在调用String ID上的save之前，必须手动分配此类的ID [英] Ids for this class must be manually assigned before calling save on String ID

问题描述

已经阅读了很多有关同一问题的问题，但我仍然无法解决此问题.

Already read lots of questions about the same issue, but I still not be able to solve this problem.

我的数据库上需要有一个String主键.

I need to have a String primary key on my database.

import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class MyClass {

    @Id
    private String myId;
    private String name;

    // getters and setters..

}

问题在于，如果我在@Id带注释的字段中使用String类型，则当我尝试保存对象时，Hibernate会引发异常.

The problem is that, if I use String type in a @Id annotated field, Hibernate throws an exception when I try to save the object.

ids for this class must be manually assigned before calling 

是的，我正在为该字段设置一个值.

And yes, I'm setting a value to the field.

我发现的解决方法:

1. 在字段中添加@GeneratedValue注释-无效
2. 将字段类型更改为Integer-对我来说不可行
3. 添加一个将myId作为参数public MyClass(String myId){ ... }接收的构造函数-不起作用
4. 使用UUID-我不能，因为该ID是由PO​​ST请求随附的字段设置的.

1. Add @GeneratedValue annotation to the field - not worked
2. Change the field type to Integer - it's not feasible for me
3. Add a constructor that receives myId as parameter public MyClass(String myId){ ... } - not worked
4. Use UUID - i can't, cause this id is set by a field that comes in with a POST request.

这些变通办法都不适合我.

None of these workarounds worked for me.

更新

我正在使用Spring Boot和Spring Data JPA.

I'm using Spring Boot and Spring Data JPA.

如何插入:

我有一个带注释的@PostMapping方法，该方法处理POST请求并调用执行某些业务逻辑的服务，并调用我的存储库以进行持久化.

I have an @PostMapping annotated method which handles POST request and call a service that do some business logic and call my repository for persisting.

我发布的请求

{
    "myId": "myId",
    "name": "myName"
}

MyService.java

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class MyService {

    @Autowired
    private MyRepository myRepository;

    public MyClass save(MyClass myClass) {
        return myRepository.save(myClass); // save() should persist my object into the database
    }
}

推荐答案

尝试这种方法

@Entity
public class MyClass{

    @Id
    @GeneratedValue(generator = "UUID")
    @GenericGenerator(
        name = "UUID",
        strategy = "org.hibernate.id.UUIDGenerator",
    )
    @Column(name = "id", updatable = false, nullable = false)
    private UUID id;

    …
}

====================================

======================================

我这样调用，并且在我的环境中一切正常:

I invoke like this and in my envirenment all work fine:

@Autowired
private EntityManager entityManager;

@PostMapping("")
@Transactional
public void add(@RequestBody MyClass myClass){
        entityManager.persist(myClass);
}

并要求通过邮件发送正文:

and requst send by post with body:

{
    "myId" : "213b2bbb1"
}

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