both classes have setter and getter methods for all fields and default constructor, constructor which takes primary key as argument) Now if I want to save Employee with departmentId (say 100), do I need to get the Department record first and then set it in employee?

Cannot I create instance of Department directly (by setting primary key(departmentId)) and set Department instance in Employee and save Employee? When I do this it is throwing org.hibernate.TransientObjectException.

Any suggestions on best practice to be followed for this?

Thank you in advance

解决方案

Thank you ChssPly76 and Wysawyg.

One of the solution could be: We will update Employee POJO as below

ManyToOne(fetch=FetchType.EAGER)
@**JoinColumn**(name = "DEPARTMENT_ID", referencedColumnName = "DEPARTMENT_ID", **insertable=false, updatable=false**)
private Department department;

@Column(name = "department_id")
private Long departmentId;

(both department and departmentId will have setter and getter methods)

and Now here (please see that both department and departmentId mapped to same column (DEPARTMENT_ID) we use department only for fetching Department details and departmentId to insert or update Employee

But I am worried if it is a better approach.

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