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https://issues.apache.org/jira/browse/WICKET-6410?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16062674#comment-16062674
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Fabian T. commented on WICKET-6410:
-----------------------------------
Hi Martin,
The behaviour when we use the “LoadableDetachableModel” is very similar to the
“AbstractReadOnlyModel”. The state handling is different, but we don’t really
need it in our case.
After a submit, “ChoiceRenderer#getObject” calls “choices.getObject()”, even if
nothing is selected in the dropdown (so the id is still null or empty). After
that, the Load method of LoadableDetachableModel is called. And in this load
method we still have our bigger SQL Statement.
In our understanding, “ChoiceRenderer#getObject” is just used to determine the
selected object in the dropdown, correct? So when no element is selected, why
do we need to call the load method? The getObject here is not called for
rendering the List in the Dropdown. The Dropdown is not refreshed, since after
submit only some components are refreshed via Ajax, but not our Dropdown with
the big SQL behind.
ChoiceRenderer:
{code:java}
@Override
public T getObject(String id, IModel<? extends List<? extends T>>
choices)
{
// We think the following four lines will prevent unnecessary
calls to getObject
// No choice selected, so no matching against the List of
choices
if (StringUtils.isBlank(id)) {
return null;
}
List<? extends T> _choices = choices.getObject();
for (int index = 0; index < _choices.size(); index++)
{
// Get next choice
final T choice = _choices.get(index);
if (getIdValue(choice, index).equals(id))
{
return choice;
}
}
return null;
}
{code}
Greetz
> ChoiceRenderer getObject always calls IModel#getObject when id is null
> ----------------------------------------------------------------------
>
> Key: WICKET-6410
> URL: https://issues.apache.org/jira/browse/WICKET-6410
> Project: Wicket
> Issue Type: Bug
> Components: wicket
> Affects Versions: 7.1.0
> Reporter: Fabian T.
> Priority: Trivial
> Attachments: debug_Screenshot.png
>
>
> {code:java}
> @Override
> public T getObject(String id, IModel<? extends List<? extends T>>
> choices)
> {
> List<? extends T> _choices = choices.getObject();
> for (int index = 0; index < _choices.size(); index++)
> {
> // Get next choice
> final T choice = _choices.get(index);
> if (getIdValue(choice, index).equals(id))
> {
> return choice;
> }
> }
> return null;
> }
> }
> {code}
> This Methode always calls „choices.getObject();”, even if the id is null or
> empty.
> In our project we got some bigger SQL Statements behind some getObject
> methods of different dropDownChoices. Avoiding to call getObject when the id
> is null or empty increases the performance.
> Feel free to correct me if I mess up something else with this fix.
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