DWR and Lazy Loading
- 1 minTime immemorial, we are all aware about the famous lazy load exceptions in Hibernate. Using a detached object does not exactly hide us from the issue. We are using DWR in our application and found that when marshalling (or unmarshalling if you insist) a detached object to JSON, DWR was erratically trying to call a null (lazyly loaded) object, causing LazyLoadExceptions.
We did not want to use OpenSessionInViewFilter, so instead as a quick fix we did what one would first think of, “It’s a demo, just eager load it!”. Well the demo was over and now was the time to investigate a better solution, and we did find it.
When using DWR, there are BeanConverters available which are responsible for this marshalling process. There was one for Hiberante, called “hibernate3”. http://directwebremoting.org/dwr/server/hibernate
The HibernateBeanConverter tries to avoid reading from un-initialized properties. (If you just want something that blindly reads everything then just use a plain BeanConverter). When exporting a detached hibernate object to DWR, use type=”hibernate3” and that should resolve the lazy load issues.
