com.sksamuel.pulsar4s.circe.package.scala Maven / Gradle / Ivy

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package com.sksamuel.pulsar4s

import java.nio.charset.StandardCharsets

import io.circe.{Decoder, Encoder, Json, Printer}
import org.apache.pulsar.client.api.Schema
import org.apache.pulsar.client.impl.schema.SchemaInfoImpl
import org.apache.pulsar.common.schema.{SchemaInfo, SchemaType}

import scala.annotation.implicitNotFound

/**
  * Automatic MessageWriter and MessageReader derivation
  *
  * == Examples ==
  *
  * {{{
  *  import io.circe.generic.auto._
  *  import com.sksamuel.pulsar4s.circe._
  *
  *  case class City(id: Int, name: String)
  *
  *  producer.send(City(1, "London"))
  *
  *  val city: City = consumer.receive
  *
  * }}}
  */
package object circe {

  @implicitNotFound(
    "No Encoder for type ${T} found. Use 'import io.circe.generic.auto._' or provide an implicit Encoder instance ")
  implicit def circeSchema[T: Manifest](implicit
                                        encoder: Encoder[T],
                                        decoder: Decoder[T],
                                        printer: Json => String = Printer.noSpaces.print): Schema[T] = new Schema[T] {
    override def clone(): Schema[T] = this
    override def encode(t: T): Array[Byte] = printer(encoder(t)).getBytes(StandardCharsets.UTF_8)
    override def decode(bytes: Array[Byte]): T =
      io.circe.jawn.decode[T](new String(bytes, StandardCharsets.UTF_8)).fold(throw _, identity)
    override def getSchemaInfo: SchemaInfo = {
      SchemaInfoImpl.builder()
        .name(manifest[T].runtimeClass.getCanonicalName)
        .`type`(SchemaType.BYTES)
        .schema(Array.empty[Byte])
        .build()
    }
  }
}