Question

大家好，我是hibernate的新手。当我在hibernate相关主题上冲浪堆栈溢出时，我发现了这个

Need clarification about mapping objects to database, annotations, and one to many relationships

阅读解决方案后，我有点困惑，并开始构建确切的场景，以了解多对一背后的实际机制，我使用oracle 11g数据库。当我运行我的项目时，hibernate会自动生成表和FK关系，但在插入数据时它面临这个问题（很明显）

WARN: HHH000437: Attempting to save one or more entities that have a non-nullable association with an unsaved transient entity. The unsaved transient entity must be saved in an operation prior to saving these dependent entities.
Unsaved transient entity: ([com.entity.Authorization#0])
Dependent entities: ([[com.entity.Job#1]])

WARN: HHH000437: Attempting to save one or more entities that have a non-nullable association with an unsaved transient entity. The unsaved transient entity must be saved in an operation prior to saving these dependent entities.
    Unsaved transient entity: ([com.entity.JobFilteration#0])
    Dependent entities: ([[com.entity.Job#1]])
    Non-nullable association(s): ([com.entity.Job.jobfilteration])

我确实完成了上面提到的上述主题的解决方案，我发布了我的实体类请帮我解决这个问题

班级工作

@Entity
@Table(name="JOB")
public class Job implements Serializable {
    @Id 
    @SequenceGenerator(name="person_seq", sequenceName="SEQ_PERSON",initialValue=1,allocationSize=1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE ,generator="person_seq")
    @Column(name="JOB_SERIAL")
    private int id;

    @Column(name="JOB_CATAGORY",nullable=false,length=200,unique=true)
    private String catagory;


    @ManyToOne(fetch=FetchType.LAZY)
    @JoinColumn (name="JOB_AUTHID", nullable = false, updatable = false, insertable = false)
    private Authorization authorization;

    @ManyToOne(fetch=FetchType.LAZY)
    @JoinColumn (name="JOB_JOBFILTERID", nullable = false, updatable = false, insertable = false)
    private JobFilteration jobfilteration;

Class JobFilteration

@Entity
@Table(name="JOB_FILTERATION")
public class JobFilteration implements Serializable {
    @Id 
    @SequenceGenerator(name="person_seq", sequenceName="SEQ_PERSON",initialValue=1,allocationSize=1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE ,generator="person_seq")
    @Column(name="FILTER_SERIAL")
    private int id;

    @Column(name="FILTERNAME",nullable=false,length=200)
    private String filtername;

课程授权

@Entity
@Table(name="AUTHORIZATION")
public class Authorization implements Serializable {
    @Id 
    @SequenceGenerator(name="person_seq", sequenceName="SEQ_PERSON",initialValue=1,allocationSize=1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE ,generator="person_seq")
    @Column(name="AUTH_ID")
    private int id;

    @Column(name="AUTHORISEDBY",nullable=false,length=200)
    private String authorisedby;

并且为了插入数据，我写了一个方法public void insertToDB(Job job)（我为三个类使用相同的序列以节省时间）然后

JoBDao jobdao= new JoBDao();
Job job= null;
Authorization auth = null;
JobFilteration jfilter = null;

try{
job= new Job();

auth = new Authorization();
    auth.setAuthorisedby("SOMEPERSON");

jfilter = new JobFilteration();
    jfilter.setFiltername("JEE");

job.setCatagory("PERMANENT");
job.setAuthorization(auth);
job.setJobfilteration(jfilter);


jobdao.addPersonandCard(job);

我认为发生异常是因为在插入其他表之前将数据插入作业表中。请帮我弄清楚我错过了什么？

Answer 1

首先尝试保存从属实体（在您的情况下授权）然后尝试保存外部实体（作业）

session.save(Authorization's object);
session.save(Job's object)

Answer 2

由于在主要实体中有两个实体，因此需要首先保存，然后在包含它们的主类中设置实体。我恐怕我真的不记得sesssion.save或session.saveOrUpdate中的哪一个函数返回bean，但是使用该方法，使用BeanUTils.copy方法并在主类中设置bean，一旦所有实体都为dne ，saveOrUpdate主实体类。

希望这有帮助！

Answer 3

最后，我已经找到了与作业类相关的问题，其余代码（类）都可以。在这里，我正在粘贴正确和修改的Job实体

@Entity
@Table(name="JOB")
public class Job implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id 
    @SequenceGenerator(name="person_seq", sequenceName="SEQ_PERSON",initialValue=1,allocationSize=1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE ,generator="person_seq")
    @Column(name="JOB_SERIAL")
    private int id;

    @Column(name="JOB_CATAGORY",nullable=false,length=200,unique=true)
    private String catagory;


    /*   The problem was inside this block */


    @ManyToOne(fetch=FetchType.LAZY,cascade = CascadeType.ALL)
    @JoinColumn (name="JOB_AUTHID", nullable = false)
    private Authorization authorization;                                 

    @ManyToOne(fetch=FetchType.LAZY,cascade = CascadeType.ALL)
    @JoinColumn (name="JOB_JOBFILTERID", nullable = false)
    private JobFilteration jobfilteration;

Answer 4

查看您要存储的对象。您尝试保存的似乎对象具有不接受空值的字段的空值。根据您的代码，所有数据库列都不可为空。这意味着您无法为这些列输入空值

关于使用Hibernate将对象映射到数据库

4 个答案: