Add Decoder method for indicating what should be returned on null path

alejandrohdezma · Apr 7, 2020 · c2e1c65 · c2e1c65
1 parent 2c0e1bc
commit c2e1c65
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Showing 2 changed files with 17 additions and 5 deletions.
diff --git a/sbt-github/src/main/scala/com/alejandrohdezma/sbt/github/json/Decoder.scala b/sbt-github/src/main/scala/com/alejandrohdezma/sbt/github/json/Decoder.scala
@@ -34,6 +34,13 @@ trait Decoder[A] {
   /** Decode the given [[Json.Value]] */
   def decode(json: Json.Value): Try[A]
 
+  /**
+   * What should this decoder return if a `Null` is found on the path to getting the value.
+   *
+   * This doesn't affect when the value itself is `Null`.
+   */
+  def onNullPath: Try[A] = NotFound.raise
+
 }
 
 object Decoder {
@@ -72,9 +79,15 @@ object Decoder {
     case value                => NotADateTime(value).raise
   }
 
-  implicit def OptionDecoder[A: Decoder]: Decoder[Option[A]] = {
-    case Json.Null => Try(None)
-    case value     => Decoder[A].decode(value).map(Some(_))
+  implicit def OptionDecoder[A: Decoder]: Decoder[Option[A]] = new Decoder[Option[A]] {
+
+    override def decode(json: Json.Value): Try[Option[A]] = json match {
+      case Json.Null => Try(None)
+      case value     => Decoder[A].decode(value).map(Some(_))
+    }
+
+    override def onNullPath: Try[Option[A]] = Try(None)
+
   }
 
   implicit def ListDecoder[A: Decoder]: Decoder[List[A]] = {

diff --git a/sbt-github/src/main/scala/com/alejandrohdezma/sbt/github/syntax/json.scala b/sbt-github/src/main/scala/com/alejandrohdezma/sbt/github/syntax/json.scala
@@ -19,7 +19,6 @@ package com.alejandrohdezma.sbt.github.syntax
 import scala.annotation.tailrec
 import scala.util.Try
 
-import com.alejandrohdezma.sbt.github.error.NotFound
 import com.alejandrohdezma.sbt.github.json.error.{InvalidPath, NotAJSONObject}
 import com.alejandrohdezma.sbt.github.json.{Decoder, Json}
 import com.alejandrohdezma.sbt.github.syntax.scalatry._
@@ -49,7 +48,7 @@ object json {
     ): Try[A] = (value, remain) match {
       case (j: Json.Value, Nil)     => j.as[A].mapFail(done.foldRight(_)(InvalidPath))
       case (j: Json.Object, h :: t) => recursiveGet(j.get(h), t, done :+ h)
-      case (Json.Null, _)           => done.foldRight(NotFound: Throwable)(InvalidPath).raise
+      case (Json.Null, _)           => Decoder[A].onNullPath.mapFail(done.foldRight(_)(InvalidPath))
       case (v, _)                   => done.foldRight(NotAJSONObject(v): Throwable)(InvalidPath).raise
     }