Puzzled. How did HQL reference object id?

dito199 · **Joined:** Tue Jan 06, 2004 8:06 am **Posts:** 13

Hi, recently I reviewed my code and something puzzled me quite a bit.

In my HQL, I have something like
"select..... from eg.Employee e .... where e.id=?"

All seems normal to me until I realized in my eg.Employee bean I never declared any id field. The primary key is userId, likewise the same for the hbm.xml which maps userId to USER_ID.

The query runs fine (I get the same result using e.userId or e.id in the HQL).

So do Hibernate automatically maps object.id to the primary key of the table?

I am currently using 2.1.8, sorry I have to post this since the topic is so vague (to me at least) I am not able to find anything relevant in the forum.

gskempes · **Joined:** Mon Nov 22, 2004 11:21 am **Posts:** 42

The mapping for your Employee class contains the tag

Code:

<id name="id" type="....

If you choose a different name, you have to refer to the new name for the id property.

Regards,
Georg

dito199 · **Joined:** Tue Jan 06, 2004 8:06 am **Posts:** 13

The mapping is as follow

Code:

<hibernate-mapping>
   <class name="eg.Employee" table="EG_EMPLOYEE">
      <id column="USER_ID" name="userId" type="string" length="32">
          <generator class="assigned"/>
      </id>   

      <property column="NAME" name="name"  type="string" length="64"/>
...
  </class>     
</hibernate-mapping>

The bean object is as follow

Code:

public class Employee {

  /** identifier field */
  private String userId;
...
  public String getUserId() { return userId;};
  public void setUserId(String uid) { this.userId = uid;}
}

Is it due to how we have identified USER_ID as id in hbm.xml and hence in HQL "employee.id" will always referenced that field?

gskempes · **Joined:** Mon Nov 22, 2004 11:21 am **Posts:** 42

Now you got me puzzled too. ;-) In such cases I read the reference manual more carefully. Indeed, in chapter 14.8 it says: "The special property (lowercase) id may be used to reference the unique identifier of an object. (You may also use its property name.)"

Regards,
Georg

P.S.: Please vote if this information is helpful