I don't want to keep a reference to to the resources byte array in the
link - I'd rather it was retrieved dynamically when requested. I also
don't really like constructing a bunch of stuff that's never going to be
used (and to be "null" - which is often a headache).
If I use the container component I outlined earlier, I can make the
model object be the object that holds the resource data (a hibernate
entity in my case). This means I can use getModelObject().getBytes(),
etc. in the wrapped link construction. An additional plus point with
this solution is that it is properly dynamic.
I think this works pretty well for this type of situation - there is no
extra null checking required (as it's all in the wrapper) and the logic
of it seems quite clear.
iainr
Luca Provenzani wrote:
why not something more directly like:
*public class ProvaLink extends ResourceLink {
ResourceReference resourceReference;
....
@Override
public boolean isVisible() {
if(resourceReference==null)return false;
else return true;
}
}
*hope to help...
Luca
2009/10/14 Iain Reddick <[email protected]>
I think my best solution is to use a lightweight container like this:
public class NullableContainer extends WebMarkupContainer {
public NullableContainer(String id) {
super(id);
}
public NullableContainer(String id, IModel model) {
super(id, model);
}
@Override
protected void onBeforeRender() {
super.onBeforeRender();
onPopulate(); }
/**
* Convenience method for lazy-adding of children
*/
protected void onPopulate() {
}
@Override
public boolean isVisible() {
return getModelObject() != null;
}
}
I then can override onPopulate() and add my children that depend on the
nullable for construction.
It's basically the logic equivalent of "if model is not null, add
children".
Iain Reddick wrote:
I'm fishing for best practice in this type of situation - do I use the
solution you outlined, or do I add a simple invisible dummy link instead of
the the resource link, or is there a better solution that I'm missing?
Luca Provenzani wrote:
i don't understand the problem....
can't you check the resource before link is rendered?
You can create a new resource object empty in the case of null
bytes....and
setVisible(false) or extend link to do this automatically on empty
resource...
Luca
2009/10/14 Iain Reddick <[email protected]>
Hi,
I need to display a resource link conditionally, based on whether a
resource exists, or is null. The resource itself is bytes in a database
and
should not be anchored to a component.
How should I handle this, with regard to the resource being nullable?
Thanks.
iainr
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