onFailure
Completes the request with the result of the computation given as argument of type Future[T] by marshalling it with the implicitly given ToResponseMarshaller[T]. Runs the inner route if the Future computation fails.
Signature
def onFailure(future: ⇒ Future[T])(implicit m: ToResponseMarshaller[T], ec: ExecutionContext): Directive1[Throwable]
The signature shown is simplified, the real signature uses magnets. [1]
[1] | See The Magnet Pattern for an explanation of magnet-based overloading. |
Description
If the future succeeds the request is completed using the values marshaller (this directive therefore requires a marshaller for the future’s type to be implicitly available). The execution of the inner route passed to a onFailure directive is deferred until the given future has completed with a failure, exposing the reason of failure as a extraction of type Throwable.
It is necessary to bring a ExecutionContext into implicit scope for this directive to work.
To handle the successful case manually as well, use the onComplete directive, instead.
Example
val route =
path("success") {
onFailure(Future { "Ok" }) { extraction =>
failWith(extraction) // not executed.
}
} ~
path("failure") {
onFailure(Future.failed[String](TestException)) { extraction =>
failWith(extraction)
}
}
Get("/success") ~> route ~> check {
responseAs[String] === "Ok"
}
Get("/failure") ~> sealRoute(route) ~> check {
status === InternalServerError
responseAs[String] === "Unsuccessful future!"
}