Re: How to correctly implement a custom error page

[Joachim Rohde]

Thanks. Again I learned something new.

On 09/07/2016 12:47 PM, Martin Grigorov wrote:
> Hi,
> 
> You can also use PageRequestHandlerTracker to get a reference to the
> requested page (first handler) and to the response page (last handler).
> Everything else looks good to me!
> 
> Martin Grigorov
> Wicket Training and Consulting
> https://twitter.com/mtgrigorov
> 
> On Wed, Sep 7, 2016 at 11:36 AM, Joachim Rohde  wrote:
> 
>> Hi,
>>
>> I need to enrich the ExceptionErrorPage with some additional information.
>> Currently I have a working solution but I'm
>> not sure, if this is the correct way.
>>
>> My first try was (in my Application-class):
>>
>> /**
>>  * Define our own exception mapper.
>>  */
>> @Override
>> public IProvider getExceptionMapperProvider() {
>> return new IProvider() {
>>
>> @Override
>> public IExceptionMapper get() {
>> return new MyCustomExceptionMapper();
>> }
>> };
>> }
>>
>> /**
>>  * Our own exception mapper, so that we can display further
>> information on the error page
>>  * in case of an exception.
>>  */
>> public class MyCustomExceptionMapper extends DefaultExceptionMapper {
>>
>> @Override
>> public IRequestHandler map(Exception e) {
>> return new RenderPageRequestHandler(new PageProvider(new
>> MyErrorPage(e, super.extractCurrentPage(;
>> }
>>
>> }
>>
>> MyErrorPage extends from ExceptionErrorPage and overwrites
>> getErrorMessage(Throwable throwable).
>>
>> During development this works just fine but it was not feeling right.
>> Therefore I proposed a patch to implement a
>> hook-method (https://issues.apache.org/jira/browse/WICKET-6240) where
>> Martin mentioned:
>>
>> "The recommended way to do this is to register custom
>> IRequestCycleListener and override its #onException() method.
>> If the exception is IWicketInternalException then return null, otherwise
>> return RenderPageRequestHandler with a custom
>> page that renders all the information you need."
>>
>> So, at the moment I'm having in my init-method:
>>
>> getRequestCycleListeners().add(new AbstractRequestCycleListener() {
>> @Override
>> public IRequestHandler onException(RequestCycle cycle,
>> Exception ex) {
>> if (ex instanceof IWicketInternalException) {
>> return null;
>> } else {
>> Page page = null;
>>
>> IRequestHandler handler =
>> cycle.getActiveRequestHandler();
>>
>> if (handler == null) {
>> handler = cycle.getRequestHandlerScheduledAfte
>> rCurrent();
>> }
>>
>> if (handler instanceof IPageRequestHandler) {
>> IPageRequestHandler pageRequestHandler =
>> (IPageRequestHandler) handler;
>> page = (Page) pageRequestHandler.getPage();
>> }
>>
>> return new RenderPageRequestHandler(new
>> PageProvider(new MyErrorPage(ex, page)));
>> }
>> }
>>
>> });
>>
>> The code to retrieve the page comes basically from 
>> DefaultExceptionMapper#extractCurrentPage().
>> My question: is this the
>> way to go? Or can I simplify the code any further?
>>
>> Joachim
>>
>> -
>> To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org
>> For additional commands, e-mail: users-h...@wicket.apache.org
>>
>>
> 

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Re: How to correctly implement a custom error page

[Martin Grigorov]

Hi,

You can also use PageRequestHandlerTracker to get a reference to the
requested page (first handler) and to the response page (last handler).
Everything else looks good to me!

Martin Grigorov
Wicket Training and Consulting
https://twitter.com/mtgrigorov

On Wed, Sep 7, 2016 at 11:36 AM, Joachim Rohde  wrote:

> Hi,
>
> I need to enrich the ExceptionErrorPage with some additional information.
> Currently I have a working solution but I'm
> not sure, if this is the correct way.
>
> My first try was (in my Application-class):
>
> /**
>  * Define our own exception mapper.
>  */
> @Override
> public IProvider getExceptionMapperProvider() {
> return new IProvider() {
>
> @Override
> public IExceptionMapper get() {
> return new MyCustomExceptionMapper();
> }
> };
> }
>
> /**
>  * Our own exception mapper, so that we can display further
> information on the error page
>  * in case of an exception.
>  */
> public class MyCustomExceptionMapper extends DefaultExceptionMapper {
>
> @Override
> public IRequestHandler map(Exception e) {
> return new RenderPageRequestHandler(new PageProvider(new
> MyErrorPage(e, super.extractCurrentPage(;
> }
>
> }
>
> MyErrorPage extends from ExceptionErrorPage and overwrites
> getErrorMessage(Throwable throwable).
>
> During development this works just fine but it was not feeling right.
> Therefore I proposed a patch to implement a
> hook-method (https://issues.apache.org/jira/browse/WICKET-6240) where
> Martin mentioned:
>
> "The recommended way to do this is to register custom
> IRequestCycleListener and override its #onException() method.
> If the exception is IWicketInternalException then return null, otherwise
> return RenderPageRequestHandler with a custom
> page that renders all the information you need."
>
> So, at the moment I'm having in my init-method:
>
> getRequestCycleListeners().add(new AbstractRequestCycleListener() {
> @Override
> public IRequestHandler onException(RequestCycle cycle,
> Exception ex) {
> if (ex instanceof IWicketInternalException) {
> return null;
> } else {
> Page page = null;
>
> IRequestHandler handler =
> cycle.getActiveRequestHandler();
>
> if (handler == null) {
> handler = cycle.getRequestHandlerScheduledAfte
> rCurrent();
> }
>
> if (handler instanceof IPageRequestHandler) {
> IPageRequestHandler pageRequestHandler =
> (IPageRequestHandler) handler;
> page = (Page) pageRequestHandler.getPage();
> }
>
> return new RenderPageRequestHandler(new
> PageProvider(new MyErrorPage(ex, page)));
> }
> }
>
> });
>
> The code to retrieve the page comes basically from 
> DefaultExceptionMapper#extractCurrentPage().
> My question: is this the
> way to go? Or can I simplify the code any further?
>
> Joachim
>
> -
> To unsubscribe, e-mail: users-unsubscr...@wicket.apache.org
> For additional commands, e-mail: users-h...@wicket.apache.org
>
>

How to correctly implement a custom error page

[Joachim Rohde]

Hi,

I need to enrich the ExceptionErrorPage with some additional information. 
Currently I have a working solution but I'm
not sure, if this is the correct way.

My first try was (in my Application-class):

/**
 * Define our own exception mapper.
 */
@Override
public IProvider getExceptionMapperProvider() {
return new IProvider() {

@Override
public IExceptionMapper get() {
return new MyCustomExceptionMapper();
}
};
}

/**
 * Our own exception mapper, so that we can display further information on 
the error page
 * in case of an exception.
 */
public class MyCustomExceptionMapper extends DefaultExceptionMapper {

@Override
public IRequestHandler map(Exception e) {
return new RenderPageRequestHandler(new PageProvider(new 
MyErrorPage(e, super.extractCurrentPage(;
}

}

MyErrorPage extends from ExceptionErrorPage and overwrites 
getErrorMessage(Throwable throwable).

During development this works just fine but it was not feeling right. Therefore 
I proposed a patch to implement a
hook-method (https://issues.apache.org/jira/browse/WICKET-6240) where Martin 
mentioned:

"The recommended way to do this is to register custom IRequestCycleListener and 
override its #onException() method.
If the exception is IWicketInternalException then return null, otherwise return 
RenderPageRequestHandler with a custom
page that renders all the information you need."

So, at the moment I'm having in my init-method:

getRequestCycleListeners().add(new AbstractRequestCycleListener() {
@Override
public IRequestHandler onException(RequestCycle cycle, Exception 
ex) {
if (ex instanceof IWicketInternalException) {
return null;
} else {
Page page = null;

IRequestHandler handler = cycle.getActiveRequestHandler();

if (handler == null) {
handler = 
cycle.getRequestHandlerScheduledAfterCurrent();
}

if (handler instanceof IPageRequestHandler) {
IPageRequestHandler pageRequestHandler = 
(IPageRequestHandler) handler;
page = (Page) pageRequestHandler.getPage();
}

return new RenderPageRequestHandler(new PageProvider(new 
MyErrorPage(ex, page)));
}
}

});

The code to retrieve the page comes basically from 
DefaultExceptionMapper#extractCurrentPage(). My question: is this the
way to go? Or can I simplify the code any further?

Joachim

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