[hibernate-issues] [Hibernate-JIRA] Created: (HHH-2416) Using interfaces instead of classes as entyties

[Pedro da Silva Garcia (JIRA)]

Using interfaces instead of  classes as entyties
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         Key: HHH-2416
         URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2416
     Project: Hibernate3
        Type: Improvement

  Components: core  
 Environment: Hibernate 
    Reporter: Pedro da Silva Garcia
    Priority: Minor


Hi folks,
I'm writing to express some of my ideas for a better ORM framework.
First i think it would be very nice to be able to map the tables to an interface instead of to a class. This would give me the ability to have many different classes implementing the same interface.
For example:
If I have a project that uses Struts 1. I would be able to use a form beam as a value object to persist data.
But this is just the begging of what I am thinking about.
The good this would be when a retrieve data from the database.
Example:
Instead of doing this

1) session.get(Cat.class, id);

It would be great to do something like this

2) session.get(CatForm.class, ICat.class, id);

and to do this

3) session.get (ICat.class, id);

In this last case Hibernate would have to generate a class that implements ICat and return it (Kind like what Tapestry framework does with the page object).

In real life I would use the example number 2 in situations like this:

public class CatDAO {

     public ICat get(Integer id, Class<ICat> returnType){
         return (ICat)session.get(returnType, ICat.class, id);
     }
     ...
}

And with the interfaces I would be able to merge entyties like
 
public class EmployeeDepartment implements IEmployee, IDepartment{

    private Integer employeeId;
    private Integer departmentId;
}

Or I could create a class to use as a query with the union of different tables.

And in the case of complex forms with data form many different tables I simply would create a form class that implements  all those different interfaces and when I do a save, all of the different entyties represented by this class would be saved.

Thanks for your attention,
Pedro

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