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https://issues.apache.org/jira/browse/WICKET-5466?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Sven Meier reassigned WICKET-5466:
----------------------------------
Assignee: Sven Meier
> ListenerInterfaceRequestHandler#respond throws ComponentNotFoundException as
> a side-effect
> ------------------------------------------------------------------------------------------
>
> Key: WICKET-5466
> URL: https://issues.apache.org/jira/browse/WICKET-5466
> Project: Wicket
> Issue Type: Bug
> Components: wicket
> Affects Versions: 6.12.0
> Reporter: Christoph Läubrich
> Assignee: Sven Meier
>
> The following exception occurs instead of a generic WicketRuntimeException:
> 16:27:56.181 WARN (RequestCycle.java:343) Handling the following exception
> [qtp9826071-207]
> org.apache.wicket.core.request.handler.ComponentNotFoundException: Could not
> find component 'xyz' on page 'class MyPage’
> at
> org.apache.wicket.core.request.handler.PageAndComponentProvider.getComponent(PageAndComponentProvider.java:182)
> ~[org.apache.wicket.core_6.12.0.jar:6.12.0]
> at
> org.apache.wicket.core.request.handler.ListenerInterfaceRequestHandler.getComponent(ListenerInterfaceRequestHandler.java:90)
> ~[org.apache.wicket.core_6.12.0.jar:6.12.0]
> at
> org.apache.wicket.core.request.handler.ListenerInterfaceRequestHandler.respond(ListenerInterfaceRequestHandler.java:231)
> ~[org.apache.wicket.core_6.12.0.jar:6.12.0]
> at
> org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:861)
> ~[org.apache.wicket.core_6.12.0.jar:6.12.0]
> at
> org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
> ~[org.apache.wicket.request_6.12.0.jar:6.12.0]
> at
> org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:261)
> [org.apache.wicket.core_6.12.0.jar:6.12.0]
> at
> org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:218)
> [org.apache.wicket.core_6.12.0.jar:6.12.0]
> at
> org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:289)
> [org.apache.wicket.core_6.12.0.jar:6.12.0]
> at
> org.apache.wicket.protocol.http.WicketFilter.processRequestCycle(WicketFilter.java:259)
> [org.apache.wicket.core_6.12.0.jar:6.12.0]
> in fact, this is a side effect, if you look at the code:
> @Override
> public void respond(final IRequestCycle requestCycle)
> {
> final IRequestablePage page = getPage();
> final boolean freshPage =
> pageComponentProvider.isPageInstanceFresh();
> final boolean isAjax =
> ((WebRequest)requestCycle.getRequest()).isAjax();
> IRequestableComponent component = null;
> try
> {
> component = getComponent();
> }
> catch (ComponentNotFoundException e)
> {
> // either the page is stateless and the component we are
> looking for is not added in the
> // constructor
> // or the page is stateful+stale and a new instances was
> created by pageprovider
> // we denote this by setting component to null
> component = null;
> }
> if ((component == null && freshPage) ||
> (component != null && getComponent().getPage() == page))
> {
> [....]
> }
> else
> {
> throw new WicketRuntimeException("Component " +
> getComponent() +
> " has been removed from page.");
> }
> }
> You see that getComponent() is called twice.
> 1) Once guarded by a catch
> - and -
> 2) once unguarded
> So if the component can't be found AND freshPage is false, as a sideeffect
> instead of the WicketRuntimeException with the removed message a
> componentnotfound exception is raised as a side effect.
> I see two possible solutions for this
> a) either it is intentional that a ComponentNotFoundException is thrown, then
> it should be thrown from the catch block like
> catch (ComponentNotFoundException e)
> {
> if (!freshPage) {
> throw e;
> }
> }
> b) if it is unintentionall in the else case ther should be a simple check
> like this
> if (component == null) {
> throw new WicketRuntimeException("Component for path
> " + getPath() +
> " and page "+page.getClass().getName()+" has been
> removed from page.");
> } else {
> throw new WicketRuntimeException("Component " +
> component +
> " has been removed from page.");
> }
> Beside this: it would be a good idea to mention at least the page class in
> either case.
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