Enumerations in Hibernate

Question

It is often useful to have a field in a DAO whose value comes from a Java enumeration. A typical example is a login DAO where you usually have a field that characterises the user as "NORMAL" or "ADMIN". In Hibernate, I would use the following 2 objects to represent this relationship in a (semi-)typesafe way:

class User {     String username;     String passwd;     UserType type; }  class UserType {     private enum Type {ADMIN, NORMAL};     private String type;      //Setters/Getters for Hibernate     public void setType(String type);     public String getType();      //Setters/Getters for user     public void setUserType(UserType.Type t);     public UserType.Type getUserType();      public static UserType fromType(UserType.Type t); } 

This works, but I find the UserType class ungly and requiring too much bureaucracy just to store a couple of values. Ideally, Hibernate should support enum fields directly and would create an extra table to store the enumeration values.

My question is: Is there any way to directly map an enumeration class in Hibernate? If not, is my pattern for representing enumerations good enough or am I missing something? What other patterns do people use?

Answer 1

using hibernate or JPA annotations:

class User {    @Enumerated(EnumType.STRING)    UserType type } 

UserType is just a standard java 5 enum.

I can't imagine this is just limited to just annotations but I don't actually know how to do this with hbm files. It may be very version dependant, I'm guessing but I'm pretty sure that hibernate 3.2+ is required.

edit: it is possible in a hbm, but is a little messy, have a look at this forum thread

Answer 2

From the Hibernate documentation: http://www.hibernate.org/272.html

You can create a new typedef for each of your enums and reference the typedefs in the property tag.

Example Mapping - inline <type> tag

  <property name='suit'>     <type name="EnumUserType">       <param name="enumClassName">com.company.project.Suit</param>     </type>   </property> 

Example Mapping - using <typedef>

  <typedef name="suit" class='EnumUserType'>       <param name="enumClassName">com.company.project.Suit</param>   </typedef>    <class ...>     <property name='suit' type='suit'/>   </class>