@Inject(optional = true) @Named("hello world") doesn't work

[Eduardo Nunes]

Hello guys,

I tried the following source code and it's not working, am I right?

@Inject(optional = true)
@Named("hello world")
private String message;

Guice is throwing the exception bellow:

Caused by: com.google.inject.ConfigurationException: Guice configuration errors:
1) No implementation for java.lang.String annotated with
@com.google.inject.name.Named(value=SignOutPage.redirectPage) was
bound.
while locating java.lang.String annotated with
@com.google.inject.name.Named(value=SignOutPage.redirectPage)

Thanks,
Eduardo S. Nunes

[limpb...@gmail.com]

I couldn't reproduce this. Could you try again with the latest
snapshot?
http://code.google.com/p/google-guice/downloads/list

If you can get it to fail reliably, please send a JUnit test case.

Cheers,
Jesse

[Eduardo Nunes]

I tried to reproduce it in a test case but I couldn't. I think the
error is inside wicket-guice library. This is part of the stacktrace:

Caused by: com.google.inject.ConfigurationException: Guice configuration errors:

1) No implementation for java.lang.String annotated with
@com.google.inject.name.Named(value=SignOutPage.redirectPage) was
bound.
while locating java.lang.String annotated with
@com.google.inject.name.Named(value=SignOutPage.redirectPage)

1 error
at com.google.inject.InjectorImpl.getProvider(InjectorImpl.java:784)
at com.google.inject.InjectorImpl.getInstance(InjectorImpl.java:789)
at org.apache.wicket.guice.GuiceProxyTargetLocator.locateProxyTarget(GuiceProxyTargetLocator.java:67)
at org.apache.wicket.proxy.LazyInitProxyFactory.createProxy(LazyInitProxyFactory.java:129)
at org.apache.wicket.guice.GuiceComponentInjector.inject(GuiceComponentInjector.java:114)
at org.apache.wicket.guice.GuiceComponentInjector.onInstantiation(GuiceComponentInjector.java:196)
at org.apache.wicket.Application.notifyComponentInstantiationListeners(Application.java:1027)

[Eduardo Nunes]

Hi,

I found the problem. It is because wicket-guice library creates a
proxy of every @inject attribute and uses a locator to get the
instance. The main problem consist in the algorithm of this locator,
it makes something like this:

- keeps a reference to a possible BindingAnnotation (Named for example)
- keeps a reference to the field type (String.class for example)
- generates a key = Key.get(TypeLiteral.get(String.class), annotation.class);
- calls injector.getInstance(key);

So, the information about the optional @Inject parameter is lost. I
took a look in the google-guice source code trying to find a solution
for this problem but it stills complex for me (I'm new to guice). I
realized that
it should use the same algorithm of SingleFieldInjector (member
injection). I saw that the most part of guice classes are not public.
Do you have any suggestions? Do you mind some way to get the bound
value with the Class definition + field definition?

Thanks anyway,
Eduardo S. Nunes

[limpb...@gmail.com]

I've opened an issue in Wicket's issue tracker.
https://issues.apache.org/jira/browse/WICKET-2241

[Guðmundur Bjarni]

I wrote a simple fix that I've attached a patch to the issue that you
created on the Wicket issue tracker. I changed the wicket-guice unit
test so that it contains an optional binding, and that seems to be
working just fine now.

regards,
Guðmundur Bjarni

[Eduardo Nunes]

This solution doesn't work for the trunk version of google-guice. I
posted a comment in the jira issue.

2009/4/25 Guðmundur Bjarni <gudmundu...@gmail.com>:

[Guðmundur Bjarni]

Thanks for pointing this out. I originally only tried it with Guice
1.0. I've tried it with trunk just now, and as you rightly point out,
it doesn't work. I've written and posted another patch that fixes it
though. :)

regards,
Guðmundur Bjarni

On Apr 27, 5:25 am, Eduardo Nunes <esnu...@gmail.com> wrote:
> This solution doesn't work for the trunk version of google-guice. I
> posted a comment in the jira issue.
>

> 2009/4/25 Guðmundur Bjarni <gudmundur.bja...@gmail.com>: