Fix #4481: allow override of READ_UNKNOWN_ENUM_VALUES_AS_NULL (#4486)

Author: cowtowncoder

release-notes/VERSION-2.x

@@ -25,6 +25,9 @@ Project: jackson-databind
  (fix by Joo-Hyuk K)
 #4450: Empty QName deserialized as `null`
  (reported by @winfriedgerlach)
+#4481: Unable to override `DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL`
+  with `JsonFormat.Feature.READ_UNKNOWN_ENUM_VALUES_AS_NULL`
+ (reported by @luozhenyu)
 
 2.17.0 (12-Mar-2024)
 

src/main/java/com/fasterxml/jackson/databind/deser/std/EnumDeserializer.java

@@ -486,8 +486,10 @@ protected CompactStringObjectMap _getToStringLookup(DeserializationContext ctxt)
 
     // @since 2.15
     protected boolean useNullForUnknownEnum(DeserializationContext ctxt) {
-        return Boolean.TRUE.equals(_useNullForUnknownEnum)
-          || ctxt.isEnabled(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL);
+        if (_useNullForUnknownEnum != null) {
+            return _useNullForUnknownEnum;
+        }
+        return ctxt.isEnabled(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL);
     }
 
     // @since 2.15

src/test/java/com/fasterxml/jackson/databind/deser/enums/EnumAltIdTest.java

@@ -93,6 +93,16 @@ enum MyEnum2352_3 {
         C;
     }
 
+    // [databind#4481]: override for "unknown as null"
+    enum Color {
+        RED, BLUE
+    }
+
+    static class Book4481 {
+        @JsonFormat(without = JsonFormat.Feature.READ_UNKNOWN_ENUM_VALUES_AS_NULL)
+        public Color color;
+    }
+
     /*
     /**********************************************************
     /* Test methods, basic
@@ -304,4 +314,25 @@ public void testEnumWithNullForUnknownValueEnumSet() throws Exception {
         assertEquals(1, pojo.value.size());
         assertTrue(pojo.value.contains(MyEnum2352_3.B));
     }
+
+    /*
+    /**********************************************************
+    /* Test methods, other
+    /**********************************************************
+     */
+
+    // [databind#4481]
+    @Test
+    public void testDefaultFromNullOverride4481() throws Exception
+    {
+        try {
+            Book4481 book = MAPPER.readerFor(Book4481.class)
+                    .with(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL)
+                    .readValue("{\"color\":\"WHITE\"}");
+            fail("Should have failed; got: "+book.color);
+        } catch (InvalidFormatException e) {
+            verifyException(e, "Cannot deserialize value of type ");
+            verifyException(e, "not one of the values accepted for Enum class");
+        }
+    }
 }