Collection of values are not saved

bobsantos · **Joined:** Wed Sep 02, 2009 1:35 pm **Posts:** 4

Hi! I am currently following the tutorial in the documentation and trying out saving a collection of values. The problem I have is that my application is saving collection of entities(Set<Course> courses) but not the collection of values(Set<String> contactDetails).

Here is my persistent class..

Code:

public class Student {
    private Long id;
    private String firstName;
    private String lastName;
    private Set<Course> courses = new HashSet<Course>();
    private Set<String> contactDetails = new HashSet<String>();

    //getters and setters
}

Here is my mapping file

Code:

<hibernate-mapping package="com.phoenixone.school.model">
    <class name="Student" table="student">
            <id name="id" column="studentId">
                   <generator class="native" />
            </id>

            <property name="firstName" />
            <property name="lastName" />

            <set name="courses" table="student_course">
                    <key column="studentId" />
                   <many-to-many column="courseId" class="Course" />
            </set>

            <set name="contactDetails" table="contactDetails">
                    <key column="studentId" />
                    <element type="string" column="contactDetail" />
            </set>
    </class>
</hibernate-mapping>

Here is the part of my DAO where I save the persistent class...

Code:

public class StudentDaoHibernate {
    public void save(Student student){
            Session session = HibernateUtil.getSessionFactory().getCurrentSession();
            session.beginTransaction();

            session.save(student);
            session.getTransaction().commit();
    }
}

Here is my test...

Code:

public class TestStudentDaoHibernate {
    public static void main(String[] args) {
            CourseDaoHibernate courseDao = new CourseDaoHibernate();

            Course c1 = new Course();
            c1.setCourseCode("CWD");
            c1.setCourseName("Web Dev");
            courseDao.save(c1);

            Set<Course> courses = new HashSet<Course>();
            courses.add(c1);

            Student student = new Student();
            student.setFirstName("Bob");
            student.setLastName("Santos");
            student.setCourses(courses);
            student.getContactDetails().add("123456789");                 

            StudentDaoHibernate dao = new StudentDaoHibernate();
            dao.save(student);
    }
}

I've tried doing the saving of the contactDetails this way but it still does not save the String...

Code:

...
Set<String> contactDetails = new HashSet<String>();
contactDetails.add("123456789");
...
student.setContactDetails(contactDetails);
...

I am not seeing any table which contains the String "123456789" that I tried to save in my test.
I've also read from Java Persistence with Hibernate that the table which contains these values are hidden from me. Is my understanding correct?
Am I missing something or just doing the saving of collection of values wrong?

Thanks in advance!

bobsantos · **Joined:** Wed Sep 02, 2009 1:35 pm **Posts:** 4

*bump*

Anyone knows where I went wrong?

Thanks!

Cameron McKenzie · **Posted:** Wed Sep 02, 2009 6:25 pm

Do you save both sides of the relationship? That might be the problem.

Where did you find that DAO? It demonstrates a few major anti-patterns with regards to transaction demarcation.

Here's a tutorial on creating simple DAOs you might want to look at:

http://jpa.ezhibernate.com/Javacode/learn.jsp?tutorial=10introductiontodataaccessojbectsdaos

For some slightly simpler tutorials to follow, check out my signature links.

bobsantos · **Joined:** Wed Sep 02, 2009 1:35 pm **Posts:** 4

Cameron McKenzie wrote:

Do you save both sides of the relationship? That might be the problem.

Where did you find that DAO? It demonstrates a few major anti-patterns with regards to transaction demarcation.

Here's a tutorial on creating simple DAOs you might want to look at:

http://jpa.ezhibernate.com/Javacode/learn.jsp?tutorial=10introductiontodataaccessojbectsdaos

For some slightly simpler tutorials to follow, check out my signature links.

Hi Cameron! Thanks for the reply. I just made the DAO myself.:( I'll definitely check out the links.

For the Set<Course> I do have both sides of the relationship as Course is another persistent class. However, with Set<String> contactDetails, which is just a value type not an entity type, do I need to have both sides of the relationship and how do I do that cause there was no mention of it in the tutorial?

bobsantos · **Joined:** Wed Sep 02, 2009 1:35 pm **Posts:** 4

*bump*

thanks in advance!