I don't want to expose the hibernate session to tapestry pages and components. I would rather keep the ui layer unaware of detached objects or the mechanism of reattaching those objects or even whether an object is detached or not. I'm looking for a way in which I can reattach the objects transparently and allow my tapestry code to simply use those objects as is.
On 2/22/06, Konstantin Ignatyev <[EMAIL PROTECTED]> wrote: > You could do reattach objects with hibernateSession.lock( object, > LockMode.NONE), but I suggest explicit reattaching with session.merge( object > ). > Explicit merging is better IMO because easily allows "wizard"-like multi > iteration editing of an object and then persisting all the changes if desired. > > With automatic reattaching all the changes will be persisted as user proceeds > and it makes harder to cancel all those changes.... > > Anthony Fox <[EMAIL PROTECTED]> wrote: I have considered a similar solution > as I use Spring as well. > However, I was looking for a way to not have to _explicitly_ reattach > objects. Rather, I would like all persistent detached objects in the > session's context to reattach automatically. A filter or interceptor > with knowledge of what objects are hibernate detached objects and > reattached them automatically would be ideal. This would ease further > development as adding new persistent properties to pages wouldn't need > the additional step of adding these properties to the list of > properties to reattach at pageRender time. Have you considered or > seen a solution like the one I have described? > > On 2/22/06, Shawn Church wrote: > > I'm doing this in several applications. I normally use Spring also, but > > that is not really necessary. Tapestry isn't aware of the persistence > > implementation, but it does have to explicitly attach (and occasionally > > merge or evict) detached objects. Since I reference my DAO services in > > my Tapestry pages already, it seemed appropriate to create a > > "HibernateService" and "HibernateLegacyService" (I probably should have > > named them something more generic) with public methods supporting > > attach, merge, and evict. I have to support multiple, unrelated > > databases, hence the multiple session-management implementations. I > > only attach in pageBeginRender, although I occasionally have to merge or > > evict in my form listener. > > > > I believe Tapestry is best suited to working with detached objects (and > > this method is one which is recommended by the Hibernate team), rather > > than storing IDs and reloading. In my case especially where I have a > > lot of composite keys, passing IDs around would be a hack. Having the > > detached object available to Tapestry makes it very nice and seamless > > when I need access to collections or other objects within that object. > > > > I don't experience lazy initialization exceptions any more (unless I've > > done something really wrong), but NonUniqueObjectExceptions can creep in > > if for example I try to load an object which happens to already have > > been loaded within the same session within a collection of a parent > > object. This is again often the result of me doing something stupid, > > but there a few (rare in my case) legitimate instances where this is > > needed. In this case, I take care to first evict (or merge if > > appropriate) the duplicate object. > > > > Shawn > > > > Quoting Anthony Fox : > > > > > Hi, > > > > > > I have an application that has a lot of hibernate detached objects > > > (with lazy loaded collections) that are persistent page properties. > > > What are best practices for reattaching these detached objects while > > > maintaining a clean separation of layers? I have my implementation > > > specific persistence layer separated into DAOs, a service layer, and > > > the tapestry ui layer. I would like to keep tapestry independent of > > > the persistence layer. I am using the OpenSessionInView pattern to > > > open a new hibernate session for each web request. However, I can't > > > determine a clean way to reattach all the hibernate detached objects > > > at the beginning of each web request. I've noticed that some people > > > use pageBeginRender() to reattach objects, but I don't want to > > > expose > > > my tapestry code to the persistence implementation. An interceptor > > > or > > > filter or something that separated the ui layer from being aware of > > > the persistence layer would be ideal. How have others dealt with > > > this > > > issue? > > > > > > Thanks, > > > Anthony > > > > > > --------------------------------------------------------------------- > > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > > For additional commands, e-mail: > > > [EMAIL PROTECTED] > > > > > > > > > > > > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: [EMAIL PROTECTED] > > For additional commands, e-mail: [EMAIL PROTECTED] > > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > > > > Konstantin Ignatyev > > > > > PS: If this is a typical day on planet earth, humans will add fifteen million > tons of carbon to the atmosphere, destroy 115 square miles of tropical > rainforest, create seventy-two miles of desert, eliminate between forty to > one hundred species, erode seventy-one million tons of topsoil, add 2,700 > tons of CFCs to the stratosphere, and increase their population by 263,000 > > Bowers, C.A. The Culture of Denial: Why the Environmental Movement Needs a > Strategy for Reforming Universities and Public Schools. New York: State > University of New York Press, 1997: (4) (5) (p.206) > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
