validate

Allows validating a precondition before handling a route.

Signature

def validate(check: => Boolean, errorMsg: String): Directive0

Description

Checks an arbitrary condition and passes control to the inner route if it returns true. Otherwise, rejects the request with a ValidationRejectionValidationRejection containing the given error message.

Example

Scala
val route =
  extractUri { uri =>
    validate(uri.path.toString.size < 5, s"Path too long: '${uri.path.toString}'") {
      complete(s"Full URI: $uri")
    }
  }

// tests:
Get("/234") ~> route ~> check {
  responseAs[String] shouldEqual "Full URI: http://example.com/234"
}
Get("/abcdefghijkl") ~> route ~> check {
  rejection shouldEqual ValidationRejection("Path too long: '/abcdefghijkl'", None)
}
Java
import static akka.http.javadsl.server.Directives.extractUri;
import static akka.http.javadsl.server.Directives.validate;

final Route route = extractUri(uri ->
  validate(() -> uri.path().length() < 5,
    "Path too long: " + uri.path(),
    () -> complete("Full URI: " + uri.toString()))
);

// tests:
testRoute(route).run(HttpRequest.GET("/234"))
  .assertEntity("Full URI: http://example.com/234");
testRoute(route).run(HttpRequest.GET("/abcdefghijkl"))
  .assertEntity("Path too long: /abcdefghijkl");
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