if i read your code correctly you provided the listview with a
reference to a model, not a list...
-igor
On Jan 21, 2008 7:43 PM, <[EMAIL PROTECTED]> wrote:
> Thanks for the tip. It worked perfectly.
> I do feel this could be a minor bug even for a fixed list
> (might not be noticeable visually). At the time ListView is
> created, it is provided with a predefined model object =this.getRecords()
> which should be the state of the listview and this.getModel
> should directly return this state. This is probably due to the program idiom
> used.
>
>
>
> >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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