Thank you , I solve most of questions , except this :
In the MyPage extends WebPage :
//fieldX returns an Integer[] array
MyPanel myPanel = new MyPanel("myPanel" , new PropertyModel(model ,
"fieldX")
{
@Override
public Object getObject()
{
Integer[] ints = (Integer[]) super.getObject();
return getMyObjectFromInts(ints);
}
});
add(myPanel);
............................................
And in the MyPanel :
public MyPanel(String id, final IModel model)
{
super(id , model);
Link myLink = new Link("myLink")
{
@Override
public void onClick()
{
Map<String , Object> parameterMap = new HashMap<String , Object>();
parameterMap.put("index" , new PropertyModel(model ,
"index").getObject().toString()); // OK
parameterMap.put("locale" , getSession().getLocale());
PageParameters pps = new PageParameters(parameterMap);
setResponsePage(HexagramPage.class , pps);
}
@Override
protected void onBeforeRender()
{
super.onBeforeRender();
add(new SimpleAttributeModifier("title" , new PropertyModel(model ,
"name").getObject().toString())); // , OK
}
};
//draw an Icon depending on index value
myLink.add(new Image("hexagramImage" , new
ResourceReference(MyObject.class , "icons/byIndex/"+ new
PropertyModel(model,"index").getObject().toString()+".gif"))); //FAILED
Here ! it goes problem!
It will throw a NPE :
java.lang.NullPointerException
at ....
at MyPage$2.getObject(MyPage.java:119) <-------- the
getMyObjectFromInts() line
at
org.apache.wicket.model.AbstractPropertyModel.getTarget(AbstractPropertyModel.java:187)
at
org.apache.wicket.model.AbstractPropertyModel.getObject(AbstractPropertyModel.java:110)
at MyPanel.<init>(MyPanel.java:49) <-------- the ResourceReference line
As MyPage shows , I use getMyObjectFromInts() to transform fieldX's return
value to my custom object....
And in MyPanel , I can successfully get myObject's index , name values , but
it fails at the last line!
It constructs a ResourceReference object by initializing a String , which
takes myObject's "index" value.
I use the same "new PropertyModel(model,"index").getObject().toString() " ,
successes first but fails second , why ?
How to solve this ?
2008/5/3 Per Newgro <[EMAIL PROTECTED]>:
> Hello smallufo:
>
> > public class MyPanel extends Panel
> > {
> > private MyObj myObj;
> >
> > public MyPanel(String id , IModel model)
> > {
> > super(id);
> > this.myObj = (MyObj) model.getObject();
> >
> > add(new Label("xxx" , myObj.getFieldX.toString()));
> > add(new Label("yyy" , myObj.getFieldY.toString()));
> >
> > }
> > }
>
> This is the problem. Don't store the instance in the panel. Use the
> provided
> model. The Labels can get their data by a PropertyModel related to that
> model.
> public class MyPanel extends Panel
> {
> // removed while not required private MyObj myObj;
>
> public MyPanel(String id , IModel model)
> {
> super(id, model); <-- use this constructor
> // removed while not required this.myObj = (MyObj) model.getObject();
>
> // instead add(new Label("xxx" , myObj.getFieldX.toString()));
> add(new Label("xxx" , new PropertyModel(model, "fieldX")));
> // instead add(new Label("yyy" , myObj.getFieldY.toString()));
> add(new Label("yyy" , new PropertyModel(model, "fieldY")));
> }
> }
>
> You simply wire the models together. So a model related to view can't be
> null
> (instanciated in panel self). That's what i mean if i always say "path to
> data". It's a description which properties have to be used to get the
> data.
> So the underlying business object can be null. The behavior if a null will
> be
> return will be determined by the component. A label for instance is
> displaying simply a blank. Textfield to.
>
> HTH
> Per
>
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>
>
