finagle/finch

Try Cookbook (goo.gl/tFS8tx) before anything else!

Dermot Haughey

@hderms

in the documentation I saw: An [[Endpoint]] that matches chunked requests and lifts their content into a generic so I tried using Transfer-Encoding: chunked as a header, but I haven't had any luck

Dermot Haughey

@hderms

seems like withStreaming(true) was the missing link in this case

Chih

@Chih47911515_twitter

Hi all! I new to Finch! Tried to find some recent docs about polymorphic endpoints, but apparently, this is quite new and no docs were updated yet. I'm wondering does anyone has any working example to share on how to use Finch with ZIO? Thanks in advance!

1 reply

ComFreek

@ComFreek

If you process Options in your endpoint, what's the best practice to .getOrElse(return BadRequest(???)?

private def foo: Endpoint[IO, String] = get(path("debug")) {
  None.getOrElse(return BadRequest(???))
  Ok("test")
}

This does not typecheck since return will return the outer function (thus BadRequest(???) is expected to be of type Endpoint[IO, String])

But ideally, we would just return from the lambda passed to get(...)

ComFreek

@ComFreek

Other question: given a list of endpoints, can I automatically pretty-print it somehow? Such that the user gets a list of GET /post/list, POST /post/edit

Ryan Plessner

@rpless

for the first I example I tend to use fold. opt.fold[Output[String]](BadRequest(???))(_ => Ok("test")) note you do have provide the type parameter to the fold

as for the pretty-printing there as a toString that kinda does this, but you would have fiddle with the output to get the format you want

ComFreek

@ComFreek

@rpless Thanks. For the prettyprinting of endpoints, in my case I get

"(GET /help :+: (POST /archive :: build-light :+: (POST /archive :: build :+: (POST /fact :: add :: body :+: (GET /fact :: list :+: (GET /scroll :: list :+: (POST /scroll :: apply :: body :+: GET /debug :: situationtheory :: print)))))))"

which is not very helpful

even the parentheses look strangely unbalanced

e.g. GET /help is a single endpoint

ComFreek

@ComFreek

--> now posted on Finagle mailing list: https://groups.google.com/g/finaglers/c/LM5KzvSRpcI

Ryan Plessner

@rpless

the parens on that print out seem correct. basically every :+: introduces a set of parens so the endpoints wind up being fairly nested

re: your question in Finaglers auto generating developer docs isn't something that is supported at the moment. its a hard problem that we haven't solved. its one of the oldest issues on the repo finagle/finch#73

zanpakuto

@zanpakuto

I'm using finchx 0.32.1. I wrote below code, but unable to understand the reason for compilation error : "Cannot resolve overloaded method"

Can anyone please help me understand? Appreciate the help.

private val greetByName : Endpoint[IO, Json] = get(path("hello") :: paramOption("name")) = {
  Ok("Hello".asJson)
}

Ryan Plessner

@rpless

Hi @zanpakuto. I think the issue is that you are using paramOption which means the mapper is going to want an argument to the function you are using for mapping. something like this might be what you are looking for:

  private val greetByName: Endpoint[IO, Json] = get(path("hello") :: paramOption("name"))({ name: Option[String] =>
    Ok("Hello".asJson)
  })

zanpakuto

@zanpakuto

@rpless , thank you. The build is fine now.

Andrew Roberts

@aroberts

I have a POST endpoint consuming jsonBody and decoding via Circe, and I don’t seem to be able to catch the decoding error if it occurs- I want to be able to return a 400 response when bad json is submitted, but the circe DecodingFailure is wrapped in a finch-private CirceError case class. Is there a better approach to achieve this end?

Ryan Plessner

@rpless

@aroberts you should be able to access the Circe error even if its wrapped in Finch's private class. getCause should give you access to the underlying Circe error

Andrew Roberts

@aroberts

oh, interesting. I’m used to declarations shaped like class CirceError(cause: Error) extends Exception(cause) with NoStackTrace. My assumption was that CirceError.cause shadowed Exception.cause, but didn’t actually override it

Daave

@Daave_gitlab

Is there a way to get all params from a application/x-www-form-urlencoded in a Map

In play I can do it like so

def formHandler: Action[Map[String, Seq[String]]] = Action.async(parse.formUrlEncoded)

I can use param but I need to get all the params and they can be dynamic

Is there a way to do this?

Sergey Kolbasov

@sergeykolbasov

hmm, I think you need your own endpoint that is going to extract it for you. You could use something like root.map(request => request.getParams()) to get the Endpoint[F, List[Entry[String, String]]

Duncan Hills Coffee Company

@DuncanHills

can someone publish 0.32.1 to maven central?

0.31 is the latest version there...

kinda strange since that release was in march

ComFreek

@ComFreek

I copied the exception encoder from the user guide: https://finagle.github.io/finch/user-guide.html#errors

But it apparently doesn't take effect, I still get 500 internal server errors with empty body upon exceptions

Where do I have to define it?

ComFreek

@ComFreek

e.g. in this code (please ignore IntelliJ's broken graying), on runtime I get an exception and the println line is not even reached

I got this example from the end2end specs of finch

ComFreek

@ComFreek

Not even this works:

import io.finch._
import cats.effect.IO
import com.twitter.finagle.Http
import com.twitter.io.Buf
import com.twitter.util.Await

object Test extends App with Endpoint.Module[IO] {
  implicit val encodeException: Encode.Text[Exception] =
    Encode.text((_, cs) => Buf.ByteArray.Owned("ERR!".getBytes(cs.name)))

  val api: Endpoint[IO, String] = get("hello") {
    throw new Exception("test")
    Ok("Hello, World!")
  }
  Await.ready(Http.server.serve(":8080", api.toServiceAs[Text.Plain]))
}

http://127.0.0.1:8080/hello does not output ERR! in the browser

Sergey Kolbasov

@sergeykolbasov

Hello @ComFreek

It's a bit trickier. That default encoder covers only "exceptions" inside of Output, i.e. BadRequest(new Exception("test"))

If you would like to cover all the exceptions, you need to set up filter on top of finagle's Service[Request, Response] or use middleware filters like here:
https://github.com/finagle/finch/blob/master/examples/src/main/scala/io/finch/middleware/Main.scala

shortly speaking in Finch we prefer to avoid exceptions as a mechanism and rather deal with errors as values, as it's much cleaner and easier to reason about

import io.finch._
import cats.effect.IO
import com.twitter.finagle.Http
import com.twitter.io.Buf
import com.twitter.util.Await

object Test extends App with Endpoint.Module[IO] {
  implicit val encodeException: Encode.Text[Exception] =
    Encode.text((_, cs) => Buf.ByteArray.Owned("ERR!".getBytes(cs.name)))

  val api: Endpoint[IO, String] = get("hello") {
    if (Random.nextBoolean()) {
      Ok("Hello, World!")
    } else {
      BadRequest(new Exception("oh no"))
    }
  }
  Await.ready(Http.server.serve(":8080", api.toServiceAs[Text.Plain]))
}

This should work

ComFreek

@ComFreek

@sergeykolbasov I understand your philosophy on values over exceptions, but for debugging receiving just a 500 Internal Server Error is utterly lacking.

I need those stack traces

Let me see if I can get the filter approach working

ComFreek

@ComFreek

In https://github.com/finagle/finch/blob/master/examples/src/main/scala/io/finch/middleware/Main.scala#L40, where does *> come from?

Sergey Kolbasov

@sergeykolbasov

It's a method of IO.

Although, it works for any F[_] : Apply with import cats.syntax.all._

Where communities thrive

People

Repo info

Activity