[CXF-7544] Support @Context-based injection into proxied CDI beans

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 3.1.13, 3.2.0
• Estimated Complexity: Unknown
• Assignee: Andriy Redko
• Reporter: Andriy Redko
• Created: 29/Oct/17 17:57
• Updated: 14/Aug/19 17:25
• Resolved: 27/Nov/17 12:08

Description

The issue pop up as part of https://github.com/apache/cxf/pull/330 discussion. In case when provider / feature / resource is a proxied CDI bean, the contextual class members (annotated with @Context) are not injected.

Test case to reproduce:

@ApplicationScoped
public class BookStoreRequestFilter implements ContainerRequestFilter {
    @Context private ResourceInfo resourceInfo;
    
    @Override
    public void filter(ContainerRequestContext requestContext) throws IOException {
        // Contextual instances should be injected independently
        if (resourceInfo == null || resourceInfo.getResourceMethod() == null) {
            requestContext.abortWith(Response.serverError().build());
        }
    }
}

CC rmannibucau

A bit more context

In some circumstances (like using @ApplicationScoped annotation for example) the CDI runtime will create a proxy class for a particular bean. As the result, the CXF side is going to bind the particular provider metadata to this proxy instance. It looks logical and unambiguous.

However, the interesting things are happening when CXF will try to inject contextual proxies (@Context annotations) into the provider instance. The injections are successful but the target object for them will be the proxy instance (not the real instance behind it). Consequently, at runtime, when the proxy delegates the call to a backing instance, all contextual proxies are null in there (simply put, not set).

How to solve

Referring to the recent discussions with sergeyb, the best solution would be to delegate the @Context annotation to CDI framework (as such, relieving the CXF from doing the injection work). This proposal may need a support from the JAX-RS specification side.

Simpler (interim?) possible solution would be to complement the CDI injection with @Context injection (delegating this work to the CXF as it works right now for non-proxy beans and non-CDI deployments). This could be done by observing ProcessInjectionTarget events and supplying our own InjectionTarget (have working PoC for this approach).

Regarding constructor injection, it seems like CXF does not support passing the arguments to provider constructor (in case of CDI, w/o @Context annotation) so I it would be another (separate) issue to look at.

Update

Addressing the issue requires a significant revamp of the CXF injection mechanism, it is turned out to be hard to solve even with @AroundConstruct or, previously, providing custom @Context injectors. The good news is that the field-based injection could be easily workarounded using setter-based injection.

@ApplicationScoped
public class BookStoreRequestFilter implements ContainerRequestFilter {
    private ResourceInfo resourceInfo;
    
    @Context 
    public void setResourceInfo(ResourceInfo resourceInfo) {
        this.resourceInfo = resourceInfo;
    }
    
    @Override
    public void filter(ContainerRequestContext requestContext) throws IOException {
        // Contextual instances should be injected independently
        if (resourceInfo == null || resourceInfo.getResourceMethod() == null) {
            requestContext.abortWith(Response.serverError().build());
        }
    }
}

The work related to CXF injection refactoring is tracked under CXF-7571

Issue Links

• relates to: CXF-7571 Revamp of the CXF injection implementation
• links to: GitHub Pull Request #339
• links to: GitHub Pull Request #346