Thanks for the clarification. I see your point now: if records are deleted
from the database, the navigation click is ignored an the page is simply
re-rendered. But if the data content has changed such that the navigation
no longer makes sense, what behavior would you prefer?

On Wed, Feb 15, 2012 at 1:37 PM, Jonathan Tougas <[email protected]> wrote:

> The PagingNavigationIncrementLink's linksTo(Page), which calls isLast()
> which calls pageable getPageCount() which ends up calling size()
> eventually. This is called during Component.canCallListenerInterface
> (*you're
> right it's not isVisible*) to verify if the link can indeed be clicked.
>
> And to be clear I am discussing multiple size() calls in one request. It
> happens when clicking on the navigation links: size() is called first as
> part of the verifying if the link is enabled (as described above), then the
> cached value is discarded just before rendering (in onBeforeRender()). Then
> size() is called again as part of the rendering, and again cached. The
> cached value is again discarded at the end of the request in onDetach().
> What I'm saying is the the first size() shouldn't occur because the page
> count should be cached from the previous rendering (it shouldn't be cleared
> in onDetach() nor readObject()).
>
> On Wed, Feb 15, 2012 at 1:09 PM, Dan Retzlaff <[email protected]> wrote:
>
> > Hi, Jonathan. Which component are you referring to? I don't see
> isVisible()
> > overrides in PagingNavigator or its helpers.
> >
> >
> > > It's state and as such should not be discarded when
> > > the request is finished, it's still needed for things like checking if
> a
> > > link was indeed visible when a click comes in for it.
> >
> >
> > How can you receive a click event for a link that was not visible?
> > Invisible components aren't rendered.
> >
> > That JIRA discusses multiple size() calls in a single request. You're
> > discussing multiple size() calls with multiple requests. Right?
> >
> > Dan
> >
> > On Wed, Feb 15, 2012 at 9:31 AM, Jonathan Tougas <[email protected]>
> > wrote:
> >
> > > I noticed two count queries go by when using the DataTable component.
> so
> > I
> > > searched and dug up this jira issue
> > > https://issues.apache.org/jira/browse/WICKET-1766 which is a "won't
> > fix".
> > >
> > > Igor states that two queries are required each request, but I see this
> > > differently:
> > >
> > > The count is a used as the basis for the paging navigator's
> isVisible(),
> > so
> > > far so good. The issue is that the count is discarded in onDetach() (as
> > > well as readObject()). It's state and as such should not be discarded
> > when
> > > the request is finished, it's still needed for things like checking if
> a
> > > link was indeed visible when a click comes in for it. If it's not
> kept, a
> > > new query to the model will be made, which might return a different
> > result
> > > - consequences ensue. The critical part of that is we are checking if
> the
> > > link *was* visible, not if it *is* visible.
> > >
> > > I think the only time it should be discarded is in the onBeforeRender()
> > > event. This is when we are actually interested in going back to the
> model
> > > to see if the value has changed. So to me this is indeed a bug. I don't
> > > mind patching something up myself, or reopening the ticket...but I
> would
> > > like a confirmation that I'm not way out in left field ;)
> > >
> > > Cheers!
> > > Jonathan Tougas
> > >
> >
>

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