wicket is doing exactly what you told it to do
you call final Object record = listItem.getModelObject(); 1000 times
which in turns calls listviewmodel.getobject().get(index); where index
varies from 1 to 1000
listviewmodel is PropertyModel(this, "records") so when its
getobject() is called (1000 times) it calls getrecords() method
thus your getrecords is called 1000 times - just like you have it setup.
you should read up on detachable models and loadable models - models
that cache a value for the duration of a request.
for example, if you replace new PropertyModel(this, "records") with
new LoadableDetachableModel() { Object load() { return getRecords();
}}
getRecords() would only be called once per request.
also if you have read the javadoc of ListView you would have noticed
that it does not recommend using ListView with database driven data.
ListView is made to work with lists. in a list an item is identified
by its index, in a database rowset an item is identified by its
primary key.
you took an example that uses static data where getrecords() is a
cheap call and expect it to work with database data without
modifications - where getrecords() is an expensive call, dont you
think that is silly?
if you want to display database data i would look into DataView and
DataTable. there are plenty examples in
http://wicketstuff.org/wicket13/repeater/
-igor
On Jan 21, 2008 6:32 PM, <[EMAIL PROTECTED]> wrote:
> I see. I guess I need to dig through more info on usage of api.
> But I just noticed the following perhaps you can point out
> surprising (to me) issue right away.
> It is a simple list view display with
>
> class Test{
> PageableListView listView = new PageableListView("records", new
> PropertyModel(this, "records"),
> rowsPerPage) {
> public void populateItem(final ListItem listItem) {
> final Object record = listItem.getModelObject();
>
> public List getRecords(){
> return <a record list from db query>
> }
>
> }
>
> what I noticed that for each populateItem call, it would invokes
> getRecords() (perhaps with further indexing). So it I have 1000 records
> in db, it would issue 1000 query for the same result list.
> What I am doing wrong here? I basically took an example class from wicket
> website and replace the fixed record list with a db query and
> could not explain the extreem slowness until I found out this problem.
>
>
>
> >you are free to write your own coding strategy that checks for
> >existence of these pages in session before creating a new instance.
> >
> >-igor
> >
> >
> >On Jan 21, 2008 6:01 PM, <[EMAIL PROTECTED]> wrote:
> >> > Would it be possible to turn a bookmarkale/stateless page object
> >> > into a stateful page during a session once user first access it.
> >>
> >> these pages are not created until accessed...so not sure what you mean
> >>
> >> >> I meant once they are created, accessing it again (say hit refresh
> >> >> button
> >on browser) should
> >> not result in a new page object recreation, instead using a way to
> >> locate the previous created object and rerender it as in a stateful
> >> page.
> >>
> >>
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