A small library (100 LOC, zero dependencies) to map an ADT to urls and urls back to ADTs. Works on Scala, Scala.js, 2.10 and 2.11.
libraryDependencies += "com.geirsson" %%% "tiny-router" % "latest.integration"It requires a bit of boilerplate to provide the implementation for each direction.
sealed abstract class Page
case object Dashboard extends Page
case class Edit(id: Int) extends Page
case class Update(from: Int, to: Float) extends Page
val router = {
import tinyrouter.TinyRouter._
tinyrouter.Router[Page](
dynamic[Edit](x => s"edit/${x.id}") {
case url"edit/${int(i)}" => Edit(i)
},
dynamic[Update](x => s"update/${x.from}/${x.to}") {
case url"update/${int(from)}/${float(to)}" => Update(from, to)
},
static(Dashboard, "dashboard")
)
}
val url = router.toUrl(Edit(2)) // Some("edit/2")
val edit = router.fromUrl("edit/2") // Some(Edit(2))You should only define one route per class of the ADT. The following will not work.
val brokenRouter = tinyrouter.Router[Page](
dynamic[Edit](x => s"edit/${x.id}") {
case url"edit/${int(i)}" => Edit(i)
},
dynamic[Edit](x => s"banana/${x.id}") {
case url"banana/${int(i)}" => Edit(i)
}
)Use scalacheck to test that your router is well-behaved. Optionally, use scalacheck-shapeless to automatically generate arbitrary instances of your page ADT. Example,
// in build.sbt: libraryDependencies += "com.github.alexarchambault" %%% "scalacheck-shapeless_1.13" % "VERSION" % "test"
import org.scalacheck.Prop.forAll
import org.scalacheck.Properties
import org.scalacheck.Shapeless._
object RouterProperties extends Properties("Router") {
property("router is comprehensive") = forAll { page: Page =>
router.toUrl(page).isDefined
}
property("routes are bijective") = forAll { page: Page =>
val url = router.toUrl(page).get
val pageFromUrl = router.fromUrl(url).get
page == pageFromUrl
}
}- scalajs-router: zero boilerplate + has way more features.
The url extractor implementation is mostly borrowed and adapted from the awesome
Playframework String Interpolating Routing DSL.