Hi-

I've been using hibernate for about 6 months for pretty standard CRUD type database interactions and like it a lot. The app I'm working on now is driven by data in a huge (4TB) data warehouse. Information in the warehouse is surfaced through materialized views and the column names in those views are identical for a majority of the views. There are currently 6 materalized views and as the warehouse team gets more investigation requests, more views will be created.

To map this stuff up via hibernate, I've had to create a class per view and essentially cut and paste the properties in beween the mapping definitions for each view. I'm only in the proof-of-concept phase for using hibernate as part of my solution but I'm thinking that it's not going to work out due to all the redundancy between mappings. As the app grows things aren't going to be maintainable.

The issue of having multiple classes is no problem since the classes have all their members defined in a common parent class. The real issue is the duplication of property definitions across mapping nodes.

Is there a way to extend mappings and override certain attributes? Or can components be defined independent of a particular class mapping and then imported?

My current worst case solution is to write some kind of code generator that takes a mapping file of my own design and generates the hibernate mappings from it. The mapping file still contains all the redundancy but the maintenance point would have no redundancies.

Any suggestions are appreciated.


Thanks.

Its very easy; just use XML external entities :)

I think I have a similar question. We are evaluating Hibernate as a possible replacement of EJB CMP. One of the advantages that we have found with Entity Beans is that in our data model, we have several tables that contain nearly identical columns. We are able to have a single Entity Bean class gernerically represent those tables, and we simply deploy multiple EJBs with that bean class for each appropriate table. Ie, the same class represents different tables. Is there a way with Hibernate to create similar mappings? Such that we have a single class:

public class MyEntity {
private Long m_id;
public Long getId() { return m_id; }
public void setId(Long n) { m_id = n; }

private String m_name;
public String getName() { return m_name; }
public void setName(String n) { m_name = n; }
}


that maps to BOTH of these tables:

CREATE TABLE TABLE_A (
ID NUMBER NOT NULL,
NAME VARCHAR2(128) NOT NULL
)

CREATE TABLE TABLE_B (
ID NUMBER NOT NULL,
NAME VARCHAR2(128) NOT NULL
)

Is this possible in Hibernate, without having to create different subclasses for each table?

In Hibernate 2.1, it is possible if you use multiple SessionFactories.

In Hibernate3 CVS, its is possible.

jimkski: Did you solve the problem you had? I am running into exactly the same mapping issue.