... In my rush to get out I hit post instead of preview. Now I've come back
and reviewed it here's a completed and *corrected* version, hopefully a bit
clearer and precise. Excuse any confusion caused.
Jeremy,
AbstractPropertyModel _should_ implement IChainingModel; this tells us about
its "type" and that's how we know it _will_ dig into passed in models
nesting models to get to a buried ModelObject. Whether you think its methods
have been correctly implemented and/or utilised here is another matter.
People will find the blog entry useful, but the issue I was (dubiously)
looking at is a bit more specific to PropertyModel's property expressions.
You and Igor are of course right that the contract is _not_ broken (as in my
initial post) - I was looking at the property expressions specifically.
public class TestPropertyModelsChainingImpl extends WebPage {
Point p = new Point(3,4);
Model m1 = new Model(p);
Model m2 = new Model(new Model(m1));
class Wrapper implements Serializable{Wrapper(Point p){this.object =
p;}Point object;}
Wrapper w = new Wrapper(p);
public TestPropertyModelsChainingImpl() {
add(new Label("x1", new PropertyModel(this, "m1.object.x")));
add(new Label("y1", new PropertyModel(this, "w.object.y")));
add(new Label("x2", new PropertyModel(m1, "x")));
add(new Label("y2", new PropertyModel(m2, "y")));
}
}
<html><body>{,},{,}</body></html>
You may need to fix the above html if it doesn't show properly
{[span wicket:id="x1"/],[span wicket:id="y1"/]},{[span
wicket:id="x2"/],[span wicket:id="y2"/]}
That gives {3,4},{3,4} as expected, and the chaining behaviour _is_ correct
when a model is passed in to the PropertyModel.
Whether
add(new Label("x", new PropertyModel(this, "m2.x")));
should also just work is in fact another matter.
Hopefully that's more sensible so I don't have to fix it again!
Regards - Cemal
http://www.jWeekend.co.uk http://jWeekend.co.uk
jWeekend wrote:
>
> Jeremy,
>
> People will find your blog entry useful, but this issue is a bit more
> specific.
>
> AbstractPropertyModel _should_ implement IChainingModel, that's how you
> know it _should_ dig values out model objects which r themselves models.
>
> Now try this:
>
> public class TestPropertyModelsChainingImpl extends WebPage {
> Point p = new Point(3,4);
> Model m = new Model(p);
> class Wrapper{Wrapper(Point p){this.object = p;}Point object;}
> Wrapper w = new Wrapper(p);
> public TestPropertyModelsChainingImpl() {
> add(new Label("x", new PropertyModel(this, "m.object.x")));
> add(new Label("y", new PropertyModel(this, "w.object.y")));
> }
> }
>
> <html><body>,</body></html>
>
>
>
>
>
>
>
> Jeremy Thomerson-5 wrote:
>>
>> John, Cemal - that method in AbstractPropertyModel absolutely does abide
>> by
>> the contract - look at what it calls (getTarget()):
>>
>> public final Object getTarget()
>> {
>> Object object = target;
>> while (object instanceof IModel)
>> {
>> Object tmp = ((IModel<?>)object).getObject();
>> if (tmp == object)
>> break;
>> object = tmp;
>> }
>> return object;
>> }
>> John - I think you're right - it is unnecessary to implement
>> IChainingModel
>> since there is no code in the wicket core codebase that calls it's
>> methods.
>> Just make sure that if you nest models inside of other custom models, you
>> do
>> call detach properly or you can end up with a memory leak. You can see
>> this
>> blog post as a simple example:
>> http://www.jeremythomerson.com/blog/2008/11/06/wicket-the-power-of-nested-models/
>>
>> Hope this helps.
>>
>> --
>> Jeremy Thomerson
>> http://www.wickettraining.com
>>
>>
>> On Thu, Dec 4, 2008 at 9:31 AM, jWeekend
>> <[EMAIL PROTECTED]>wrote:
>>
>>>
>>> John,
>>>
>>> Well spotted. AbstractPropertyModel implements IChainingModel but breaks
>>> its
>>> contract :
>>> * Models that implement this interface will support chaining of
>>> IModels.
>>> getObject() of a
>>> * IChainingModel should do something like:
>>> *
>>> * <pre>
>>> * if ( object instanceof IModel) { return ((IModel)object).getObject()}
>>> * else return object;
>>> * </pre>
>>>
>>> Its getObject() implementation does not abide by this.
>>> /**
>>> * @see org.apache.wicket.model.IModel#getObject()
>>> */
>>> public Object getObject()
>>> {
>>> final String expression = propertyExpression();
>>> if (Strings.isEmpty(expression))
>>> {
>>> // Return a meaningful value for an empty
>>> property
>>> expression
>>> return getTarget();
>>> }
>>>
>>> final Object target = getTarget();
>>> if (target != null)
>>> {
>>> return PropertyResolver.getValue(expression,
>>> target);
>>> }
>>> return null;
>>> }
>>>
>>> Regards - Cemal
>>> http://www.jWeekend.co.uk <http://www.jweekend.co.uk/>
>>> http://jWeekend.co.uk <http://jweekend.co.uk/>
>>>
>>>
>>>
>>> John Patterson wrote:
>>> >
>>> > Hi,
>>> >
>>> > I'm messing about with nested models and see the IChainingModel
>>> interface
>>> > which is implemented by the PropertyModels but its methods never
>>> actually
>>> > seems to be used.
>>> >
>>> > So I'm just checking that I haven't missed anything... for nested
>>> models
>>> I
>>> > don't actually need to implement this right?
>>> >
>>> > This is its def:
>>> >
>>> >
>>> > public interface IChainingModel<T> extends IModel<T>
>>> > {
>>> > /**
>>> > * Sets the model that is chained inside this model.
>>> > *
>>> > * @param model
>>> > */
>>> > public void setChainedModel(IModel< ? > model);
>>> >
>>> > /**
>>> > * Returns the chained model if there is a chained model.
>>> > *
>>> > * @return The chained model
>>> > */
>>> > public IModel< ? > getChainedModel();
>>> >
>>> > }
>>> >
>>> > Thanks,
>>> >
>>> > John
>>> >
>>> >
>>> >
>>>
>>> --
>>> View this message in context:
>>> http://www.nabble.com/IChainingModel-tp20835085p20835745.html
>>> Sent from the Wicket - User mailing list archive at Nabble.com.
>>>
>>>
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>>>
>>>
>>
>>
>
>
--
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http://www.nabble.com/IChainingModel-tp20835085p20853246.html
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