How to map a set of enum type in Hibernate?

Question

In hibernate, is it possible to define a mapping for a class to a set of enums?

I've been able to find examples of how to define mappings of Sets and I've been able to find separate examples for how to map Enums, but I cannot figure out how to define a of Enums for a class.

Could anyone please provide me with an example?

This is being built on top of an existing application, so I cannot alter the database schema.

This is the relation I wish to model. Wicket is a normal class and WicketType is a Java Enum.

+----------------+    +------------+    +------------+
| Wicket         |    | Ref Table  |    | WicketType |
+----------------+    +------------+    +------------+
| INT     | W_ID |    |            |    | W_TypeId   |
| ....    |      | FK | W_ID       | FK | WicketType |
| INT     | TYPE |----| W_TypeId   |----|            |
+----------------+    +------------+    +------------+

Thanks again

Answer 1

Does this not do what you need?

To elaborate on the flippant initial response, the reference provides a means to use the ordinal of the enum to map enumerations.

In this case it's actually simpler than it looks, because you are hosting the enums in a set, you need to provide an accessor for the WicketType to the sub-type of IntEnumUserType, the super-type will take care of mapping the ordinal to the instance.

package test;

public class WicketTypeState extends IntEnumUserType<WicketType> {
    private WicketType wicketType;

public WicketTypeState() {
 // we must give the values of the enum to the parent.
 super(WicketType.class, WicketType.values());
}

    public WicketType getWicketType() {
        return wicketType;
    }

    public void setWicketType(final WicketType wicketType) {
        this.wicketType = wicketType;
    }
}

Define the mappings for the enum table:

<hibernate-mapping package="test">  
  <class name="Wicket" table="Wicket">
    <id name="id" column="ID"/>
    <set name="wicketTypes" table="WicketType" inverse="true">
      <key column="ID"/>
      <one-to-many class="test.WicketTypeState"/>
    </set>
  </class>
</hibernate-mapping>

Then for the type with the set of enums, define a set mapping for that property:

<hibernate-mapping package="test">
  <class name="WicketTypeState" lazy="true" table="WicketType">
    <id name="WicketType" 
      type="test.WicketTypeState"/>
  </class>
</hibernate-mapping>

This worked on my box(tm), let me know if you need any more info.

Answer 2

Hi,

The sample code below shows how what you want can be achieved with annotations.

@Entity
@Table (name = "wicket")
public class Wicket {

    ...
    ...

    private List<WicketType> wicketTypes = new ArrayList<WicketType>();

    @CollectionOfElements(fetch=FetchType.EAGER)
    @JoinTable(
            name="wicket_wicket_types", // ref table.
            joinColumns = {@JoinColumn(name="wicket_id")}
    )
    @Column(name="wicket_type_id")
    public List<WicketType> getWicketTypes() {
        return this.wicketTypes;
    }

    public void setWicketTypes(List<WicketType> wicketTypes) {
        this.wicketTypes = wicketTypes;
    }
    ...
    ...
}

WicketType is a standard Java 5 Enum whose order and ordinals of enum declarations match order and the column (wicket_type_id) values in the wicket_type table.

public enum WicketType {
   WICKET_TYPE1, WICKET_TYPE2 ...
}