TJ- TJ- - 3 months ago 21
SQL Question

Hibernate SQL transformation fails for Enum field type

I am using a SQL query and then transforming the result using Hibernates's

Transformers.aliasToBean()
.
One of the columns in my query is an enum. The transformation somehow fails for the enum. What should I do? Which datatype should I use? I want more than 1 character to transform the result into my enum type.

This is how the simplified version of my query/code looks like (b is an enum in the table profiles):

session.createSQLQuery("select a, b from profiles").setResultTransformer(Transformers.aliasToBean(Profile.class))
.list();


Exception :
expected type: Foo.ProfileStateEnum, actual value: java.lang.Character

Answer

Assuming that the java enum type that corresponds to column b is Foo.ProfileStateEnum, the following code snippet should work for you. (I tested with Hibernate 4.1.6)

import java.util.Properties;
import org.hibernate.type.Type;
import org.hibernate.type.IntegerType;
import org.hibernate.internal.TypeLocatorImpl.TypeLocatorImpl;
import org.hibernate.type.TypeResolver.TypeResolver;
import org.hibernate.type.EnumType;

Properties params = new Properties();
params.put("enumClass", "Foo.ProfileStateEnum");
params.put("type", "12"); /*type 12 instructs to use the String representation of enum value*/
/*If you are using Hibernate 5.x then try:
params.put("useNamed", true);*/
Type myEnumType = new TypeLocatorImpl(new TypeResolver()).custom(EnumType.class, params);

List<Profile> profileList= getSession().createSQLQuery("select a as ID, b from profiles")
            .addScalar("ID", IntegerType.INSTANCE)
            .addScalar("b", myEnumType )
            .setResultTransformer(Transformers.aliasToBean(Profile.class))
            .list();