[OPENJPA-660] ClassCastException when using OneToMany Relation and collection is subclass using Discriminator with SINGLE_TABLE strategy.

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.0.4, 1.1.0, 1.2.0
• Fix Version/s: 1.2.0
• Component/s: jpa
• Assignee: Pinaki Poddar
• Reporter: Vikram Bhatia
• Created: 16/Jul/08 10:09
• Updated: 21/Sep/16 14:21
• Resolved: 25/Jul/08 20:50

Description

If the entity has OneToMany relation and collection is declared as subclass which uses SINGLE_TABLE inheritance strategy, it fetches all rows irrespective of Discriminator value and throws ClassCastException.

There is entity Department (table dept) having OneToMany relation with another entity FullTimeEmployee.

@OneToMany (mappedBy="dept", cascade=CascadeType.ALL)
private Collection<FullTimeEmployee> fullTimeEmployees;

There is abstract class Employee with
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="TYPE")

There are two entity classes FullTimeEmployee and PartTimeEmployee which extends Employee (table emp) with Discriminator values 'F' and 'P' respectively.

Now, suppose emp table contains 2 rows of PartTimeEmployee and 2 rows of FullTimeEmployee and if test class fetches Department object and calls dept.getFullTimeEmployees(), it throws ClassCastException as it gets 4 rows and doesn't use discriminator and subclass type while generating SQL query.