ClassCassException when using HandlerAspect and Path parameters.

[Petter-K]

Describe the bug
We are getting ClassCastExceptions when using a route with Path paramters, and a middleware that adds context.
class zio.http.Request cannot be cast to class scala.Tuple2 (zio.http.Request and scala.Tuple2 are in unnamed module of loader 'app')
Tuple2 is increasing if we add more path params

To Reproduce
Run this snipped

import zio.http._
import zio._

import scala.annotation.nowarn

object Reproducer extends ZIOAppDefault {
  case class WebSession(id: Int)

  def maybeWebSession: HandlerAspect[Any, Option[WebSession]] =
    HandlerAspect.interceptIncomingHandler(
      Handler.fromFunctionZIO[Request] { req =>
        ZIO.succeed((req, None))
      }
    )

  @nowarn("msg=dead code following this construct")
  override def run: ZIO[Any, Any, Any] = {
    // fails at Handler.scala line 57 with 
    val route = Method.GET / "base" / string("1") -> handler((a: String, req: Request) => {
      withContext((c: Option[WebSession]) => {
        ZIO.logInfo("Hello").as(Response.ok)
      })
    }) @@ maybeWebSession



    (for {
      port <- Server.install(Routes(route))
      _ <- ZIO.logInfo(s"Installed on port " + port)
      _ <- ZIO.never
    } yield ()).provide(Server.default)

  }
}

run: curl -v 127.0.0.1:8080/base/1

Expected behaviour
Log Hello and return 200 Ok

Additional context
Same error in scala 2 and 3.
Using Intellij breakpoints on all exception, it stops at Handler.scala - line 57

[jdegoes]

/bounty $150 for fix and test case.

[algora-pbc]

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Attempt	Started (GMT+0)	Solution
🔴 @varshith257	Sep 18, 2024, 1:46:20 PM	WIP
🟢 @987Nabil		#3150

[varshith257]

/attempt #3141

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[algora-pbc]

💡 @987Nabil submitted a pull request that claims the bounty. You can visit your bounty board to reward.

[algora-pbc]

@varshith257: Reminder that in 7 days the bounty will become up for grabs, so please submit a pull request before then 🙏

[algora-pbc]

The bounty is up for grabs! Everyone is welcome to /attempt #3141 🙌

[Petter-K]

Any update on this?

[987Nabil]

I have a proposal. But it is breaking. I want to take a look agin together with @jdegoes

[sullivan-]

I took a quick look at the PR. Am I right in thinking that we are trying to convert a runtime ClassCastException into a compiler error? Of course it would be better to have a compile time error, but I think there is a bigger question -- Why can't HandlerAspects be usable for Handlers with inputs such as (String, Request)? These kinds of handlers are the handlers we are supposed to use with the path codecs.

As it is, it seems impossible for me to combine my authentication HandlerAspect with a PathCodec.string. This seems like a very serious limitation. Unless there is some workaround I am not aware of?

Maybe it would make more sense to stick the path codecs into the R of a Handler[-R, +Err, -In, +Out] somehow rather than into the In?

[sullivan-]

FWIW here is my failing case. it gives the same ClassCastException:

object ChallengeSpec extends ZIOSpecDefault:

  def handleMessage(message: String, request: Request): ZIO[Int, Response, Response] =
    ZIO.service[Int].map(i => Response.text(s"$message $i"))

  val authenticationAspect: HandlerAspect[Any, Int] =
    HandlerAspect.interceptIncomingHandler(Handler.fromFunction[Request] { request =>
      (request, 7)
    })

  val routes = Routes(
    Method.DELETE / string("message") -> handler(handleMessage) @@ authenticationAspect
  )

  def spec = test("handler should route") {
    for
      response <- routes.runZIO(Request.delete(URL(root) / "twenty"))
      body <- response.body.asString
    yield
      assert(response.status)(equalTo(Status.Ok)) &&
      assert(body)(equalTo("twenty 7"))
  }

It seems I have two paths forward: Either rewrite HandlerAspect to have looser type params (seems an incredibly hard prospect for me), or rewrite my authentication code to no longer be an aspect.