Thanks for the explanation. Still, one questions remains: is there
a fundamental problem with the first approach or is it ok to use
the object directly?
J.
Igor Vaynberg wrote:
final TestItem itemModel = (TestItem) item.getModelObject();
^ on this line you retrieve the object from the model, you then use
this reference inside the onclick() which is called during another
request. since you use the model object reference directly it is not
loaded from the model.
my code, on the other hand, never keeps a direct reference to the
model object, instead it retrieves it from the model inside onclick()
-igor
On Thu, Oct 2, 2008 at 10:10 AM, Jürgen Lind <[EMAIL PROTECTED]> wrote:
Igor Vaynberg wrote:
your link works on the object and not on the model, instead
add(new link("delete", item.getmodel()) { onclick() {
delete(getmodelobject()); }});
Thank you for your quick reply.
Well the code is roughly the same(?) as in Listing 5.12 of WiA and there
a custom Model is used to illustrate the solution. However, I thought my
test would show me the problem first... Using your code above, the
effect is as expected, i.e. the "wrong" (new) item is returned to be
deleted.
Now, the question is, what is wrong with my first implementation?
It would seem that the problem that is solved using a custom ItemModel
does not even occur. Or does that code prevent wicket from effectively
detaching model objects and should thus be avoided? What would be the
best practice here?
J.
-igor
On Thu, Oct 2, 2008 at 9:04 AM, Jürgen Lind <[EMAIL PROTECTED]>
wrote:
Hi there,
I have been struggling for some time now to understand how
LoadableDetachableModel and a ListView work together. The starting point
was Chapter 5.5.2 of "Wicket in Action" where it is recommended to
provide
your own ItemModel if the underlying list changes frequently. To try out
how Wicket behaves without such a custom ItemModel, I wrote the following
Test:
<body>
<em wicket:id="listview">
<span wicket:id="label"></span><a wicket:id="delete">delete</a>
</em>
</body>
LoadableDetachableModel model = new LoadableDetachableModel() {
@Override
protected Object load() {
System.out.println("load");
return Arrays.asList(new TestItem[] {
new TestItem("a" + Math.random()),
new TestItem("b" + Math.random()),
new TestItem("c" + Math.random()) });
}
protected void onDetach() {
System.out.println("detach");
}
};
ListView listview = new ListView("listview", model) {
protected void populateItem(ListItem item) {
final TestItem itemModel = (TestItem) item.getModelObject();
item.add(new Label("label", itemModel.toString()));
item.add(new Link("delete") {
@Override
public void onClick() {
System.out.println("Delete " + itemModel);
}
});
}
};
add(listview);
Now, I would expect that when I hit the "delete" link, Wicket would call
the
"load" Method of the LoadableDetachableModel before printing "Delete..."
as
the
default implementation will use the index and the list to determine the
item
to
delete. To my surprise, however, the "Delete..." message is printed with
the
correct item and the "load" Method is called afterwards. In my
understanding,
this contradicts the idea of the LoadableDetachableModel since Wicket
seems
to
have a copy of the original list somewhere so that it can determine the
list
item on which the action was invoked before loading the underlying list.
Can someone spot my mistake?
Thanks,
J.
--
Dr. Jürgen Lind
iteratec GmbH Fon: +49 (0)89 614551-44
Inselkammerstrasse 4 Fax: +49 (0)89 614551-10
82008 Unterhaching Web: www.iteratec.de
Sitz und Registergericht der iteratec GmbH: München HRB 113 519
Geschäftsführer: Klaus Eberhardt, Mark Goerke, Inge Hanschke, Ralf Menzel
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
--
Dr. Jürgen Lind
iteratec GmbH Fon: +49 (0)89 614551-44
Inselkammerstrasse 4 Fax: +49 (0)89 614551-10
82008 Unterhaching Web: www.iteratec.de
Sitz und Registergericht der iteratec GmbH: München HRB 113 519
Geschäftsführer: Klaus Eberhardt, Mark Goerke, Inge Hanschke, Ralf Menzel
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
--
Dr. Jürgen Lind
iteratec GmbH Fon: +49 (0)89 614551-44
Inselkammerstrasse 4 Fax: +49 (0)89 614551-10
82008 Unterhaching Web: www.iteratec.de
Sitz und Registergericht der iteratec GmbH: München HRB 113 519
Geschäftsführer: Klaus Eberhardt, Mark Goerke, Inge Hanschke, Ralf Menzel
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
