ServletContext is invalid in MessageBodyWriter if handling async CompletionStage

[rickardoberg]

ServletContext is invalid in MessageBodyWriter if handling async CompletionStage

[jansupol]

The MessageBodyWriter is a singleton, it is not recreated for each request. Whatever injected, it would not be aligned with the current request.

Possibly, you can try to inject InjectionManager class and try to call injectionManager.getInstance(HttpServletRequest.class) in the writeTo method.

The lifecycle of HttpServletRequest class is handled by the Servlet container, i.e. by Jetty. If Jetty invalidates, Jersey cannot prevent that.

[rickardoberg]

I'm injecting Provider<HttpServletRequest>into the MessageBodyWriter constructor, which in writeTo returns a proxy to the correct object. This part is fine. The issue is that because of the asynchronous nature of returning a CompletionStage<MyType> from the resource the request has not been reassociated correctly with the servletcontext. There's some scope fixing (or similar) that needs to happen before calling writeTo, when the result is a CompletionStage. The main issue is that HttpServletRequest.getServletContext needs to return the correct value.

[jansupol]

There are two possibilities:

• The injected HttpServletRequest provided does not belong to the current request
• Jetty ended the current request and set the HttpServletRequest.getServletContext to return null.

You might be trying to provide request-scoped information outside of a request. The JAX-RS way which avoids the injection is to utilize WriterInterceptor.getProperty during the entity writing and setting up the property in the resource class or in the ContainerFilter where the request-scoped information is available.