recoverRejections

Signature

def recoverRejections(f: immutable.Seq[Rejection] ⇒ RouteResult): Directive0

Description

Low level directive – unless you’re sure you need to be working on this low-level you might instead want to try the handleRejections directive which provides a nicer DSL for building rejection handlers.

Transforms rejections from the inner route with an immutable.Seq[Rejection] ⇒ RouteResult function. a Function<Iterable<Rejection>, RouteResult>. A RouteResultRouteResult is either a Complete(HttpResponse(...)) Complete containing the HttpResponseHttpResponse or a Rejected(rejections). Rejected containing the rejections.

Note

To learn more about how and why rejections work read the Rejections section of the documentation.

Example

Scala
val authRejectionsToNothingToSeeHere = recoverRejections { rejections =>
  if (rejections.exists(_.isInstanceOf[AuthenticationFailedRejection]))
    Complete(HttpResponse(entity = "Nothing to see here, move along."))
  else if (rejections == Nil) // see "Empty Rejections" for more details
    Complete(HttpResponse(StatusCodes.NotFound, entity = "Literally nothing to see here."))
  else
    Rejected(rejections)
}
val neverAuth: Authenticator[String] = creds => None
val alwaysAuth: Authenticator[String] = creds => Some("id")

val route =
  authRejectionsToNothingToSeeHere {
    pathPrefix("auth") {
      path("never") {
        authenticateBasic("my-realm", neverAuth) { user =>
          complete("Welcome to the bat-cave!")
        }
      } ~
        path("always") {
          authenticateBasic("my-realm", alwaysAuth) { user =>
            complete("Welcome to the secret place!")
          }
        }
    }
  }

// tests:
Get("/auth/never") ~> route ~> check {
  status shouldEqual StatusCodes.OK
  responseAs[String] shouldEqual "Nothing to see here, move along."
}
Get("/auth/always") ~> route ~> check {
  status shouldEqual StatusCodes.OK
  responseAs[String] shouldEqual "Welcome to the secret place!"
}
Get("/auth/does_not_exist") ~> route ~> check {
  status shouldEqual StatusCodes.NotFound
  responseAs[String] shouldEqual "Literally nothing to see here."
}
Java
import akka.http.javadsl.server.directives.SecurityDirectives.ProvidedCredentials;

import static akka.http.javadsl.server.Directives.authenticateBasic;
import static akka.http.javadsl.server.Directives.recoverRejections;

final Function<Optional<ProvidedCredentials>, Optional<Object>> neverAuth =
  creds -> Optional.empty();
final Function<Optional<ProvidedCredentials>, Optional<Object>> alwaysAuth =
  creds -> Optional.of("id");

final Route originalRoute = pathPrefix("auth", () ->
  Directives.concat(
    path("never", () ->
      authenticateBasic("my-realm", neverAuth, obj ->  complete("Welcome to the bat-cave!"))
    ),
    path("always", () ->
      authenticateBasic("my-realm", alwaysAuth, obj -> complete("Welcome to the secret place!"))
    )
  )
);

final Function<Iterable<Rejection>, Boolean> existsAuthenticationFailedRejection =
  rejections ->
    StreamSupport.stream(rejections.spliterator(), false)
      .anyMatch(r -> r instanceof AuthenticationFailedRejection);

final Route route = recoverRejections(rejections -> {
  if (existsAuthenticationFailedRejection.apply(rejections)) {
    return RouteResults.complete(
      HttpResponse.create().withEntity("Nothing to see here, move along."));
  } else if (!rejections.iterator().hasNext()) { // see "Empty Rejections" for more details
    return RouteResults.complete(
        HttpResponse.create().withStatus(StatusCodes.NOT_FOUND)
          .withEntity("Literally nothing to see here."));
  } else {
    return RouteResults.rejected(rejections);
  }
}, () -> originalRoute);

// tests:
testRoute(route).run(HttpRequest.GET("/auth/never"))
  .assertStatusCode(StatusCodes.OK)
  .assertEntity("Nothing to see here, move along.");
testRoute(route).run(HttpRequest.GET("/auth/always"))
  .assertStatusCode(StatusCodes.OK)
  .assertEntity("Welcome to the secret place!");
testRoute(route).run(HttpRequest.GET("/auth/does_not_exist"))
  .assertStatusCode(StatusCodes.NOT_FOUND)
  .assertEntity("Literally nothing to see here.");
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