Hi

I have a problem using maps with Hibernate v3 that is best explained using the Department – Employee one to many scenario.

My dept.hbn.xml mapping would be:

[code]
<hibernate-mapping>
<class name="com.unibasex.wom.to.DeptTO" table="DEPT" schema="WOM" lazy="false">
<id name="deptId" column="DEPT_ID" type="java.lang.Long" unsaved-value="null">
<generator class="seqhilo">
<param name="sequence">DEPT_SEQ</param>
<param name="max_lo">100</param>
</generator>
</id>
<property name="deptName" column="DEPT_NAME" type="java.lang.Byte" length="1" />

<!-- associations -->
<map name="employees" lazy="false" inverse="true" cascade="save-update">
<key column="DEPT_ID"/>
<index column="EMP_ID" type="long"/>
<one-to-many class="com.unibasex.wom.to.EmpTO"/>
</map>
</class>
</hibernate-mapping>
[/code]

And my emp.hbn.xml would be:

[code]
<hibernate-mapping>
<class name="com.unibasex.wom.to.EmpTO" table="EMP" schema="WOM" lazy="false">
<id name="empId" column="EMP_ID" type="java.lang.Long" unsaved-value="null">
<generator class="seqhilo">
<param name="sequence">EMP_SEQ</param>
<param name="max_lo">100</param>
</generator>
</id>

<property name="firstName" column="FIRST_NAME" type="java.lang.String" length="50" />
<property name="lastNAme" column="LAST_NAME" type="java.lang.String" length="50" />

<!-- associations -->
<many-to-one name="Department" class="com.unibasex.wom.to.DeptTO">
<column name="DEPT_ID" />
</many-to-one>
</class>
</hibernate-mapping>
[/code]

Now the problem is when I want to create a department and say 2 employees and then persist it in one transaction. When I add the 2 employees to a hashMap I need to use arbitary keys for the hashMap. It all works fine in that these keys are obviously not used when persisting and if I later have to load this data then the hashMap will contain the employee id as the keys of the hashMap. But staright after I have created the data the dept’s employee hashMap is incorrect as it contains the arbituary values as the keys.

Example Code:

[code]
//Create department
DeptTO deptTO = new DeptTO();
deptTO.setName(“Accounting”);

//Create 2 employees
EmpTO emp1TO = newEmpTO();
emp1TO.setFirstName(“John”);
emp1TO.setLastName(“Smith”);
emp1TO.setDepartment(deptTO);
EmpTO emp2TO = newEmpTO();
emp2TO.setFirstName(“Jane”);
emp2TO.setLastName(“Doe”);
emp2TO.setDepartment(deptTO);

//Assign employees to the new department
HashMap empMap = new HashMAp();
empMap.put(new Long(1),emp1);
empMap.put(new Long(2),emp2);
deptTO.setEmployees(empMap);
[/code]

The only way I can see to get around this is to code the department manager so that after it has persisted the data it reads the employee hashMap and re-creates it using the employee id’s as the hashMap keys.

Example Code:

[code]
HashMap newEmpMap = new HashMap();
for (Iterator it = deptTO.getEmployees().values().iterator(); it.hasNext();) {
EmpTO empTO = (EmpTO) it.next();
newEmpMap.put(empTO.getEmpId(), empTO);
}
deptTO.setEmployees(newEmpMap);
[/code]

Any help and/or advice would be greatly appreciated.

Is this not a bug as Hibernate should, after persisting, update the map's key values with the object's primary key (ie Employee Id)?

Andrew