I've found a bug in wicket with the use of FeedbackPanel for messages on
events during page construction.
For example when a page is constructed using information from the dao to
fill a dropdownChoice and some non-fatal event occurs during the trip to
the dao.
The bug is this:
- If a feedbackPanel is created in the Page constructor, info messages
added during onAttach do not reach it. The only way to get these
messages on the feedbackPanel is to explicitely add them through the
Session:
getSession().info("message");
And then the page has to be refreshed to view the messages - no
surprise, this is in the API.
- And if the feedbackPanel is created during onAttach, the error below
occurs. I sometimes use onAttach to call a method to initialize
components because that way i have a page and therefore a full path
during component construction, enabling me to get to use
internationalization.
Here is the simplest code producing the bug:
import wicket.markup.html.WebPage;
import wicket.markup.html.panel.FeedbackPanel;
public class TestPage extends WebPage {
public TestPage() {
add(new FeedbackPanel("feedback"));
}
@Override
protected void onAttach() {
super.onAttach();
// if the feedbackPanel is created and/or added here instead of
in the constructor,
// an error occurs
//add(new FeedbackPanel("feedback"));
info("Hello user, a non-fatal exception occured during page
construction");
}
}
I have tried what happens if a form and other components are added to
the page but its basically the same.
If the feedbackPanel was instantiated and added to the form during the
overridden onAttach methos, the same error appeared.
Is this really a bug?
cheers,
Ivana
************ BEGIN ERROR **************
WicketMessage: Exception in rendering component: [MarkupContainer
[Component id = feedbackul, page = testPackage.TestPage, path =
51:feedback:feedbackul.FeedbackPanel$2, isVisible = true, isVersioned =
false]]
Root cause:
java.lang.NullPointerException
at wicket.markup.html.list.ListView.renderItem(ListView.java:676)
at wicket.markup.html.list.ListView.onRender(ListView.java:637)
at wicket.Component.render(Component.java:1526)
at wicket.MarkupContainer.renderNext(MarkupContainer.java:1334)
at wicket.MarkupContainer.renderComponentTagBody(MarkupContainer.java:982)
at wicket.MarkupContainer.onComponentTagBody(MarkupContainer.java:917)
at wicket.Component.renderComponent(Component.java:1712)
.
.
.
Page
[Page class = testPackage.TestPage, id = 51]:
# Path Size Type Model Object
1 <auto>_header 481 bytes
wicket.markup.html.internal.HtmlHeaderContainer
2 _<body> 425 bytes
wicket.markup.html.internal.HtmlBodyContainer
3 feedback 1.5K
wicket.markup.html.panel.FeedbackPanel
4 feedback:feedbackul 2.7K
wicket.markup.html.WebMarkupContainer
5 feedback:feedbackul:messages 2.7K
wicket.markup.html.list.ListView [[FeedbackMessage message =
"Hello user, a non-fatal exception occured during page
construction", reporter = 51, level = INFO], [FeedbackMessage
message = "Hello user, a non-fatal exception occured during page
construction", reporter = null, level = INFO], [FeedbackMessage
message = "Hello user, a non-fatal exception occured during page
construction", reporter = null, level = INFO], [FeedbackMessage
message = "Hello user, a non-fatal exception occured during page
construction", reporter = null, level = INFO], [FeedbackMessage
message = "Hello user, a non-fatal exception occured during page
construction", reporter = null, level = INFO]]
************ END ERROR **************
--
Ivana Cace
Func. Internet Integration
W http://www.func.nl
T +31 20 4230000
F +31 20 4223500
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