Inheritance with EBean

[J. O. Meyer]

Hi,

I'm coming from Play 1.2 with Siena as ORM and am just in the process of moving to Play 2 with EBean. So I'm still a newbie to EBean.

I have the following requirements to my database tables:

- each of my tables shall have some change history information "createdOn", "lastChangeOn", ...

- some (most) of my tables will also have a column "tenant", since it's gonna be a multi-tenant system

So, coming from Siena, I just thought I can define my class hierarchy in Play 2 like this:

@MappedSuperclass

public class BaseModel extends Model {

    @Id

    public Long id;

    public Date createdOn;

    public Date lastChangeOn;

    @ManyToOne

    public User createdBy;

    

    @ManyToOne

    public User lastChangeBy;

    // ...

}

@MappedSuperclass

public class TenantBaseModel extends BaseModel {

    @Constraints.Required

    @ManyToOne

    public Tenant tenant;

    // ...

}

The idea is basically, that I want to inherit my models for the tables without tenant from class BaseModel and the tables with tenant from class TenantBaseModel, e.g. like this:

@Entity

@Table(name="roles")

public class Role extends TenantBaseModel {

    

    @Constraints.Required

    @Formats.NonEmpty

    public String name;

    

    public String description;

    // ...

}

When trying to run this app, I get the following runtime error:

PersistenceException: Error with [models.Role] It has not been enhanced but it's superClass [class models.TenantBaseModel] is? (You are not allowed to mix enhancement in a single inheritance hierarchy) marker[play.db.ebean.Model] className[models.Role] 

So I'm just realizing that my naive approach might not fit EBean's concept. The tables for which I want to reuse the mapping code will be independent from each other. Obviously I don't want a single table for all my inherited models, and obviously I don't want a join table with a table holding some time stamps and the rest of my tables referencing there.

What is the best way to go here ?

Is it possible to use a common superclass for the timestamp fields at all ?

Or do I have to include these fields in each and every new model class mapping to a table ?

Thanks,

J.

[Rob Bygrave]

That error you are seeing is an Enhancement error - so you can't 'conclude' anything except that the Role class was not enhanced (I wonder if Role is in a separate jar or anything like that?). I think you should be able to do what you are trying.

You could 'convert' it to non-play java ... and use the normal Ebean enhancement, if that all worked then that would probably point the finger at the Play enhancement.


Cheers, Rob.

[J. O. Meyer]

Hi Rob,

thx for the reply. You were right, the issue was a missing configuration in Play.

I found a related discussion in the Play group:

https://groups.google.com/d/msg/play-framework/OFQUzO4Kvf4/5UPBZfaXz-UJ

Now it works.

J.