I have my business/domain objects, lets say Customer. I have a CustomerDAO interface and an implementation of it. Now inside my Category object I want a method called 'getOrders' which executes a Hibernate Query to retreive certain 'Order' objects. I don't want to use a mapped field for this, I want to execute a Query each time, as the orders returned depend on many parameters.

My question is, what is the best way to design this? I need access to the session to do a query, or I need to pass in an OrderDao object to the Customer object and put the method in there. Is that the best thing to do? I thought it was best to keep domain unaware of the persistance layer.

Any advice gratefully received.

Hi
The requirement is to have a getOrders() method, that retrieve the orders. And the getOrders() depends somehow on the Customer object. The correct way of working is to create a in the OrderDao object.

Regards.

But if I have a customer object and I want to execute a method on the customer object, that requires use of this fictional getOrders method then where does the orderDao come from. You are making the customer object aware of the OrderDao. Does that make sense ?

Ie,

lets say I want to do something like

Customer customer = .....
customer.cancelOutstandingOrders();

....

public void cancelOutstandingOrders() {

// get all orders, iterate through cancelling outstanding ones
for (Order order : getOrders()) {

....
}

}

The point is 'what is the nature of Customer ?'.
Customer is a Domain object (or at least sounds like). In a distributed environment, Customer will be serialized and used in another JVM (or in case of WS only Customer data will be used in a .net program).
That's why it's usually not a good idea to add behavior on the domain object, and to let it in a business class (service).

Code would look like:


In this case CustomerService uses
* CustomerDao in method find(...),
* and OrderDao to process cancelOutstandingOrders(...)

I see, so the CustomerService object is aware of the various DAOs and of the various domain objects ?

Yep.

Thanks for your help.

Is this a popular or common way of doing things ?
I found this blog arguing against it (and to be honest I seem to agree with this blogger!).
http://martinfowler.com/bliki/AnemicDomainModel.html

Please convince me otherwise!

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