super(l) stores the model as an instance variable on the superclass. When
getObject() is called on the LDM, it checks to see if the instance
variable (the model object) is null. If it is null, load() will be called
to populate the model. Once the request is complete the model is detached
(instance variable set to null). Then the cycle repeats...
A use case for super(l) is SortableDataProvider (SDP) seen below and taken
from Wicket repeaters example. The SDP retrieves the records of interest
for pagination using iterator(), then creates a model. If the object was
not passed into the DetachableContactModel, the load() method would make
another db call to populate the model.
public class SortableContactDataProvider extends SortableDataProvider<Contact>
{
public SortableContactDataProvider() {
// set default sort
setSort("firstName", SortOrder.ASCENDING);
}
public Iterator<Contact> iterator(int first, int count) {
return service.find(first, count, getSort()).iterator();
}
public int size() {
return service.getCount();
}
public IModel<Contact> model(Contact object) {
return new DetachableContactModel(object);
}
}
From: James Carman <ja...@carmanconsulting.com>
To: users@wicket.apache.org
Date: 03/01/2011 01:11 PM
Subject: Re: Perfomance of IDataProvider
Sent by: jcar...@carmanconsulting.com
It is referenced by the superclass (LoadableDetachableModel in this
case). It will "cache" the list until after the request cycle is
complete. Upon subsequent request cycles, the load() method will be
called to re-load the list.
On Tue, Mar 1, 2011 at 12:51 PM, Juansoft <andresnet2...@yahoo.es> wrote:
> Thank for the replies!
>
>
> MZemeck wrote:
>>
>> Here's a start, please anyone correct me if I've made any mistakes...
>>
>> public class ListLDM extends LoadableDetachableModel<List> {
>>
>> private String id;
>>
>> public ListLDM(List l, String id) {
>> //constructor with primed model
>> super(l);
>> this.id = id;
>> }
>>
>> public ListLDM(String id) {
>> //constructor with empty model
>> this.id = id;
>> }
>>
>> @Override
>> protected List load() {
>> return service.getList(id);
>> }
>>
>> }
>>
>>
>>
>
> In this example , the object that you're wrap in the inner model ("List
l"
> that you are send in super() constructor) is not used anywhere... ¿i'm
> wrong? in this case , ¿why should be using this (in reference a List l
in
> constructor)?
>
>
>
>
> -----
> Another "wicket" newbie programmer
> ********************************
> Wicket en Español -
>
> http://aprendiendowicket.wordpress.com
> --
> View this message in context:
http://apache-wicket.1842946.n4.nabble.com/Perfomance-of-IDataProvider-tp3325777p3330259.html
> Sent from the Users forum mailing list archive at Nabble.com.
>
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