optionalHeaderValue

Signature

def optionalHeaderValue[T](f: HttpHeader

Description

Traverses the list of request headers with the specified function and extracts the first value the function returns as Some(value).

The optionalHeaderValue directive is similar to the headerValue directive but always extracts an Option value instead of rejecting the request if no matching header could be found.

Example

Scala
Java
sourcedef extractHostPort: HttpHeader => Option[Int] = {
  case h: `Host` => Some(h.port)
  case x         => None
}

val route =
  optionalHeaderValue(extractHostPort) {
    case Some(port) => complete(s"The port was $port")
    case None       => complete(s"The port was not provided explicitly")
  } ~ // can also be written as:
  optionalHeaderValue(extractHostPort) { port =>
    complete {
      port match {
        case Some(p) => s"The port was $p"
        case _       => "The port was not provided explicitly"
      }
    }
  }

// tests:
Get("/") ~> Host("example.com", 5043) ~> route ~> check {
  responseAs[String] shouldEqual "The port was 5043"
}
Get("/") ~> Route.seal(route) ~> check {
  responseAs[String] shouldEqual "The port was not provided explicitly"
}
sourceimport static org.apache.pekko.http.javadsl.server.Directives.complete;
import static org.apache.pekko.http.javadsl.server.Directives.optionalHeaderValue;

final Function<HttpHeader, Optional<Integer>> extractHostPort =
    header -> {
      if (header instanceof Host) {
        return Optional.of(((Host) header).port());
      } else {
        return Optional.empty();
      }
    };

final Route route =
    optionalHeaderValue(
        extractHostPort,
        port -> {
          if (port.isPresent()) {
            return complete("The port was " + port.get());
          } else {
            return complete("The port was not provided explicitly");
          }
        });

// tests:
testRoute(route)
    .run(HttpRequest.GET("/").addHeader(Host.create("example.com", 5043)))
    .assertEntity("The port was 5043");

testRoute(route).run(HttpRequest.GET("/")).assertEntity("The port was not provided explicitly");
1.0.1