字段“id_employeer”没有默认值

Question

我不明白为什么我应用程序会删除异常“字段'ID_Employeer'没有默认值”。

id_employeer是我的主键，当我试图将任何信息保存到我的数据库时，我得到了这个异常，但是，当我只是试图从DB读取信息时，它是正常的。

我读了关于StackOverflow的主题，但我仍然不明白我应用程序中的答案。我正在使用Hibernate5.2.11。

我的characterinfo.hbm.xml:

    <?xml version="1.0"?>

<!--
  ~ Hibernate, Relational Persistence for Idiomatic Java
  ~
  ~ License: GNU Lesser General Public License (LGPL), version 2.1 or later.
  ~ See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
  -->
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

    <class name="CharacterInfo" table="employees">
        <id name="Id" column="id_employeer">
            <generator class="native"/>
        </id>
        <property name="Login" column="employeer_login"/>



    </class>

</hibernate-mapping>

我的冬眠：

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import java.util.List;


public class HibernateUtility {


    SessionFactory sessionFactory;

    public void saving(Object object){
        Session session = sessionFactory.openSession();
        session.beginTransaction();
        session.save( object);
        //session.save( new CharacterInfo().getLogin());
        session.getTransaction().commit();
        session.close();
    }

    public void reading(){
        Session session = sessionFactory.openSession();
        session.beginTransaction();
        List result = session.createQuery("from CharacterInfo").list();
        for ( CharacterInfo characterInfo : (List<CharacterInfo>) result ) {
            System.out.println( "CharacterInfo (" + characterInfo.getLogin() + ") : " + characterInfo.getLogin() );
        }
        session.getTransaction().commit();
        session.close();
    }


    protected void setUp() throws Exception {

        final StandardServiceRegistry registry = new StandardServiceRegistryBuilder().configure()
                .build();

        try {
            sessionFactory = new MetadataSources(registry).buildMetadata().buildSessionFactory();


        } catch (Exception e) {
            StandardServiceRegistryBuilder.destroy(registry);
        }
    }




}

下一个CharacterInfo类

import org.hibernate.annotations.GenericGenerator;

import javax.persistence.*;


@Entity
@Table( name = "employees")
public class CharacterInfo {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "Id_employeer")
    private int id ;

    @Column(name = "employeer_Login")
    private String login;


    public CharacterInfo() {}

    public int getId() {
        return id;

    }

    public void setId(int id) {
        this.id = id;
    }


    public String getLogin() {
        return login;
    }

    public void setLogin(String login) {
        this.login = login;
    }



}

主类

public class main {


    public static void main(String args[]) throws Exception {
        HibernateUtility hibernateUtility = new HibernateUtility();
        CharacterInfo characterInfo = new CharacterInfo();
        characterInfo.setId(1);
        characterInfo.setLogin("PawJaw");
        hibernateUtility.setUp();
        hibernateUtility.saving(characterInfo);


    }
}

最后例外

Answer 1

首先，如果您使用的是Hibernate注释，那么就不需要使用Hibernate XML映射文件。

您的错误可能是因为您的数据库模式。Id_employeer列不是自动递增的。