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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