Question

I have a pretty complex domain entities. I want to have lazy loading for all of associations. So the scenario is like this:

1.get an instance of my business logic.

2.get an object o from business.

3.ask o to give me other associated objects.

4.prepare the view.

To get rid of hibernate exceptions about closed session when lazy load other objects, I’ve come up to the idea to open and close entire session in controller. Is it a good idea? Are there any better solutions?

Thank you

Answer 1

Session in view is a bad practice.

Here is a suggestion for layers which are typically used to work around this problem:

Controller

• The controller is only concerned with handling web requests, interpreting them into objects that your services will deal with, and returning services results as web responses. I usually have only one transactional service method call in each controller method, preferring to keep all data access for one controller operation within a single transaction.

Service

• The service layer is only concerned with accepting data from controller, obtaining the data it needs (from data layer) to perform its operations, and returning meaningful results. The service should fully load all lazy-loaded entities required by the controller. The service methods here are transactional and won’t have lazy loading issues, and you can assemble results from multiple DAO’s. That way DAO’s don’t need to know about each other.

Data Access

• The data access layer is only concerned with persistence (CRUD), allowing access to data with filtering, ordering, and so on.