如何使用实体管理器插入记录而不定义主键字段？

Question

I have trying to insert a record into the database (MySQL), using Entity Class and Entity Manager. But one of the field is an auto incrementing primary key, so unless I provide an value manually, the insertion is not successful.

public boolean newContributor(String name, String email, String country, Integer contactable, String address) {
        Contributors contributor = new Contributors(); //entity class
        contributor.setId(??????); //this is Primary Key field and is of int datatype
        contributor.setName(name);
        contributor.setEmail(email);
        contributor.setCountry(country);    
        contributor.setContactable(contactable);
        contributor.setAddress(address);

        em.persist(contributor);
        return true;
    }

How to solve such problem? Is there a way to tell the entity manager to attempt the insert without the ID field and use NULL value instead.

Update: Here is a portion of the entity class defining the id

...
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Basic(optional = false)
@NotNull
@Column(name = "id")
private Integer id;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 50)
....

Answer 1

Is there a way to tell the entity manager to attempt the insert without the ID field and use NULL value instead?

Sure. You need to remove the @NotNull annotation for id field in the @Entity definition, and also remove the row:

contributor.setId(??????);

from method newContributor() . The reason for this is that the @NotNull annotation enforces a validation check in the JPA stack. It doesn't mean that the field is NOT NULL at a database level. See here a discussion about this issue.

The rest of the code looks fine.