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Fix pagination beyond page 2 #29

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ChristopherDavenport merged 1 commit into from
Oct 15, 2019
Merged

Fix pagination beyond page 2 #29

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39 changes: 23 additions & 16 deletions core/src/main/scala/io/chrisdavenport/github/internals/RequestConstructor.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -6,12 +6,13 @@ import cats.implicits._
import fs2._
import org.http4s._
import org.http4s.implicits._
import org.http4s.client.Client
import org.http4s.client.{Client, UnexpectedStatus}
import org.http4s.headers.Authorization

import _root_.io.chrisdavenport.github._
import cats.data.Kleisli
import org.http4s.headers.Link
import org.http4s._

import scala.util.matching.Regex


object RequestConstructor {
Expand Down Expand Up @@ -46,44 +47,49 @@ object RequestConstructor {
c.expect[B](req)
}

private val RE_LINK: Regex = "[\\s]*<(.*)>; rel=\"(.*)\"".r

private def getNextUri[F[_]: MonadError[*[_], Throwable]](r: Response[F]): Option[Uri] = {
for {
next <- r.headers.toList.map(Link.matchHeader).collect{
case Some(Link(uri, Some("next"), _, _, _)) => uri
}.headOption
} yield next
r.headers.toList.flatMap {
case Header(name, value) if name == "Link".ci => value.split(",").toList
case _ => Nil
}.collectFirstSome {
case RE_LINK(uri, "next") => Uri.fromString(uri).toOption
case _ => None
}
}

def runPaginatedRequest[F[_]: Sync, B: EntityDecoder[F, ?]](
auth: Option[Auth],
extendedUri: Uri,
): Kleisli[Stream[F, ?], Client[F], B] = Kleisli{ c =>
val uri = Uri.resolve(baseUrl(auth), extendedUri)

unfoldLoopEval(uri){uri =>
unfoldLoopEval(uri){ uri =>
val baseReq = Request[F](method = Method.GET, uri = uri)
.withHeaders(extraHeaders)
val req = auth.fold(baseReq)(setAuth(_)(baseReq))
c.run(req).use{resp =>
resp.as[B].map{
c.fetch(req) { resp =>
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@ChristopherDavenport ChristopherDavenport Oct 8, 2019

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Why did we switch from run to fetch. run is clearer use semantics in my opinion.

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@timo-schmid timo-schmid Oct 17, 2019

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No clear reason - I just didn't know how to do it using f.
But looking at it now, I think it should also work using use as well.
I guess this part can be changed back - I can do it if you want.

if(resp.status.isSuccess)
resp.as[B].map {
(_, getNextUri(resp))
}
}
else
MonadError[F, Throwable].raiseError[(B, Option[Uri])](UnexpectedStatus(resp.status))
}
}
}


//These two will be in the next version of fs2



/** Like [[unfoldLoop]], but takes an effectful function. */
private def unfoldLoopEval[F[_], S, O](s: S)(f: S => F[(O, Option[S])]): Stream[F, O] =
Pull
.loop[F, O, S](
s =>
Pull.eval(f(s)).flatMap {
case (o, sOpt) => Pull.output1(o) >> Pull.pure(sOpt)
case (o, sOpt) =>
Pull.output1(o) >> Pull.pure(sOpt)
}
)(s)
.void
Expand All @@ -109,4 +115,5 @@ object RequestConstructor {
Header("User-Agent", "github.scala/" ++ _root_.io.chrisdavenport.github.BuildInfo.version),
Header("Accept", "application/vnd.github.v3+json")
)

}