Question

我在插入时遇到问题。我想在结果表中保存详细信息而不保存父表中的外键参数。有三个pojo类：

@Entity
@Table(name="course")
public class Course implements Serializable{
   private static final long serialVersionUID = 1L;

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

   @Column(name="course_id",nullable = false)
   private String course_id; 

   @Column( name="course_name")
   private String course_name;

   public int getId() {
       return id;
   }


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


   public String getCourse_id() {
       return course_id;
   }


   public void setCourse_id(String course_id) {
       this.course_id = course_id;
   }


   public String getCourse_name() {
       return course_name;
   }


   public void setCourse_name(String course_name) {
       this.course_name = course_name;
   }


   **@OneToMany(fetch = FetchType.EAGER, mappedBy = "course")
   private Set<Result> result = new HashSet<Result>(0);
   public Set<Result> getResult() {
       return this.result;
   }

   public void setResult(Set<Result> result) {
       this.result = result;
   }**
}

第二堂课是Student.java

@Entity
@Table(name ="student")
public class Student implements Serializable {

/**
 * 
 */
   private static final long serialVersionUID = 1L;
   //Attribute----------------------------------
   @Id
   @Column(name="id")
   @GeneratedValue(strategy=GenerationType.AUTO)
   private int id;

   public int getId() {
       return id;
   }

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

   //Attribute----------------------------------
   @Column(name="student_id", nullable=false)
   private long student_id;

   public long getStudent_id() {
       return student_id;
   }

   public void setStudent_id(long student_id) {
       this.student_id = student_id;
   }

   //Attribute----------------------------------
   @Column(name="student_name")
   private String student_name;

   public String getStudent_name() {
       return student_name;
   }

   public void setStudent_name(String student_name) {
       this.student_name = student_name;
   }

   //Attribute----------------------------------
   @Column(name="student_contact_number")
   private long student_contact_number;

   public long getStudent_contact_number() {
       return student_contact_number;
   }

   public void setStudent_contact_number(long student_contact_number) {
       this.student_contact_number = student_contact_number;
   }


   //This is for the foreign key element in the Result.java POJO class
   @OneToMany(fetch = FetchType.LAZY,cascade = {CascadeType.ALL}, mappedBy = "student")
   private Set<Result> result = new HashSet<Result>(0);

   public Set<Result> getResult() {
       return this.result;
   }

   public void setResult(Set<Result> result) {
       this.result = result;
   }
}

第三个是Result.java，它包含外键

@Entity
@Table(name="result")
public class Result implements Serializable{
   private static final long serialVersionUID = 1L;

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

   public int getId() {
       return id;
   }

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

   @Column(name="semester")
   private int semester;

   public int getSemester() {
       return semester;
   }

   public void setSemester(int semester) {
       this.semester = semester;
   }

   @Column(name="marks")
   private int marks;

   public int getMarks() {
       return marks;
   }

   public void setMarks(int marks) {
       this.marks = marks;
   }



   @ManyToOne(fetch = FetchType.LAZY)
   @JoinColumn(name = "student_id", nullable = false)
   private Student student;
   public Student getStudent() {
       return this.student;
   }

   public void setStudent(Student student_id) {
       this.student = student_id;
   }

   @ManyToOne(fetch = FetchType.LAZY)
   @JoinColumn(name = "course_id", nullable = false)
   private Course course;
   public Course getCourse() {
       return this.course;
   }

   public void setCourse(Course course) {
       this.course = course;
   }
}

现在我用来插入的代码是这样的：

Session session;
Transaction t;
Query query;

Configuration cfg=new Configuration();  
cfg.configure("hibernate.cfg.xml");  

//@SuppressWarnings("deprecation")
SessionFactory factory=cfg.buildSessionFactory();  


session=factory.openSession();  

t=session.beginTransaction();  
Result result;
Course cs;
Student st;

for(int i=0; i<jsrm.get(0).size(); i++)
{

   result=new Result();
   cs= new Course();
   st=new Student();
   cs.setCourse_id(jsrm.get(0).get(i).getcourse_id());
   st.setStudent_id(Integer.parseInt(jsrm.get(0).get(i).getstudent_id()));

   result.setSemester(Integer.parseInt(jsrm.get(0).get(i).getsemester()));

   result.setMarks(Integer.parseInt(jsrm.get(0).get(i).getmarks()));
   result.setCourse(cs);
   result.setStudent(st);

   session.save(result);
}

t.commit();//transaction is committed  
session.close();

错误是

org.hibernate.TransientPropertyValueException：非null属性引用瞬态值 - 必须先保存瞬态实例当前操作：Result.course - ＆gt;当然

有没有办法存储数据而不保存课程和学生。

在具有外键

0 个答案: