Improve documentation samples on access to HTTP headers from controller

[Flash1232]

What would be the intended way to access request extensions (which we use to populate the Authorization header) set via WebGraphQlInterceptor (https://docs.spring.io/spring-graphql/docs/current-SNAPSHOT/reference/html/#web-interception) from inside a controller method?

I picked up from this conversation and the docs that this option exists and was curious about the best solution to this. For now I am trying to access the Reactor Context's ServerWebExchange object to get the headers. This doesn't seem as the "right way" to go about this though.

[rstoyanchev]

One option is to extract whatever you need and put it in the GraphQLContext. The interceptor gives you access to the headers:

class MyInterceptor implements WebGraphQlInterceptor {

    @Override
    public Mono<WebGraphQlResponse> intercept(WebGraphQlRequest request, Chain chain) {
        List<String> fooHeaderValue = request.getHeaders().get("fooHeader");
        request.configureExecutionInput((executionInput, builder) ->
                builder.graphQLContext(Collections.singletonMap("fooHeader", fooHeaderValue)).build());
        return chain.next(request);
    }
}

Then in your controller access that:

@Controller
class MyController {

    @QueryMapping
    Foo getFoo(@ContextValue String fooHeader) {
            // ...
    }
}

We could improve the documentation example in the Server Interception section with this example instead, which seems a more likely use case.

[Flash1232]

Thanks for your quick feedback!

This makes a lot of sense now and also for the documentation. As far as I understand, Extensions are primarily used for response error handling and as such are not exposed to the Controller methods.

This resolves the issue perfectly.