To mine opinion this Best practise is confusing. It is just a matter of do not share Wicket components between pages because Wicket will not detect while serializing pages that components are already serialized.
The case of sharing anonymous IModel implementations is a special case because implicitly a Wicket component is shared. So you have to be careful with sharing models. Regards, Rik On 17 mei 2010, at 18:55, Jeremy Thomerson wrote: > You should use PageReference (Page#getPageReference()). > > -- > Jeremy Thomerson > http://www.wickettraining.com > > > > On Sun, May 16, 2010 at 11:52 PM, Rik van der Kleij > <rikvdkl...@gmail.com>wrote: > >> Hi Jeremy, >> >> So an instance field inside a page that points to another page is also >> something you should avoid? In our application we using this pattern a lot >> (for going back to previous page) but it never seems to be any problem. So >> probably because our pages don't consume a lot of memory. >> >> Regards, >> Rik >> >> On 17 mei 2010, at 06:13, Jeremy Thomerson wrote: >> >>> In general, you should not pass references to components to other pages. >>> That section on anonymous inner classes is telling you that when you >> create >>> an anonymous inner class and pass it to another page, you >>> will inadvertently be passing a reference to the outer class, which is >>> typically a page. This builds up memory and you will get a OOM. Passing >>> models between pages is absolutely fine - as long as you're not >> accidentally >>> passing a bunch of other stuff with it (including large domain objects - >>> which should be detached by using a detachable model). The page linked >> to >>> even says that you will often pass models between pages. >>> >>> -- >>> Jeremy Thomerson >>> http://www.wickettraining.com >>> >>> >>> >>> On Sun, May 16, 2010 at 11:05 PM, Rik van der Kleij < >> rikvdkl...@gmail.com>wrote: >>> >>>> Hi Bernard and Mike, >>>> >>>> According to >>>> >> https://cwiki.apache.org/WICKET/best-practices-and-gotchas.html#BestPracticesandGotchas-AnonymousInnerclassessharingmodels >> could eventually lead to Out of memory error. >>>> >>>> Holding a page reference in an instance field that points to another >> page >>>> looks the same but it is doesn't seems to be a problem. What's the >>>> difference? >>>> >>>> Regards, >>>> Rik >>>> >>>> >>>> On 16 mei 2010, at 04:39, Michael O'Cleirigh wrote: >>>> >>>>> Hello, >>>>> >>>>> I'm not sure on the answer to your question about the anonymous inner >>>> class but in general sharing models between pages can be a bad idea. >>>>> >>>>> The memory issues comes into play if the IModel is like Model and the >>>> contained object is not transient (it is serialized as part of the >> page). >>>>> >>>>> While Pages are serialized each page is serialized independently so on >>>> page reload the IModel from the first page is no longer the same object >>>> instance as the IModel from the second page. At deserialization time >> the >>>> page1.model.getObject().equals page2.model.getObject() but >>>> page1.model.getObject() != page2.model.getObject(); so any changes to >> either >>>> model are not shared between then. >>>>> >>>>> This is not a problem if the model is loadable since the memory of the >>>> page it is contained in doesn't matter as the value is loaded from the >>>> backend db or some other independent data source like the httpsession, >> or >>>> with wicketApplication. >>>>> >>>>> You can see the same effect if you try and share a model between a >> panel >>>> and a ModelWindow that uses a PageCreator >>>>> >>>>> Hope this helps, >>>>> >>>>> Mike >>>>>> Hi, >>>>>> >>>>>> Can someone explain me why it is a memory issue when an instance of an >>>> anonymous IModel class is passed to another page to be shared, but it >> seems >>>> to be no problem when a page reference is passed to another page and is >> put >>>> in an instance field (for example to be used in a button to navigate >> back to >>>> previous page)? >>>>>> >>>>>> Many thanks. >>>>>> >>>>>> Regards, >>>>>> Rik >>>>>> >>>>>> >>>>>> >>>>>> --------------------------------------------------------------------- >>>>>> To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org >>>>>> For additional commands, e-mail: users-h...@wicket.apache.org >>>>>> >>>>>> >>>>> >>>>> >>>>> --------------------------------------------------------------------- >>>>> To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org >>>>> For additional commands, e-mail: users-h...@wicket.apache.org >>>>> >>>> >>>> >>>> --------------------------------------------------------------------- >>>> To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org >>>> For additional commands, e-mail: users-h...@wicket.apache.org >>>> >>>> >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org >> For additional commands, e-mail: users-h...@wicket.apache.org >> >> --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org For additional commands, e-mail: users-h...@wicket.apache.org
