"invalid stream header" exception - Lob with JPA and MySQL

Question

I have a field defined like this

@MappedSupperclass
public abstract class BaseItem {

    ...
    @Lob @Basic(fetch=FetchType.EAGER)
    private String description;
    ...
}

@Entity
public class Item extends BaseItem {
}

I'm using MySQL 5 and the desccription field type is TEXT.

While trying to read an object of type Item I get the following error:

java.io.StreamCorruptedException: invalid stream header: 6576656E
    at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:782)
    at java.io.ObjectInputStream.<init>(ObjectInputStream.java:279)
    at org.datanucleus.store.rdbms.datatype.BlobImpl.getObject(BlobImpl.java:121)
    at org.datanucleus.store.rdbms.mapping.AbstractLargeBinaryRDBMSMapping.getObjectForBytes(AbstractLargeBinaryRDBMSMapping.java:362)
    at org.datanucleus.store.rdbms.mapping.AbstractLargeBinaryRDBMSMapping.getObject(AbstractLargeBinaryRDBMSMapping.java:395)
    at org.datanucleus.store.mapped.mapping.AbstractContainerMapping.getObject(AbstractContainerMapping.java:228)
    at org.datanucleus.store.rdbms.fieldmanager.ResultSetGetter.fetchObjectField(ResultSetGetter.java:176)
    at org.datanucleus.state.AbstractStateManager.replacingObjectField(AbstractStateManager.java:2353)
    ...

Do you have any idea of what are the possible causes for this?

I'm using JDK6 and DataNucleus 3.1.1.

Answer 1

Removing the @Lob annotation fixed the issue.