Extension method to deserialize JSON string to object.

JacksonJsonSugar.scala

package us.aharon.test.json

import com.fasterxml.jackson.databind.json.JsonMapper
import com.fasterxml.jackson.module.scala.DefaultScalaModule

import scala.reflect.{ClassTag, classTag}

/**
 * Extension methods for [[String]]s.
 */
private object StringExtension {
  /**
   * [[String]]s that contain JSON objects.
   */
  implicit class JsonString(self: String) {
    /**
     * Convert the JSON [[String]] to the type provided by [[T]].
     * @param mapper A Jackson JSON mapper instance.
     * @tparam T Deserialize to this type.
     */
    def fromJson[T: ClassTag]()(implicit mapper: JsonMapper): T =
      mapper.readValue(self, classTag[T].runtimeClass.asInstanceOf[Class[T]])
  }
}

/**
 * Include the implicit JSON mapper.
 */
trait JsonSupport {
  implicit val mapper: JsonMapper = JsonMapper.builder()
    .addModule(DefaultScalaModule)
    .build()
}

object JacksonJsonSugar extends App with JsonSupport {

  /**
   * Example object as a target for JSON deserialization.
   */
  case class Example(a: Int, b: Double, c: String)

  val exampleJson =
    """
      |{
      |  "a": 1,
      |  "b": 2.2,
      |  "c": "example"
      |}""".stripMargin

  val expected = Example(1, 2.2, "example")

  import us.aharon.test.json.StringExtension.JsonString
  val actual = exampleJson.fromJson[Example]

  println(s"Example JSON:\n$exampleJson")
  println(s"Expected:  $expected")
  println(s"Actual:  $actual")

  assert(expected == actual)
}