Spring boot create a duplication of record from mysql

问题

i have a record of data

entity is given as follows in primary key

@GeneratedValue(strategy = GenerationType.IDENTITY)
    @Id
    @Column(name = "id",unique = true,nullable = false)
    public Long id;

what i have tried and even tried with object mapper which has some other issues

Record abc =dao.findById(11);
abc.setId(Null); //not working  
dao.save(abc) //not working

so what i am trying to do is a record with primary key as 1 when saved it should save as a new record ?

回答1:

you should create a new object:

Record abc =dao.findById(11);
Record def = new Record(abc);
dao.save(def)

and in Record class, you should have a constructor like this:

public Record(){}
public Record(Record rec){
    this.field1 = rec.field1;
}

回答2:

You can do it by creating another Object. Clone object by using beanUtils...

Try with this:

        Record abc =dao.findById(11);
        Record copyAbc = new Record();
        org.springframework.beans.BeanUtils.copyProperties(copyAbc,abc);
        copyAbc.setId(null);
        dao.save(copyAbc);

回答3:

You can do like this

• Detach your entity from EntityManager
• Set id to null
• Save entity

@PersistenceContext
EntityManager em;

...

em.detach(entity)

EDIT : It appear my answer has some issues. Please don't use it, i finally used the accepted answer

来源：https://stackoverflow.com/questions/61478262/spring-boot-create-a-duplication-of-record-from-mysql