Lift Framework example source code file (JsonScalaz.scala)

This example Lift Framework source code file (JsonScalaz.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Lift Framework tags/keywords

a, error, jobject, jsonr, jsonr, jsonw, jvalue, jvalue, result, result, string, string, uncategorizederror, unexpectedjsonerror

The Lift Framework JsonScalaz.scala source code

/*
 * Copyright 2009-2010 WorldWide Conferencing, LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package net.liftweb.json.scalaz

import scalaz._
import Scalaz._
import net.liftweb.json._

trait Types {
  type Result[A] = ValidationNEL[Error, A]

  sealed trait Error
  case class UnexpectedJSONError(was: JValue, expected: Class[_ <: JValue]) extends Error
  case class NoSuchFieldError(name: String, json: JValue) extends Error
  case class UncategorizedError(key: String, desc: String, args: List[Any]) extends Error

  case object Fail {
    def apply[A](key: String, desc: String, args: List[Any]): Result[A] = 
      UncategorizedError(key, desc, args).fail.liftFailNel

    def apply[A](key: String, desc: String): Result[A] = 
      UncategorizedError(key, desc, Nil).fail.liftFailNel
  }

  implicit def JValueShow[A <: JValue]: Show[A] = new Show[A] {
    def show(json: A) = compact(render(json)).toList
  }

  implicit def JValueZero: Zero[JValue] = zero(JNothing)
  implicit def JValueSemigroup: Semigroup[JValue] = semigroup(_ ++ _)
  implicit def JValueEqual: Equal[JValue] = equalA

  trait JSONR[A] {
    def read(json: JValue): Result[A]
  }

  trait JSONW[A] {
    def write(value: A): JValue
  }

  trait JSON[A] extends JSONR[A] with JSONW[A]

  implicit def Result2JSONR[A](f: JValue => Result[A]): JSONR[A] = new JSONR[A] {
    def read(json: JValue) = f(json)
  }

  def fromJSON[A: JSONR](json: JValue): Result[A] = implicitly[JSONR[A]].read(json)
  def toJSON[A: JSONW](value: A): JValue = implicitly[JSONW[A]].write(value)

  def field[A: JSONR](name: String)(json: JValue): Result[A] = json match {
    case JObject(fs) => 
      fs.find(_.name == name)
        .map(f => implicitly[JSONR[A]].read(f.value))
        .orElse(implicitly[JSONR[A]].read(JNothing).fold(_ => none, x => some(Success(x))))
        .getOrElse(NoSuchFieldError(name, json).fail.liftFailNel)
    case x => UnexpectedJSONError(x, classOf[JObject]).fail.liftFailNel
  }

  def validate[A: JSONR](name: String): Kleisli[Result, JValue, A] = kleisli(field[A](name))

  def makeObj(fields: Traversable[(String, JValue)]): JObject = 
    JObject(fields.toList.map { case (n, v) => JField(n, v) })
}

object JsonScalaz extends Types with Lifting with Base with Tuples