Example for medium article on Circe

CirceDemo.sc

#!/usr/bin/env amm

import $ivy.`io.circe::circe-core:0.13.0`
import $ivy.`io.circe::circe-generic:0.13.0`
import $ivy.`io.circe::circe-parser:0.13.0`

import io.circe._
import io.circe.generic.semiauto._
import io.circe.parser._
import io.circe.syntax._

import java.net.URL
import java.nio.file.{Files, Paths}
import java.util.{Base64, UUID}

import scala.util.Try

case class Blob(uuid: UUID, url: String, checksum: Array[Byte])
case class Catalog(uuid: UUID, name: Option[String], blobs: List[Blob])

implicit val byteArrayEncoder: Encoder[Array[Byte]] = new Encoder[Array[Byte]] {
    final def apply(xs: Array[Byte]): Json =
      Json.fromString(new String(Base64.getEncoder().encode(xs)))
  }
implicit val byteArrayDecoder: Decoder[Array[Byte]] = Decoder
  .decodeString
  .emapTry(str => Try(Base64.getDecoder.decode(str.getBytes)))

implicit val blogDecoder: Decoder[Blob] = deriveDecoder
implicit val blogEncoder: Encoder[Blob] = deriveEncoder

implicit val catalogDecoder: Decoder[Catalog] = deriveDecoder
implicit val catalogEncoder: Encoder[Catalog] = deriveEncoder


val json = Files.readString(Paths.get("CirceDemo.json"))

val r = for {
  doc <- parse(json)
  e <- doc.as[List[Catalog]]
} yield e

r match {
  case Left(e) => 
    println(e)
  case Right(v) => 
    println(v.asJson)
}

// decode[List[Catalog]](json) match {
//   case Left(e) => 
//     println(e)
//   case Right(v) => 
//     println(v.asJson)
// }