Google App Engine - Querying related table using Key object

Google App Engine – Querying related table using Key object

This is just a short note on how to query related entities in JDO. As I have found out, we cannot use the entity key as its shown in the Data Store Viewer on the GAE admin console eg. zzR0ZXN0cgkLEgNGb28XGQw and compare that using someRelatedEntityKey == zR0ZXN0cgkLEgNGb28XGQw, instead we just provide the whole Key object to the query using query parameters.
Eg. Select users belonging to a department:

 String queryStr = "SELECT FROM " + User.class.getName() + "  WHERE departmentKey = :paramOne"

//and then:

List<User> users = (List<User>) pm.newQuery(queryStr).execute(departmetnKey);

Where pm is an instance of PersistenceManager, departmentKey is a Key object to the Department entity and paramOne is a named query parameter.

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