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Need some ideas on the mapping

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Mendrik

Post subject: Need some ideas on the mapping

Posted: Sun Feb 05, 2006 3:57 am

Newbie

Joined: Fri Mar 19, 2004 8:11 pm
Posts: 3

I'm currently writing a web application, that will handle generic objects. So I will have most likely one object with a set of fields, that have a type and a value. I was wondering how to do the mapping. Any ideas?

So what I have so far:

package org.mendrik.suigeneris.model;

import org.apache.log4j.Logger;
import org.mendrik.suigeneris.meta.FieldSupport;
import org.mendrik.suigeneris.persistence.Dao;

import java.util.HashMap;
import java.util.Map;

/**
* @author Andreas Prudzilko
*/
public class Data extends ModelObject {

private FieldSupport fieldSupport;

[...]

public static final Dao<Data> DAO = new Dao<Data>(Data.class);

public Dao<? extends ModelObject> getDao() {
return DAO;
}

}

FieldSupport now holds basically a List of Field elements that consist of an unique key and a value. And of course it's all subclassed by classes like StringField, TextField, ImageField etc....

Now I'm kinda stuck on the mapping. My database layout though seems clear to me. I will have a Data table, a Data_Field table (for the set of fields to describe) and a Field table, that actually holds the values. Now I'm not sure if it's the smartest thing to do, but my Field table has columns for each possible value type:

field_id, name, stringvalue, textvalue, datevalue, numbervalue, ...

Any ideas how to do it better?

Oh and currently I'm also stuck with hibernate annotations.
I have:

new AnnotationConfiguration().configure("/config/hibernate.cfg.xml")
.addClass(Project.class)
.buildSessionFactory();

But it is still complaining about unknown entity project ?!
The cfg.xml holds only info about db connection.

Cheers,

Andreas

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Mendrik

Post subject: Uhm...

Posted: Sun Feb 05, 2006 5:20 am

Newbie

Joined: Fri Mar 19, 2004 8:11 pm
Posts: 3

Ok me again :-D

I can't get those annotations to run. And i followed the instructions from the docs.

Code:

<hibernate-configuration>

        [...]

        <!-- mapping files -->
        <mapping package="org.mendrik.suigeneris.model"/>
        <mapping class="org.mendrik.suigeneris.model.ModelObject"/>
        <mapping class="org.mendrik.suigeneris.model.Project"/>

    </session-factory>

</hibernate-configuration>

Then I have:

Code:

@Entity
@Table(name="project")
public class Project extends ModelObject {

    private static Logger log = Logger.getLogger(Project.class.getName());

    public Project() {
      //  data = new HashSet<Data>();
    }

    private String name;
    public String getName() {return name;}
    public void setName(String name) {this.name = name;}

    /*
    private Set<Data> data;

    public Set<Data> getData() {
        return data;
    }
    */


    public static final Dao<Project> DAO = new Dao<Project>(Project.class);

    public Dao<? extends ModelObject> getDao() {
        return DAO;
    }

}

and

Code:

@MappedSuperclass
public abstract class ModelObject {

    @EmbeddedId @GeneratedValue(strategy= GenerationType.IDENTITY)
    private Long id;
    public Long getId() {return id;}
    public void setId(Long id) {this.id = id;}

    public abstract Dao<? extends ModelObject> getDao();

}

Now trying:

Code:

<%
    Project p = new Project();
    p.getDao().save(p);
%>

gives me a frustrating:

org.hibernate.MappingException: Unknown entity: org.mendrik.suigeneris.model.Project
at org.hibernate.impl.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:513)
at org.hibernate.impl.SessionImpl.getEntityPersister(SessionImpl.java:1321)
at org.hibernate.engine.ForeignKeys.isTransient(ForeignKeys.java:180)
at org.hibernate.event.def.AbstractSaveEventListener.getEntityState(AbstractSaveEventListener.java:460)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:84)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
at org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java:531)
at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:523)
at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:519)
at org.mendrik.suigeneris.persistence.Dao$1.execute(Dao.java:26)
at org.mendrik.suigeneris.persistence.Transaction.run(Transaction.java:28)
at org.mendrik.suigeneris.persistence.Dao.save(Dao.java:24)

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