Created
July 17, 2016 21:25
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circe in finch question
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| import com.twitter.app.Flag | |
| import com.twitter.finagle.http.{Request, Response} | |
| import com.twitter.finagle.{Http, ListeningServer, Service} | |
| import com.twitter.server.TwitterServer | |
| import com.twitter.util.Await | |
| import io.circe.{Encoder, Json} | |
| import io.finch._ | |
| import io.finch.circe._ | |
| import io.finch.circe.dropNullKeys._ | |
| import io.circe.generic.auto._ | |
| import io.circe.syntax._ | |
| import com.twitter.finagle.http.Message | |
| import com.twitter.finagle.http.Message.ContentTypeJson | |
| import com.twitter.io.Buf._ | |
| object RestServer extends TwitterServer { | |
| // -- Model ---------------------------- | |
| sealed trait BaseModel | |
| final case class Foo(id: String) extends BaseModel | |
| final case class Bar(param: String) extends BaseModel | |
| final case class FooBar(foo: Foo, bars:List[Bar]) extends BaseModel | |
| // -- Backend Mock ---------------------------- | |
| def getFooList(a:String = "")= List(Foo("1"), Foo("2")) | |
| def getBarList(a:String = "")= List(Bar("a"), Bar("b")) | |
| def getFooBar() =FooBar(Foo("3"), List(Bar("c"),Bar("d"))) | |
| // -- Encoders ---------------------------- | |
| // QUESTION 1 - Expected to be able to use base type (BaseModel) encoder by default and | |
| // overwrite encoder just for some specific types | |
| // but this doesn't work | |
| //implicit val baseEncoder = Encoder.instance[BaseModel] { f => f.asJson } | |
| /* Error:(36, 7) not enough arguments for method asJson: | |
| (implicit encoder: io.circe.Encoder[RestServer.BaseModel])io.circe.Json. | |
| Unspecified value parameter encoder. | |
| f.asJson | |
| ^ | |
| */ | |
| // QUESTION 2 - Moreover, expected to see the build-in cicle encoder for case classes | |
| implicit val fooEncoder = Encoder.instance[Foo] { f => | |
| f.asJson | |
| } | |
| implicit val barEncoder = Encoder.instance[Bar] { f => | |
| f.asJson | |
| } | |
| implicit val foobarEncoder = Encoder.instance[FooBar] { f => | |
| f.asJson | |
| } | |
| implicit def fooResponseEncoder: EncodeResponse[Foo] = | |
| EncodeResponse(ContentTypeJson)(f => Utf8(Map("data" -> f).asJson.noSpaces)) | |
| implicit def barResponseEncoder: EncodeResponse[Bar] = | |
| EncodeResponse(ContentTypeJson)(b => Utf8(Map("data" -> b).asJson.noSpaces)) | |
| // QUESTION 3: The same, why need to explicitly declare natural encoding for case classes | |
| implicit def fooListResponseEncoder: EncodeResponse[List[Foo]] = | |
| EncodeResponse(ContentTypeJson)(fooList => Utf8(Json.arr(fooList map {_.asJson}:_*).asJson.noSpaces)) | |
| implicit def barListResponseEncoder: EncodeResponse[List[Bar]] = | |
| EncodeResponse(ContentTypeJson)(barList => Utf8(Json.arr(barList map {_.asJson}:_*).asJson.noSpaces)) | |
| // QUESTION 4: Is something may be omitted, relying on previous encoders ? | |
| // {foo: {"id":"1"}, bars: [{param:"a"}, {"param":"b"}] | |
| // | |
| implicit def fooBarResponseEncoder: EncodeResponse[FooBar] = | |
| EncodeResponse(ContentTypeJson)(f => | |
| Utf8(Map("foo" -> f.foo.asJson, | |
| "bars" -> Json.arr(f.bars map {_. asJson}: _*)).asJson.noSpaces)) | |
| // -- Endpoints ---------------------------- | |
| val fooListApi: Endpoint[List[Foo]] = get("v1" :: "foos" ) { | |
| Ok(getFooList()) | |
| } | |
| val fooApi: Endpoint[Foo] = get("v1" :: "foos" :: string ) { | |
| (a: String) => | |
| Ok(getFooList(a)(0)) | |
| } | |
| val barListApi: Endpoint[List[Bar]] = get("v1" :: "bars" ) { | |
| Ok(getBarList() ) | |
| } | |
| val barApi: Endpoint[Bar] = get("v1" :: "bars" :: string ) { | |
| (a: String) => | |
| Ok(getBarList(a)(0) ) | |
| } | |
| val foobarApi: Endpoint[FooBar] = get("v1" :: "foobar" ) { | |
| Ok(getFooBar) | |
| } | |
| // Finch-finagle service | |
| val apiService: Service[Request, Response] = | |
| (fooListApi :+: fooApi :+: barListApi :+: barApi :+: foobarApi).handle({ | |
| case e: Exception => NotFound(e) | |
| }).toService | |
| val port: Flag[Int] = flag("port", 8081, "TCP port for HTTP server") | |
| def main(): Unit = { | |
| val server: ListeningServer = Http.server.serve(s":${port()}", apiService) | |
| println("Listening: " + port() ) | |
| onExit { server.close() } | |
| Await.ready(adminHttpServer) | |
| } | |
| } |
Author
Author
Thanks @vkostyukov! Fixed just by removing import io.finch.circe.dropNullKeys._ everywhere.
Discussion was held here https://gitter.im/finagle/finch?at=578c7988196179690eff3eca
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See below the new version with all custom trivial encoders removed. I want to use embedded Circe’ generic derivation for case classes and ADTs. But this leads to the inability to find out proper encoders
The part of build.sbt class
And the content of project/build.properties