Closes: json4s#641.

* Fix MappingException message when parsing missing Option field with strict option parsing enabled
livongo · Dec 20, 2019 · 9d609bb · 9d609bb
1 parent c00e137
commit 9d609bb
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Showing 2 changed files with 27 additions and 3 deletions.
diff --git a/core/src/main/scala/org/json4s/Extraction.scala b/core/src/main/scala/org/json4s/Extraction.scala
@@ -587,10 +587,9 @@ object Extraction {
           else x
         } catch {
           case e @ MappingException(msg, _) =>
-            if (descr.isOptional &&
-                (!formats.strictOptionParsing || extract(json, ScalaType[Null](implicitly)) == null))
+            if (descr.isOptional && !formats.strictOptionParsing) {
               defv(None)
-            else fail("No usable value for " + descr.name + "\n" + msg, e)
+            } else fail("No usable value for " + descr.name + "\n" + msg, e)
         }
       }
     }

diff --git a/tests/src/test/scala/org/json4s/ExtractionBugs.scala b/tests/src/test/scala/org/json4s/ExtractionBugs.scala
@@ -327,5 +327,30 @@ abstract class ExtractionBugs[T](mod: String) extends Specification with JsonMet
       val json = Extraction.decompose(obj)
       json mustEqual JObject("s" -> JString("hello"), "i" -> JInt(3))
     }
+
+    "Extract error should preserve error message when strict option parsing is enabled" in {
+      implicit val formats = new DefaultFormats {
+        override val strictOptionParsing: Boolean = true
+      }
+
+      val obj = parse("""{"opt": "not an int"}""".stripMargin)
+
+      Extraction.extract[OptionOfInt](obj) must throwA(
+        new MappingException(
+          """
+            |No usable value for opt
+            |Do not know how to convert JString(not an int) into int
+            |""".stripMargin.trim))
+    }
+
+    "Extract should succeed for optional field with null value" in {
+      val obj = parse("""{"opt":null}""".stripMargin)
+      Extraction.extract[OptionOfInt](obj) must_== OptionOfInt(None)
+    }
+
+    "Extract should succeed for missing optional field" in {
+      val obj = parse("""{}""".stripMargin)
+      Extraction.extract[OptionOfInt](obj) must_== OptionOfInt(None)
+    }
   }
 }