Posted by : Munish Gogna Sunday, May 1, 2011

First of all nothing very fancy or technical about this post :)

Let's say you have an enum declaration as shown below and you want to store these values as String (not the evil ordinals) in the database:

public enum UserSex {
 MALE, FEMALE, UNKNOWN
}

To save this enum as String in database, the table where this enum is referenced should declare a column of type varchar as shown below:
`user_sex` varchar(255) DEFAULT NULL

The entity (say User) should use this enumeration as shown below:

@Entity
@Table(name = "user")
public class User {

private Integer id;
private UserSex userSex;

@Id
public Integer getId() {
 return id;
}

@Enumerated(EnumType.STRING)
 @Column(name ="user_sex")
 public UserSex getUserSex() {
  return userSex;
 }

 public void setId(Integer id) {
  this.id = id;
 } 

 public void setUserSex(UserSex userSex) {
  this.userSex = userSex;
 }

That's all. Now if you want to load all MALE users, you can use this column in JPA queries as

public List<User> getAllMaleUsers() {
  return entityManager.createQuery(
    "select user from User as user where user.userSex=:userSex")
    .setParameter("userSex", UserSex.MALE).getResultList();
 }

Please note that this will work only in case you have complete control on the database side, in case the column is declared as integer or varchar having length say 1 then you will have to write your own converter or fall back to evil ordinal().

NOTE: I'm guessing but I'm pretty sure that for using ENUM as String hibernate 3.2+ is required. So if anyone out there is interested in knowing my POM dependencies then here are they (specific to JBOSS AS 5.1.0 deployment)


   
javaee
   javaee-api
   5
   compile
  
  

   javax.persistence
   ejb3-persistence
   1.0
   provided
  
  
   org.hibernate
   hibernate-entitymanager
   3.3.1.ga
   
    
     javax.persistence
     persistence-api
    
    
     jboss
     jboss-common-core
    
    
     jboss
     javassist
    
   
  

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