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Posted to users@wicket.apache.org by Daniel Watrous <dw...@gmail.com> on 2013/07/23 17:20:49 UTC
Wicket, Guice and the $Proxy object
Hi,
I'm having an issue that I suspect is related to the wicket integration
with Guice. Any help is appreciated.
I have a Page class that uses field injection to inject a DAO. I then want
to cast my DAO to a more specific type (what I inject is the interface).
Here's what that looks like
public class CnavModify extends ConsoleBasePage {
@Inject private CnavUrlDAO cnavUrlDAO;
public CnavModify(PageParameters parameters) {
super(parameters);
if (parameters.get("cnavid").toString() != null) {
cnavid = new ObjectId(parameters.get("cnavid").toString());
}
if (cnavid != null) {
cnavUrlModel = new
DetachableCnavUrlModel(((MorphiaCnavUrlDAO)cnavUrlDAO).getCnavById(cnavid));
}
}
}
When I try to cast it I get the following error:
Last cause: $Proxy23 cannot be cast to
com.hp.honeybadger.persistence.dao.morphia.MorphiaCnavUrlDAO
I am able to use the CnavUrlDAO as a CnavUrlDAO, but its type is $Proxy23
and I am unable to cast it to a concrete type.
Is this Guice or Wicket related? Any idea how to get around this?
Thanks,
Daniel
Re: Wicket, Guice and the $Proxy object
Posted by Daniel Watrous <dw...@gmail.com>.
Here's a little more detail when I debug and attempt to do just the cast:
Cannot cast an instance of "class $Proxy23 (loaded by instance of
org.eclipse.jetty.webapp.WebAppClassLoader(id=3511))" to an instance of
"class com.hp.honeybadger.persistence.dao.morphia.MorphiaCnavUrlDAO (loaded
by instance of sun.misc.Launcher$AppClassLoader(id=2450))"
On Tue, Jul 23, 2013 at 9:20 AM, Daniel Watrous <dw...@gmail.com>wrote:
> Hi,
>
> I'm having an issue that I suspect is related to the wicket integration
> with Guice. Any help is appreciated.
>
> I have a Page class that uses field injection to inject a DAO. I then want
> to cast my DAO to a more specific type (what I inject is the interface).
> Here's what that looks like
>
> public class CnavModify extends ConsoleBasePage {
>
> @Inject private CnavUrlDAO cnavUrlDAO;
> public CnavModify(PageParameters parameters) {
> super(parameters);
> if (parameters.get("cnavid").toString() != null) {
> cnavid = new ObjectId(parameters.get("cnavid").toString());
> }
> if (cnavid != null) {
> cnavUrlModel = new
> DetachableCnavUrlModel(((MorphiaCnavUrlDAO)cnavUrlDAO).getCnavById(cnavid));
> }
> }
> }
>
> When I try to cast it I get the following error:
>
> Last cause: $Proxy23 cannot be cast to
> com.hp.honeybadger.persistence.dao.morphia.MorphiaCnavUrlDAO
>
> I am able to use the CnavUrlDAO as a CnavUrlDAO, but its type is $Proxy23
> and I am unable to cast it to a concrete type.
>
> Is this Guice or Wicket related? Any idea how to get around this?
>
> Thanks,
> Daniel
>
Re: Wicket, Guice and the $Proxy object
Posted by Daniel Watrous <dw...@gmail.com>.
Here's a post that helped me understand this better:
http://stackoverflow.com/questions/16047829/proxy-cannot-be-cast-to-class
On Tue, Jul 23, 2013 at 2:15 PM, Daniel Watrous <dw...@gmail.com>wrote:
> Dan,
>
> Good point. After considering I decided to modify my interface to expose
> the function I need and let the implementation worry about casting where
> necessary.
>
> Thanks,
> Daniel
>
>
> On Tue, Jul 23, 2013 at 9:58 AM, Dan Retzlaff <dr...@gmail.com> wrote:
>
>> @Inject the implementation, not the interface. @Inject'd implementations
>> have some code smell, but no more than downcasting.
>>
>>
>> On Tue, Jul 23, 2013 at 8:40 AM, Daniel Watrous <dwmaillist@gmail.com
>> >wrote:
>>
>> > That being the case, is there any way to get an instance that I can
>> cast to
>> > a concrete type?
>> >
>> >
>> > On Tue, Jul 23, 2013 at 9:27 AM, Martin Grigorov <mgrigorov@apache.org
>> > >wrote:
>> >
>> > > Hi,
>> > >
>> > >
>> > > On Tue, Jul 23, 2013 at 6:20 PM, Daniel Watrous <dwmaillist@gmail.com
>> > > >wrote:
>> > >
>> > > > Hi,
>> > > >
>> > > > I'm having an issue that I suspect is related to the wicket
>> integration
>> > > > with Guice. Any help is appreciated.
>> > > >
>> > > > I have a Page class that uses field injection to inject a DAO. I
>> then
>> > > want
>> > > > to cast my DAO to a more specific type (what I inject is the
>> > interface).
>> > > > Here's what that looks like
>> > > >
>> > > > public class CnavModify extends ConsoleBasePage {
>> > > >
>> > > > @Inject private CnavUrlDAO cnavUrlDAO;
>> > > > public CnavModify(PageParameters parameters) {
>> > > > super(parameters);
>> > > > if (parameters.get("cnavid").toString() != null) {
>> > > > cnavid = new
>> ObjectId(parameters.get("cnavid").toString());
>> > > > }
>> > > > if (cnavid != null) {
>> > > > cnavUrlModel = new
>> > > >
>> > > >
>> > >
>> >
>> DetachableCnavUrlModel(((MorphiaCnavUrlDAO)cnavUrlDAO).getCnavById(cnavid));
>> > > > }
>> > > > }
>> > > > }
>> > > >
>> > > > When I try to cast it I get the following error:
>> > > >
>> > > > Last cause: $Proxy23 cannot be cast to
>> > > > com.hp.honeybadger.persistence.dao.morphia.MorphiaCnavUrlDAO
>> > > >
>> > > > I am able to use the CnavUrlDAO as a CnavUrlDAO, but its type is
>> > $Proxy23
>> > > > and I am unable to cast it to a concrete type.
>> > > >
>> > > > Is this Guice or Wicket related? Any idea how to get around this?
>> > > >
>> > >
>> > > It is an error in your assumption.
>> > >
>> > > Wicket injects a proxy that implements CnavUrlDAO but knows nothing
>> about
>> > > the specific implementation about this interface.
>> > > Whenever the proxy is used it delegates the call to the bean/service
>> > > returned by Guice's injector (something like:
>> > > Injector.getBinding(CnavUrlDAO.class).doSomething()).
>> > >
>> > >
>> > > >
>> > > > Thanks,
>> > > > Daniel
>> > > >
>> > >
>> >
>>
>
>
Re: Wicket, Guice and the $Proxy object
Posted by Daniel Watrous <dw...@gmail.com>.
Dan,
Good point. After considering I decided to modify my interface to expose
the function I need and let the implementation worry about casting where
necessary.
Thanks,
Daniel
On Tue, Jul 23, 2013 at 9:58 AM, Dan Retzlaff <dr...@gmail.com> wrote:
> @Inject the implementation, not the interface. @Inject'd implementations
> have some code smell, but no more than downcasting.
>
>
> On Tue, Jul 23, 2013 at 8:40 AM, Daniel Watrous <dwmaillist@gmail.com
> >wrote:
>
> > That being the case, is there any way to get an instance that I can cast
> to
> > a concrete type?
> >
> >
> > On Tue, Jul 23, 2013 at 9:27 AM, Martin Grigorov <mgrigorov@apache.org
> > >wrote:
> >
> > > Hi,
> > >
> > >
> > > On Tue, Jul 23, 2013 at 6:20 PM, Daniel Watrous <dwmaillist@gmail.com
> > > >wrote:
> > >
> > > > Hi,
> > > >
> > > > I'm having an issue that I suspect is related to the wicket
> integration
> > > > with Guice. Any help is appreciated.
> > > >
> > > > I have a Page class that uses field injection to inject a DAO. I then
> > > want
> > > > to cast my DAO to a more specific type (what I inject is the
> > interface).
> > > > Here's what that looks like
> > > >
> > > > public class CnavModify extends ConsoleBasePage {
> > > >
> > > > @Inject private CnavUrlDAO cnavUrlDAO;
> > > > public CnavModify(PageParameters parameters) {
> > > > super(parameters);
> > > > if (parameters.get("cnavid").toString() != null) {
> > > > cnavid = new
> ObjectId(parameters.get("cnavid").toString());
> > > > }
> > > > if (cnavid != null) {
> > > > cnavUrlModel = new
> > > >
> > > >
> > >
> >
> DetachableCnavUrlModel(((MorphiaCnavUrlDAO)cnavUrlDAO).getCnavById(cnavid));
> > > > }
> > > > }
> > > > }
> > > >
> > > > When I try to cast it I get the following error:
> > > >
> > > > Last cause: $Proxy23 cannot be cast to
> > > > com.hp.honeybadger.persistence.dao.morphia.MorphiaCnavUrlDAO
> > > >
> > > > I am able to use the CnavUrlDAO as a CnavUrlDAO, but its type is
> > $Proxy23
> > > > and I am unable to cast it to a concrete type.
> > > >
> > > > Is this Guice or Wicket related? Any idea how to get around this?
> > > >
> > >
> > > It is an error in your assumption.
> > >
> > > Wicket injects a proxy that implements CnavUrlDAO but knows nothing
> about
> > > the specific implementation about this interface.
> > > Whenever the proxy is used it delegates the call to the bean/service
> > > returned by Guice's injector (something like:
> > > Injector.getBinding(CnavUrlDAO.class).doSomething()).
> > >
> > >
> > > >
> > > > Thanks,
> > > > Daniel
> > > >
> > >
> >
>
Re: Wicket, Guice and the $Proxy object
Posted by Dan Retzlaff <dr...@gmail.com>.
@Inject the implementation, not the interface. @Inject'd implementations
have some code smell, but no more than downcasting.
On Tue, Jul 23, 2013 at 8:40 AM, Daniel Watrous <dw...@gmail.com>wrote:
> That being the case, is there any way to get an instance that I can cast to
> a concrete type?
>
>
> On Tue, Jul 23, 2013 at 9:27 AM, Martin Grigorov <mgrigorov@apache.org
> >wrote:
>
> > Hi,
> >
> >
> > On Tue, Jul 23, 2013 at 6:20 PM, Daniel Watrous <dwmaillist@gmail.com
> > >wrote:
> >
> > > Hi,
> > >
> > > I'm having an issue that I suspect is related to the wicket integration
> > > with Guice. Any help is appreciated.
> > >
> > > I have a Page class that uses field injection to inject a DAO. I then
> > want
> > > to cast my DAO to a more specific type (what I inject is the
> interface).
> > > Here's what that looks like
> > >
> > > public class CnavModify extends ConsoleBasePage {
> > >
> > > @Inject private CnavUrlDAO cnavUrlDAO;
> > > public CnavModify(PageParameters parameters) {
> > > super(parameters);
> > > if (parameters.get("cnavid").toString() != null) {
> > > cnavid = new ObjectId(parameters.get("cnavid").toString());
> > > }
> > > if (cnavid != null) {
> > > cnavUrlModel = new
> > >
> > >
> >
> DetachableCnavUrlModel(((MorphiaCnavUrlDAO)cnavUrlDAO).getCnavById(cnavid));
> > > }
> > > }
> > > }
> > >
> > > When I try to cast it I get the following error:
> > >
> > > Last cause: $Proxy23 cannot be cast to
> > > com.hp.honeybadger.persistence.dao.morphia.MorphiaCnavUrlDAO
> > >
> > > I am able to use the CnavUrlDAO as a CnavUrlDAO, but its type is
> $Proxy23
> > > and I am unable to cast it to a concrete type.
> > >
> > > Is this Guice or Wicket related? Any idea how to get around this?
> > >
> >
> > It is an error in your assumption.
> >
> > Wicket injects a proxy that implements CnavUrlDAO but knows nothing about
> > the specific implementation about this interface.
> > Whenever the proxy is used it delegates the call to the bean/service
> > returned by Guice's injector (something like:
> > Injector.getBinding(CnavUrlDAO.class).doSomething()).
> >
> >
> > >
> > > Thanks,
> > > Daniel
> > >
> >
>
Re: Wicket, Guice and the $Proxy object
Posted by Daniel Watrous <dw...@gmail.com>.
That being the case, is there any way to get an instance that I can cast to
a concrete type?
On Tue, Jul 23, 2013 at 9:27 AM, Martin Grigorov <mg...@apache.org>wrote:
> Hi,
>
>
> On Tue, Jul 23, 2013 at 6:20 PM, Daniel Watrous <dwmaillist@gmail.com
> >wrote:
>
> > Hi,
> >
> > I'm having an issue that I suspect is related to the wicket integration
> > with Guice. Any help is appreciated.
> >
> > I have a Page class that uses field injection to inject a DAO. I then
> want
> > to cast my DAO to a more specific type (what I inject is the interface).
> > Here's what that looks like
> >
> > public class CnavModify extends ConsoleBasePage {
> >
> > @Inject private CnavUrlDAO cnavUrlDAO;
> > public CnavModify(PageParameters parameters) {
> > super(parameters);
> > if (parameters.get("cnavid").toString() != null) {
> > cnavid = new ObjectId(parameters.get("cnavid").toString());
> > }
> > if (cnavid != null) {
> > cnavUrlModel = new
> >
> >
> DetachableCnavUrlModel(((MorphiaCnavUrlDAO)cnavUrlDAO).getCnavById(cnavid));
> > }
> > }
> > }
> >
> > When I try to cast it I get the following error:
> >
> > Last cause: $Proxy23 cannot be cast to
> > com.hp.honeybadger.persistence.dao.morphia.MorphiaCnavUrlDAO
> >
> > I am able to use the CnavUrlDAO as a CnavUrlDAO, but its type is $Proxy23
> > and I am unable to cast it to a concrete type.
> >
> > Is this Guice or Wicket related? Any idea how to get around this?
> >
>
> It is an error in your assumption.
>
> Wicket injects a proxy that implements CnavUrlDAO but knows nothing about
> the specific implementation about this interface.
> Whenever the proxy is used it delegates the call to the bean/service
> returned by Guice's injector (something like:
> Injector.getBinding(CnavUrlDAO.class).doSomething()).
>
>
> >
> > Thanks,
> > Daniel
> >
>
Re: Wicket, Guice and the $Proxy object
Posted by Martin Grigorov <mg...@apache.org>.
Hi,
On Tue, Jul 23, 2013 at 6:20 PM, Daniel Watrous <dw...@gmail.com>wrote:
> Hi,
>
> I'm having an issue that I suspect is related to the wicket integration
> with Guice. Any help is appreciated.
>
> I have a Page class that uses field injection to inject a DAO. I then want
> to cast my DAO to a more specific type (what I inject is the interface).
> Here's what that looks like
>
> public class CnavModify extends ConsoleBasePage {
>
> @Inject private CnavUrlDAO cnavUrlDAO;
> public CnavModify(PageParameters parameters) {
> super(parameters);
> if (parameters.get("cnavid").toString() != null) {
> cnavid = new ObjectId(parameters.get("cnavid").toString());
> }
> if (cnavid != null) {
> cnavUrlModel = new
>
> DetachableCnavUrlModel(((MorphiaCnavUrlDAO)cnavUrlDAO).getCnavById(cnavid));
> }
> }
> }
>
> When I try to cast it I get the following error:
>
> Last cause: $Proxy23 cannot be cast to
> com.hp.honeybadger.persistence.dao.morphia.MorphiaCnavUrlDAO
>
> I am able to use the CnavUrlDAO as a CnavUrlDAO, but its type is $Proxy23
> and I am unable to cast it to a concrete type.
>
> Is this Guice or Wicket related? Any idea how to get around this?
>
It is an error in your assumption.
Wicket injects a proxy that implements CnavUrlDAO but knows nothing about
the specific implementation about this interface.
Whenever the proxy is used it delegates the call to the bean/service
returned by Guice's injector (something like:
Injector.getBinding(CnavUrlDAO.class).doSomething()).
>
> Thanks,
> Daniel
>