Removing support for the undefined keyword, which is part of JavaScript but not JSON itself.

Author: bathalh

README.markdown

@@ -113,15 +113,14 @@ For example, a PATCH request may have a payload like this:
 ```json
     { "id":"234565434567898789098765",
       "field1": "new value",
-      "field3": null,
-      "field4": undefined }
+      "field3": null }
 ```
-which would tell the server to update field1 to "new value", set field3 to null, and leave field2 and field4
-unchanged. With a standard scala `Option`, it is impossible to tell whether the values of field2, field3,
-and field4 in the original payload were `null` or `undefined` since any missing values translate to `None`.
+which would tell the server to update field1 to "new value", set field3 to null, and leave field2
+unchanged. With a standard scala `Option`, it is impossible to tell whether the values of field2 and field3
+in the original payload were `null` or undefined since any missing values translate to `None`.
 
-The `Tription` solves that problem by defining `Value` for present values, `Null` for null values, and
-`Undefined` for values which are missing or explicitly marked as undefined.
+The `Tription` solves that problem by defining `Value` for present values, `Null` for values explicitly marked
+null, and `Undefined` for values which are missing.
 
 `Tription`s can be used just like `Option`s:
 ```scala
@@ -183,8 +182,8 @@ object MyJsonProtocol extends DefaultJsonProtocol {
 #### NullOptions
 
 The `NullOptions` trait supplies an alternative rendering mode for optional case class members. Normally optional
-members that are undefined (`None`/`Undefined`) are not rendered at all. By mixing in this trait into your custom JsonProtocol you
-can enforce the rendering of undefined members as `null`.
+members that are undefined (`None`/`Undefined`) are not rendered at all. By mixing in this trait into your custom
+JsonProtocol you can enforce the rendering of undefined members as `null`.
 (Note that this only affect JSON writing, spray-json will always read missing `Option` members as well as `null`
 `Option` members as `None` and missing `Tription` members as `Undefined`.)
 

src/main/scala/spray/json/CompactPrinter.scala

@@ -33,10 +33,11 @@ trait CompactPrinter extends JsonPrinter {
 
   protected def printObject(members: Map[String, JsValue], sb: StringBuilder) {
     sb.append('{')
-    printSeq(members, sb.append(',')) { m =>
-      printString(m._1, sb)
-      sb.append(':')
-      print(m._2, sb)
+    val definedMembers = members filter { case (_, v) => v != JsUndefined }
+    printSeq(definedMembers, sb.append(',')) { m =>
+      printString( m._1, sb )
+      sb.append( ':' )
+      print( m._2, sb )
     }
     sb.append('}')
   }

src/main/scala/spray/json/JsValue.scala

@@ -68,7 +68,8 @@ case class JsArray(elements: Vector[JsValue]) extends JsValue {
 }
 object JsArray {
   val empty = JsArray(Vector.empty)
-  def apply(elements: JsValue*) = new JsArray(elements.toVector)
+  def apply(elements: JsValue*) = if( elements contains JsUndefined ) throw new IllegalStateException( "JSON arrays cannot contain undefined values" )
+                                  else new JsArray(elements.toVector)
   @deprecated("Use JsArray(Vector[JsValue]) instead", "1.3.0")
   def apply(elements: List[JsValue]) = new JsArray(elements.toVector)
 }
@@ -123,5 +124,5 @@ case object JsFalse extends JsBoolean {
   */
 case object JsNull extends JsValue
 
-/** The representation for JSON undefined. **/
+/** The representation for JSON missing value. **/
 case object JsUndefined extends JsValue

src/main/scala/spray/json/JsonParser.scala

@@ -60,7 +60,6 @@ class JsonParser(input: ParserInput) {
     (cursorChar: @switch) match {
       case 'f' => simpleValue(`false`(), JsFalse)
       case 'n' => simpleValue(`null`(), JsNull)
-      case 'u' => simpleValue(`undefined`(), JsUndefined)
       case 't' => simpleValue(`true`(), JsTrue)
       case '{' => advance(); `object`()
       case '[' => advance(); `array`()
@@ -72,7 +71,6 @@ class JsonParser(input: ParserInput) {
 
   private def `false`() = advance() && ch('a') && ch('l') && ch('s') && ws('e')
   private def `null`() = advance() && ch('u') && ch('l') && ws('l')
-  private def `undefined`() = advance() && ch('n') && ch('d') && ch('e') && ch('f') && ch('i') && ch('n') && ch('e') && ws('d')
   private def `true`() = advance() && ch('r') && ch('u') && ws('e')
 
   // http://tools.ietf.org/html/rfc4627#section-2.2

src/main/scala/spray/json/JsonPrinter.scala

@@ -44,11 +44,11 @@ trait JsonPrinter extends (JsValue => String) {
   protected def printLeaf(x: JsValue, sb: JStringBuilder) {
     x match {
       case JsNull      => sb.append("null")
-      case JsUndefined => sb.append("undefined")
       case JsTrue      => sb.append("true")
       case JsFalse     => sb.append("false")
       case JsNumber(x) => sb.append(x)
       case JsString(x) => printString(x, sb)
+      case JsUndefined => throw new IllegalStateException( "Cannot display JsUndefined" )
       case _           => throw new IllegalStateException
     }
   }

src/main/scala/spray/json/PrettyPrinter.scala

@@ -40,8 +40,9 @@ trait PrettyPrinter extends JsonPrinter {
   protected def organiseMembers(members: Map[String, JsValue]): Seq[(String, JsValue)] = members.toSeq
 
   protected def printObject(members: Map[String, JsValue], sb: StringBuilder, indent: Int) {
-    sb.append("{\n")    
-    printSeq(organiseMembers(members), sb.append(",\n")) { m =>
+    sb.append("{\n")
+    val definedMembers = members filter { case (_, v) => v != JsUndefined }
+    printSeq(organiseMembers(definedMembers), sb.append(",\n")) { m =>
       printIndent(sb, indent + Indent)
       printString(m._1, sb)
       sb.append(": ")

src/main/scala/spray/json/ProductFormats.scala

@@ -51,17 +51,17 @@ trait ProductFormats extends ProductFormatsInstances {
   protected def fromField[T](value: JsValue, fieldName: String)
                                      (implicit reader: JsonReader[T]) = value match {
     case x: JsObject if
-    (reader.isInstanceOf[OptionFormat[_]] &
+      (reader.isInstanceOf[OptionFormat[_]] &
         !x.fields.contains(fieldName)) =>
       None.asInstanceOf[T]
     case x: JsObject if
-    (reader.isInstanceOf[TriptionFormat[_]] &
+      (reader.isInstanceOf[TriptionFormat[_]] &
         !x.fields.contains(fieldName)) =>
       Undefined.asInstanceOf[T]
     case x: JsObject =>
       try reader.read(x.fields(fieldName))
       catch {
-        case e: NoSuchElementException => Undefined
+        case e: NoSuchElementException =>
           deserializationError("Object is missing required member '" + fieldName + "'", e, fieldName :: Nil)
         case DeserializationException(msg, cause, fieldNames) =>
           deserializationError(msg, cause, fieldName :: fieldNames)

src/main/scala/spray/json/Tription.scala

@@ -11,11 +11,11 @@ package spray.json
   *       "field3: null }
   * </code>
   * which would tell the server to update field1 to 7, set field3 to null, and leave field2 alone.
-  * With a standard scala `Option`, it is impossible to tell whether the payload of the request had field2 and field3
+  * With a standard scala `Option`, it is impossible to tell whether field2 and field3 were
   * null or undefined since any missing values translate to `None`.
   *
-  * The Tription solves that problem by defining `Value` for present values, `Null` for null values, and
-  * `Undefined` for values which are missing or explicitly marked as undefined.
+  * The Tription solves that problem by defining `Value` for present values, `Null` for values
+  * explicitly set to null, and `Undefined` for values which are not there at all.
   *
   * Created by bathalh on 2/19/16.
   */

src/test/scala/spray/json/CompactPrinterSpec.scala

@@ -24,8 +24,13 @@ class CompactPrinterSpec extends Specification {
     "print JsNull to 'null'" in {
       CompactPrinter(JsNull) mustEqual "null"
     }
-    "print JsUndefined to 'undefined'" in {
-      CompactPrinter(JsUndefined) mustEqual "undefined"
+    "throw exception when printing JsUndefined" in {
+      try {
+        CompactPrinter(JsUndefined) mustEqual "undefined"
+      } catch {
+        case ise: IllegalStateException =>
+          ise.getMessage mustEqual "Cannot display JsUndefined"
+      }
     }
     "print JsTrue to 'true'" in {
       CompactPrinter(JsTrue) mustEqual "true"
@@ -67,9 +72,17 @@ class CompactPrinterSpec extends Specification {
       CompactPrinter(JsObject("key" -> JsNumber(42), "key2" -> JsString("value")))
               mustEqual """{"key":42,"key2":"value"}"""
     )
+    "properly print a simple JsObject with undefined values" in (
+        CompactPrinter(JsObject("key" -> JsNumber(42), "key2" -> JsString("value"), "key3" -> JsUndefined))
+            mustEqual """{"key":42,"key2":"value"}"""
+        )
+    "properly print a simple JsObject with only undefined values" in (
+        CompactPrinter(JsObject("key" -> JsUndefined, "key2" -> JsUndefined))
+            mustEqual "{}"
+        )
     "properly print a simple JsArray" in (
-      CompactPrinter(JsArray(JsNull, JsUndefined, JsNumber(1.23), JsObject("key" -> JsBoolean(true))))
-              mustEqual """[null,undefined,1.23,{"key":true}]"""
+      CompactPrinter(JsArray(JsNull, JsNumber(1.23), JsObject("key" -> JsBoolean(true))))
+              mustEqual """[null,1.23,{"key":true}]"""
     )
     "properly print a JSON padding (JSONP) if requested" in {
       CompactPrinter(JsTrue, Some("customCallback")) mustEqual("customCallback(true)")

src/test/scala/spray/json/JsonParserSpec.scala

@@ -24,9 +24,6 @@ class JsonParserSpec extends Specification {
     "parse 'null' to JsNull" in {
       JsonParser("null") === JsNull
     }
-    "parse 'undefined' to JsUndefined" in {
-      JsonParser("undefined") === JsUndefined
-    }
     "parse 'true' to JsTrue" in {
       JsonParser("true") === JsTrue
     }
@@ -60,8 +57,8 @@ class JsonParserSpec extends Specification {
               JsObject("key" -> JsNumber(42), "key2" -> JsString("value"))
     )
     "parse a simple JsArray" in (
-      JsonParser("""[null, undefined, 1.23 ,{"key":true } ] """) ===
-              JsArray(JsNull, JsUndefined, JsNumber(1.23), JsObject("key" -> JsTrue))
+      JsonParser("""[null, 1.23 ,{"key":true } ] """) ===
+              JsArray(JsNull, JsNumber(1.23), JsObject("key" -> JsTrue))
     )
     "parse directly from UTF-8 encoded bytes" in {
       val json = JsObject(