Getting path parameter from RoutingContext

[kyngs]

I have a method bean that automatically fetches data for a path parameter. For example:
ApiClass:

@Path("v0/server/{server}/something")
public class ApiClass {
    @Inject
    ServerInfo server;
    ... methods
}

BeanProducer:

    @Produces
    @DefaultBean
    @RequestScoped
    public ServerInfo server(RoutingContext context) {
        var name = context.pathParam("server");
        ... logic
    }

However, when I try to test it, the pathParam method returns null. The standard @PathParam annotation works correctly, but I cannot use it outside of ApiClass. Is there any way to do this?

[mschorsch]

I'm not sure if this ist the root of the problem, but ApiClass must also have the annotation @RequestScoped.

[kyngs]

I'm not sure if this ist the root of the problem, but ApiClass must also have the annotation @RequestScoped.

Well doing so also broke the @PathParam annotation.

[jonjanisch]

@kyngs Have you found a solution for this? I need to accomplish the same thing.

[kyngs]

Unfortunately, I did not.

[mkouba]

I think that you're mixing two APIs - JAX-RS (@Path) and Vert.x Web (RoutingContext). The RoutingContext does not know anything about JAX-RS path params. I.e. RoutingContext#pathParam() only handles the path params specified on a Vert.x route, not a JAX-RS resource.

[jonjanisch]

The code looks something like this:

@Produces
@DefaultBean
@RequestScoped
public MyContext getMyContext(RoutingContext routingContext) {
    // Using normalizedPath, not sure if that's the best way, but it works
    Matcher matcher = pattern.matcher(routingContext.normalizedPath());  
    // some error handling
    String a = matcher.group("a");
    Long b = Long.parseLong(matcher.group("b"));
    return new MyContext(new A(a), new B(b));
}

[kyngs]

Can you provide the regex pattern? I probably won't use it, but it might be useful for other users if they require this functionality.

[jonjanisch]

That would be something specific for whatever URL structure their using. For us we have standardized URL, e.g.

/api/a/<a-id>/b/<b-id>/lots/of/subresources

So for now I'm using a simple regex like this:

\/api\/a\/(?<a>\w+)\/b\/(?<b>\d+)\/(?:.)*

where ?<a> and ?<b> are the named capture groups. This is still POC at this time. I have not merged the code into our app yet so I'll probably need to double check the regex further later.

[geoand]

I haven't tried it, but:

    public static class PathSegmentProducer {

        @RequestScoped
        List<PathSegment> pathSegments(UriInfo uriInfo) {
            return uriInfo.getPathSegments();
        }
    }

should allow you to inject List<PathSegment> into any CDI bean.

I'll warn you though that is not really a supported use case, so if someone comes to me in the future saying it doesn't work, I can't say I'll go out of my way to fix it :)

[kyngs]

So, is there going to be a proper API implemented in the future for this? Or we will have to stick with the workaround?

[geoand]

It's unlikely there will be.