We're in the process of reconsidering the ListView implementation alltogether I
think.
If you really want this, you could provide a custom list that does this. That
list could lazily load it's size: when not set yet, you load the actual list
(e.g. from a database), but when set, return it. And then the actual loading
should occur when one of it's accessor methods (like get(int) is called.
E.g (haven't tested it, but the idea should work):
public class LazyList extends ArrayList
{
private int size = -1;
private boolean loaded = false;
public LazyList(List list)
{
addAll(list);
}
public int size()
{
if(size == -1)
{
load();
this.size = super.size();
}
}
public get(int index)
{
load();
return super.get(index);
}
public void unload()
{
this.loaded = false;
}
private void load()
{
if(!loaded)
{
this.loaded = true;
// do loading here and call super.addAll(..)
}
}
.... etc ....
}
and your model is like:
public class MyModel extends AbstractDetachableModel
private LazyList myList; // keep reference to list allways; it'll usually be
empty
protected void onAttach()
{
if(myList == null)
{
myList = new LazyList(getSomeList());
}
}
protected void onDetach()
{
myList.unload();
}
protected Object onGetObject(Component component)
{
return myList;
}
.... etc ....
Btw, this might be a usefull pattern to either put on the Wiki or in contrib.
It's far more efficient for those cases where you have a list that doesn't
change over requests, are that you want to 'push' the changes in, together with
a ListView that doesn't remove it's items on each request.
Eelco
It just happens that in my case - using a ListView - the list view calls
getModelObject within the onRender method (via getViewSize) this is causing
my detached model to re-attach for every request - even repeated
IredirectListener requests.
Could this component possibly be changed to remember the size of the list ?
Cameron
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