Ive got a couple of entities which are related to each other but are rarely needed and contain a large amount of data.

The objects are linked by a primary key, so lets say "company.id" and "group.company_id". Now the group entity does not contain a property called "CompanyID" mainly because its only used when inserting and then never changed afterwards, so i thought it would be redundant to have within the entity.

Now i need to be able to retrieve a list of groups based on the company_id, but as the property is not within the entity i cannot seem to do it via the criteria, and if i do the SQL manually it doesnt seem to map it properly and i cant find any examples, so i was wondering if anyone had any details on how to achieve this...

Hi,

You can try using sql queries like below
String companyId = 1000;
StringBuffer sqlQ = new StringBuffer();
List<Object[]> groupList= new ArrayList<Object[]>();
sqlQ ="Select group_id from group where company_id = ";
sqlQ.append(companyId);
SQLQuery sqlQuery = session.createSQLQuery(sqlQ.toString());
groupList= sqlQuery.list();
if (groupList!= null) {
final Iterator<Object[]> itrgroupList = groupList.iterator();
while (itrgroupList .hasNext()) {
final Object[] groupObj= (Object[]) itrgroupList.next();
system.out.println(groupObj[0]);
}

Cheers,
Sudhir

your group entity doesn't have a Company entity reference, and not company_id property?
if it should never be updated but only inserted for new groups, you can use this feature:

<property name="HireDate" column="HIRE_DATE" not-null="true" insert="true" update="false"/>
setting the property as insertable but not updateable

in my opinion you should always avoid drifting to corner cases, because they are less tested, and even if working good, it might be confusing understanding how to use them properly
but having the property and setting it to be not updateable seems very reasonable