Question

I have two classes which need to be XML mapped (eventually they will all be modified to Annotations, but currently we need to support the XML mappings).

I have a User object which currently looks like this:

public class User {
    private Key key;
    private Name name;
}

I need to add in Preferences for some of these users (we have two different types of users which share the same object).

public class Preferences {
   private Person person; //The person key acts as our foreign and primary key
   private Integer numToShow;
   private String defaultScreenToShow;
}

My person XML is as such:

<hibernate-mapping package="com.example.entities">
    <id key column="PERSON_ID" /> <!-- Leaving out custom generator -->

     <!-- 
         Not sure what the column needs to be here, as 
         preferences are in own table.  Also read it has to 
         be a faked out many-to-one here as not all users will
         have preferences. 
     -->
    <many-to-one name="preferences" not-null="false" /> 
    <component class="com.example.entities.Name">
        <property column="first_name" name="first" />
        <property column="last_name" name="last" />
    </component>

</hibernate-mapping>

My preferences XML file is as such:

<hibernate-mapping package="com.example.entities">
    <property column="default_screen" name="defaultScreenToShow" />
    <property column="number_search_results" name="numToShow" />
    <!-- Not sure what the ID needs to be here -->
</hibernate-mapping>

I’m pretty green with Hibernate in all honesty, but this seems like something which should be pretty easy to map in. I thought I had the mappings done properly, but I get a deserialization exception upon trying to load a person (I’ve marked the classes as Serializable — to no avail).

Answer 1

I was able to solve this in my desired way (Annotating the new class, and adding to the XML of the old class — When I used XML in each situation, I was only able to store the Ordinal value of the enum, which wasn’t desired).

Person.hbm.xml
<join table="PREFS_JOIN_TABLE" optional="true">
    <key column="PERSON_ID" />
    <many-to-one name="preferences" column="PREFERENCES_ID" not-null="true" unique="true" cascade="all"/>
</join>

My new class, which I was able to annotate, now looks like:

@Entity
@Table(name = "PREFERENCES")
public class UserPreferences implements Preferences {
    private Long id;
    private Panel defaultPanelToShow;
    private Person person;

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator="prefSeq")
    @SequenceGenerator(name="prefSeq", sequenceName = "SQ_PREFERENCES_ID", allocationSize = 10, initialValue = 1)
    @Column(name="PREFERENCES_ID")
    public Long getId() {
        return id;
    }

    @Column(name="DEFAULT_USER_PANEL")
    @Enumerated(EnumType.STRING)
    public Panel getDefaultRequestPanel() {
        return defaultPanelToShow;
    }

    @OneToOne
    @JoinTable(name="PREFS_JOIN_TABLE", joinColumns=@JoinColumn(name="PREFERENCES_ID", unique=true), inverseJoinColumns=@JoinColumn(name="PERSON_ID", unique=true))
    public Person getPerson() {
        return person;
    }
}