Problem in running one to many

sureshkalle · **Joined:** Fri Jul 30, 2010 2:02 pm **Posts:** 6

Hi,

I am facing the following issue while running one to many relationship.

Basically my code includes,
1. COURSE table and STUDENT table.
2. COURSE will be the master table containing different course names having CNO as Course Number as primary key.
3. STUDENT table contains SNO, SNAME and CNO as Student Number, Student Name and Course Number under which student is under going.
4. Following is the piece of Code.

StudentOneToMany POJO

Code:

public class StudentOneToMany {
      private Long studentNo;
      private String studentName;
               getters & setters ;  
}

Course POJO

Code:

public class Course {
   private long courseNo;
   private String courseName;
   private StudentOneToMany[] studentOneToManyArray;
           getters & setters;

Student.hbm.xml

Code:

<class name="edu.model.StudentOneToMany" table="STUDENTONETOMANY">
    <id name="studentNo" column="STUDENTNO">   
         <generator class="sequence" />
    </id>
    <property name="studentName" column="SNAME"/>
    
  </class>

Course.hbm.xml

Code:

<class name="edu.model.Course" table="COURSE">
    <id name="courseNo" column="CNO">   
         <generator class="sequence" />
    </id>
    <property name="courseName" column="CNAME"/>
    
    <array name="studentOneToManyArray">
     <key column="CNO"/>
     <list-index column="idx" />
     <one-to-many class="edu.model.StudentOneToMany" />
     </array>
  </class>

Hibernateconfig.xml

Code:

  <session-factory>
       
       <property name="hibernate.connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
       <property name="hibernate.connection.url">jdbc:oracle:thin:@localhost:1521:SURESH</property>
       <property name="hibernate.connection.username">scott</property>
       <property name="hibernate.connection.password">tiger</property>
       <property name="dialect">org.hibernate.dialect.Oracle9Dialect</property>
       <property name="hibernate.show_sql">true</property>
       <property name="hibernate.hbm2ddl.auto">update</property>
       <property name="hibernate.use_sql_comments">true</property>
       <mapping resource="edu/mapping/Student.hbm.xml" />
       <mapping resource="edu/mapping/StudentXtra.hbm.xml" />
       <mapping resource="edu/mapping/Employee.hbm.xml" />
       <mapping resource="edu/mapping/StudentOneToMany.hbm.xml" />
       <mapping resource="edu/mapping/Course.hbm.xml" />
  </session-factory>

Please note these two tables are not present under database
Below is the Main Program

Code:

public static void main(String args[]){
      Session session = SessionUtil.currentSession();
      Transaction transaction = session.beginTransaction();
      StudentOneToMany studentOne = new StudentOneToMany();
      StudentOneToMany studentTwo = new StudentOneToMany();
      studentOne.setStudentName("abcd");
      studentTwo.setStudentName("efgh");
      
      StudentOneToMany[] studentOneToManyArray = new StudentOneToMany[] {studentOne, studentTwo};
      
      Course course = new Course();
      course.setCourseName("MCA");
      course.setStudentOneToManyArray(studentOneToManyArray);
      session.save(studentOneToManyArray);
      session.save(course);
      transaction.commit();
   }

I am getting the following exception and tables are being created but data is not getting inserted into the table, please help me out

Code:

[color=#FF0000]log4j:WARN No appenders could be found for logger (edu.util.SessionUtil).
log4j:WARN Please initialize the log4j system properly.
Exception in thread "main" org.hibernate.MappingException: Unknown entity: [Ledu.model.StudentOneToMany;
   at org.hibernate.impl.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:628)
   at org.hibernate.impl.SessionImpl.getEntityPersister(SessionImpl.java:1366)
   at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:121)
   at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)
   at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:56)
   at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)
   at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:50)
   at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)
   at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:563)
   at org.hibernate.impl.SessionImpl.save(SessionImpl.java:551)
   at org.hibernate.impl.SessionImpl.save(SessionImpl.java:547)
   at edu.main.OneToManyTest.main(OneToManyTest.java:24)[/color]

shynate26 · **Posted:** Mon Aug 09, 2010 8:41 am

This seems to be a problem in configuration file. Trying having pojo & hbm in same package . Get back with your results.

sureshkalle · **Joined:** Fri Jul 30, 2010 2:02 pm **Posts:** 6

In that case, table won't get created under database right? For me table is getting created under database, but not able to insert data into it.

shynate26 · **Posted:** Wed Aug 11, 2010 12:02 am

Tables got created because you have specified hbm2ddl.auto=update. What ever the changes you make in the mapping files its get reflected. But it clearly gives you error message unknown entity. So the mapping file not able to locate your entity file.