Querying JSON

implementation.scala

package jsonquery

object `package` {
  
  import dispatch.json._
  
  implicit def jsonToSearchable(json: JsValue) = new {
    def \ (selector: String): Either[String, JsValue] = json match {
      case JsObject(map) => {
        (for {
          value <- map.get(JsString(selector))
        } yield {
          Right(value)
        }) getOrElse Left("'%s' is undefined on object: %s".format(selector, json))
      }
      case _ => Left("'%s' is undefined on object: %s".format(selector, json))
    }
  }
  
  implicit def eitherToSearchable(e: Either[String, JsValue]) = new {
    def \ (selector: String): Either[String, JsValue] = {
      for {
        json <- e.right
        result <- (json \ selector).right
      } yield result
    }
  }
}

specs.scala

package jsonquery

import org.specs2.mutable._
import dispatch.json._

class SJsonQuerySpec extends Specification {
  
  val json = JsObject(List(
          JsString("foo")->JsString("bar"),
          JsString("baz")->JsNumber(42),
          JsString("bah")->JsObject(List(
                JsString("nested")->JsNumber(1)
              ))
        ))
  
  val jsonArray = new JsArray(List(
          JsObject(List(JsString("foo")->JsString("bar"))),
          JsObject(List(JsString("foo")->JsString("baz")))
        ))
  
  
  "sjson-query" should {
    "find a value from an object and its key" >> {
      (json \ "foo").right.get must be_== (JsString("bar"))
      (for {
        JsString(value) <- (json \ "foo").right.toOption
      } yield {
        value
      }).get must be_== ("bar")
    }
    
    "return an error on unsuccessful search" >> {
      (json \ "bar").isLeft must beTrue
    }
    
    "allow to search consecutively" >> {
      (json \ "bah" \ "nested").right.get must be_== (JsNumber(1))
    }
  }
}