CODEWITHSUNDEEP
javaplayframeworkakkaplayframework-2.2
Artur
Artur

Reputation: 337

Play Framework 2.2.x recover flatmap

I want to recover my promise and return delegate.call(context) from it, but i can only return SimpleResult.

public class Authenticate extends Action<Authentication> {
    @Override
    public Promise<SimpleResult> call(final Context context) throws Throwable {
        WSRequestHolder holder = WS.url(...);
        final Promise<Response> promise = holder.get();
        Promise<SimpleResult> result = promise.flatMap(new Function<Response, Promise<SimpleResult>>() {
            @Override
            public Promise<SimpleResult> apply(Response response) throws Throwable {
                JsonNode user = response.asJson().path("response");
                context.args.put("user", user);
                return delegate.call(context);
            }
        }).recover(new Function<Throwable, SimpleResult>() {
            @Override
            public SimpleResult apply(Throwable e) {
                /* cant return delegate.call(context); from here */
                return redirect(routes.Application.index());
            }
        });
        return result;
    }
}

Maybe there are other standard and better ways to store userinfo before method calls?

Upvotes: 1

Views: 1296

Answers (2)

James Roper
James Roper

Reputation: 12850

The solution you posted is not a good solution, you should never, ever use Await.result when doing asynchronous programming, you risk causing deadlocks and massive performance issues.

We need to add a recoverWith method to the Play promise API, but until that happens, you can do this (using JDK8 syntax for brevity):

public class Authenticate extends Action<Authentication> {
  public Promise<SimpleResult> call(final Context context) throws Throwable {
    Promise<SimpleResult> result = WS.url(...).get();
    Promise<SimpleResult> result = promise.flatMap( response -> {
      JsonNode user = response.asJson().path("response");
      context.args.put("user", user);
      return delegate.call(context);
    }).map(Promise::pure).recover( e -> {
      return delegate.call(ontext)(routes.Application.index());
    }).flatMap(a -> a);
    return result;
  }
}

Basically, the above unflattens the Promise<SimpleResult> into Promise<Promise<SimpleResult>> by mapping with Promise::pure, then you can recover returning Promise<SimpleResult>, then you it flattens the promise of a promise by flatMapping with the identity function.

Upvotes: 5

Artur
Artur

Reputation: 337

I solved this problem:

WSRequestHolder holder = WS.url(...)
final Promise<Response> userPromise = holder.get();
Promise<SimpleResult> result = Promise.promise(new Function0<Response>() {
    @Override
    public Response apply() throws Throwable {
        Timeout timeout = new Timeout(2000);
        Future<Response> future = userPromise.wrapped();                
        Response response = Await.result(future, timeout.duration());   
        return response;
    }
}).flatMap(new Function<Response, Promise<SimpleResult>>() {
    @Override
    public Promise<SimpleResult> apply(Response response) throws Throwable {
        try {
            JsonNode userInfo = response.asJson();
            context.args.put("user", userInfo);
        } catch(Exception ex) {
        }   
        return delegate.call(context);
    }               
});
return result;

Upvotes: 0

Related Questions