Akka HTTP 模糊隐式转换

Question

我正在通过这个 example 学习 Akka HTTP。为了学习，我把它转成了一个Maven项目。但是，使用 Akka v2.3.12 和 Akka Stream v1.0 时出现如下编译错误。 POST DSL 失败并出现类似的错误，为简洁起见我没有发布这些错误。我怎样才能得到运行的例子？

pathPrefix("ip") {
(get & path(Segment)) { ip =>
  complete {
    fetchIpInfo(ip).map[ToResponseMarshallable] {
      case Right(ipInfo) => ipInfo
      case Left(errorMessage) => BadRequest -> errorMessage
    }
  }
}

[ERROR]  found   : akka.http.scaladsl.server.Directive[(String,)]
[ERROR]  required: ?{def apply: ?}
[ERROR] Note that implicit conversions are not applicable because they are ambiguous:
[ERROR]  both method addDirectiveApply in object Directive of type [L](directive: akka.http.scaladsl.server.Directive[L])(implicit hac: akka.http.scaladsl.server.util.ApplyConverter[L])hac.In => akka.http.scaladsl.server.Route
[ERROR]  and method fromDirective in object ConjunctionMagnet of type [L, R](other: akka.http.scaladsl.server.Directive[R])(implicit join: akka.http.scaladsl.server.util.TupleOps.Join[L,R])akka.http.scaladsl.server.ConjunctionMagnet[L]{type Out = akka.http.scaladsl.server.Directive[join.Out]}
[ERROR]  are possible conversion functions from akka.http.scaladsl.server.Directive[(String,)] to ?{def apply: ?}
[ERROR]         (get & path(Segment)) { ip =>

error: akka.http.scaladsl.server.Directive[(String,)] does not take parameters
[ERROR]         (get & path(Segment)) { ip =>

Answer 1

事实证明这是由于 Spray（以及 akka-http）使用的深 implicit 链，因此正确导入至关重要。很少有示例显示导入和那些使用旧库的示例。

Akka HTTP 模糊隐式转换

Akka HTTP ambiguous implicit conversion

scala

rest

akka-stream

akka-http