I'm trying to create a simple project/task management application. A project contains tasks, which can be either assigned to a user (ProjectMember), or stored in a tray (TaskTray), it it's not assigned to any user.

I have a syntax question for the hibernate query language:

Here's what the classes would look like

class Task
{
long id;
TaskOwner assignedTo;
}

abstract class TaskOwner
{
long id;
}

class ProjectMember extends TaskOwner
{
User user;
}

class TaskTray extends TaskOwner
{
String trayName;
}

class User
{
long id;
String firstName;
String lastName;
}

So a task is assigned to a taskOwner, which is either a ProjectMember, or a TaskTray.

Now, I want to create a hibernate query to retrieve all the tasks for a particular user. The closest I've been able to come up with would be the following, but it's invalid syntax:

Query query = getSession().createQuery(
"from Task as task " +
"inner join ProjectMember as member " +
"where task.assignedTo.id = member.id " +
"and member.user = :user ");

Does anyone know how to express this query properly? I can't do "where task.assignedTo.user = :user", because I'd have to cast assignedTo to ProjectMember first, and I don't know how to do that.

Thanks.... Patrick Arnesen

when you do joins in HQL, you're specifying Class attributes so it would be
.... inner join task.assignedTo as assignedTo


I might be able to give you more info if you post your mapping files.

The problem is that the Task.assignedTo property is of type TaskOwner, but that's the abstract subclass, which does not expose the property I want. I only want the tasks where Task.assignedTo joins to a TaskOwner of type ProjectMember, and once the join is complete, I want to access a property of the subclass.

(I got around this by collapsing the superclass and 2 subclasses into a single class, but it's a pretty ugly solution)

Sorry, my previous post should read:

he problem is that the Task.assignedTo property is of type TaskOwner, but that's the abstract SUPERCLASS

Try