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https://issues.apache.org/jira/browse/WICKET-1130?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12581695#action_12581695
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Alastair Maw commented on WICKET-1130:
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So this sort of thing is a limitation in cglib. We need to proxy the class
using an Enhancer, so that it can be serialized, and the class needs to have a
zero-arg constructor in order for cglib to be able to do that.
I don't understand why this is failing for you, as you should surely be
injecting against an interface, in which case this should work just fine.
I.e:
bind(javax.persistence.EntityManager.class).toInstance(hibernateEntityManager)
or whatever.
So no, this probably isn't ever going to be fixed, as it's pretty much
impossible to do so.
There are two alternatives:
- We inject the object, not a proxy. This will either cause serialization
errors (in your case), or the session size to blow up. Neither sounds good.
- We get clever about serializing/deserializing pages, and effectively do the
"proxying" there. We'd probably need to require annotations for this - it's not
going to make it in before 1.4.
> Injection of Bound Instance Fails with Exception
> ------------------------------------------------
>
> Key: WICKET-1130
> URL: https://issues.apache.org/jira/browse/WICKET-1130
> Project: Wicket
> Issue Type: Bug
> Components: wicket-guice
> Affects Versions: 1.3.0-beta4
> Reporter: Daniel Spiewak
> Assignee: Alastair Maw
> Fix For: 1.3.3
>
>
> If I try to inject an explicitly bound instance into a component, injection
> fails with an exception in the creation of the CGLIB proxy:
> java.lang.IllegalArgumentException: Superclass has no null constructors but
> no arguments were given
> Stupidly, I forgot to save the whole stack trace and the code is now gone
> from my codebase (since I needed it to work). To repeat:
> @Override
> public void configure() {
> bind(EntityManager.class).toInstance(manager);
> }
> Seems wicket-guice is assuming that it needs to create a new instance of
> everything that's injected, and since EntityManager doesn't have a no-args
> constructor, such an action fails. Just an assumption anyway...
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