I have to map a class Account


class Account{

String number
double balance
.....
Pointer customer
Pointer jointcustomer
Pointer agent
}


Pointer here represents a class with two attributes (id,name)
On a webpage when the user clicks on the agent Pointer it navigates away to the agent details.
pointer is a object used to hold references to other things. The UI tier knows how to interpret this and provide display and hyperlinks.

select number, balance...... ,
customer.id, customer.name, (Pointer is construted using these)
agent.id, agent.name
from ..... customer, agent ....


In my code currently I have

Account= new Account();
account.setAmount(results.getDouble("amount"));
String id = results.getString("customer.id");
....
account.setCustomer ( new Pointer(id, name););


ManytoOne relationship from Account to customer.
ManytoOne relationship from Account to jointcustomer.
ManytoOne relationship from Account to agent.





I am trying to use Hibernate to refactor existing code which is working fine . My objective is to keep the same object so that other tiers are not affected.


How do I map this ? (specificallyPointer since the tables and columns change accourding to the usage)




<class name="Account" table="Account" >
......
...
<many-to-one name="customer" column="cust_id" not- null="true" />
<many-to-one name="agent" column="agent_id" not- null="true" />
.......
....

<class name="Pointer" table="Customer">
<id name="Id" column="cust_id" >
<generator class="native"/>
</id>
<property name="Name" column="cust_name"/>

</class>


<class name="Pointer" table="Agent">
<id name="Id" column="agent_id" >
<generator class="native"/>
</id>
<property name="Name" column="agent_name"/>

</class>



thanks for the help

Unfortunately, in the current releases of Hibernate what you would have to do to acheive this is define subclasses of your Pointer class for each type of entity it can reference and then map those subclasses. That would look something like:


Assuming you would also have independent mappings for Customer and Agent, this is essentially the "light weight" pattern described in the Hibernate patterns section of the site. Check that out for limitations to this approach.

In general, Hibernate works better if you utiize a (for lack of a better term) normalized domain model. So what if you did something like this instead:



Or even, better have a base class used by all your domain entities which forces subclasses to define a getPointer() method. That way you'd be able to centralize the way a Pointer looks for a given entity. Then the getCustomer() pointer accessor method above could just be: