hibernate - automatic conversion of column value (string to enum)

Question

Is there any way to do something like this. I have an entity called person.

@Entity
@Table(name = "PERSON")
public class Person {
   @Column(name = "NAME", length = 128, columnDefinition = "VARCHAR2(128)")
   String name;
   @Column(name = "NATIONALITY", length = 128, columnDefinition = "VARCHAR2(128)")
   String nationality;
}

The 'NATIONALITY' column has numeric values - every number is a code of a country. I would like to map the 'nationality' field to my custom enum and create some method transforming code<->country.

@Entity
@Table(name = "PERSON")
public class Person {
   @Column(name = "NAME", length = 128, columnDefinition = "VARCHAR2(128)")
   String name;
   @Column(name = "NATIONALITY", length = 128, columnDefinition = "VARCHAR2(128)")
   Nationality nationality;
}

enum Nationality {
   USA, Brazil, Germany; // etc.
}

public static Nationality codeToNationality(String code);

Is there any hibernate methods for something like this? I can't modify columns definitions - the database is read only.

The second thing I'd like to achieve is to exclude any entities of unresolved nationality codes. The entities of codeToNationality(...) == null would be invisible to hibernate.

My model (persons, nationalities) is only an example.

Thanks for any help!

Mikko Maunu · Accepted Answer · 2012-07-23 10:01:37Z

4

Both problems:

mapping enum to some string in general and
mapping unknown to null

can be solved via creating appropriate UserType.

Some example about enums and custom user type can be found from here. General description of custom types is part of Hibernate documentation.

Other option is to provide specific setters for enum, and these will convert to and from string value which is mapped to database column. This can be feasible if this custom type is needed only in this entity.

edited Jul 23, 2012 at 10:01

answered Jul 23, 2012 at 9:39

Mikko Maunu

42.3k11 gold badges143 silver badges142 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Justin Wrobel Over a year ago

This post's third solution shows the setter/getter method.

Korgen · Accepted Answer · 2012-07-23 09:50:47Z

0

for your first problem have a look at the @Enumerated JPA Annotation, this will map your Strings to the enums. With a (EnumType.STRING) attribute you should be able to override the name() of the enum-values and return the Strings exactly as they are in the DB.

answered Jul 23, 2012 at 9:50

Korgen

5,4191 gold badge32 silver badges46 bronze badges

1 Comment

Mikko Maunu Over a year ago

Otherwise fine idea, but you cannot override final method.

T.Dabrowski · Accepted Answer · 2012-07-24 12:47:44Z

0

Ok, I've used UserType to convert String to Nationality.

public Object nullSafeGet(ResultSet rs, String[] names, SessionImplementor session, Object owner) throws HibernateException, SQLException {
   String value = rs.getString(names[0]);
   // resolve nationality
   return /nationality found/ ? /Nationality object/ : null;
}

Now I have other problem. How to create Criteria for finding only resolved nationalities?

When I do

criteria.add(Restrictions.isNotNull("nationality"));

the criteria queries the String field, not Nationality field, which is always not null.

I understand that Criteria works on raw database (before transformation to java entities), so how can I get what I want - filter rows of unresolved nationalities?

answered Jul 24, 2012 at 12:47

T.Dabrowski

1652 gold badges5 silver badges14 bronze badges

1 Comment

Brian Agnew Over a year ago

This isn't an answer, but rather a new question!

Collectives™ on Stack Overflow

hibernate - automatic conversion of column value (string to enum)

3 Answers 3

1 Comment

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related