How do we implement q Params in Helidon SE

Question

I am new to Helidon SE and would like to know if there is a way to implement q params in REST service created via Helidon SE. Any help in this regard is truly appreciated.

Thanks, Gaurav

Answer 1

If you want to use and read params in the following way e.g.

http://localhost:8080/?q=test&k=test2

Then -in case of Helidon SE- do the following to get those parameters:

private void getParam(ServerRequest request, ServerResponse response) {

    Map params = request.queryParams().toMap();
    logger.info("params: " + params);
    logger.info("q: " + params.get("q"));
    logger.info("k: " + params.get("k"));
    
    ...

}

Obviously the getParam method is configured for "/" path.

Answer 2

How do I retrieve query parameters in a Helidon SE application: Here is one example,

HelloService.java

public class HelloService implements Service {

    private static final JsonBuilderFactory JSON = Json.createBuilderFactory(Collections.emptyMap());

    HelloService(Config config) {
    }

    @Override
    public void update(Rules rules) {
        rules.get("/", this::getDefaultMessageHandler);
    }

    private void getDefaultMessageHandler(ServerRequest request, ServerResponse response) {
        var params = request.queryParams().toMap();
        System.out.println("name: " + params.get("name").get(0));
        System.out.println("email: " + params.get("email").get(0));

        sendResponse(response, params.get("name").get(0));
    }

    private void sendResponse(ServerResponse response, String name) {

        var returnObject = JSON.createObjectBuilder().add("name", name).build();
        response.send(returnObject);
    }

}

Main

public class HelidonSeRestHelloWorldApplication {

    public static void main(final String[] args) {
        startServer();
    }

    private static Single<WebServer> startServer() {

        var config = Config.create();
        var server = WebServer.builder(createRouting(config)).config(config.get("server"))
                .addMediaSupport(JsonpSupport.create()).build();
        var webserver = server.start();

        webserver.thenAccept(ws -> {
         System.out.println("Web server started! http://localhost:" + ws.port() + "/hello");
    
            ws.whenShutdown().thenRun(() -> System.out.println("Web server is down!"));
        }).exceptionallyAccept(t -> {
            System.out.println("Web startup failed: " + t.getMessage());
        });

        return webserver;
    }

    private static Routing createRouting(Config config) {

        var helloService = new HelloService(config);

        return Routing.builder()

                .register("/hello", helloService).build();
    }
}

application.properties

server.port=9080

Run the application and hit http://localhost:9080/hello?name=alpha&email=alpha@alpha.alpha

Console output:

name: alpha
email: alpha@alpha.alpha

---

---

++ How do I retrieve path parameters in a Helidon SE application:

Main

public class HelidonSeRestHelloWorldApplication {

    ...........................
    ...........................

    private static Routing createRouting(Config config) {

        var helloService = new HelloService(config);

        return Routing.builder()

                .register("/hello/{name}", helloService).build();
    }
}

HelloService.java

    public class HelloService implements Service {

    ............
    ...........
    private void getDefaultMessageHandler(ServerRequest request, ServerResponse response) {
        var name = request.path().absolute().param("name");
        System.out.println(name);

        sendResponse(response, name);
    }

    .................
    .................

}

Run the application and hit: http://localhost:9080/hello/alpha