Question

I have a Bean class called Bean_A that is map to table_A, and this Bean_A class is inherited from a base bean class, and the base bean class will have a unique_reference_key variable that will going to save into the database together with the Bean_A class. I already have the hibernate file ready for the Bean_A and the unique_reference_key field in table_A.

May I know how could I map the base bean class in hibernate to ensure this unique_reference_key variable is save into database when I was saving the Bean_A object? Take note that this base bean class is not map to any table in database, and there is no such table that “represent” the base bean.

Before I throw out this question, I have consult the following article but still couldn’t get any clue on it.

1. Hibernate simplifies inheritance mapping
2. Hibernate Chapter 5.Basic O/R Mapping

Answer 1

I have found the solution on how to map the base bean property into Bean_A in hibernate.

In hibernate:

<class name="com.dao.pojo.BaseBean" abstract="true">
   <id name="theId" type="string">
      <column name="primary_key" length="15" />
   </id>
   <property name="unique_ref_key" type="java.lang.String" column="unique_ref_key"/>

   <union-subclass name="com.dao.pojo.Bean_A" table="table_A" lazy="false">
      ...
   </union-subclass>
</class>

Please note that theId was originally from Bean_A and it has been move to BaseBean. A new field, unique_ref_key, is created inside table_A.

In JAVA:

public abstract class BaseBean {
   private String theId;
   private String unique_ref_key;

   // getter and setter
}

public class Bean_A extends BeseBean {
   ...
}

Hope this solution can help others.