Hibernate version:3.1
Database:MySQL 5


Hi,

I have been struggling with this error for a whole day - am becoming more familiar with Hibernate source than I wanted to (an excellent piece of software, though).

I am getting a ClassCastException when try to reassociate a detached instance of my "User" object. It has to do with the way the Role object is associated - I am not using the default ID association, but rather, its username property.

My mapping files and exception stack traces are below. Any help would be hugely appreciated.

Thanks.

Lee.

User Mapping:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.fsg.mainsite.common">
<class name="User" table="USER" dynamic-update="true" dynamic-insert="true" lazy="false">
<id name="id" type="java.lang.Long" column="ID">
<generator class="native"/>
</id>
<property name="username" column="USERNAME" type="java.lang.String" length="40" not-null="true"/>
<property name="password" column="PASSWORD" length="40" not-null="true"/>
<property name="firstName" column="FIRST_NAME" length="40" not-null="true"/>

<set name="roles" table="USER_ROLE" cascade="none" lazy="false" fetch="join">
<key column="USERNAME" property-ref="username"/>
<many-to-many class="Role" column="ROLE_ID"/>
</set>
</class>
</hibernate-mapping>

Role mapping:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.fsg.mainsite.common">
<class name="Role" table="ROLE" dynamic-update="true" dynamic-insert="true" lazy="false">
<id name="id" type="java.lang.Long" column="ID"/>
<property name="name" column="NAME" length="40" not-null="true"/>
<property name="description" column="DESCRIPTION" length="200" />
</class>
</hibernate-mapping>

Stack Trace (and log output excerpt):

DEBUG opened session at timestamp: 4679251227717632
DEBUG updating detached instance
DEBUG updating [com.fsg.mainsite.common.User#1]
java.lang.ClassCastException: java.lang.Long
at org.hibernate.type.StringType.toString(StringType.java:44)
at org.hibernate.type.NullableType.toLoggableString(NullableType.java:169)
at org.hibernate.pretty.MessageHelper.collectionInfoString(MessageHelper.java:187)
at org.hibernate.event.def.ReattachVisitor.removeCollection(ReattachVisitor.java:60)
at org.hibernate.event.def.OnUpdateVisitor.processCollection(OnUpdateVisitor.java:46)
at org.hibernate.event.def.AbstractVisitor.processValue(AbstractVisitor.java:101)
at org.hibernate.event.def.AbstractVisitor.processValue(AbstractVisitor.java:61)
at org.hibernate.event.def.AbstractVisitor.processEntityPropertyValues(AbstractVisitor.java:55)
at org.hibernate.event.def.AbstractVisitor.process(AbstractVisitor.java:123)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performUpdate(DefaultSaveOrUpdateEventListener.java:267)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsDetached(DefaultSaveOrUpdateEventListener.java:216)
at org.hibernate.event.def.DefaultUpdateEventListener.performSaveOrUpdate(DefaultUpdateEventListener.java:33)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
at org.hibernate.impl.SessionImpl.fireUpdate(SessionImpl.java:586)
at org.hibernate.impl.SessionImpl.update(SessionImpl.java:574)
at org.hibernate.impl.SessionImpl.update(SessionImpl.java:566)
at com.fsg.mainsite.DataInserter.test5(DataInserter.java:193)
at com.fsg.mainsite.DataInserter.main(DataInserter.java:72)

Java Code:

User user = DaoFactory.getUserDao().findByUsername("lee");
HibernateUtil.commitTransaction();
HibernateUtil.closeSession();

Session session = HibernateUtil.getSession();
session.update(user); // Fails on this line !!!
System.out.println("user=" + user);

And what does the POJO look like ?

Is field "id" a long type ?

In the Mappings:


You can only have foreign key references via the primary key, not via the username, I think.

THe POJOs are as follows. Although username is a unique key, the primary key is Long for both Role and User. I hope that I don't have to do the association by primary key, because the J2EE security framework requires that I have a "USERNAME" field in teh ROLE table. If there is a way to have that extra field in the role table, that should work as well.

public class User
{
private Long id;
private String username;
private String password;
private String firstName;
private String lastName;
private Set<Role> roles;

public User()
{
roles = new HashSet<Role>();
}

public boolean equals(Object obj)
{
if (obj == null)
return false;
else
{
User otherUser = (User)obj;
if (this.getUsername().equals(otherUser.getUsername()))
return true;
}
return false;
}

public int hashCode()
{
return getUsername().hashCode();
}

}



public class Role
{
private Long id;
private String name;
private String description;

Role()
{

}

public Role(Long id, String name)
{
super();
this.id = new Long(id);
this.name = name;
}

public boolean equals(Object o)
{
boolean result = (o != null && o instanceof Role && name.equals(((Role)o).name));
return result;
}

public int hashCode()
{
return name.hashCode();
}

public String getDescription()
{
return description;
}

public void setDescription(String description)
{
this.description = description;
}

public Long getId()
{
return id;
}

protected void setId(Long id)
{
this.id = id;
}

public String getName()
{
return name;
}

protected void setName(String name)
{
this.name = name;
}
}

I posted this a few days ago, and have included all details relating to the "bug". Nobody has come up with an answer, so I can assume this is a bug. There are a couple of workarounds but they're quite ugly. Does anyone know how I can determine if this is indeed a bug, and if so, when it will be fixed?

If your posting (or a question you are referring to) was not answered by anybody, the possible reasons are:

- http://www.hibernate.org/ForumMailingli ... AskForHelp
- You did not submit enough information
- Nobody knows the answer or has the free time to answer

What you can do now:

- Do the things listed in After Posting
- Add missing and/or more information
- Consider commercial support for guaranteed expert response times

This is a high-traffic forum run by volunteers with hundreds of postings made every day. The community works because people try to help others in their free time. Nobody is paid for this service or has to pay.

You should not expect a timely response and you should not rely on a public community forum for critical cases.

All community members should respect the rules of this forum and treat others like they would prefer to be treated.

Can you recommend the "best" (price+service) place to get commercial support?

Thanks.

Lee.

http://opensource.atlassian.com/project ... e/HHH-2052

Please vote for it!

Thanks!

Different problem, I think.



Something seems very odd when your unique String is being used as a foreign key to a Long.