Resteasy/Guice Unable to find contextual data of type: javax.servlet.ServletConfig

I don’t use the default implementation of resteasy servlet dispatcher. I use filter dispatcher, so i need change how the api’s are read.

Here are how my filter dispatcher works: https://gist.github.com/stickfigure/5ff4b814b8a08e4e1f57

Here the code:

@Path("/swagger.{type:json}")
public class SwaggerResource  extends BaseApiListingResource {

    @Context
    ServletContext context;

    @GET
    @Produces({MediaType.APPLICATION_JSON})
    @ApiOperation(value = "The swagger definition in either JSON", hidden = true)
    public Response getListing(
            @Context Application app,
            @Context ServletConfig sc,
            @Context FilterConfig fc,
            @Context HttpHeaders headers,
            @Context UriInfo uriInfo,
            @PathParam("type") String type) {
        return getListingJsonResponse(app, context, mergeConfig(sc, fc), headers, uriInfo);
    }

    private ServletConfig mergeConfig(ServletConfig sc, FilterConfig fc) {
        try {
            sc.getInitParameter("test");
        } catch (Exception e) {
            return new ServletConfigWrapper(fc);
        }
        return sc;
    }

    private static class ServletConfigWrapper implements ServletConfig {

        private FilterConfig fc;

        public ServletConfigWrapper(FilterConfig fc) {
            this.fc = fc;
        }

        @Override
        public String getServletName() {
            return fc.getFilterName();
        }

        @Override
        public ServletContext getServletContext() {
            return fc.getServletContext();
        }

        @Override
        public String getInitParameter(String name) {
            return fc.getInitParameter(name);
        }

        @Override
        public Enumeration<String> getInitParameterNames() {
            return fc.getInitParameterNames();
        }
    }

}

[kaosko]

Same thing for Tapestry5 that runs as a filter. As an answer to @frantuma, it’ll basically happen in any environment where ServletConfig isn’t available (but injects a proxy for the ServletConfig to ApiListingResource). Figured I’ll do the same as @niom and create my own subclass instead.

[niom]

I had a similar problem with our project.

We are using Jersey JAX-RS configuration and using pure filter based configuration. When using pure filter based configuration there is no ServletConfig but instead of FilterConfig that can be injected.

Swagger has a class: ApiListingResource that is used as the listing client.

public class ApiListingResource extends BaseApiListingResource {

    @Context
    ServletContext context;

    @GET
    @Produces({MediaType.APPLICATION_JSON, "application/yaml"})
    @ApiOperation(value = "The swagger definition in either JSON or YAML", hidden = true)
    public Response getListing(
            @Context Application app,
            @Context ServletConfig sc, // this is not found!!
            @Context HttpHeaders headers,
            @Context UriInfo uriInfo,
            @PathParam("type") String type) {
        if (StringUtils.isNotBlank(type) && type.trim().equalsIgnoreCase("yaml")) {
            return getListingYamlResponse(app, context, sc, headers, uriInfo);
        } else {
            return getListingJsonResponse(app, context, sc, headers, uriInfo);
        }
    }
...

now with pure filter configuration the injection of the ServletConfig will fail because there is no such thing.

So what would need to happen is that swagger should provide a proper ResourceListing file that would contain FilterConfig as an alternative for the ServletConfig parameter.

So we ended up creating a own FilterApiListingResource that would work something like this:

@javax.ws.rs.Path("/swagger.{type:json|yaml}")
public class FilterApiListingResource extends BaseApiListingResource {

    @GET
    @Produces({"application/json", "application/yaml"})
    @ApiOperation(
        value = "The swagger definition in either JSON or YAML",
        hidden = true
    )
    public Response getListing(@Context Application app, @Context FilterConfig fc, @Context HttpHeaders headers, @Context UriInfo uriInfo, @PathParam("type") String type) {
        return StringUtils.isNotBlank(type) && type.trim().equalsIgnoreCase("yaml") ? this.getListingYamlResponse(app, fc.getServletContext(), null, headers, uriInfo) : this.getListingJsonResponse(app, fc.getServletContext(), null, headers, uriInfo);
    }
}

in this way have the FilterConfig. ServletContext will be null because one does not exist.

what we are not sure is what information is missing when the ServletContext is null in BaseApiListingResource.