Hi all, Our Wicket 1.4 project (currently 1.4.3) uses tabs on some pages to display linked information. For example, an Account may have a User. On the Account page, there would be a User tab in this case. The User is a PropertyModel on a LoadableDetachableModel for the Account (which grabs from the DB).
We notice that whenever one tab accesses any part of the model in its constructor, we get two queries to the database to display the page. Some digging revealed the cause: Tabbed panel does the following (simplified). 1. Instantiate the new Panel being switched to (which causes the LoadableDetachableModel to load() as the constructor uses it) 2. call addOrReplace with this new Panel. This causes the old Panel to be removed and detach() to be called on it. Unfortunately, the other tab also had a PropertyModel on the same Account object. This means that the LoadableDetachableModel that's already queried the db within this request will detach() Later, the rendering causes the LoadableDetachableModel to load() again. It could be argued that we shouldn't be accessing the model directly in the constructor but instead setting PropertyModels on its attributes to be displayed at render time. I have managed to fix almost all of our pages to do this*, but the problem is how fragile this is. It's difficult to write a test case that verifies that no page needlessly causes two loads() in any LodableDetachableModel, and the consequence of such a mistake would be no less than doubling the load on the database. I suggest that TabbedPanel should instead remove any old tab before instantiating the new tab so models won't be unexpectedly detached before rendering even happens. I would be willing to supply a JIRA and patch unless somebody out there a knows better way to do all of this :) Thanks, Neil * My main obstacle has been PageParameters links which don't seem to be able to take a Model as an argument. Is there a way to work around this?
